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Sample records for alien dna introgression

  1. SNP Discovery for mapping alien introgressions in wheat

    PubMed Central

    2014-01-01

    Background Monitoring alien introgressions in crop plants is difficult due to the lack of genetic and molecular mapping information on the wild crop relatives. The tertiary gene pool of wheat is a very important source of genetic variability for wheat improvement against biotic and abiotic stresses. By exploring the 5Mg short arm (5MgS) of Aegilops geniculata, we can apply chromosome genomics for the discovery of SNP markers and their use for monitoring alien introgressions in wheat (Triticum aestivum L). Results The short arm of chromosome 5Mg of Ae. geniculata Roth (syn. Ae. ovata L.; 2n = 4x = 28, UgUgMgMg) was flow-sorted from a wheat line in which it is maintained as a telocentric chromosome. DNA of the sorted arm was amplified and sequenced using an Illumina Hiseq 2000 with ~45x coverage. The sequence data was used for SNP discovery against wheat homoeologous group-5 assemblies. A total of 2,178 unique, 5MgS-specific SNPs were discovered. Randomly selected samples of 59 5MgS-specific SNPs were tested (44 by KASPar assay and 15 by Sanger sequencing) and 84% were validated. Of the selected SNPs, 97% mapped to a chromosome 5Mg addition to wheat (the source of t5MgS), and 94% to 5Mg introgressed from a different accession of Ae. geniculata substituting for chromosome 5D of wheat. The validated SNPs also identified chromosome segments of 5MgS origin in a set of T5D-5Mg translocation lines; eight SNPs (25%) mapped to TA5601 [T5DL · 5DS-5MgS(0.75)] and three (8%) to TA5602 [T5DL · 5DS-5MgS (0.95)]. SNPs (gsnp_5ms83 and gsnp_5ms94), tagging chromosome T5DL · 5DS-5MgS(0.95) with the smallest introgression carrying resistance to leaf rust (Lr57) and stripe rust (Yr40), were validated in two released germplasm lines with Lr57 and Yr40 genes. Conclusion This approach should be widely applicable for the identification of species/genome-specific SNPs. The development of a large number of SNP markers will facilitate the precise introgression and

  2. Development and validation of cross-transferable and polymorphic DNA markers for detecting alien genome introgression in Oryza sativa from Oryza brachyantha.

    PubMed

    Ray, Soham; Bose, Lotan K; Ray, Joshitha; Ngangkham, Umakanta; Katara, Jawahar L; Samantaray, Sanghamitra; Behera, Lambodar; Anumalla, Mahender; Singh, Onkar N; Chen, Meingsheng; Wing, Rod A; Mohapatra, Trilochan

    2016-08-01

    African wild rice Oryza brachyantha (FF), a distant relative of cultivated rice Oryza sativa (AA), carries genes for pests and disease resistance. Molecular marker assisted alien gene introgression from this wild species to its domesticated counterpart is largely impeded due to the scarce availability of cross-transferable and polymorphic molecular markers that can clearly distinguish these two species. Availability of the whole genome sequence (WGS) of both the species provides a unique opportunity to develop markers, which are cross-transferable. We observed poor cross-transferability (~0.75 %) of O. sativa specific sequence tagged microsatellite (STMS) markers to O. brachyantha. By utilizing the genome sequence information, we developed a set of 45 low cost PCR based co-dominant polymorphic markers (STS and CAPS). These markers were found cross-transferrable (84.78 %) between the two species and could distinguish them from each other and thus allowed tracing alien genome introgression. Finally, we validated a Monosomic Alien Addition Line (MAAL) carrying chromosome 1 of O. brachyantha in O. sativa background using these markers, as a proof of concept. Hence, in this study, we have identified a set molecular marker (comprising of STMS, STS and CAPS) that are capable of detecting alien genome introgression from O. brachyantha to O. sativa.

  3. Alien Introgression for FHB Resistance in Wheat - Challenges and Strategies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over one thousand accessions of wheat relatives at different ploidy levels and wheat-alien species derivatives with varied chromosome constitutions were evaluated for Fusarium head blight (FHB) resistance. FHB resistance identified from the relatives and derivatives were introgressed into adapted br...

  4. Chromosome engineering for alien gene introgression in wheat: Progress and prospective

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chromosome engineering is a useful strategy for introgression of desirable genes from wild relatives into cultivated wheat. However, it has been a challenge to transfer a small amount of alien chromatin containing the gene of interest from one genome to another non-homologous genome through classic...

  5. Identification of exotic genetic components and DNA methylation pattern analysis of three cotton introgression lines from Gossypium bickii.

    PubMed

    He, Shou-Pu; Sun, Jun-Ling; Zhang, Chao; Du, Xiong-Ming

    2011-01-01

    The impact of alien DNA fragments on plant genome has been studied in many species. However, little is known about the introgression lines of Gossypium. To study the consequences of introgression in Gossypium, we investigated 2000 genomic and 800 epigenetic sites in three typical cotton introgression lines, as well as their cultivar (Gossypium hirsutum) and wild parents (Gossypium bickii), by amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP). The results demonstrate that an average of 0.5% of exotic DNA segments from wild cotton is transmitted into the genome of each introgression line, with the addition of other forms of genetic variation. In total, an average of 0.7% of genetic variation sites is identified in introgression lines. Simultaneously, the overall cytosine methylation level in each introgression line is very close to that of the upland cotton parent (an average of 22.6%). Further dividing patterns reveal that both hypomethylation and hypermethylation occurred in introgression lines in comparison with the upland cotton parent. Sequencing of nine methylation polymorphism fragments showed that most (7 of 9) of the methylation alternations occurred in the noncoding sequences. The molecular evidence of introgression from wild cotton into introgression lines in our study is identified by AFLP. Moreover, the causes of petal variation in introgression lines are discussed.

  6. Gene trees reveal repeated instances of mitochondrial DNA introgression in orangethroat darters (percidae: etheostoma).

    PubMed

    Bossu, Christen M; Near, Thomas J

    2009-02-01

    Phylogenies of closely related animal species are often inferred using mitochondrial DNA (mtDNA) gene sequences. The accuracy of mtDNA gene trees is compromised through hybridization that leads to introgression of mitochondrial genomes. Using DNA sequences from 6 single-copy nuclear genes and 2 regions of the mitochondrial genome, we investigated the temporal and geographic signature of mitochondrial and nuclear introgression in the Etheostoma spectabile darter clade. Phylogenetic analyses of the nuclear genes result in the monophyly of the E. spectabile clade; however, with respect to sampled specimens of 5 species (Etheostoma fragi, Etheostoma uniporum, Etheostoma pulchellum, Etheostoma burri, and E. spectabile), the mitochondrial phylogeny is inconsistent with E. spectabile clade monophyly. Etheostoma uniporum and E. fragi are both fixed for heterospecific mitochondrial genomes. Limited nuclear introgression is restricted to E. uniporum. Our analyses show that the pattern of introgression is consistently asymmetric, with movement of heterospecific mitochondrial haplotypes and nuclear alleles into E. spectabile clade species; introgressive hybridization spans broad temporal scales; and introgression is restricted to species and populations in the Ozarks. The introgressed mitochondrial genome observed in E. fragi has an obscure phylogenetic placement among darters, an ancient age, and is possibly a mitochondrial fossil from an Etheostoma species that has subsequently gone extinct. These results indicate that introgression, both ancient and more contemporaneous, characterizes the history of diversification in the E. spectabile species clade and may be relatively common among clades comprising the species-rich North American freshwater fauna.

  7. Dynamics of mtDNA introgression during species range expansion: insights from an experimental longitudinal study

    PubMed Central

    Mastrantonio, V.; Porretta, D.; Urbanelli, S.; Crasta, G.; Nascetti, G.

    2016-01-01

    Introgressive hybridization represents one of the long-lasting debated genetic consequences of species range expansion. Mitochondrial DNA has been shown to heavily introgress between interbreeding animal species that meet in new sympatric areas and, often, asymmetric introgression from local to the colonizing populations has been observed. Disentangling among the evolutionary and ecological processes that might shape this pattern remains difficult, because they continuously act across time and space. In this context, long-term studies can be of paramount importance. Here, we investigated the dynamics of mitochondrial introgression between two mosquito species (Aedes mariae and Ae. zammitii ) during a colonization event that started in 1986 after a translocation experiment. By analyzing 1,659 individuals across 25 years, we showed that introgression occurred earlier and at a higher frequency in the introduced than in the local species, showing a pattern of asymmetric introgression. Throughout time, introgression increased slowly in the local species, becoming reciprocal at most sites. The rare opportunity to investigate the pattern of introgression across time during a range expansion along with the characteristics of our study-system allowed us to support a role of demographic dynamics in determining the observed introgression pattern. PMID:27460445

  8. Sources of stem rust resistance in wheat-alien introgression lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most devastating diseases of wheat and the novel highly virulent race of TTKSK and its lineage are threatening wheat production worldwide. The objective of the study was to identify new sources of resistance in wheat-alien introgre...

  9. Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance.

    PubMed

    Ali, N; Heslop-Harrison, Js Pat; Ahmad, H; Graybosch, R A; Hein, G L; Schwarzacher, T

    2016-08-01

    Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a cost-effective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chromatin in four genetically diverse populations of wheat (Triticum aestivum) lines incorporating chromosome segments from Thinopyrum intermedium and Secale cereale (rye). Out of 20 experimental lines, 10 carried Th. intermedium chromatin as T4DL*4Ai#2S translocations, while, unexpectedly, 7 lines were positive for alien chromatin (Th. intermedium or rye) on chromosome 1B. The newly described rye 1RS chromatin, transmitted from early in the pedigree, was associated with enhanced WSMV resistance. Under field conditions, the 1RS chromatin alone showed some resistance, while together with the Th. intermedium 4Ai#2S offered superior resistance to that demonstrated by the known resistant cultivar Mace. Most alien wheat lines carry whole chromosome arms, and it is notable that these lines showed intra-arm recombination within the 1BS arm. The translocation breakpoints between 1BS and alien chromatin fell in three categories: (i) at or near to the centromere, (ii) intercalary between markers UL-Thin5 and Xgwm1130 and (iii) towards the telomere between Xgwm0911 and Xbarc194. Labelled genomic Th. intermedium DNA hybridised to the rye 1RS chromatin under high stringency conditions, indicating the presence of shared tandem repeats among the cereals. The novel small alien fragments may explain the difficulty in developing well-adapted lines carrying Wsm1 despite improved tolerance to the virus. The results will facilitate directed chromosome engineering producing agronomically desirable WSMV-resistant germplasm.

  10. Interspecific X-chromosome and mitochondrial DNA introgression in the Iberian hare: selection or allele surfing?

    PubMed

    Melo-Ferreira, José; Alves, Paulo C; Rocha, Jorge; Ferrand, Nuno; Boursot, Pierre

    2011-07-01

    Introgression from a resident species into an invading one is predicted to occur through the demographic process of "allele surfing," and to particularly affect genomic regions transmitted by the lower migrating sex, such as mtDNA. This could explain that northern Iberian populations of Lepus granatensis harbor high frequencies of mtDNA from L. timidus, an arctic hare it replaced there after deglaciation. We report that variation of introgressed timidus-like mtDNA reflects several predicted effects of this process: increasing frequency and diversity in the direction of expansion, strong perpendicular phylogeographic structure and signs of postglacial demographic growth. However, demographic inferences for the granatensis and timidus-like mtDNA lineages suggest the latter may have outcompeted the former in northern Iberia. Autosomal introgression occurs at low frequencies and species-wide rather than only in the north. If this difference with mtDNA resulted from sex-biased migration, an intermediate pattern should prevail for the X-chromosome, but we report species-wide and high-frequency introgression of an X-fragment. Either selection favored this ubiquitous X-introgression, or more complex postglacial expansion patterns prevailed, with different consequences depending on the genomic and geographic region. This illustrates the difficulty of distinguishing demographic and selective effects and the need for genome and species-wide based demographic models.

  11. Exploring the Effect of Asymmetric Mitochondrial DNA Introgression on Estimating Niche Divergence in Morphologically Cryptic Species

    PubMed Central

    Wielstra, Ben; Arntzen, Jan W.

    2014-01-01

    If potential morphologically cryptic species, identified based on differentiated mitochondrial DNA, express ecological divergence, this increases support for their treatment as distinct species. However, mitochondrial DNA introgression hampers the correct estimation of ecological divergence. We test the hypothesis that estimated niche divergence differs when considering nuclear DNA composition or mitochondrial DNA type as representing the true species range. We use empirical data of two crested newt species (Amphibia: Triturus) which possess introgressed mitochondrial DNA from a third species in part of their ranges. We analyze the data in environmental space by determining Fisher distances in a principal component analysis and in geographical space by determining geographical overlap of species distribution models. We find that under mtDNA guidance in one of the two study cases niche divergence is overestimated, whereas in the other it is underestimated. In the light of our results we discuss the role of estimated niche divergence in species delineation. PMID:24743746

  12. [Nuclear-cytoplasmic compatibility and the state of mitochondrial and chloroplast DNA regions in alloplasmic recombinant and introgressive lines (H. vulgare)-T. aestivum].

    PubMed

    Pershina, L A; Trubacheva, N V; Sinyavskaya, M G; Devyatkina, E P; Kravtsova, L A

    2014-10-01

    Alloplasmic lines combining alien nuclear and cytoplasmic genomes are convenient models for studying the mechanisms of nuclear-cytoplasmic compatibility/incompatibility. In the.present study, we have investigated the correlation between the characters and state of mitochondrial (mt) and chloroplast (cp) DNA regions in alloplasmic recombinant common wheat lines with barley cytoplasm characterized by partial or total fertility. Fertility restoration in the studied lines (Hordeum vulgare)-Triticum aestivum is determined by different ratios of the genetic material of common wheat variety Pyrotrix 28, which is a fertility restorer in the cytoplasm of barley, and varietySaratovskaya 29, which is a fixer of sterility. In partially fertile lines with nuclear genomes dominated by the genetic material of Saratovskaya 29, plant growth and development are suppressed. In these lines we have identified the barley homoplasmy of cpDNA regions infA and rpoB and the heteroplasmy of the 18S/5S mt repeat and the cpDNA ycf5 region. Nuclear-cytoplasmic compatibility in lines with reduced fertility (the genetic material of Pyrotrix 28 predominates in their nuclear genomes) is associated with restoration of normal plant growth and development and the changes in thestate of the studied cpDNA and mtDNA regions towards the wheat type. Thus, in fertile lines, the cpDNA regions (infA, rpoB) and the 18S/5S mt repeat were identified in the homoplasmic wheat state; though the cpDNAycf5 region was in the heteroplasmic state, it was dominated by the wheat type of the copies. The nuclearicytoplasmic compatibility is not broken as a result of introgression of the alien genetic material into the nuclear genome of one of the fertile lines; the plants of introgressive lines are fertile and normally developed, and the states of the cpDNA and mtDNA regions correspond to their states in fertile recombinant lines.

  13. The Elusive Nature of Adaptive Mitochondrial DNA Evolution of an Arctic Lineage Prone to Frequent Introgression

    PubMed Central

    Melo-Ferreira, José; Vilela, Joana; Fonseca, Miguel M.; da Fonseca, Rute R.; Boursot, Pierre; Alves, Paulo C.

    2014-01-01

    Mitochondria play a fundamental role in cellular metabolism, being responsible for most of the energy production of the cell in the oxidative phosphorylation (OXPHOS) pathway. Mitochondrial DNA (mtDNA) encodes for key components of this process, but its direct role in adaptation remains far from understood. Hares (Lepus spp.) are privileged models to study the impact of natural selection on mitogenomic evolution because 1) species are adapted to contrasting environments, including arctic, with different metabolic pressures, and 2) mtDNA introgression from arctic into temperate species is widespread. Here, we analyzed the sequences of 11 complete mitogenomes (ten newly obtained) of hares of temperate and arctic origins (including two of arctic origin introgressed into temperate species). The analysis of patterns of codon substitutions along the reconstructed phylogeny showed evidence for positive selection in several codons in genes of the OXPHOS complexes, most notably affecting the arctic lineage. However, using theoretical models, no predictable effect of these differences was found on the structure and physicochemical properties of the encoded proteins, suggesting that the focus of selection may lie on complex interactions with nuclear encoded peptides. Also, a cloverleaf structure was detected in the control region only from the arctic mtDNA lineage, which may influence mtDNA replication and transcription. These results suggest that adaptation impacted the evolution of hare mtDNA and may have influenced the occurrence and consequences of the many reported cases of massive mtDNA introgression. However, the origin of adaptation remains elusive. PMID:24696399

  14. Evolutionary neutrality of mtDNA introgression: evidence from complete mitogenome analysis in roe deer.

    PubMed

    Matosiuk, M; Sheremetyeva, I N; Sheremetyev, I S; Saveljev, A P; Borkowska, A

    2014-11-01

    Introgressive hybridization offers a unique platform for studying the molecular basis of natural selection acting on mitogenomes. Most of the mtDNA protein-coding genes are extremely conserved; however, some of the observed variations have potentially adaptive significance. Here, we evaluated whether the evolution of mtDNA in closely related roe deer species affected by widespread mtDNA introgression is neutral or adaptive. We characterized and compared 16 complete mitogenomes of European (Capreolus capreolus) and Siberian (C. pygargus) roe deer, including four of Siberian origin introgressed into European species. The average sequence divergence of species-specific lineages was estimated at 2.8% and varied across gene classes. Only 21 of 315 fixed differences identified in protein-coding genes represented nonsynonymous changes. Only three of them were determined to have arisen in the C. pygargus lineage since the time to the most recent common ancestor (TMRCA) of both Capreolus species, reflecting a decelerated evolutionary ratio. The almost four-fold higher dN /dS ratio described for the European roe deer lineage is constrained by overall purifying selection, especially pronounced in the ND4 and ND5 genes. We suggest that the highly divergent C. capreolus lineage could have maintained a capability for genomic incorporation of the well-preserved and almost ancestral type of mtDNA present in C. pygargus. Our analyses did not indicate any signs of positive selection for Siberian roe deer mtDNA, suggesting that the present widespread introgression is evolutionarily neutral.

  15. Genotyping-by-Sequencing Uncovers the Introgression Alien Segments Associated with Sclerotinia Basal Stalk Rot Resistance from Wild Species-I. Helianthus argophyllus and H. petiolaris.

    PubMed

    Qi, Lili; Long, Yunming; Talukder, Zahirul I; Seiler, Gerald J; Block, Charles C; Gulya, Thomas J

    2016-01-01

    Basal stalk rot (BSR), caused by Sclerotinia sclerotiorum, is a devastating disease in sunflower worldwide. The progress of breeding for Sclerotinia BSR resistance has been hampered due to the lack of effective sources of resistance for cultivated sunflower. Our objective was to transfer BSR resistance from wild annual Helianthus species into cultivated sunflower and identify the introgressed alien segments associated with BSR resistance using a genotyping-by-sequencing (GBS) approach. The initial crosses were made between the nuclear male sterile HA 89 with the BSR resistant plants selected from wild Helianthus argophyllus and H. petiolaris populations in 2009. The selected resistant F1 plants were backcrossed to HA 458 and HA 89, respectively. Early generation evaluations of BSR resistance were conducted in the greenhouse, while the BC2F3 and subsequent generations were evaluated in the inoculated field nurseries. Eight introgression lines; six from H. argophyllus (H.arg 1 to H.arg 6), and two from H. petiolaris (H.pet 1 and H.pet 2), were selected. These lines consistently showed high levels of BSR resistance across seven environments from 2012 to 2015 in North Dakota and Minnesota, USA. The mean BSR disease incidence (DI) for H.arg 1 to H.arg 6, H.pet 1, and H.pet 2 was 3.0, 3.2, 0.8, 7.2, 7.7, 1.9, 2.5, and 4.4%, compared to a mean DI of 36.1% for Cargill 270 (susceptible hybrid), 31.0% for HA 89 (recurrent parent), 19.5% for HA 441 (resistant inbred), and 11.6% for Croplan 305 (resistant hybrid). Genotyping of the highly BSR resistant introgression lines using GBS revealed the presence of the H. argophyllus segments in linkage groups (LGs) 3, 8, 9, 10, and 11 of the sunflower genome, and the H. petiolaris segments only in LG8. The shared polymorphic SNP loci in the introgression lines were detected in LGs 8, 9, 10, and 11, indicating the common introgression regions potentially associated with BSR resistance. Additionally, a downy mildew resistance gene, Pl17

  16. Genotyping-by-Sequencing Uncovers the Introgression Alien Segments Associated with Sclerotinia Basal Stalk Rot Resistance from Wild Species—I. Helianthus argophyllus and H. petiolaris

    PubMed Central

    Qi, Lili; Long, Yunming; Talukder, Zahirul I.; Seiler, Gerald J.; Block, Charles C.; Gulya, Thomas J.

    2016-01-01

    Basal stalk rot (BSR), caused by Sclerotinia sclerotiorum, is a devastating disease in sunflower worldwide. The progress of breeding for Sclerotinia BSR resistance has been hampered due to the lack of effective sources of resistance for cultivated sunflower. Our objective was to transfer BSR resistance from wild annual Helianthus species into cultivated sunflower and identify the introgressed alien segments associated with BSR resistance using a genotyping-by-sequencing (GBS) approach. The initial crosses were made between the nuclear male sterile HA 89 with the BSR resistant plants selected from wild Helianthus argophyllus and H. petiolaris populations in 2009. The selected resistant F1 plants were backcrossed to HA 458 and HA 89, respectively. Early generation evaluations of BSR resistance were conducted in the greenhouse, while the BC2F3 and subsequent generations were evaluated in the inoculated field nurseries. Eight introgression lines; six from H. argophyllus (H.arg 1 to H.arg 6), and two from H. petiolaris (H.pet 1 and H.pet 2), were selected. These lines consistently showed high levels of BSR resistance across seven environments from 2012 to 2015 in North Dakota and Minnesota, USA. The mean BSR disease incidence (DI) for H.arg 1 to H.arg 6, H.pet 1, and H.pet 2 was 3.0, 3.2, 0.8, 7.2, 7.7, 1.9, 2.5, and 4.4%, compared to a mean DI of 36.1% for Cargill 270 (susceptible hybrid), 31.0% for HA 89 (recurrent parent), 19.5% for HA 441 (resistant inbred), and 11.6% for Croplan 305 (resistant hybrid). Genotyping of the highly BSR resistant introgression lines using GBS revealed the presence of the H. argophyllus segments in linkage groups (LGs) 3, 8, 9, 10, and 11 of the sunflower genome, and the H. petiolaris segments only in LG8. The shared polymorphic SNP loci in the introgression lines were detected in LGs 8, 9, 10, and 11, indicating the common introgression regions potentially associated with BSR resistance. Additionally, a downy mildew resistance gene, Pl17

  17. Recurrent introgression of mitochondrial DNA among hares (Lepus spp.) revealed by species-tree inference and coalescent simulations.

    PubMed

    Melo-Ferreira, J; Boursot, P; Carneiro, M; Esteves, P J; Farelo, L; Alves, P C

    2012-05-01

    Understanding recent speciation history requires merging phylogenetic and population genetics approaches, taking into account the persistence of ancestral polymorphism and possible introgression. The emergence of a clear phylogeny of hares (genus Lepus) has been hampered by poor genomic sampling and possible occurrence of mitochondrial DNA (mtDNA) introgression from the arctic/boreal Lepus timidus into several European temperate and possibly American boreal species. However, no formal test of introgression, taking also incomplete lineage sorting into account, has been done. Here, to clarify the yet poorly resolved species phylogeny of hares and test hypotheses of mtDNA introgression, we sequenced 14 nuclear DNA and 2 mtDNA fragments (8205 and 1113 bp, respectively) in 50 specimens from 11 hare species from Eurasia, North America, and Africa. By applying an isolation-with-migration model to the nuclear data on subsets of species, we find evidence for very limited gene flow from L. timidus into most temperate European species, and not into the American boreal ones. Using a multilocus coalescent-based method, we infer the species phylogeny, which we find highly incongruent with mtDNA phylogeny using parametric bootstrap. Simulations of mtDNA evolution under the speciation history inferred from nuclear genes did not support the hypothesis of mtDNA introgression from L. timidus into the American L. townsendii but did suggest introgression from L. timidus into 4 temperate European species. One such event likely resulted in the complete replacement of the aboriginal mtDNA of L. castroviejoi and of its sister species L. corsicanus. It is remarkable that mtDNA introgression in hares is frequent, extensive, and always from the same donor arctic species. We discuss possible explanations for the phenomenon in relation to the dynamics of range expansions and species replacements during the climatic oscillations of the Pleistocene.

  18. Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a costeffective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chrom...

  19. Male-killing Wolbachia and mitochondrial DNA: selective sweeps, hybrid introgression and parasite population dynamics.

    PubMed Central

    Jiggins, Francis M

    2003-01-01

    Mitochondrial DNA (mtDNA) sequences are widely used as neutral genetic markers in insects. However, patterns of mtDNA variability are confounded by the spread of maternally transmitted parasites, which are genetically linked to the mitochondria. We have investigated these effects in the butterflies Acraea encedon (which is host to two strains of male-killing Wolbachia bacteria) and A. encedana (which is host to one strain). Within a population, the mitochondria are in linkage disequilibrium with the different male-killers. Furthermore, there has been a recent selective sweep of the mtDNA, which has led to the loss of mitochondrial variation within populations and erased any geographical structure. We also found that one of the male-killers, together with the associated mtDNA, has introgressed from A. encedana into A. encedon within the last 16,000 years. Interestingly, because butterflies are female heterogametic, this will presumably have also led to the introgression of genes on the W sex chromosome. Finally, in A. encedon the mitochondria in uninfected females are unaltered by the spread of the male-killer and have diverse, geographically structured mtDNA. This means we can reject the hypothesis that the male-killer is at a stable equilibrium maintained by imperfect transmission of the bacterium. Instead, some other form of balancing selection may be maintaining uninfected females in the population and preventing the species from going extinct due to a shortage of males. PMID:12750316

  20. Hybridization and Introgression among Species of Sunfish (Lepomis): Analysis by Mitochondrial DNA and Allozyme Markers

    PubMed Central

    Avise, John C.; Saunders, Nancy C.

    1984-01-01

    We explore the potential of mitochondrial DNA (mtDNA) analysis, alone and in conjunction with allozymes, to study low-frequency hybridization and introgression phenomena in natural populations. MtDNAs from small samples of nine species of sunfish (Lepomis, Centrarchidae) were purified and digested with each of 13 informative restriction enzymes. Digestion profiles for all species were highly distinct: estimates of overall fragment homology between pairs of species ranged from 0–36%. Allozymes encoded by nine nuclear genes also showed large frequency differences among species and together with mtDNA provided many genetic markers for hybrid identification. A genetic analysis of 277 sunfish from two locations in north Georgia revealed the following: (1) a low frequency of interspecific hybrids, all of which appeared to be F1's; (2) the involvement of five sympatric Lepomis species in the production of these hybrids; (3) no evidence for introgression between species in our study locales (although for rare hybridization, most later-generation backcrosses would not be reliably distinguished from parentals); (4) a tendency for hybridizations to take place preferentially between parental species differing greatly in abundance; (5) a tendency for the rare species in a hybrid cross to provide the female parent. Our data suggest that absence of conspecific pairing partners and mating stimuli for females of rarer species may be important factors in increasing the likelihood of interspecific hybridization. The maternal inheritance of mtDNA offers at least two novel advantages for hybridization analysis: (1) an opportunity to determine direction in hybrid crosses; and (2) due to the linkage among mtDNA markers, an increased potential to distinguish effects of introgression from symplesiomorphy or character convergence. PMID:6090268

  1. Parental Analysis of Introgressive Hybridization between African and European Honeybees Using Nuclear DNA Rflps

    PubMed Central

    Hall, H. G.

    1990-01-01

    African honeybees, introduced into Brazil 33 years ago, have spread through most of South and Central America and have largely replaced the extant European bees. Due to a paucity of genetic markers, genetic interactions between European and African bees are not well understood. Three restriction fragment length polymorphisms (RFLPs), detected with random, nuclear DNA probes, are described. The polymorphisms are specific to bees of European descent, possibly specific to certain European races. Each European marker was found present at a high frequency in U.S. colonies but absent in South African bees. Previous mitochondrial DNA studies of neotropical bees have revealed negligible maternal gene flow from managed European apiaries into feral African populations. The findings reported here with nuclear DNA show paternal gene flow between the two but suggest asymmetries in levels of introgressive hybridization. Managed colonies in southern Mexico, derived from European maternal lines, showed diminished levels of the European nuclear markers, reflecting significant hybridization with African drones. The European alleles were present only at low frequencies in feral swarms from the same area. The swarms were of African maternal descent. In Venezuelan colonies, also derived from African maternal lines, the European markers were almost totally absent. The results point to limited paternal introgression from European colonies into the African honeybee populations. These findings dispute other views regarding modes of Africanization. PMID:1974226

  2. Parental analysis of introgressive hybridization between African and European honeybees using nuclear DNA RFLPs.

    PubMed

    Hall, H G

    1990-07-01

    African honeybees, introduced into Brazil 33 years ago, have spread through most of South and Central America and have largely replaced the extant European bees. Due to a paucity of genetic markers, genetic interactions between European and African bees are not well understood. Three restriction fragment length polymorphisms (RFLPs), detected with random, nuclear DNA probes, are described. The polymorphisms are specific to bees of European descent, possibly specific to certain European races. Each European marker was found present at a high frequency in U.S. colonies but absent in South African bees. Previous mitochondrial DNA studies of neotropical bees have revealed negligible maternal gene flow from managed European apiaries into feral African populations. The findings reported here with nuclear DNA show paternal gene flow between the two but suggest asymmetries in levels of introgressive hybridization. Managed colonies in southern Mexico, derived from European maternal lines, showed diminished levels of the European nuclear markers, reflecting significant hybridization with African drones. The European alleles were present only at low frequencies in feral swarms from the same area. The swarms were of African maternal descent. In Venezuelan colonies, also derived from African maternal lines, the European markers were almost totally absent. The results point to limited paternal introgression from European colonies into the African honeybee populations. These findings dispute other views regarding modes of Africanization.

  3. Invasion dynamics of two alien Carpobrotus (Aizoaceae) taxa on a Mediterranean island: I. Genetic diversity and introgression.

    PubMed

    Suehs, C M; Affre, L; Médail, F

    2004-01-01

    This study, based on morphological and isozyme analysis, clearly discriminates two invasive Carpobrotus taxa, C. edulis and C. acinaciformis, in the Hyères archipelago off the southeastern coast of France. However, three different allelic combinations demonstrate the presence of intermediate individuals resulting from an introgression of part of the C. edulis genome into that of C. acinaciformis. Both taxa have higher than average genetic (C. edulis: P(0.95)=62.5%, A=2.25+/-0.70, H(o)=0.329+/-0.324; C. acinaciformis: P(0.95)=75%, A=2.38+/-0.42, H(o)=0.645+/-0.109) and clonal diversities (C. edulis: IP=0.37; C. acinaciformis: IP=0.48). Furthermore, C. acinaciformis has an excess of heterozygotes (F=-0.585+/-0.217), probably due to introgression. The relationship between the probability of clonal identity for two individuals and distance indicates that C. acinaciformis relies more on clonal reproduction than on sexual recruitment (seed recruitment/vegetative propagation=u/v=0.027), in contrast to C. edulis, whose probability of clonal identity did not vary with distance. The overwhelming clonal growth and high genetic diversities of C. acinaciformis and the previously recorded invasion potential for C. edulis raises concern for intensified invasion via hybridisation.

  4. Alien genes introgression and development of alien monosomic addition lines from a threatened species, Allium roylei Stearn, to Allium cepa L.

    PubMed

    Vu, Hoa Q; Yoshimatsu, Yasuyuki; Khrustaleva, Ludmila I; Yamauchi, Naoki; Shigyo, Masayoshi

    2012-05-01

    To produce alien monosomic addition lines (AMALs) of Allium cepa (genomes CC, 2n = 2x = 16) carrying extrachromosomes from Allium roylei (RR, 2n = 2x = 16), reciprocal backcrossing of allotriploids (2n = 24, CCR) with diploids (2n = 16, CC) and selfing of a single allotriploid were carried out. The chromosome numbers in the BC(2)F(1) and BC(1)F(2) progenies ranged from 16 to 32. Forty-eight plants were recorded to possess 2n = 17 among a total of 169 plants in observation. Through the analyses of isozymes, expressed sequence tag (EST) markers, and karyotypes, all eight possible types of A. cepa-A. roylei monosomic addition lines (CC+1R-CC+8R) could be identified. Seven types of representative AMALs (without CC+2R) were used for the GISH analysis of somatic chromosomes. Except for CC+6R, all AMALs showed an entire (unrecombined) extrachromosome from A. roylei in the integral diploid background of A. cepa. A single recombination between A. cepa and A. roylei was observed on the extrachromosome in the remaining type. All alloplasmic AMALs possessing A. roylei cytoplasm showed high or complete pollen sterility. Only the autoplasmic CC+4R with A. cepa cytoplasm possessed relatively high pollen fertility. The bulbs of CC+4R displayed the distinct ovoid shape that discriminates them from spherical or oval ones in other AMALs. Downy mildew screening in the field showed higher resistance in A. roylei, a hypo-allotriploid (CCR-nR, 2n = 23), and an allotriploid (CCR, 2n = 24). Meanwhile, no complete resistance was found in some AMALs examined. This was the first trial toward the establishment of a complete set of A. cepa-A. roylei monosomic additions.

  5. Introgression of wheat DNA markers from A, B and D genomes in early generation progeny of Aegilops cylindrica Host x Triticum aestivum L. hybrids.

    PubMed

    Schoenenberger, N; Felber, F; Savova-Bianchi, D; Guadagnuolo, R

    2005-11-01

    Introgression from allohexaploid wheat (Triticum aestivum L., AABBDD) to allotetraploid jointed goatgrass (Aegilops cylindrica Host, CCDD) can take place in areas where the two species grow in sympatry and hybridize. Wheat and Ae. cylindrica share the D genome, issued from the common diploid ancestor Aegilops tauschii Coss. It has been proposed that the A and B genome of bread wheat are secure places to insert transgenes to avoid their introgression into Ae. cylindrica because during meiosis in pentaploid hybrids, A and B genome chromosomes form univalents and tend to be eliminated whereas recombination takes place only in D genome chromosomes. Wheat random amplified polymorphic DNA (RAPD) fragments, detected in intergeneric hybrids and introgressed to the first backcross generation with Ae. cylindrica as the recurrent parent and having a euploid Ae. cylindrica chromosome number or one supernumerary chromosome, were assigned to wheat chromosomes using Chinese Spring nulli-tetrasomic wheat lines. Introgressed fragments were not limited to the D genome of wheat, but specific fragments of A and B genomes were also present in the BC1. Their presence indicates that DNA from any of the wheat genomes can introgress into Ae. cylindrica. Successfully located RAPD fragments were then converted into highly specific and easy-to-use sequence characterised amplified regions (SCARs) through sequencing and primer design. Subsequently these markers were used to characterise introgression of wheat DNA into a BC1S1 family. Implications for risk assessment of genetically modified wheat are discussed.

  6. Surfing the wave on a borrowed board: range expansion and spread of introgressed organellar genomes in the seaweed Fucus ceranoides L.

    PubMed

    Neiva, João; Pearson, Gareth A; Valero, Myriam; Serrão, Ester A

    2010-11-01

    For many taxa, introgression represents an important source of genetic variation, but the specific contexts allowing locally introgressed material to spread and largely replace native allelic lineages throughout a species range remain poorly understood. Recent demographic-genetic simulations of spatial expansions show that the stochastic surfing of alien alleles during range expansions may constitute a general mechanism leading to extensive introgression, but empirical evidence remain scarce and difficult to distinguish from selection. In this study, we report a compelling case of such a phenomenon in the estuarine alga Fucus ceranoides. We re-assessed the phylogenetic relationships among F. ceranoides and its marine congeners F. vesiculosus and F. spiralis using nuclear, mitochondrial and chloroplast sequence data, and conducted a mtDNA phylogeographic survey in F. ceranoides. Our phylogenetic analyses revealed a recent and asymmetric introgression of a single F. vesiculosus cytoplasm into F. ceranoides. The phylogeographic scope of introgression was striking, with native and introgressed mtDNA displaying disjunct distributions south and north of the English Channel. A putative Pleistocene climatic refugium was detected in NW Iberia, and the extensive and exclusive spread of the alien cytoplasm throughout Northern Europe was inferred to have occurred concurrently with the species post-glacial, northwards range expansion. This massive spread of a foreign organelle throughout the entire post-glacial recolonization range represents good empirical evidence of an alien cytoplasm surfing the wave of a range expansion and the first description of such a phenomenon in the marine realm.

  7. Extensive mitochondrial introgression in North American Great Black-backed Gulls (Larus marinus) from the American Herring Gull (Larus smithsonianus) with little nuclear DNA impact.

    PubMed

    Pons, J-M; Sonsthagen, S; Dove, C; Crochet, P-A

    2014-03-01

    Recent genetic studies have shown that introgression rates among loci may greatly vary according to their location in the genome. In particular, several cases of mito-nuclear discordances have been reported for a wide range of organisms. In the present study, we examine the causes of discordance between mitochondrial (mtDNA) and nuclear DNA introgression detected in North American populations of the Great Black-backed Gull (Larus marinus), a Holarctic species, from the Nearctic North American Herring Gull (Larus smithsonianus). Our results show that extensive unidirectional mtDNA introgression from Larus smithsonianus into Larus marinus in North America cannot be explained by ancestral polymorphism but most likely results from ancient hybridization events occurring when Larus marinus invaded the North America. Conversely, our nuclear DNA results based on 12 microsatellites detected very little introgression from Larus smithsonianus into North American Larus marinus. We discuss these results in the framework of demographic and selective mechanisms that have been postulated to explain mito-nuclear discrepancies. We were unable to demonstrate selection as the main cause of mito-nuclear introgression discordance but cannot dismiss the possible role of selection in the observed pattern. Among demographic explanations, only drift in small populations and bias in mate choice in an invasive context may explain our results. As it is often difficult to demonstrate that selection may be the main factor driving the introgression of mitochondrial DNA in natural populations, we advocate that evaluating alternative demographic neutral hypotheses may help to indirectly support or reject hypotheses invoking selective processes.

  8. Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum.

    PubMed

    Woodcock, M Ryan; Vaughn-Wolfe, Jennifer; Elias, Alexandra; Kump, D Kevin; Kendall, Katharina Denise; Timoshevskaya, Nataliya; Timoshevskiy, Vladimir; Perry, Dustin W; Smith, Jeramiah J; Spiewak, Jessica E; Parichy, David M; Voss, S Randal

    2017-12-01

    The molecular genetic toolkit of the Mexican axolotl, a classic model organism, has matured to the point where it is now possible to identify genes for mutant phenotypes. We used a positional cloning-candidate gene approach to identify molecular bases for two historic axolotl pigment phenotypes: white and albino. White (d/d) mutants have defects in pigment cell morphogenesis and differentiation, whereas albino (a/a) mutants lack melanin. We identified in white mutants a transcriptional defect in endothelin 3 (edn3), encoding a peptide factor that promotes pigment cell migration and differentiation in other vertebrates. Transgenic restoration of Edn3 expression rescued the homozygous white mutant phenotype. We mapped the albino locus to tyrosinase (tyr) and identified polymorphisms shared between the albino allele (tyr (a) ) and tyr alleles in a Minnesota population of tiger salamanders from which the albino trait was introgressed. tyr (a) has a 142 bp deletion and similar engineered alleles recapitulated the albino phenotype. Finally, we show that historical introgression of tyr (a) significantly altered genomic composition of the laboratory axolotl, yielding a distinct, hybrid strain of ambystomatid salamander. Our results demonstrate the feasibility of identifying genes for traits in the laboratory Mexican axolotl.

  9. Introgressive hybridization and the evolutionary history of the herring gull complex revealed by mitochondrial and nuclear DNA

    PubMed Central

    2010-01-01

    Background Based on extensive mitochondrial DNA (mtDNA) sequence data, we previously showed that the model of speciation among species of herring gull (Larus argentatus) complex was not that of a ring species, but most likely due more complex speciation scenario's. We also found that two species, herring gull and glaucous gull (L. hyperboreus) displayed an unexpected biphyletic distribution of their mtDNA haplotypes. It was evident that mtDNA sequence data alone were far from sufficient to obtain a more accurate and detailed insight into the demographic processes that underlie speciation of this complex, and that extensive autosomal genetic analysis was warranted. Results For this reason, the present study focuses on the reconstruction of the phylogeographic history of a limited number of gull species by means of a combined approach of mtDNA sequence data and 230 autosomal amplified fragment length polymorphism (AFLP) loci. At the species level, the mtDNA and AFLP genetic data were largely congruent. Not only for argentatus and hyperboreus, but also among a third species, great black-backed gull (L. marinus) we observed two distinct groups of mtDNA sequence haplotypes. Based on the AFLP data we were also able to detect distinct genetic subgroups among the various argentatus, hyperboreus, and marinus populations, supporting our initial hypothesis that complex demographic scenario's underlie speciation in the herring gull complex. Conclusions We present evidence that for each of these three biphyletic gull species, extensive mtDNA introgression could have taken place among the various geographically distinct subpopulations, or even among current species. Moreover, based on a large number of autosomal AFLP loci, we found evidence for distinct and complex demographic scenario's for each of the three species we studied. A more refined insight into the exact phylogeographic history within the herring gull complex is still impossible, and requires detailed autosomal

  10. The hidden history of the snowshoe hare, Lepus americanus: extensive mitochondrial DNA introgression inferred from multilocus genetic variation.

    PubMed

    Melo-Ferreira, José; Seixas, Fernando A; Cheng, Ellen; Mills, L Scott; Alves, Paulo C

    2014-09-01

    Hybridization drives the evolutionary trajectory of many species or local populations, and assessing the geographic extent and genetic impact of interspecific gene flow may provide invaluable clues to understand population divergence or the adaptive relevance of admixture. In North America, hares (Lepus spp.) are key species for ecosystem dynamics and their evolutionary history may have been affected by hybridization. Here we reconstructed the speciation history of the three most widespread hares in North America - the snowshoe hare (Lepus americanus), the white-tailed jackrabbit (L. townsendii) and the black-tailed jackrabbit (L. californicus) - by analysing sequence variation at eight nuclear markers and one mitochondrial DNA (mtDNA) locus (6240 bp; 94 specimens). A multilocus-multispecies coalescent-based phylogeny suggests that L. americanus diverged ~2.7 Ma and that L. californicus and L. townsendii split more recently (~1.2 Ma). Within L. americanus, a deep history of cryptic divergence (~2.0 Ma) was inferred, which coincides with major speciation events in other North American species. While the isolation-with-migration model suggested that nuclear gene flow was generally rare or absent among species or major genetic groups, coalescent simulations of mtDNA divergence revealed historical mtDNA introgression from L. californicus into the Pacific Northwest populations of L. americanus. This finding marks a history of past reticulation between these species, which may have affected other parts of the genome and influence the adaptive potential of hares during climate change.

  11. Mitochondrial and nuclear DNA analysis revealed a cryptic species and genetic introgression in Littorina sitkana (Mollusca, Gastropoda).

    PubMed

    Azuma, Noriko; Yamazaki, Tomoyasu; Chiba, Susumu

    2011-12-01

    We investigated mitochondrial and nuclear DNA genotypes in nominal Littorina sitkana samples from 2 localities in Eastern Hokkaido, northern Japan. Our results indicated the existence of cryptic species. In the analysis of partial mitochondrial Cytchrome b gene sequences, haplotypes of L. sitkana samples were monophyletic in a phylogenetic tree with orthologous sequences from other Littorina species, but were apparently separated in 2 clades. One included typical L. sitkana (CBa clade) samples, which formed a clade with an allopatric species, L. horikawai. The other, CBb, was independent from CBa and L. horikawai. Haplotypes of the mitochondrial 16S rRNA gene also separated into 2 clades. We additionally examined intron sequence of the heat shock cognate 70 (HSC70) nuclear gene and identified 17 haplotypes. These were also separated into 2 clades, HSCa and HSCb. Among the examined Hokkaido samples, 60% of individuals were heterozygotes. However, each heterozygote consisted of haplotypes from the same clade, HSCa or HSCb, and no admixture of HSCa and HSCb haplotypes was observed. These results indicate reproductive isolation between the 2 clades. Among the genotyped Hokkaido samples, 93% of individuals had CBa + HSCa or CBb + HSCb genotypes, and 7% had CBb + HSCa genotypes. The discrepancy between the mtDNA and nuclear DNA haplotypes in a few individuals may have been caused by genetic introgression due to past hybridization.

  12. Hybridization and massive mtDNA unidirectional introgression between the closely related Neotropical toads Rhinella marina and R. schneideri inferred from mtDNA and nuclear markers

    PubMed Central

    2011-01-01

    Background The classical perspective that interspecific hybridization in animals is rare has been changing due to a growing list of empirical examples showing the occurrence of gene flow between closely related species. Using sequence data from cyt b mitochondrial gene and three intron nuclear genes (RPL9, c-myc, and RPL3) we investigated patterns of nucleotide polymorphism and divergence between two closely related toad species R. marina and R. schneideri. By comparing levels of differentiation at nuclear and mtDNA levels we were able to describe patterns of introgression and infer the history of hybridization between these species. Results All nuclear loci are essentially concordant in revealing two well differentiated groups of haplotypes, corresponding to the morphologically-defined species R. marina and R. schneideri. Mitochondrial DNA analysis also revealed two well-differentiated groups of haplotypes but, in stark contrast with the nuclear genealogies, all R. schneideri sequences are clustered with sequences of R. marina from the right Amazon bank (RAB), while R. marina sequences from the left Amazon bank (LAB) are monophyletic. An Isolation-with-Migration (IM) analysis using nuclear data showed that R. marina and R. schneideri diverged at ≈ 1.69 Myr (early Pleistocene), while R. marina populations from LAB and RAB diverged at ≈ 0.33 Myr (middle Pleistocene). This time of divergence is not consistent with the split between LAB and RAB populations obtained with mtDNA data (≈ 1.59 Myr), which is notably similar to the estimate obtained with nuclear genes between R. marina and R. schneideri. Coalescent simulations of mtDNA phylogeny under the speciation history inferred from nuclear genes rejected the hypothesis of incomplete lineage sorting to explain the conflicting signal between mtDNA and nuclear-based phylogenies. Conclusions The cytonuclear discordance seems to reflect the occurrence of interspecific hybridization between these two closely related

  13. The Effect of Homoeologous Meiotic Pairing in Tetraploid Hordeum bulbosum L. × H. vulgare L. Hybrids on Alien Introgressions in Offspring.

    PubMed

    Scholz, Margret; Pendinen, Galina

    2016-01-01

    The pairing behaviour of the individual chromosome arms of Hordeum vulgare (Hv) with their homoeologous arms of H. bulbosum (Hb) at metaphase I of meiosis in tetraploid Hb × Hv hybrids and the frequencies of recombined Hv chromosome arms in selfed offspring were studied on differentially visualized chromosomes after fluorescent in situ hybridisation. The frequencies of paired Hv-Hb arms in the F2 and F3 hybrids were correlated with the frequencies of recombined Hv chromosomes in progenies. Self-generation of hybrids, the number of Hv and Hb chromosomes, and the number of recombined Hv chromosomes of the hybrids strongly influenced the Hv-Hb pairing frequency in meiosis. Within the offspring of F2 and F3 hybrids both Hv plants and hybrids were detected. In contrast, all progenies of the F4 hybrid were hybrids which exhibited centromere misdivisions. The highest frequencies of homoeologous pairing in hybrids and most recombinants were obtained for the barley chromosome 1HL. Recombinants for 4HL, 5HS, 6HS, and 7HS were rarely found. Meiotic pairing and recombinants involving chromosome 1HS were never observed. The results of this study demonstrate that fertile tetraploid interspecific hybrids with a high intergenomic pairing at meiosis are valuable basic material for introgression breeding in barley.

  14. Introgression of coyote mitochondrial DNA into sympatric North American gray wolf populations

    USGS Publications Warehouse

    Lehman, N.; Eisenhawer, A.; Hansen, K.; Mech, L.D.; Peterson, R.O.; Gogan, P.J.P.; Wayne, R.K.

    1991-01-01

    Mitochondrial DNA (mtDNA) genotypes of gray wolves and coyotes from localities throughout North America were determined using restriction fragment length polymorphisms. Of the 13 genotypes found among the wolves, 7 are clearly of coyote origin, indicating that genetic transfer of coyote mtDNA into wolf populations has occurred through hybridization. The transfer of mtDNA appears unidirectional from coyotes into wolves because no coyotes sampled have a wolf-derived mtDNA genotype. Wolves possessing coyote-derived genotypes are confined to a contiguous geographic region in Minnesota, Ontario, and Quebec, and the frequency of coyote-type mtDNA in these wolf populations is high (>50%). The ecological history of the hybrid zone suggests that hybridization is taking place in regions where coyotes have only recently become abundant following conversion of forests to farmlands. Dispersing male wolves unable to find conspecific mates may be pairing with female coyotes in deforested areas bordering wolf territories. Our results demonstrate that closely related species of mobile terrestrial vertebrates have the potential for extensive genetic exchange when ecological conditions change suddenly.

  15. Lack of Genotype and Phenotype Correlation in a Rice T-DNA Tagged Line Is Likely Caused by Introgression in the Seed Source

    PubMed Central

    Wei, Fu-Jin; Tsai, Yuan-Ching; Hsu, Yu-Ming; Chen, Yu-An; Huang, Ching-Ting; Wu, Hshin-Ping; Huang, Lin-Tzu; Lai, Ming-Hsin; Kuang, Lin-Yun; Lo, Shuen-Fang; Yu, Su-May; Lin, Yann-Rong; Hsing, Yue-Ie Caroline

    2016-01-01

    Rice (Oryza sativa) is one of the most important crops in the world. Several rice insertional mutant libraries are publicly available for systematic analysis of gene functions. However, the tagging efficiency of these mutant resources–the relationship between genotype and phenotype–is very low. We used whole-genome sequencing to analyze a T-DNA–tagged transformant from the Taiwan Rice Insertional Mutants (TRIM) resource. The phenomics records for M0028590, one of the TRIM lines, revealed three phenotypes–wild type, large grains, and tillering dwarf–in the 12 T1 plants. Using the sequencing data for 7 plants from three generations of this specific line, we demonstrate that introgression from an indica rice variety might occur in one generation before the seed was used for callus generation and transformation of this line. In addition, the large-grain trait came from the GS3 gene of the introgressed region and the tillering dwarf phenotype came from a single nucleotide change in the D17 gene that occurred during the callus induction to regeneration of the transformant. As well, another regenerant showed completely heterozygous single-nucleotide polymorphisms across the whole genome. In addition to the known sequence changes such as T-DNA integration, single nucleotide polymorphism, insertion, deletion, chromosome rearrangement and doubling, spontaneous outcrossing occurred in the rice field may also explain some mutated traits in a tagged mutant population. Thus, the co-segregation of an integration event and the phenotype should be checked when using these mutant populations. PMID:27186981

  16. A comparative mitogenomic analysis of the potential adaptive value of Arctic charr mtDNA introgression in brook charr populations (Salvelinus fontinalis Mitchill).

    PubMed

    Doiron, Sarah; Bernatchez, Louis; Blier, Pierre U

    2002-11-01

    Wild brook charr populations (Salvelinus fontinalis) completely introgressed with the mitochondrial genome (mtDNA) of arctic charr (Salvelinus alpinus) are found in several lakes of northeastern Québec, Canada. Mitochondrial respiratory enzymes of these populations are thus encoded by their own nuclear DNA and by arctic charr mtDNA. In the present study we performed a comparative sequence analysis of the whole mitochondrial genome of both brook and arctic charr to identify the distribution of mutational differences across these two genomes. This analysis revealed 47 amino acid replacements, 45 of which were confined to subunits of the NADH dehydrogenase complex (Complex I), one in the cox3 gene (Complex IV), and one in the atp8 gene (Complex V). A cladistic approach performed with brook charr, arctic charr, and two other salmonid fishes (rainbow trout [Oncorhynchus mykiss] and Atlantic salmon [Salmo salar]) revealed that only five amino acid replacements were specific to the charr comparison and not shared with the other two salmonids. In addition, five amino acid substitutions localized in the nad2 and nad5 genes denoted negative scores according to the functional properties of amino acids and, therefore, could possibly have an impact on the structure and functional properties of these mitochondrial peptides. The comparison of both brook and arctic charr mtDNA with that of rainbow trout also revealed a relatively constant mutation rate for each specific gene among species, whereas the rate was quite different among genes. This pattern held for both synonymous and nonsynonymous nucleotide positions. These results, therefore, support the hypothesis of selective constraints acting on synonymous codon usage.

  17. Range expansion underlies historical introgressive hybridization in the Iberian hare

    PubMed Central

    Marques, João P.; Farelo, Liliana; Vilela, Joana; Vanderpool, Dan; Alves, Paulo C.; Good, Jeffrey M.; Boursot, Pierre; Melo-Ferreira, José

    2017-01-01

    Introgressive hybridization is an important and widespread evolutionary process, but the relative roles of neutral demography and natural selection in promoting massive introgression are difficult to assess and an important matter of debate. Hares from the Iberian Peninsula provide an appropriate system to study this question. In its northern range, the Iberian hare, Lepus granatensis, shows a northwards gradient of increasing mitochondrial DNA (mtDNA) introgression from the arctic/boreal L. timidus, which it presumably replaced after the last glacial maximum. Here, we asked whether a south-north expansion wave of L. granatensis into L. timidus territory could underlie mtDNA introgression, and whether nuclear genes interacting with mitochondria (“mitonuc” genes) were affected. We extended previous RNA-sequencing and produced a comprehensive annotated transcriptome assembly for L. granatensis. We then genotyped 100 discovered nuclear SNPs in 317 specimens spanning the species range. The distribution of allele frequencies across populations suggests a northwards range expansion, particularly in the region of mtDNA introgression. We found no correlation between variants at 39 mitonuc genes and mtDNA introgression frequency. Whether the nuclear and mitochondrial genomes coevolved will need a thorough investigation of the hundreds of mitonuc genes, but range expansion and species replacement likely promoted massive mtDNA introgression. PMID:28120863

  18. Range expansion underlies historical introgressive hybridization in the Iberian hare.

    PubMed

    Marques, João P; Farelo, Liliana; Vilela, Joana; Vanderpool, Dan; Alves, Paulo C; Good, Jeffrey M; Boursot, Pierre; Melo-Ferreira, José

    2017-01-25

    Introgressive hybridization is an important and widespread evolutionary process, but the relative roles of neutral demography and natural selection in promoting massive introgression are difficult to assess and an important matter of debate. Hares from the Iberian Peninsula provide an appropriate system to study this question. In its northern range, the Iberian hare, Lepus granatensis, shows a northwards gradient of increasing mitochondrial DNA (mtDNA) introgression from the arctic/boreal L. timidus, which it presumably replaced after the last glacial maximum. Here, we asked whether a south-north expansion wave of L. granatensis into L. timidus territory could underlie mtDNA introgression, and whether nuclear genes interacting with mitochondria ("mitonuc" genes) were affected. We extended previous RNA-sequencing and produced a comprehensive annotated transcriptome assembly for L. granatensis. We then genotyped 100 discovered nuclear SNPs in 317 specimens spanning the species range. The distribution of allele frequencies across populations suggests a northwards range expansion, particularly in the region of mtDNA introgression. We found no correlation between variants at 39 mitonuc genes and mtDNA introgression frequency. Whether the nuclear and mitochondrial genomes coevolved will need a thorough investigation of the hundreds of mitonuc genes, but range expansion and species replacement likely promoted massive mtDNA introgression.

  19. Evidence of Natural Hybridization and Introgression between Vasconcellea Species (Caricaceae) from Southern Ecuador Revealed by Chloroplast, Mitochondrial and Nuclear DNA Markers

    PubMed Central

    VAN DROOGENBROECK, B.; KYNDT, T.; ROMEIJN-PEETERS, E.; VAN THUYNE, W.; GOETGHEBEUR, P.; ROMERO-MOTOCHI, J. P.; GHEYSEN, G.

    2006-01-01

    • Background and Aims Vasconcellea × heilbornii is believed to be of natural hybrid origin between V. cundinamarcensis and V. stipulata, and is often difficult to discriminate from V. stipulata on morphological grounds. The aim of this paper is to examine individuals of these three taxa and of individuals from the closely related species V. parviflora and V. weberbaueri, which all inhabit a hybrid zone in southern Ecuador. • Methods Molecular data from mitochondrial, chloroplast and nuclear DNA from 61 individuals were analysed. • Key Results Molecular analysis confirmed occasional contemporary hybridization between V. stipulata, V. cundinamarcensis and V. × heilbornii and suggested the possible involvement of V. weberbaueri in the origin of V. × heilbornii. In addition, the molecular data indicated unidirectional introgression of the V. cundinamarcensis nuclear genome into that of V. stipulata. Several of the individuals examined with morphology similar to that of V. stipulata had genetic traces of hybridization with V. cundinamarcensis, which only seems to act as pollen donor in interspecific hybridization events. Molecular analyses also strongly suggested that most of the V. × heilbornii individuals are not F1 hybrids but instead are progeny of repeated backcrosses with V. stipulata. • Conclusions The results of the present study point to the need for re-evaluation of natural populations of V. stipulata and V. × heilbornii. In general, this analysis demonstrates the complex patterns of genetic and morphological diversity found in natural plant hybrid zones. PMID:16500954

  20. An evaluation of introgression of Atlantic coast striped bass mitochondrial DNA in a Gulf of Mexico population using formalin-preserved museum collections.

    PubMed

    Wirgin, I; Maceda, L; Stabile, J; Mesing, C

    1997-10-01

    Striped bass Morone saxatilis populations in drainages along the Gulf of Mexico coast (Gulf) were depleted in the 1950s and 1960s, probably because of anthropogenic influences. It is believed that only the Apalachicola-Chattahoochee-Flint (A-C-F) river system continually supported a naturally reproducing population of Gulf lineage. Striped bass juveniles of Atlantic coast (Atlantic) ancestry were introduced to restore population abundances in the A-C-F from the late 1960s to the mid 1970s and in many other Gulf rivers from the 1960s to the present. We previously identified mtDNA polymorphisms that were unique to approximately 60% of striped bass from the A-C-F and which confirmed the continued successful natural reproduction of striped bass of Gulf maternal ancestry within the system. However, the genetic relatedness of the extant A-C-F population to 'pure' Gulf striped bass was not addressed. In this study, we determined the frequency of a diagnostic mtDNA XbaI polymorphism in samples of 'pure' Gulf striped bass that were collected from the A-C-F prior to the introduction of Atlantic fish, that were obtained from museum collections, and that were originally preserved in formalin. PCR primers were developed that allowed for amplification of a 191-bp mtDNA fragment that contained the diagnostic XbaI restriction site. Using RFLP and direct sequence analyses of the PCR amplicons, we found no significant differences in mtDNA XbaI genotype frequencies between the archived samples and extant A-C-F samples collected over a 15-year period. This indicates that significant maternally mediated introgression of Atlantic mtDNA genomes into the A-C-F gene pool has not occurred. Additionally, we found no evidence of the unique Gulf mtDNA genotype in striped bass from extant populations in Texas, Louisiana and the Mississippi River. These results highlight the importance of the A-C-F as a repository of striped bass to restore extirpated Gulf populations and the potential use of

  1. Evolution of Bombina bombina and Bombina variegata (Anura: Discoglossidae) in the Carpathian Basin: a history of repeated mt-DNA introgression across species.

    PubMed

    Vörös, Judit; Alcobendas, Marina; Martínez-Solano, Iñigo; García-París, Mario

    2006-03-01

    , possibly mediated by the invasion of B. bombina; and (iv) we have detected discordances between morphology and mt-DNA data in the Transdanubia region (Bakony Mountains, Mecsek Mountains, Orség area), suggesting mt-DNA introgression across species in this regions. These results are discussed with reference to previous biogeographic hypotheses.

  2. [Phylogeography of mitochondrial DNA in South Asian Dolly Varden char Salvelinus curilus Pallas, 1814 (Salmoniformes, Salmonidae): mediated gene introgression?].

    PubMed

    Shed'ko, S V; Ginatulina, L K; Miroshnichenko, I L; Nemkova, G A

    2007-02-01

    In 41 individuals of South Asian Dolly Varden char Salvelinus curilus, nucleotide sequences of tRNA-Pro gene fragment (27 bp) and mtDNA control region (483-484 bp) were analyzed. The fish were collected in 20 localities covering virtually the whole range of the species: Kuril Islands, Sakhalin Island. and Primorye. In addition, six individuals of three other char species (S. albus, S. malma, and S. leucomaenis), which are closely related to S. curilus and inhabit the Russian Far East, were examined. In all, we detected 12 different variants of mtDNA haplotypes that formed three distinct groups differing in 14--20 nucleotide positions. The first group consisted of six haplotypes found in S. curilus in Kuril Islands, Sakhalin, and Primorye (mtDNA phylogroup OKHOTSKIA). The second group comprised four haplotypes representing the mtDNA phylogroup BERING, which had been described earlier (Brunner et al, 2001); they were found in S. curilus in Kuril Islands and Sakhalin, as well as in S. albus and S. malma in Kamchatka and northern Kurils. The third group included two haplotypes detected in S. leucomaenis. The existence of two mtDNA lineages (OKHOTSKIA and BERING) in S. curilus from Kurils and Sakhalin was explained by hybridization and DNA transfer from S. malma to S. curilus. The absence of the BERING haplotypes in S. curilus from Primorye water reservoirs is related to the physical isolation of the Sea of Okhotsk and Sea of Japan basins in past epochs. On the basis of comparing phylogenetic trees, constructed from the data on allozyme and mtDNA variation, we suggest that in this case, an indirect transfer of mtDNA in Alpinoid chars--> S. malma-->S. curilus chain could occur.

  3. Molecular and ecological signs of mitochondrial adaptation: consequences for introgression?

    PubMed Central

    Boratyński, Z; Melo-Ferreira, J; Alves, P C; Berto, S; Koskela, E; Pentikäinen, O T; Tarroso, P; Ylilauri, M; Mappes, T

    2014-01-01

    The evolution of the mitochondrial genome and its potential adaptive impact still generates vital debates. Even if mitochondria have a crucial functional role, as they are the main cellular energy suppliers, mitochondrial DNA (mtDNA) introgression is common in nature, introducing variation in populations upon which selection may act. Here we evaluated whether the evolution of mtDNA in a rodent species affected by mtDNA introgression is explained by neutral expectations alone. Variation in one mitochondrial and six nuclear markers in Myodes glareolus voles was examined, including populations that show mtDNA introgression from its close relative, Myodes rutilus. In addition, we modelled protein structures of the mtDNA marker (cytochrome b) and estimated the environmental envelopes of mitotypes. We found that massive mtDNA introgression occurred without any trace of introgression in the analysed nuclear genes. The results show that the native glareolus mtDNA evolved under past positive selection, suggesting that mtDNA in this system has selective relevance. The environmental models indicate that the rutilus mitotype inhabits colder and drier habitats than the glareolus one that can result from local adaptation or from the geographic context of introgression. Finally, homology models of the cytochrome b protein revealed a substitution in rutilus mtDNA in the vicinity of the catalytic fraction, suggesting that differences between mitotypes may result in functional changes. These results suggest that the evolution of mtDNA in Myodes may have functional, ecological and adaptive significance. This work opens perspective onto future experimental tests of the role of natural selection in mtDNA introgression in this system. PMID:24690754

  4. [Genetic variation and phylogeography of the bank vole (Clethrionomys glareolus, Arvicolinae, Rodentia) in Russia with special reference to the introgression of the mtDNA of a closely related species, red-backed vole (C. rutilus)].

    PubMed

    Abramson, N I; Rodchenkova, E N; Kostygov, A Iu

    2009-05-01

    Totally, 294 bank voles (Clethrionomys glareolus) and 18 red-backed voles (C. rutilus) from 62 sites of European Russia were studied. Incomplete sequences (967 bp) of the mitochondrial cytochrome b gene were determined for 93 C. glareolus individuals from 56 sites and 18 C. rutilus individuals from the same habitats. Analysis of the cytochrome b gene variation has demonstrated that practically the entire European part of Russia, Ural, and a considerable part of Western Europe are inhabited by bank voles of the same phylogroup, displaying an extremely low genetic differentiation. Our data suggest that C. glareolus very rapidly colonized over the presently occupied territory in the post-Pleistocene period from no more than two (central European and western European) refugia for ancestral populations with a small efficient size. PCR typing of the mitochondrial cytochrome b gene allowed us to assess the scale of mtDNA introgression from a closely related species, C. rutilus, and to outline the geographical zone of this introgression. Comparison with the red-backed vole haplotypes in the habitats shared by both species favors the hypothesis of an ancient hybridization event (mid-Holocene) and a subsequent introgression. These results suggest that the hybridization took place in the southern and middle Pre-Ural region.

  5. [Detection of the introgression of genome elements of Aegilops cylindrica Host. into Triticum aestivum L. genome with ISSR-analysis].

    PubMed

    Galaev, A V; Babaiants, L T; Sivolap, Iu M

    2003-01-01

    Comparative analysis of introgressive and parental forms of wheat was carried out to reveal the sites of donor genome with new loci of resistance to fungal diseases. By ISSR-method 124 ISSR-loci were detected in the genomes of 18 individual plants of introgressive line 5/20-91; 17 of them have been related to introgressive fragments of Ae. cylindrica genome in T. aestivum. It was shown that ISSR-method is effective for detection of the variability caused by introgression of alien genetic material to T. aestivum genome.

  6. Distinguishing between Incomplete Lineage Sorting and Genomic Introgressions: Complete Fixation of Allospecific Mitochondrial DNA in a Sexually Reproducing Fish (Cobitis; Teleostei), despite Clonal Reproduction of Hybrids

    PubMed Central

    Choleva, Lukas; Musilova, Zuzana; Kohoutova-Sediva, Alena; Paces, Jan; Rab, Petr; Janko, Karel

    2014-01-01

    Distinguishing between hybrid introgression and incomplete lineage sorting causing incongruence among gene trees in that they exhibit topological differences requires application of statistical approaches that are based on biologically relevant models. Such study is especially challenging in hybrid systems, where usual vectors mediating interspecific gene transfers - hybrids with Mendelian heredity - are absent or unknown. Here we study a complex of hybridizing species, which are known to produce clonal hybrids, to discover how one of the species, Cobitis tanaitica, has achieved a pattern of mito-nuclear mosaic genome over the whole geographic range. We appplied three distinct methods, including the method using solely the information on gene tree topologies, and found that the contrasting mito-nuclear signal might not have resulted from the retention of ancestral polymorphism. Instead, we found two signs of hybridization events related to C. tanaitica; one concerning nuclear gene flow and the other suggested mitochondrial capture. Interestingly, clonal inheritance (gynogenesis) of contemporary hybrids prevents genomic introgressions and non-clonal hybrids are either absent or too rare to be detected among European Cobitis. Our analyses therefore suggest that introgressive hybridizations are rather old episodes, mediated by previously existing hybrids whose inheritance was not entirely clonal. Cobitis complex thus supports the view that the type of resulting hybrids depends on a level of genomic divergence between sexual species. PMID:24971792

  7. [Introgression of nuclear and mitochondrial DNA markers of Mus musculus musculus to aboriginal populations of wild mice from central Asia (M. m. wagneri) and south Siberia (M. m. gansuensis)].

    PubMed

    Spiridonova, L N

    2014-01-01

    Variability of the nucleotide sequences of the second intron of the b1-chain of hemoglobin (Hbb-b1) and complete control region of mitochondrial DNA (D-loop) was studied in aboriginal and commensal populations of M. m. wagneri from Central Asia and M. m. gansuensis from South Siberia. A difference in frequency of the hemoglobin Hbb(w1) type for natural and urban populations of mice was shown. All mice from natural habitats of studied areas kept musculus-type of mtDNA. Apparently, the substitution of taxonpecific mitochondrial haplotypes of wagneri and gansuensis might occur due to absorbing hybridization with nominate subspecies musculus, what is consistent with the results on nuclear DNA (Hbb-b1 gene) of this work. Two differentiated haplo groups among aboriginal subspecies wagneri were discovered first time (d = 0.01), one of which included house mice from Turkmenistan. This may indicate on mtDNA introgression from commensal forms of Turkmenistan into natural populations of Kazakhstan mice. The castaneus-type of mtDNA was detected in two individuals from the natural habitat of Kazakhstan and Turkmenistan, it had not been met in Central Asia before. It is suggested that the gene flow of nuclear and mitochondrial genomes in microevolution processes in M. musculus is directed from the commensal forms towards wild populations.

  8. Comparative Phylogenomic Assessment of Mitochondrial Introgression among Several Species of Chipmunks (Tamias)

    PubMed Central

    Demboski, John R.; Good, Jeffrey M.; Forshee, Nicholas; Hunter, Samuel S.; Sullivan, Jack

    2017-01-01

    Many species are not completely reproductively isolated, resulting in hybridization and genetic introgression. Organellar genomes, such as those derived from mitochondria (mtDNA) and chloroplasts, introgress frequently in natural systems; however, the forces shaping patterns of introgression are not always clear. Here, we investigate extensive mtDNA introgression in western chipmunks, focusing on species in the Tamias quadrivittatus group from the central and southern Rocky Mountains. Specifically, we investigate the role of selection in driving patterns of introgression. We sequenced 51 mtDNA genomes from six species and combine these sequences with other published genomic data to yield annotated mitochondrial reference genomes for nine species of chipmunks. Genomic characterization was performed using a series of molecular evolutionary and phylogenetic analyses to test protein-coding genes for positive selection. We fit a series of maximum likelihood models using a model-averaging approach, assessed deviations from neutral expectations, and performed additional tests to search for codons under the influence of selection. We found no evidence for positive selection among these genomes, suggesting that selection has not been the driving force of introgression in these species. Thus, extensive mtDNA introgression among several species of chipmunks likely reflects genetic drift of introgressed alleles in historically fluctuating populations. PMID:28172670

  9. Alien associations.

    PubMed

    Planck, Brenda L

    2007-01-01

    This story is a highly fictionalized account of events that took place during a year of Fellowship in Forensic Psychiatry, 1997-1998, at the Yale University School of Medicine, Division of Psychiatry and the Law. It is dedicated to my co-fellow, Theresa Stathas, MD, whose kindness, warmth, and support were appreciated during my fellowship year. She generously provided me with alien-themed items, such as a ballpoint pen decorated with 23 alien heads and 56 alien eyes, throughout that year.

  10. Alienation Incident.

    ERIC Educational Resources Information Center

    Wasserman, Louis

    1979-01-01

    Critiques Marxian "cures" for alienation as discussed in Karl Marx's "Economic and Philosophical Manuscripts." Also traces the activity of a former student who joined the revolution in Cuba. Journal available from 7 Harwood Drive, Amherst, New York, 14226. (KC)

  11. The aliens inside human DNA: HERV-W/MSRV/syncytin-1 endogenous retroviruses and neurodegeneration.

    PubMed

    Dolei, Antonina; Uleri, Elena; Ibba, Gabriele; Caocci, Maurizio; Piu, Claudia; Serra, Caterina

    2015-07-04

    The human genome contains remnants of ancestral retroviruses now endogenously transmitted, called human endogenous retroviruses (HERVs). HERVs can be variably expressed, and both beneficial and detrimental effects have described. This review focuses on the MSRV and syncytin-1 HERV-W elements in relationship to neurodegeneration in view of their neuro-pathogenic and immune-pathogenic properties. Multiple sclerosis (MS) and a neurodegenerative disease (neuroAIDS) are reported in this review. In vivo studies in patients and controls for molecular epidemiology and follow-up studies are reviewed, along with in vitro cellular studies of the effects of treatments and of molecular mechanisms. HERV-W/MSRV has been repeatedly found in MS patients (in blood, spinal fluid, and brain samples), and MRSV presence/load strikingly parallels MS stages and active/remission phases, as well as therapy outcome. The DNA of MS patients has increased MSRVenv copies, while syncytin-1 copies are unchanged in controls. Presence of MSRV in the spinal fluid predicted the worst MS progression, ten years in advance. The Epstein-Barr virus (EBV) activates HERV-W/MSRV both in vitro and in vivo. With respect to neuroAIDS, the HIV transactivator of transcription (Tat) protein activates HERV-W/MSRV in monocytes/macrophages and astrocytes indirectly by interaction with TLR4 and induction of TNFa. HERV-W/MSRV can be considered a biomarker for MS behavior and therapy outcome. Regarding MS pathogenesis, we postulate the possibility for EBV of an initial trigger of future MS, years later, and for MSRV of a direct role of effector of neuropathogenesis during MS. Additionally, HERV-W/MSR/syncytin-1 activation by HIV Tat could contribute to the HIV-related neurodegeneration.

  12. Alien Abductions

    NASA Astrophysics Data System (ADS)

    Nickell, Joe

    2000-03-01

    Since the beginning of the modern UFO craze in 1947, an elaborate mythology has developed concerning alleged extraterrestrial visitations. ``Flying saucer" sightings (typically involving misperceptions of such mundane phenomena as meteors and research balloons) began to be accompanied in the 1950s by reports from ``contactees," persons who claimed to have had close encounters with, even to have been transported to distant planets by, UFO occupants. By the 1960s came reports of sporadic ``abductions" which have proliferated in correlation with media interest. (Indeed, by interaction between claimants and media the portrayal of aliens has evolved from a multiplicity of types into the rather standardized big-eyed humanoid model.) While evidence of alien contact has often been faked--as by spurious photos, ``crop circles," and the notorious ``Alien Autopsy" film--few alien abduction reports appear to be hoaxes. Most seem instead to come from sincere, sane individuals. Nevertheless, not one has been authenticated, and serious investigation shows that such claims can be explained as sleep-related phenomena (notably ``waking dreams"), hypnotic confabulation, and other psychological factors. As is typical of other mythologies, the alien myth involves supernormal beings that may interact with humans, and it purports to explain the workings of the universe and humanity's place within it.

  13. Genetic and Epigenetic Alterations of Brassica nigra Introgression Lines from Somatic Hybridization: A Resource for Cauliflower Improvement

    PubMed Central

    Wang, Gui-xiang; Lv, Jing; Zhang, Jie; Han, Shuo; Zong, Mei; Guo, Ning; Zeng, Xing-ying; Zhang, Yue-yun; Wang, You-ping; Liu, Fan

    2016-01-01

    Broad phenotypic variations were obtained previously in derivatives from the asymmetric somatic hybridization of cauliflower “Korso” (Brassica oleracea var. botrytis, 2n = 18, CC genome) and black mustard “G1/1” (Brassica nigra, 2n = 16, BB genome). However, the mechanisms underlying these variations were unknown. In this study, 28 putative introgression lines (ILs) were pre-selected according to a series of morphological (leaf shape and color, plant height and branching, curd features, and flower traits) and physiological (black rot/club root resistance) characters. Multi-color fluorescence in situ hybridization revealed that these plants contained 18 chromosomes derived from “Korso.” Molecular marker (65 simple sequence repeats and 77 amplified fragment length polymorphisms) analysis identified the presence of “G1/1” DNA segments (average 7.5%). Additionally, DNA profiling revealed many genetic and epigenetic differences among the ILs, including sequence alterations, deletions, and variation in patterns of cytosine methylation. The frequency of fragments lost (5.1%) was higher than presence of novel bands (1.4%), and the presence of fragments specific to Brassica carinata (BBCC 2n = 34) were common (average 15.5%). Methylation-sensitive amplified polymorphism analysis indicated that methylation changes were common and that hypermethylation (12.4%) was more frequent than hypomethylation (4.8%). Our results suggested that asymmetric somatic hybridization and alien DNA introgression induced genetic and epigenetic alterations. Thus, these ILs represent an important, novel germplasm resource for cauliflower improvement that can be mined for diverse traits of interest to breeders and researchers. PMID:27625659

  14. Genetic and Epigenetic Alterations of Brassica nigra Introgression Lines from Somatic Hybridization: A Resource for Cauliflower Improvement.

    PubMed

    Wang, Gui-Xiang; Lv, Jing; Zhang, Jie; Han, Shuo; Zong, Mei; Guo, Ning; Zeng, Xing-Ying; Zhang, Yue-Yun; Wang, You-Ping; Liu, Fan

    2016-01-01

    Broad phenotypic variations were obtained previously in derivatives from the asymmetric somatic hybridization of cauliflower "Korso" (Brassica oleracea var. botrytis, 2n = 18, CC genome) and black mustard "G1/1" (Brassica nigra, 2n = 16, BB genome). However, the mechanisms underlying these variations were unknown. In this study, 28 putative introgression lines (ILs) were pre-selected according to a series of morphological (leaf shape and color, plant height and branching, curd features, and flower traits) and physiological (black rot/club root resistance) characters. Multi-color fluorescence in situ hybridization revealed that these plants contained 18 chromosomes derived from "Korso." Molecular marker (65 simple sequence repeats and 77 amplified fragment length polymorphisms) analysis identified the presence of "G1/1" DNA segments (average 7.5%). Additionally, DNA profiling revealed many genetic and epigenetic differences among the ILs, including sequence alterations, deletions, and variation in patterns of cytosine methylation. The frequency of fragments lost (5.1%) was higher than presence of novel bands (1.4%), and the presence of fragments specific to Brassica carinata (BBCC 2n = 34) were common (average 15.5%). Methylation-sensitive amplified polymorphism analysis indicated that methylation changes were common and that hypermethylation (12.4%) was more frequent than hypomethylation (4.8%). Our results suggested that asymmetric somatic hybridization and alien DNA introgression induced genetic and epigenetic alterations. Thus, these ILs represent an important, novel germplasm resource for cauliflower improvement that can be mined for diverse traits of interest to breeders and researchers.

  15. Biased introgression of mitochondrial and nuclear genes: a comparison of diploid and haplodiploid systems.

    PubMed

    Patten, Manus M; Carioscia, Sara A; Linnen, Catherine R

    2015-10-01

    Hybridization between recently diverged species, even if infrequent, can lead to the introgression of genes from one species into another. The rates of mitochondrial and nuclear introgression often differ, with some taxa showing biases for mitochondrial introgression and others for nuclear introgression. Several hypotheses exist to explain such biases, including adaptive introgression, sex differences in dispersal rates, sex-specific prezygotic isolation and sex-specific fitness of hybrids (e.g. Haldane's rule). We derive a simple population genetic model that permits an analysis of sex-specific demographic and fitness parameters and measures the relative rates of mitochondrial and nuclear introgression between hybridizing pairs. We do this separately for diploid and haplodiploid species. For diploid taxa, we recover results consistent with previous hypotheses: an excess of one sex among the hybridizing migrants or sex-specific prezygotic isolation causes a bias for one type of marker or the other; when Haldane's rule is obeyed, we find a mitochondrial bias in XY systems and a nuclear bias in ZW systems. For haplodiploid taxa, the model reveals that owing to their unique transmission genetics, they are seemingly assured of strong mitochondrial biases in introgression rates, unlike diploid taxa, where the relative fitness of male and female hybrids can tip the bias in either direction. This heretofore overlooked aspect of hybridization in haplodiploids provides what is perhaps the most likely explanation for differential introgression of mitochondrial and nuclear markers and raises concerns about the use of mitochondrial DNA barcodes for species delimitation in these taxa.

  16. DNA-based identification of invasive alien species in relation to Canadian federal policy and law, and the basis of rapid-response management.

    PubMed

    Thomas, Vernon G; Hanner, Robert H; Borisenko, Alex V

    2016-11-01

    Managing invasive alien species in Canada requires reliable taxonomic identification as the basis of rapid-response management. This can be challenging, especially when organisms are small and lack morphological diagnostic features. DNA-based techniques, such as DNA barcoding, offer a reliable, rapid, and inexpensive toolkit for taxonomic identification of individual or bulk samples, forensic remains, and even environmental DNA. Well suited for this requirement, they could be more broadly deployed and incorporated into the operating policy and practices of Canadian federal departments and should be authorized under these agencies' articles of law. These include Fisheries and Oceans Canada, Canadian Food Inspection Agency, Transport Canada, Environment Canada, Parks Canada, and Health Canada. These efforts should be harmonized with the appropriate provisions of provincial jurisdictions, for example, the Ontario Invasive Species Act. This approach necessitates that a network of accredited, certified laboratories exists, and that updated DNA reference libraries are readily accessible. Harmonizing this approach is vital among Canadian federal agencies, and between the federal and provincial levels of government. Canadian policy and law must also be harmonized with that of the USA when detecting, and responding to, invasive species in contiguous lands and waters. Creating capacity in legislation for use of DNA-based identifications brings the authority to fund, train, deploy, and certify staff, and to refine further developments in this molecular technology.

  17. The Genetic Cost of Neanderthal Introgression.

    PubMed

    Harris, Kelley; Nielsen, Rasmus

    2016-06-01

    Approximately 2-4% of genetic material in human populations outside Africa is derived from Neanderthals who interbred with anatomically modern humans. Recent studies have shown that this Neanderthal DNA is depleted around functional genomic regions; this has been suggested to be a consequence of harmful epistatic interactions between human and Neanderthal alleles. However, using published estimates of Neanderthal inbreeding and the distribution of mutational fitness effects, we infer that Neanderthals had at least 40% lower fitness than humans on average; this increased load predicts the reduction in Neanderthal introgression around genes without the need to invoke epistasis. We also predict a residual Neanderthal mutational load in non-Africans, leading to a fitness reduction of at least 0.5%. This effect of Neanderthal admixture has been left out of previous debate on mutation load differences between Africans and non-Africans. We also show that if many deleterious mutations are recessive, the Neanderthal admixture fraction could increase over time due to the protective effect of Neanderthal haplotypes against deleterious alleles that arose recently in the human population. This might partially explain why so many organisms retain gene flow from other species and appear to derive adaptive benefits from introgression.

  18. Pollen-mediated introgression and hybrid speciation in Louisiana irises.

    PubMed Central

    Arnold, M L; Buckner, C M; Robinson, J J

    1991-01-01

    Populations of the "Louisiana iris" species Iris fulva, I. hexagona, and I. nelsonii were examined genetically to test for interspecific gene flow between I. fulva and I. hexagona, for pollen- versus seed-mediated introgression between these species, and for the presumed hybrid origin of I. nelsonii. Genetic markers were identified by using both a polymerase chain reaction-like method that allows the identification of random, nuclear markers and standard polymerase chain reaction experiments involving specific chloroplast DNA (cpDNA) oligonucleotides. Restriction endonuclease digestions of the cpDNA amplification products resolved diagnostic restriction site differences for I. fulva and I. hexagona. The distribution of the species-specific nuclear markers supports a hypothesis of bidirectional introgression between I. fulva and I. hexagona. Thus, individuals analyzed from a contemporary hybrid population demonstrate multilocus genotypes that are indicative of advanced-generation hybrid individuals. Furthermore, several markers from the alternate species were present in low frequency in one allopatric population each of I. fulva and I. hexagona. Data from the nuclear analysis also support the hypothesized hybrid origin of I. nelsonii from the interaction of I. fulva and I. hexagona. Finally, cpDNA data support the hypothesis that the localized and the dispersed introgression are largely due to pollen transfer. In addition to the biological implications, this study demonstrates the power of the polymerase chain reaction methodology for the rapid identification of random and specific genetic markers for testing evolutionary genetic hypotheses. Images PMID:11607153

  19. When COI barcodes deceive: complete genomes reveal introgression in hairstreaks.

    PubMed

    Cong, Qian; Shen, Jinhui; Borek, Dominika; Robbins, Robert K; Opler, Paul A; Otwinowski, Zbyszek; Grishin, Nick V

    2017-02-08

    Two species of hairstreak butterflies from the genus Calycopis are known in the United States: C. cecrops and C. isobeon Analysis of mitochondrial COI barcodes of Calycopis revealed cecrops-like specimens from the eastern US with atypical barcodes that were 2.6% different from either USA species, but similar to Central American Calycopis species. To address the possibility that the specimens with atypical barcodes represent an undescribed cryptic species, we sequenced complete genomes of 27 Calycopis specimens of four species: C. cecrops, C. isobeon, C. quintana and C. bactra Some of these specimens were collected up to 60 years ago and preserved dry in museum collections, but nonetheless produced genomes as complete as fresh samples. Phylogenetic trees reconstructed using the whole mitochondrial and nuclear genomes were incongruent. While USA Calycopis with atypical barcodes grouped with Central American species C. quintana by mitochondria, nuclear genome trees placed them within typical USA C. cecrops in agreement with morphology, suggesting mitochondrial introgression. Nuclear genomes also show introgression, especially between C. cecrops and C. isobeon About 2.3% of each C. cecrops genome has probably (p-value < 0.01, FDR < 0.1) introgressed from C. isobeon and about 3.4% of each C. isobeon genome may have come from C. cecrops. The introgressed regions are enriched in genes encoding transmembrane proteins, mitochondria-targeting proteins and components of the larval cuticle. This study provides the first example of mitochondrial introgression in Lepidoptera supported by complete genome sequencing. Our results caution about relying solely on COI barcodes and mitochondrial DNA for species identification or discovery.

  20. Asymmetric hybridization and introgression between pink salmon and chinook salmon in the Laurentian Great Lakes

    USGS Publications Warehouse

    Rosenfield, Jonathan A.; Todd, Thomas; Greil, Roger

    2000-01-01

    Among Pacific salmon collected in the St. Marys River, five natural hybrids of pink salmon Oncorhynchus gorbuscha and chinook salmon Oncorhynchus tshawytscha and one suspected backcross have been detected using morphologic, meristic, and color evidence. One allozyme (LDH, l-lactate dehydrogenase from muscle) and one nuclear DNA locus (growth hormone) for which species-specific fixed differences exist were analyzed to detect additional hybrids and to determine if introgression had occurred. Restriction fragment length polymorphism of mitochondrial DNA (mtDNA) was used to identify the maternal parent of each hybrid. Evidence of introgression was found among the five previously identified hybrids. All hybrid specimens had chinook salmon mtDNA, indicating that hybridization between chinook salmon and pink salmon in the St. Marys River is asymmetric and perhaps unidirectional. Ecological, physiological, and sexual selection forces may contribute to this asymmetric hybridization. Introgression between these highly differentiated species has implications for management, systematics, and conservation of Pacific salmon.

  1. IN DEFENSE OF ALIENATION.

    ERIC Educational Resources Information Center

    KENISTON, KENNETH

    THE TERM ALIENATION IS IN IMMINENT DANGER OF BECOMING PART OF THE VOCABULARY OF POLITE ABUSE. ONE OF THE WORD'S VIRTUES IS ITS AMBIGUITY. IN THE SOCIOLOGICAL TRADITION, ALIENATION REFERS TO A STRUCTURAL CONDITION. PEOPLE ARE ALIENATED MORE OR LESS AGAINST THEIR WILL. IN THE PSYCHOLOGICAL MEANING, ALIENATION PRESUPPOSES SOME INNER ATTITUDE,…

  2. Sequence-Based SSR Marker Development and Their Application in Defining the Introgressions of LA0716 (Solanum pennellii) in the Background of cv. M82 (Solanum lycopersicum)

    PubMed Central

    Long, Wenbo; Li, Ye; Zhou, Wenjuan; Ling, Hong-Qing; Zheng, Shusong

    2013-01-01

    The introgression lines (ILs) from cv. M82 (Solanum lycopersicum) × LA0716 (S. pennellii) have been proven to be exceptionally useful for genetic analysis and gene cloning. The introgressions were originally defined by RFLP markers at their development. The objectives of this study are to develop polymorphic SSR markers, and to re-define the DNA introgression from LA0716 in the ILs. Tomato sequence data was scanned by software to generate SSR markers. In total, 829 SSRs, which could be robustly amplified by PCR, were developed. Among them, 658 SSRs were dinucleotide repeats, 162 were trinucleotide repeats, and nine were tetranucleotide repeats. The 829 SSRs together with 96 published RFLPs were integrated into the physical linkage map of S. lycopersicum. Introgressions of DNA fragments from LA0716 were re-defined among the 75 ILs using the newly developed SSRs. A specific introgression of DNA fragment from LA0716 was identified in 72 ILs as described previously by RFLP, whereas the specific DNA introgression described previously were not detected in the ILs LA4035, LA4059 and LA4091. The physical location of each investigated DNA introgression was finely determined by SSR mapping. Among the 72 ILs, eight ILs showed a shorter and three ILs (IL3-2, IL12-3 and IL12-3-1) revealed a longer DNA introgression than that framed by RFLPs. Furthermore, 54 previously undefined segments were found in 21 ILs, ranging from 1 to 11 DNA introgressions per IL. Generally, the newly developed SSRs provide additional markers for genetic studies of tomatoes, and the fine definition of DNA introgressions from LA0716 would facilitate the use of the ILs for genetic analysis and gene cloning. PMID:24339899

  3. Introgression versus immigration in hybridizing high-dispersal echinoderms.

    PubMed

    Harper, Fiona M; Addison, Jason A; Hart, Michael W

    2007-10-01

    Phylogeographic studies designed to estimate rates and patterns of genetic differentiation within species often reveal unexpected and graphically striking cases of allele or haplotype sharing between species (introgression) via hybridization and backcrossing. Does introgression between species significantly influence population genetic structure relative to more conventional sources of differentiation (drift) and similarity (dispersal) among populations within species? Here we use mtDNA sequences from four species in two genera of sea urchins and sea stars to quantify the relative magnitude of gene flow across oceans and across species boundaries in the context of the trans-Arctic interchange of marine organisms between the Pacific and Atlantic oceans. In spite of the much smaller distances between sympatric congeners, rates of gene flow between sympatric species via heterospecific gamete interactions were small and significantly lower than gene flow across oceans via dispersal of planktonic larvae. We conclude that, in these cases at least, larvae are more effective than gametes as vectors of gene flow.

  4. Extensive Hybridization and Introgression between Melastoma candidum and M. sanguineum

    PubMed Central

    Liu, Ting; Chen, Yunyun; Chao, Lifang; Wang, Shuqiong; Wu, Wei; Dai, Seping; Wang, Feng; Fan, Qiang; Zhou, Renchao

    2014-01-01

    Natural hybridization can lead to various evolutionary outcomes in plants, including hybrid speciation and interspecific gene transfer. It can also cause taxonomic problems, especially in plant genera containing multiple species. In this study, the hybrid status of Melastoma affine, the most widespread taxon in this genus, and introgression between its putative parental species, M. candidum and M. sanguineum, were assessed on two sites, Hainan and Guangdong, using 13 SSR markers and sequences of a chloroplast intergenic spacer. Bayesian-based STRUCTURE analysis detected two most likely distinct clusters for the three taxa, and 76.0% and 73.9% of the morphologically identified individuals of M. candidum and M. sanguineum were correctly assigned, respectively. 74.5% of the M. affine individuals had a membership coefficient to either parental species between 0.1 and 0.9, suggesting admixture between M. candidum and M. sanguineum. Furthermore, NewHybrids analysis suggested that most individuals of M. affine were F2 hybrids or backcross hybrids to M. candidum, and that there was extensive introgression between M. candidum and M. sanguineum. These SSR data thus provides convincing evidence for hybrid origin of M. affine and extensive introgression between M. candidum and M. sanguineum. Chloroplast DNA results were consistent with this conclusion. Much higher hybrid frequency on the more disturbed Guangdong site suggests that human disturbance might offer suitable habitats for the survival of hybrids, a hypothesis that is in need of further testing. PMID:24797959

  5. When and how did Bos indicus introgress into Mongolian cattle?

    PubMed

    Yue, Xiangpeng; Li, Ran; Liu, Li; Zhang, Yunsheng; Huang, Jieping; Chang, Zhenhua; Dang, Ruihua; Lan, Xianyong; Chen, Hong; Lei, Chuzhao

    2014-03-10

    The Mongolian cattle are one of the most widespread breeds with strictly Bos taurus morphological features in northern China. In our current study, we presented a diversity of mitochondrial DNA (mtDNA) D-loop region and Y chromosome SNP markers in 25 male and 8 female samples of Mongolian cattle from the Xinjiang Uygur autonomous region in Western China, and detected 21 B. taurus and four Bos indicus (zebu) mtDNA haplotypes. Among four B. indicus mtDNA haplotypes, two haplotypes belonged to I1 haplogroup and the remaining two haplotypes belonged to I2 haplogroup. In contrast, all 25 male Mongolian cattle samples revealed B. taurus Y chromosome haplotype and no B. indicus haplotypes were found. Historical and archeological records indicate that B. taurus was introduced to Xinjiang during the second millennium BC and B. indicus appeared in this region by the second century AD. The two types of cattle coexisted for many centuries in Xinjiang, as depicted in clay and wooden figurines unearthed in the Astana cemetery in Turfan (3rd-8th century AD). Multiple lines of evidence suggest that the earliest B. indicus introgression in the Mongolian cattle may have occurred during the 2nd-7th centuries AD through the Silk Road around the Xinjiang region. This conclusion differs from the previous hypothesis that zebu introgression to Mongolian cattle happened during the Mongol Empire era in the 13th century.

  6. Evidence of sexually dimorphic introgression in Pinaleno Mountain Apache trout

    USGS Publications Warehouse

    Porath, M.T.; Nielsen, J.L.

    2003-01-01

    The high-elevation headwater streams of the Pinaleno Mountains support small populations of threatened Apache trout Oncorhynchus apache that were stocked following the chemical removal of nonnative salmonids in the 1960s. A fisheries survey to assess population composition, growth, and size structure confirmed angler reports of infrequent occurrences of Oncorhynchus spp. exhibiting the external morphological characteristics of both Apache trout and rainbow trout O. mykiss. Nonlethal tissue samples were collected from 50 individuals in the headwaters of each stream. Mitochondrial DNA (mtDNA) sequencing and amplification of nuclear microsatellite loci were used to determine the levels of genetic introgression by rainbow trout in Apache trout populations at these locations. Sexually dimorphic introgression from the spawning of male rainbow trout with female Apache trout was detected using mtDNA and microsatellites. Estimates of the degree of hybridization based on three microsatellite loci were 10-88%. The use of nonlethal DNA genetic analyses can supplement information obtained from standard survey methods and be useful in assessing the relative importance of small and sensitive populations with a history of nonnative introductions.

  7. Hybridization and introgression in a mixed population of the intertidal seaweeds Fucus evanescens and F. serratus.

    PubMed

    Coyer, J A; Hoarau, G; Stam, W T; Olsen, J L

    2007-11-01

    The introduced Fucus evanescens (hermaphroditic) and the native F. serratus (dioecious) have been in secondary contact along the Danish coast of the Kattegat Sea for 60-100 years and dioecious hybrids have been observed at Blushøj for several years. Hybridization in Fucus is unusual because it appears to always involve a hermaphroditic and a dioecious parental pair. We determined the degree and spatial patterns of introgression for 286 individuals using 10 microsatellite loci and cpDNA. Hybrids accounted for nearly 13% of the population, yet parental species were well differentiated (F(ST) = 0.633). The presence of F. evanescens chloroplasts in 100% of F(1) hybrids revealed asymmetrical hybridization. Fucus evanescens cpDNA was observed in 50% of introgressed and 5.4% of pure F. serratus, but no F. serratus cpDNA was found in F. evanescens. In contrast, nuclear DNA introgression was symmetrical with an equal amount ( approximately 1.5%) of genes introgressed into each parental species. Survivorship and viability data suggest selection against hybrids in the hybrid zone.

  8. Genetic analysis of hybridization and introgression between wild mongoose and brown lemurs

    PubMed Central

    Pastorini, Jennifer; Zaramody, Alphonse; Curtis, Deborah J; Nievergelt, Caroline M; Mundy, Nicholas I

    2009-01-01

    Background Hybrid zones generally represent areas of secondary contact after speciation. The nature of the interaction between genes of individuals in a hybrid zone is of interest in the study of evolutionary processes. In this study, data from nuclear microsatellites and mitochondrial DNA sequences were used to genetically characterize hybridization between wild mongoose lemurs (Eulemur mongoz) and brown lemurs (E. fulvus) at Anjamena in west Madagascar. Results Two segments of mtDNA have been sequenced and 12 microsatellite loci screened in 162 brown lemurs and mongoose lemurs. Among the mongoose lemur population at Anjamena, we identified two F1 hybrids (one also having the mtDNA haplotype of E. fulvus) and six other individuals with putative introgressed alleles in their genotype. Principal component analysis groups both hybrids as intermediate between E. mongoz and E. fulvus and admixture analyses revealed an admixed genotype for both animals. Paternity testing proved one F1 hybrid to be fertile. Of the eight brown lemurs genotyped, all have either putative introgressed microsatellite alleles and/or the mtDNA haplotype of E. mongoz. Conclusion Introgression is bidirectional for the two species, with an indication that it is more frequent in brown lemurs than in mongoose lemurs. We conclude that this hybridization occurs because mongoose lemurs have expanded their range relatively recently. Introgressive hybridization may play an important role in the unique lemur radiation, as has already been shown in other rapidly evolving animals. PMID:19196458

  9. Parapatric genetic introgression and phenotypic assimilation: testing conditions for introgression between Hercules beetles (Dynastes, Dynastinae).

    PubMed

    Huang, Jen-Pan

    2016-11-01

    The prevalence and consequences of genetic introgression between species have been intensively debated. I used Hercules beetles as examples to test for conditions that may be associated with the occurrence of introgression. RADseq data were used to reconstruct the species tree and history of introgression between Hercules beetles. Image data from museum specimens were used to investigate the phenotypic similarity of two adaptive traits between species from two distinct climatic realms (Nearctic vs. Neotropical). Genetic introgression was identified between Hercules beetles living in geographic proximity (parapatric). Phylogenetic relatedness and phenotypic similarity did not predict nor preclude genetic introgression between species. Phenotypic assimilation in body coloration was evident between distantly related Hercules beetles codistributed in Central America, where directional introgression was also statistically supported from the putative donor to receiver lineages. The number of introgressed loci was significantly higher between species with than without phenotypic similarity. I discuss the implications of recent studies on adaptive genetic introgression by providing supporting evidence from the Hercules beetle system.

  10. Introgression between invasive and native blue mussels (genus Mytilus) in the central California hybrid zone.

    PubMed

    Saarman, Norah P; Pogson, Grant H

    2015-09-01

    The ecological and genetic factors determining the extent of introgression between species in secondary contact zones remain poorly understood. Here, we investigate the relative importance of isolating barriers and the demographic expansion of invasive Mytilus galloprovincialis on the magnitude and the direction of introgression with the native Mytilus trossulus in a hybrid zone in central California. We use double-digest restriction-site-associated DNA sequencing (ddRADseq) to genotype 1337 randomly selected single nucleotide polymorphisms and accurately distinguish early and advanced generation hybrids for the first time in the central California Mytilus spp. hybrid zone. Weak levels of introgression were observed in both directions but were slightly more prevalent from the native M. trossulus into the invasive M. galloprovincialis. Few early and advanced backcrossed individuals were observed across the hybrid zone confirming the presence of strong barriers to interbreeding. Heterogeneous patterns of admixture across the zone of contact were consistent with the colonization history of M. galloprovincialis with more extensive introgression in northern localities furthest away from the putative site of introduction in southern California. These observations reinforce the importance of dynamic spatial and demographic expansions in determining patterns of introgression between close congeners, even in those with high dispersal potential and well-developed reproductive barriers. Our results suggest that the threat posed by invasive M. galloprovincialis is more ecological than genetic as it has displaced, and continues to displace the native M. trossulus from much of central and southern California.

  11. Genetic diversity enhanced by ancient introgression and secondary contact in East Pacific black mangroves.

    PubMed

    Nettel, Alejandro; Dodd, Richard S; Afzal-Rafii, Zara; Tovilla-Hernández, Cristian

    2008-06-01

    Regional distribution of genetic diversity in widespread species may be influenced by hybridization with locally restricted, closely related species. Previous studies have shown that Central American East Pacific populations of the wide-ranged Avicennia germinans, the black mangrove, harbour higher genetic diversity than the rest of its range. Genetic diversity in this region might be enhanced by introgression with the locally restricted Avicennia bicolor. We tested the hypotheses of ancient hybridization using phylogenetic analysis of the internal transcribed spacer region (ITS) of the nuclear ribosomal DNA and intergenic chloroplast DNA; we also tested for current hybridization by population level analysis of nuclear microsatellites. Our results unveiled ancient ITS introgression between a northern Pacific Central American A. germinans lineage and A. bicolor. However, microsatellite data revealed contemporary isolation between the two species. Polymorphic ITS sequences from Costa Rica and Panama are consistent with a zone of admixture between the introgressant ITS A. germinans lineage and a southern Central American lineage of A. germinans. Interspecific introgression influenced lineage diversity and divergence at the nuclear ribosomal DNA; intraspecific population differentiation and secondary contact are more likely to have enhanced regional genetic diversity in Pacific Central American populations of the widespread A. germinans.

  12. The aliens are hiding

    NASA Astrophysics Data System (ADS)

    2015-06-01

    In reply to the physicsworld.com news story “Trail goes cold on alien hotspots, for now” (28 April, http://ow.ly/MeOpZ; see also p5), which described the results of a survey that looked for unexplained pockets of infrared radiation that could have been produced by advanced alien civilizations.

  13. Alienation and Education.

    ERIC Educational Resources Information Center

    Reimanis, Gunars

    This paper reviews the author's research on the role of certain aspects of alienation in education. The first part of the paper discusses similarities between anomie and locus of reinforcement control, as they assess the normlessness and powerlessness aspects of alienation. The second part reports results from studies attempting to modify one's…

  14. Alienation and Illness.

    ERIC Educational Resources Information Center

    Kobasa, Suzanne C.

    Reviews of studies of four groups (business executives, lawyers, Army officers, and working women) which demonstrate the health-damaging effects of alienation in certain life situations show that, when under stress, members of these groups who feel alienated fall ill, medically and/or psychiatrically. Three models are described which may explain…

  15. Alienation from School

    ERIC Educational Resources Information Center

    Hascher, Tina; Hagenauer, Gerda

    2010-01-01

    Two studies aimed at understanding the time course of alienation from school and school factors that may influence alienation from school during early adolescence. In Study 1, 434 students from grade 5-8 participated (cross-sectional design). In Study 2, we followed 356 students from grade 6-7 (longitudinal design). The results confirm the…

  16. The Roots Of Alienation

    ERIC Educational Resources Information Center

    Bronfenbrenner, Urie

    1973-01-01

    Alienation in our society takes several forms--withdrawal, hostility, or efforts to reform. The author traces the roots of alienation to our neglect of many of the needs of children, particularly their need for interaction with adults. Among his many recommendations are: modified work schedules to permit more time with children and systems for…

  17. Cryptic interspecific introgression and genetic differentiation within Gossypium aridum (Malvaceae) and its relatives.

    PubMed

    Alvarez, Inés; Wendel, Jonathan F

    2006-03-01

    Interspecific gene flow is increasingly recognized as an important evolutionary phenomenon in plants. A surprising observation is that historical introgression is often inferred between species that presently have geographic and reproductive barriers that would appear to prohibit the inferred sexual exchange. A striking example concerns Gossypium aridum (subsection Erioxylum); previous analyses have shown that populations from Colima (southwestern Mexico) have a chloroplast genome (cpDNA) similar to that of a different taxonomic subsection (Integrifolia) that presently is confined to Baja California and the Galapagos Islands, whereas other G. aridum populations share a cpDNA lineage with each other and with other species in subsection Erioxylum. To evaluate further the possibility that this cpDNA evidence reflects introgression as opposed to some other evolutionary process, as well as to explore patterns of genetic diversity and similarity in both subsections, we conducted amplified fragment-length polymorphism (AFLP) analysis using 50 populations representing all seven species in the two subsections. Genetic diversity is high in G. aridum, and is strongly correlated with geography, as are similarities among the five species in subsection Erioxylum. This subsection is genetically distant from the two species in subsection Integrifolia, whose populations are highly similar inter se. Populations of G. aridum from Colima are genetically distinct from the remainder of the species, and exhibit a comparatively high frequency of AFLP fragments that otherwise are diagnostic of the Integrifolia lineage. These data implicate intersubsectional introgression between presently allopatric and genetically isolated clades, giving rise to a morphologically cryptic, introgressant entity. Biogeographic considerations suggest that this history was initiated following migration of one or more seeds from Baja California to the Colima coast, perhaps during the Pleistocene. We suggest

  18. Discordant introgression in a rapidly expanding hybrid swarm

    PubMed Central

    Ward, Jessica L; Blum, Mike J; Walters, David M; Porter, Brady A; Burkhead, Noel; Freeman, Byron

    2012-01-01

    The erosion of species boundaries can involve rapid evolutionary change. Consequently, many aspects of the process remain poorly understood, including the formation, expansion, and evolution of hybrid swarms. Biological invasions involving hybridization present exceptional opportunities to study the erosion of species boundaries because timelines of interactions and outcomes are frequently well known. Here, we examined clinal variation across codominant and maternally inherited genetic markers as well as phenotypic traits to characterize the expansion and evolution of a hybrid swarm between native Cyprinella venusta and invasive Cyprinella lutrensis minnows. Discordant introgression of phenotype, microsatellite multilocus genotype, and mtDNA haplotype indicates that the observable expansion of the C. venusta × C. lutrensis hybrid swarm is a false invasion front. Both parental and hybrid individuals closely resembling C. lutrensis are numerically dominant in the expansion wake, indicating that the non-native parental phenotype may be selectively favored. These findings show that cryptic introgression can extend beyond the phenotypic boundaries of hybrid swarms and that hybrid swarms likely expand more rapidly than can be documented from phenotypic variation alone. Similarly, dominance of a single parental phenotype following an introduction event may lead to instances of species erosion being mistaken for species displacement without hybridization. PMID:25568058

  19. Discordant introgression in a rapidly expanding hybrid swarm

    USGS Publications Warehouse

    Ward, Jessica L.; Blum, Mike J.; Walters, David M.; Porter, Brady A.; Burkhead, Noel; Freeman, Byron

    2012-01-01

    The erosion of species boundaries can involve rapid evolutionary change. Consequently, many aspects of the process remain poorly understood, including the formation, expansion, and evolution of hybrid swarms. Biological invasions involving hybridization present exceptional opportunities to study the erosion of species boundaries because timelines of interactions and outcomes are frequently well known. Here, we examined clinal variation across codominant and maternally inherited genetic markers as well as phenotypic traits to characterize the expansion and evolution of a hybrid swarm between native Cyprinella venusta and invasive Cyprinella lutrensis minnows. Discordant introgression of phenotype, microsatellite multilocus genotype, and mtDNA haplotype indicates that the observable expansion of the C. venusta x C. lutrensis hybrid swarm is a false invasion front. Both parental and hybrid individuals closely resembling C. lutrensis are numerically dominant in the expansion wake, indicating that the non-native parental phenotype may be selectively favored. These findings show that cryptic introgression can extend beyond the phenotypic boundaries of hybrid swarms and that hybrid swarms likely expand more rapidly than can be documented from phenotypic variation alone. Similarly, dominance of a single parental phenotype following an introduction event may lead to instances of species erosion being mistaken for species displacement without hybridization.

  20. The ubiquitous mountain hare mitochondria: multiple introgressive hybridization in hares, genus Lepus.

    PubMed

    Alves, Paulo C; Melo-Ferreira, José; Freitas, Hélder; Boursot, Pierre

    2008-09-12

    Climatic oscillations during the glaciations forced dramatic changes in species distributions, such that some presently temperate regions were alternately occupied by temperate and arctic species. These species could have met and hybridized during climatic transitions. This phenomenon happened for three hare species present in Iberia (Lepus granatensis, Lepus europaeus and Lepus castroviejoi), which display high frequencies of mitochondrial DNA (mtDNA) from Lepus timidus, an arctic/boreal species presently extinct in Iberia. Here, we extend our previous geographical survey to determine whether the distribution of this mtDNA lineage extends beyond the northern half of the Iberian Peninsula, where it is found at high frequencies. We also review the taxonomy, distribution and molecular phylogeny of the genus Lepus. The phylogenetic inference reveals the presence of L. timidus-like mtDNA in several other hare species in Asia and North America, suggesting that the mitochondrial introgression observed in Iberia might be generalized. Comparison with the available nuclear gene phylogenies suggests that introgression could have happened repeatedly, possibly during different climatic transitions. We discuss demographic and adaptive scenarios that could account for the repetition in time and space of this spectacular phenomenon and suggest ways to improve our understanding of its determinants and consequences. Such high levels of introgressive hybridization should discourage attempts to revise hare taxonomy based solely on mtDNA.

  1. Alienation Attitudes and Exploratory Behavior.

    ERIC Educational Resources Information Center

    Maddi, Salvatore R.

    In order to give the psychological conception of alienation greater cogency relative to the influence of sociological alienation, research is needed that ties alienation attitudes to individual personal behavior. It was hypothesized that the stronger the alienation attitudes of people, the weaker will be their exploratory behavior. Thus,…

  2. IView: Introgression library visualization and query tool

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near-isogenic lines (NIL) are powerful genetic resources to analyze phenotypic variation and are important to map-base clone genes underlying mutations and traits. With many thousands of distinct genotypes, querying introgression libraries for lines of interest is an issue. We have created a tool ...

  3. Mining wild species elleles from introgressed genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tomato (Solanum Section Lycopersicon) is composed of one cultivated (S. lycopersicum) and 12 wild species. Because the species are closely related to each other, introgression breeding has been extensive and released cultivars have been improved for many more traits using wild alleles than has any o...

  4. [Molecular-genetic analysis of wheat (T. aestivum L.) genome with introgression of Ae. cylindrica Host genetic elements].

    PubMed

    Galaev, A V; Sivolap, Iu M

    2005-01-01

    Wheat-aegilops hybrid plants Triticum aestivum L. (2n = 42) x Aegilops cylindrica Host (2n = 28) were investigated with using microsatellite markers. In two BC1F9 lines some genome modifications connected with losing DNA fragments of initial variety or appearing of Aegilops genome elements were detected. In some investigated hybrids new amplicons lacking in parental plants were found. Substitution of wheat chromosomes for aegilops chromosomes was not revealed. Analysis of microsatellite loci in BC2F5 plants showed stable introgression of aegilops genetic elements into wheat; elimination of some transferred aegilops DNA fragments in the course of backcrossing; decreasing size of introgressive elements after backcrossing. Introgressive lines were classified according to genome changes.

  5. Life under alien skies

    NASA Astrophysics Data System (ADS)

    Dartnell, Lewis

    2012-04-01

    As the number of confirmed extrasolar planets increases, so does the likelihood that some of them will harbour life. Lewis Dartnell describes some preliminary - but increasingly well founded - efforts to predict what alien plants and animals might look like.

  6. A new method to scan genomes for introgression in a secondary contact model.

    PubMed

    Geneva, Anthony J; Muirhead, Christina A; Kingan, Sarah B; Garrigan, Daniel

    2015-01-01

    Secondary contact between divergent populations or incipient species may result in the exchange and introgression of genomic material. We develop a simple DNA sequence measure, called Gmin, which is designed to identify genomic regions experiencing introgression in a secondary contact model. Gmin is defined as the ratio of the minimum between-population number of nucleotide differences in a genomic window to the average number of between-population differences. Although it is conceptually simple, one advantage of Gmin is that it is computationally inexpensive relative to model-based methods for detecting gene flow and it scales easily to the level of whole-genome analysis. We compare the sensitivity and specificity of Gmin to those of the widely used index of population differentiation, FST, and suggest a simple statistical test for identifying genomic outliers. Extensive computer simulations demonstrate that Gmin has both greater sensitivity and specificity for detecting recent introgression than does FST. Furthermore, we find that the sensitivity of Gmin is robust with respect to both the population mutation and recombination rates. Finally, a scan of Gmin across the X chromosome of Drosophila melanogaster identifies candidate regions of introgression between sub-Saharan African and cosmopolitan populations that were previously missed by other methods. These results show that Gmin is a biologically straightforward, yet powerful, alternative to FST, as well as to more computationally intensive model-based methods for detecting gene flow.

  7. Current and historical hybridization with differential introgression among three species of cyprinid fishes (genus Cyprinella).

    PubMed

    Broughton, Richard E; Vedala, Krishna C; Crowl, Tessa M; Ritterhouse, Lauren L

    2011-05-01

    Hybridization is common among freshwater fishes, particular among the Cyprinidae. We used two mitochondrial genes and one nuclear gene to characterize hybridization among two species pairs of Cyprinella in southwestern North America. Genalogical patterns revealed that C. lutrensis and C. venusta are currently hybridizing in several localities producing apparent F(1), F(2) and backcross generations, yet there was no evidence for introgression outside of local hybrid zones. Alternatively, mitochondrial haplotypes from C. lutrensis appear to have introgressed into a C. lepida population in the Nueces River completely replacing the native C. lepida haplotype. There was no evidence of introgression of nuclear DNA and there does not appear to be ongoing hybridization. The population of C. lepida from the nearby Frio River exhibits no evidence of hybridization with C. lutrensis. Thus, contact between C. lutrensis and C. venusta results in the formation of localized hybrid swarms, while contact between C. lutrensis and C. lepida has resulted in complete mitochondrial introgression in the Nueces River or no apparent hybridization in the Frio River. The three different outcomes of contact between these species illustrate the variable nature of interspecific reproductive interactions and provide an excellent system in which to better understand the factors influencing hybridization among freshwater fishes.

  8. Multiple gene genealogies reveal asymmetrical hybridization and introgression among strongylocentrotid sea urchins.

    PubMed

    Addison, Jason A; Pogson, Grant H

    2009-03-01

    The evolution of incompatibilities between eggs and sperm is thought to play important roles in establishing and maintaining reproductive isolation among species of broadcast-spawning marine invertebrates. However, the effectiveness of gametic isolation in initiating the speciation process and/or in limiting the introgression of genes among species at later stages of divergence remains largely unknown. In the present study, we collected DNA sequence data from five loci in four species of Strongylocentrotus sea urchins (S. droebachiensis, S. pallidus, S. purpuratus, and S. franciscanus) to test whether the susceptibility of S. droebachiensis eggs to fertilization by heterospecific sperm results in gene flow between species. Despite the potential for introgression, a small but statistically significant signal of introgression was observed only between the youngest pair of sister taxa (S. pallidus and S. droebachiensis) that was strongly asymmetrical (from the former into the latter). No significant gene flow was observed for either S. purpuratus or S. franciscanus despite the ability of their sperm to readily fertilize the eggs of S. droebachiensis. Our results demonstrate that asymmetrical gamete compatibilities in strongylocentrotids can give rise to asymmetrical patterns of introgression but suggest that gamete traits alone cannot be responsible for maintaining species integrities. The genetic boundaries between strongylocentrotid urchin species in the northeast Pacific appear to be related to postzygotic isolating mechanisms that scale with divergence times and not intrinsic gametic incompatibilities per se.

  9. A New Method to Scan Genomes for Introgression in a Secondary Contact Model

    PubMed Central

    Geneva, Anthony J.; Muirhead, Christina A.; Kingan, Sarah B.; Garrigan, Daniel

    2015-01-01

    Secondary contact between divergent populations or incipient species may result in the exchange and introgression of genomic material. We develop a simple DNA sequence measure, called Gmin, which is designed to identify genomic regions experiencing introgression in a secondary contact model. Gmin is defined as the ratio of the minimum between-population number of nucleotide differences in a genomic window to the average number of between-population differences. Although it is conceptually simple, one advantage of Gmin is that it is computationally inexpensive relative to model-based methods for detecting gene flow and it scales easily to the level of whole-genome analysis. We compare the sensitivity and specificity of Gmin to those of the widely used index of population differentiation, FST, and suggest a simple statistical test for identifying genomic outliers. Extensive computer simulations demonstrate that Gmin has both greater sensitivity and specificity for detecting recent introgression than does FST. Furthermore, we find that the sensitivity of Gmin is robust with respect to both the population mutation and recombination rates. Finally, a scan of Gmin across the X chromosome of Drosophila melanogaster identifies candidate regions of introgression between sub-Saharan African and cosmopolitan populations that were previously missed by other methods. These results show that Gmin is a biologically straightforward, yet powerful, alternative to FST, as well as to more computationally intensive model-based methods for detecting gene flow. PMID:25874895

  10. Asymmetric introgression of African genes in honeybee populations (Apis mellifera L.) in Central Mexico.

    PubMed

    Kraus, F B; Franck, P; Vandame, R

    2007-08-01

    The Africanization of the honeybee (Apis mellifera) in South America is one of the most spectacular examples of biological invasions. In this study, we analyzed the Africanization process in Central Mexico along an altitudinal transect from 72 to 2800 m, using both mitochondrial and nuclear DNA markers. The mitochondrial analysis revealed that the two high-altitude populations had a significantly greater percentage of African mitotypes (95%) than the three lowland populations (67%), indicating successful spreading of Africanized swarms to these altitudes. All populations (highland and lowland) had a similar overall proportion of African alleles at nuclear loci (58%). Thus, all populations showed an asymmetric introgression of African nuclear and mtDNA. Colonies with African mitotypes had, on average, significantly more African nuclear alleles (60%) than those with European mitotypes (51%). Furthermore, the three lowland populations showed clear signs of linkage disequilibrium, while the two high-altitude populations did not, indicating recent genetic introgression events into the lowland populations.

  11. Evidence for introgressive hybridization of captive markhor (Capra falconeri) with domestic goat: cautions for reintroduction.

    PubMed

    Hammer, Sabine E; Schwammer, Harald M; Suchentrunk, Franz

    2008-04-01

    Markhors (Capra falconeri) are among the most endangered mammal species, and several conservation measures, including ex situ breeding, are implemented to prevent their extinction. We studied sequence diversity and differentiation of the first hypervariable segment of the mitochondrial DNA control region among C. f. heptneri and C. f. megaceros kept in four zoos in relationship to lineages of other wild and domestic goats, to assess for the first time the level of molecular distinctness and variability among those subspecies, and to check for possible introgression by related Capra taxa, such as domestic goats. Levels of differentiation between some Capra falconeri lineages and modern domestic goats were similar to levels between other wild goat species (i.e., Capra aegagrus, Capra ibex) and domestic goats. Among pure markhor lineages, paraphyly was observed for C. f. heptneri, suggesting occurrence of shared ancestral polymorphism among markhor subspecies and/or ancient or recent gene exchange between subspecies. Interestingly, 35.7% of all studied markhors from three zoos are introgressed by the domestic goat. Furthermore, despite relatively small breeding group sizes, markhors have maintained a relatively high proportion of mtDNA variation within zoo groups. In any case, the existence of markhors introgressed with domestic goat DNA in zoos should be considered when selecting markhors for ex situ breeding programs with the aim of building up a stock for later reintroduction into the wild.

  12. Introgressive hybridization in a trophically polymorphic cichlid

    PubMed Central

    Hulsey, C Darrin; García-de-León, Francisco J

    2013-01-01

    Trophically polymorphic species could represent lineages that are rapidly diverging along an ecological axis or could phenotypically mark the collapse of species through introgressive hybridization. We investigated patterns of introgression between the trophically polymorphic cichlid fish Herichthys minckleyi and its relative H. cyanoguttatus using a combination of population genetics and species tree analyses. We first examined the distribution of mitochondrial haplotypes within the alternative H. minckleyi pharyngeal jaw morphotypes that are endemic to the small desert valley of Cuatro Ciénegas. We recovered two clusters of mitochondrial haplotypes. The first contained a number of slightly differentiated cytochrome b (cytb) haplotypes that showed some phylogeographic signal and were present in both jaw morphotypes. The other haplotype was monomorphic, highly differentiated from the other cluster, present in equal frequencies in the morphotypes, and identical to H. cyanoguttatus haplotypes found outside Cuatro Ciénegas. Then, we investigated whether H. minckleyi individuals with the H. cyanoguttatus cytb were more evolutionarily similar to H. cyanoguttatus or other H. minckleyi using a species tree analysis of 84 nuclear loci. Both H. minckleyi pharyngeal morphotypes, regardless of their cytb haplotype, were quite distinct from H. cyanoguttatus. However, hybridization could be blurring subdivision within H. minckleyi as the alternative jaw morphotypes were not genetically distinct from one another. Accounting for introgression from H. cyanoguttatus will be essential to understand the evolution of the trophically polymorphic cichlid H. minckleyi. PMID:24340193

  13. Cytogenetic and Molecular Characterization of B-Genome Introgression Lines of Brassica napus L.

    PubMed

    Dhaliwal, Inderpreet; Mason, Annaliese S; Banga, Shashi; Bharti, Sakshi; Kaur, Beerpal; Gurung, Allison Mary; Salisbury, Phillip Anthony; Batley, Jacqueline; Banga, Surinder Singh

    2017-01-05

    Brassica napus introgression lines (ILs), having B-genome segments from B. carinata, were assessed genetically for extent of introgression and phenotypically for siliqua shatter resistance. Introgression lines had 7-9% higher DNA content, were meiotically stable, and had almost normal pollen fertility/seed set. Segment introgressions were confirmed by fluorescent genomic in situ hybridization (fl-GISH), SSR analyses, and SNP studies. Genotyping with 48 B-genome specific SSRs detected substitutions from B3, B4, B6, and B7 chromosomes on 39 of the 69 ILs whereas SNP genotyping detected a total of 23 B-segments (≥3 Mb) from B4, B6, and B7 introgressed into 10 of the 19 (C1, C2, C3, C5, C6, C8, C9, A3, A9, A10) chromosomes in 17 ILs. The size of substitutions varied from 3.0 Mb on chromosome A9 (IL59) to 42.44 Mb on chromosome C2 (IL54), ranging from 7 to 83% of the recipient chromosome. Average siliqua strength in ILs was observed to be higher than that of B. napus parents (2.2-6.0 vs. 1.9-4.0 mJ) while siliqua strength in some of the lines was almost equal to that of the donor parent B. carinata (6.0 vs.7.2 mJ). These ILs, with large chunks of substituted B-genome, can prove to be a useful prebreeding resource for germplasm enhancement in B. napus, especially for siliqua shatter resistance.

  14. Cytogenetic and Molecular Characterization of B-Genome Introgression Lines of Brassica napus L.

    PubMed Central

    Dhaliwal, Inderpreet; Mason, Annaliese S.; Banga, Shashi; Bharti, Sakshi; Kaur, Beerpal; Gurung, Allison Mary; Salisbury, Phillip Anthony; Batley, Jacqueline; Banga, Surinder Singh

    2016-01-01

    Brassica napus introgression lines (ILs), having B-genome segments from B. carinata, were assessed genetically for extent of introgression and phenotypically for siliqua shatter resistance. Introgression lines had 7–9% higher DNA content, were meiotically stable, and had almost normal pollen fertility/seed set. Segment introgressions were confirmed by fluorescent genomic in situ hybridization (fl-GISH), SSR analyses, and SNP studies. Genotyping with 48 B-genome specific SSRs detected substitutions from B3, B4, B6, and B7 chromosomes on 39 of the 69 ILs whereas SNP genotyping detected a total of 23 B-segments (≥3 Mb) from B4, B6, and B7 introgressed into 10 of the 19 (C1, C2, C3, C5, C6, C8, C9, A3, A9, A10) chromosomes in 17 ILs. The size of substitutions varied from 3.0 Mb on chromosome A9 (IL59) to 42.44 Mb on chromosome C2 (IL54), ranging from 7 to 83% of the recipient chromosome. Average siliqua strength in ILs was observed to be higher than that of B. napus parents (2.2–6.0 vs. 1.9–4.0 mJ) while siliqua strength in some of the lines was almost equal to that of the donor parent B. carinata (6.0 vs.7.2 mJ). These ILs, with large chunks of substituted B-genome, can prove to be a useful prebreeding resource for germplasm enhancement in B. napus, especially for siliqua shatter resistance. PMID:27821632

  15. Genetic structure of Miscanthus sinensis and Miscanthus sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression.

    PubMed

    Clark, Lindsay V; Stewart, J Ryan; Nishiwaki, Aya; Toma, Yo; Kjeldsen, Jens Bonderup; Jørgensen, Uffe; Zhao, Hua; Peng, Junhua; Yoo, Ji Hye; Heo, Kweon; Yu, Chang Yeon; Yamada, Toshihiko; Sacks, Erik J

    2015-07-01

    Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable high-density genotyping. Throughout Japan, tetraploid Miscanthus sacchariflorus and diploid Miscanthus sinensis are common, and occasionally hybridize. In this study, 667 M. sinensis and 78 M. sacchariflorus genotypes from Japan were characterized using 20 704 SNPs and ten plastid microsatellites. Similarity of SNP genotypes between diploid and tetraploid M. sacchariflorus indicated that the tetraploids originated through autopolyploidy. Structure analysis indicated a gradient of introgression from diploid M. sinensis into tetraploid M. sacchariflorus throughout Japan; most tetraploids had some M. sinensis DNA. Among phenotypically M. sacchariflorus tetraploids, M. sinensis ancestry averaged 7% and ranged from 1-39%, with introgression greatest in southern Japan. Unexpectedly, rare (~1%) diploid M. sinensis individuals from northern Japan were found with 6-27% M. sacchariflorus ancestry. Population structure of M. sinensis in Japan included three groups, and was driven primarily by distance, and secondarily by geographic barriers such as mountains and straits. Miscanthus speciation is a complex and dynamic process. In contrast to limited introgression between diploid M. sacchariflorus and M. sinensis in northern China, selection for adaptation to a moderate maritime climate probably favoured cross-ploidy introgressants in southern Japan. These results will help guide the selection of Miscanthus accessions for the breeding of biomass cultivars.

  16. Genetic structure of Miscanthus sinensis and Miscanthus sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression

    DOE PAGES

    Clark, Lindsay V.; Stewart, J. Ryan; Nishiwaki, Aya; ...

    2015-01-24

    Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable high-density genotyping. Throughout Japan, tetraploid Miscanthus sacchariflorus and diploid Miscanthus sinensis are common, and occasionally hybridize. In this study, 667 M. sinensis and 78 M. sacchariflorus genotypes from Japan were characterized using 20 704 SNPs and ten plastid microsatellites. Similarity of SNP genotypes between diploid and tetraploid M. sacchariflorus indicated that the tetraploids originated through autopolyploidy. Structure analysis indicatedmore » a gradient of introgression from diploid M. sinensis into tetraploid M. sacchariflorus throughout Japan; most tetraploids had some M. sinensis DNA. Among phenotypically M. sacchariflorus tetraploids, M. sinensis ancestry averaged 7% and ranged from 1-39%, with introgression greatest in southern Japan. Unexpectedly, rare (~1%) diploid M. sinensis individuals from northern Japan were found with 6-27% M. sacchariflorus ancestry. Population structure of M. sinensis in Japan included three groups, and was driven primarily by distance, and secondarily by geographic barriers such as mountains and straits. Miscanthus speciation is a complex and dynamic process. In contrast to limited introgression between diploid M. sacchariflorus and M. sinensis in northern China, selection for adaptation to a moderate maritime climate probably favoured cross-ploidy introgressants in southern Japan. Ultimately, these results will help guide the selection of Miscanthus accessions for the breeding of biomass cultivars.« less

  17. Human fascioliasis and the presence of hybrid/introgressed forms of Fasciola hepatica and Fasciola gigantica in Vietnam.

    PubMed

    Le, Thanh Hoa; De, Nguyen Van; Agatsuma, Takeshi; Thi Nguyen, Thanh Giang; Nguyen, Quoc Doanh; McManus, Donald P; Blair, David

    2008-05-01

    The two species common of liver fluke, Fasciola hepatica and Fasciola gigantica, cause human fascioliasis. Hybrids between these species, and introgressed forms of Fasciola, are known from temperate and subtropical regions of eastern Asia. Here, we report the presence of hybrid and/or introgressed liver flukes in Vietnam where it has recently been recognised that human fascioliasis is an important zoonotic disease. Specimens examined came from domestic stock (cattle and buffalo) at slaughter and also from human patients. DNA sequences were obtained from the nuclear ribosomal second internal transcribed spacer (ITS-2) and from portions of two mitochondrial protein-coding genes. Mitochondrial sequences in every case were similar to those of Fasciola gigantica. Nuclear ITS-2 sequences belonged to one or other of the Fasciola species, or, sequences from both were found in the same individual worm. This study extends the known range of hybrids or introgressed forms of Fasciola into tropical regions of Asia.

  18. 8 CFR 211.5 - Alien commuters.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the...

  19. 8 CFR 211.5 - Alien commuters.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the...

  20. 8 CFR 211.5 - Alien commuters.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the...

  1. 8 CFR 211.5 - Alien commuters.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the...

  2. 8 CFR 211.5 - Alien commuters.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Alien commuters. 211.5 Section 211.5 Aliens...: IMMIGRANTS; WAIVERS § 211.5 Alien commuters. (a) General. An alien lawfully admitted for permanent residence.... An alien commuter engaged in seasonal work will be presumed to have taken up residence in the...

  3. Y-chromosome evidence supports asymmetric dog introgression into eastern coyotes

    PubMed Central

    Wheeldon, Tyler J; Rutledge, Linda Y; Patterson, Brent R; White, Bradley N; Wilson, Paul J

    2013-01-01

    Hybridization has played an important role in the evolutionary history of Canis species in eastern North America. Genetic evidence of coyote–dog hybridization based on mitochondrial DNA (mtDNA) is lacking compared to that based on autosomal markers. This discordance suggests dog introgression into coyotes has potentially been male biased, but this hypothesis has not been formally tested. Therefore, we investigated biparentally, maternally, and paternally inherited genetic markers in a sample of coyotes and dogs from southeastern Ontario to assess potential asymmetric dog introgression into coyotes. Analysis of autosomal microsatellite genotypes revealed minimal historical and contemporary admixture between coyotes and dogs. We observed only mutually exclusive mtDNA haplotypes in coyotes and dogs, but we observed Y-chromosome haplotypes (Y-haplotypes) in both historical and contemporary coyotes that were also common in dogs. Species-specific Zfy intron sequences of Y-haplotypes shared between coyotes and dogs confirmed their homology and indicated a putative origin from dogs. We compared Y-haplotypes observed in coyotes, wolves, and dogs profiled in multiple studies, and observed that the Y-haplotypes shared between coyotes and dogs were either absent or rare in North American wolves, present in eastern coyotes, but absent in western coyotes. We suggest the eastern coyote has experienced asymmetric genetic introgression from dogs, resulting from predominantly historical hybridization with male dogs and subsequent backcrossing of hybrid offspring with coyotes. We discuss the temporal and spatial dynamics of coyote–dog hybridization and the conditions that may have facilitated the introgression of dog Y-chromosomes into coyotes. Our findings clarify the evolutionary history of the eastern coyote. PMID:24101990

  4. Paroxysmal alien hand syndrome.

    PubMed Central

    Leiguarda, R; Starkstein, S; Nogués, M; Berthier, M; Arbelaiz, R

    1993-01-01

    Four patients are described who presented with a paroxysmal form of the alien hand syndrome. Two patients with damage to one frontomedial cortex had brief episodes of abnormal motor behaviour of the contralateral arm that featured groping, grasping, and apparently purposeful but perseverative movements, which both patients interpreted as alien or foreign. The other two patients, with posterior parietal damage, reported a paroxysmal feeling of unawareness of the location of the contralateral arm, lack of recognition of the arm as their own, purposeless movements, and personification of the arm. These cases represent a new form of the alien hand syndrome manifested by brief, paroxysmal episodes, which may be due to ictal mechanisms. Images PMID:8331355

  5. Genetic drift or natural selection? Hybridization and asymmetric mitochondrial introgression in two Caribbean lizards (Anolis pulchellus and Anolis krugi).

    PubMed

    Jezkova, T; Leal, M; Rodríguez-Robles, J A

    2013-07-01

    Hybridization and gene introgression can occur frequently between closely related taxa, but appear to be rare phenomena among members of the species-rich West Indian radiation of Anolis lizards. We investigated the pattern and possible mechanism of introgression between two sister species from Puerto Rico, Anolis pulchellus and Anolis krugi, using mitochondrial (ND2) and nuclear (DNAH3, NKTR) DNA sequences. Our findings demonstrated extensive introgression of A. krugi mtDNA (k-mtDNA) into the genome of A. pulchellus in western Puerto Rico, to the extent that k-mtDNA has mostly or completely replaced the native mtDNA of A. pulchellus on this part of the island. We proposed two not mutually exclusive scenarios to account for the interspecific matings between A. pulchellus and A. krugi. We inferred that hybridization events occurred independently in several populations, and determined that k-mtDNA haplotypes harboured in individuals of A. pulchellus can be assigned to four of the five major mtDNA clades of A. krugi. Further, the spatial distribution of k-mtDNA clades in the two species is largely congruent. Based on this evidence, we concluded that natural selection was the probable driving mechanism for the extensive k-mtDNA introgression into A. pulchellus. Our two nuclear data sets yielded different results. DNAH3 showed reciprocal monophyly of A. pulchellus and A. krugi, indicating no effect of hybridization on this marker. In contrast, the two species shared nine NKTR alleles, probably due to incomplete lineage sorting. Our study system will provide an excellent opportunity to experimentally assess the behavioural and ecological mechanisms that can lead to hybridization in closely related taxa.

  6. Footprints of alien technology

    NASA Astrophysics Data System (ADS)

    Davies, P. C. W.

    2012-04-01

    If alien civilizations do, or did, exist, their technology will impact their environment. Some consideration has been given to the detection of large-scale astro-engineering, such as Dyson spheres. However, a very advanced technology might leave more subtle footprints requiring sophisticated scientific methods to uncover. We must not overlook the possibility that alien technology has impacted our immediate astronomical environment, even Earth itself, but probably a very long time ago. This raises the question of what traces, if anything, might remain today. I shall consider the possibilities of biological, geological and physical traces, and suggest ways that we might search for them.

  7. Natural Hybridization and Introgression between Ligularia cymbulifera and L. tongolensis (Asteraceae, Senecioneae) in Four Different Locations

    PubMed Central

    Yu, Jiaojun; Kuroda, Chiaki; Gong, Xun

    2014-01-01

    Natural hybridization has been considered to represent an important factor influencing the high diversity of the genus Ligularia Cass. in the Hengduan Mountains, China. Natural hybridization has been confirmed to occur frequently in Ligularia. To date, however, it has been demonstrated only within a single population. In this paper, we present evidence of natural hybridization in Ligularia from four different locations. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and three chloroplast intergenic spacers (trnK-rps16, trnL-rpl32 and trnQ-5'rps16) of 149 accessions of putative hybrids and their putative parents (L. cymbulifera and L. tongolensis) were analyzed for evidence of hybridization. The ITS data clearly distinguished two putative parental species and sympatric L. vellerea and supported the hypothesis that those morphological intermediates were products of natural hybridization between L. cymbulifera and L. tongolensis. Moreover, several identified morphological parents were actual introgressed products. Because of hybridization and introgression, chloroplast DNA sequences generated a poorly resolved network. The present results indicate that varying degrees of hybridization and introgression occur differently depending on the habitat context. We conclude that gene flow caused by natural hybridization in Ligularia indeed plays an important role in the species diversity. PMID:25551379

  8. Adaptation and possible ancient interspecies introgression in pigs identified by whole-genome sequencing.

    PubMed

    Ai, Huashui; Fang, Xiaodong; Yang, Bin; Huang, Zhiyong; Chen, Hao; Mao, Likai; Zhang, Feng; Zhang, Lu; Cui, Leilei; He, Weiming; Yang, Jie; Yao, Xiaoming; Zhou, Lisheng; Han, Lijuan; Li, Jing; Sun, Silong; Xie, Xianhua; Lai, Boxian; Su, Ying; Lu, Yao; Yang, Hui; Huang, Tao; Deng, Wenjiang; Nielsen, Rasmus; Ren, Jun; Huang, Lusheng

    2015-03-01

    Domestic pigs have evolved genetic adaptations to their local environmental conditions, such as cold and hot climates. We sequenced the genomes of 69 pigs from 15 geographically divergent locations in China and detected 41 million variants, of which 21 million were absent from the dbSNP database. In a genome-wide scan, we identified a set of loci that likely have a role in regional adaptations to high- and low-latitude environments within China. Intriguingly, we found an exceptionally large (14-Mb) region with a low recombination rate on the X chromosome that appears to have two distinct haplotypes in the high- and low-latitude populations, possibly underlying their adaptation to cold and hot environments, respectively. Surprisingly, the adaptive sweep in the high-latitude regions has acted on DNA that might have been introgressed from an extinct Sus species. Our findings provide new insights into the evolutionary history of pigs and the role of introgression in adaptation.

  9. Aliens and atheism

    NASA Astrophysics Data System (ADS)

    Campos, Sergio; de Muynck, Willem; Virginia; Peerally, Abed; Tyler, David; Stephen

    2014-11-01

    In reply to the physicsworld.com blog post "Aliens and atheists" (2 October, http://ow.ly/CQzu4), about a survey that found that atheists are more likely than religious people to believe that life exists on other planets.

  10. Alien Life Imagined

    NASA Astrophysics Data System (ADS)

    Brake, Mark

    2012-11-01

    1. Kosmos: aliens in ancient Greece; 2. The world turned upside down: Copernicanism and the voyages of discovery; 3. In Newton's train: pluralism and the system of the world; 4. Extraterrestrials in the early machine age; 5. After Darwin: the war of the worlds; 6. Einstein's sky: life in the new universe; 7. Ever since SETI: astrobiology in the space age; References; Index.

  11. The Origins of Alienation

    ERIC Educational Resources Information Center

    Bronfenbrenner, Urie

    1974-01-01

    Evolutionary changes in the structure of the American family have led to an increase in the estrangement between young people and adults in the United States. The role of day care services, peer groups, schools, the community, and the organization of work are discussed in terms of their contribution to this alienation as well as possible changes…

  12. Forgetting and remembering alienation theory.

    PubMed

    Yuill, Chris

    2011-01-01

    Alienation theory has acted as the stimulus for a great deal of research and writing in the history of sociology. It has formed the basis of many sociological "classics" focused on the workplace and the experiences of workers, and has also been mobilized to chart wider social malaise and individual troubles. Alienation theory usage has, however, declined significantly since its heyday of the 1960s and 1970s. Here, the reasons why alienation theory was "forgotten" and what can be gained by "remembering" alienation theory are explored. to realize this ambition this article proceeds by (1) briefly visiting differing definitions of alienation theory, before charting its high point, and the various debates and tensions of the time, during the 1960s and 1970s; (2) analysing the reasons why alienation theory fell from grace from the 1980s onwards; (3) elaborating how and why alienation theory is still relevant for sociology and the wider social sciences today.

  13. Interspecific introgressive origin of genomic diversity in the house mouse.

    PubMed

    Liu, Kevin J; Steinberg, Ethan; Yozzo, Alexander; Song, Ying; Kohn, Michael H; Nakhleh, Luay

    2015-01-06

    We report on a genome-wide scan for introgression between the house mouse (Mus musculus domesticus) and the Algerian mouse (Mus spretus), using samples from the ranges of sympatry and allopatry in Africa and Europe. Our analysis reveals wide variability in introgression signatures along the genomes, as well as across the samples. We find that fewer than half of the autosomes in each genome harbor all detectable introgression, whereas the X chromosome has none. Further, European mice carry more M. spretus alleles than the sympatric African ones. Using the length distribution and sharing patterns of introgressed genomic tracts across the samples, we infer, first, that at least three distinct hybridization events involving M. spretus have occurred, one of which is ancient, and the other two are recent (one presumably due to warfarin rodenticide selection). Second, several of the inferred introgressed tracts contain genes that are likely to confer adaptive advantage. Third, introgressed tracts might contain driver genes that determine the evolutionary fate of those tracts. Further, functional analysis revealed introgressed genes that are essential to fitness, including the Vkorc1 gene, which is implicated in rodenticide resistance, and olfactory receptor genes. Our findings highlight the extent and role of introgression in nature and call for careful analysis and interpretation of house mouse data in evolutionary and genetic studies.

  14. Introgression and selection shaped the evolutionary history of sympatric sister-species of coral reef fishes (genus: Haemulon).

    PubMed

    Bernal, Moisés A; Gaither, Michelle R; Simison, W Brian; Rocha, Luiz A

    2017-01-01

    Closely related marine species with large overlapping ranges provide opportunities to study mechanisms of speciation, particularly when there is evidence of gene flow between such lineages. Here, we focus on a case of hybridization between the sympatric sister-species Haemulon maculicauda and H. flaviguttatum, using Sanger sequencing of mitochondrial and nuclear loci, as well as 2422 single nucleotide polymorphisms (SNPs) obtained via restriction site-associated DNA sequencing (RADSeq). Mitochondrial markers revealed a shared haplotype for COI and low divergence for CytB and CR between the sister-species. On the other hand, complete lineage sorting was observed at the nuclear loci and most of the SNPs. Under neutral expectations, the smaller effective population size of mtDNA should lead to fixation of mutations faster than nDNA. Thus, these results suggest that hybridization in the recent past (0.174-0.263 Ma) led to introgression of the mtDNA, with little effect on the nuclear genome. Analyses of the SNP data revealed 28 loci potentially under divergent selection between the two species. The combination of mtDNA introgression and limited nuclear DNA introgression provides a mechanism for the evolution of independent lineages despite recurrent hybridization events. This study adds to the growing body of research that exemplifies how genetic divergence can be maintained in the presence of gene flow between closely related species.

  15. Extensive introgressive hybridization within the northern oriole group (Genus Icterus) revealed by three-species isolation with migration analysis

    PubMed Central

    Jacobsen, Frode; Omland, Kevin E

    2012-01-01

    Until recently, studies of divergence and gene flow among closely-related taxa were generally limited to pairs of sister taxa. However, organisms frequently exchange genes with other non-sister taxa. The “northern oriole” group within genus Icterus exemplifies this problem. This group involves the extensively studied hybrid zone between Baltimore oriole (Icterus galbula) and Bullock's oriole (I. bullockii), an alleged hybrid zone between I. bullockii and black-backed oriole (I. abeillei), and likely mtDNA introgression between I. galbula and I. abeillei. Here, we examine the divergence population genetics of the entire northern oriole group using a multipopulation Isolation-with-Migration (IM) model. In accordance with Haldane's rule, nuclear loci introgress extensively beyond the I. galbula–I. bullockii hybrid zone, while mtDNA does not. We found no evidence of introgression between I. bullockii and I. abeillei or between I. galbula and I. abeillei when all three species were analyzed together in a three-population model. However, traditional pairwise analysis suggested some nuclear introgression from I. abeillei into I. galbula, probably reflecting genetic contributions from I. bullockii unaccounted for in a two-population model. Thus, only by including all members of this group in the analysis was it possible to rigorously estimate the level of gene flow among these three closely related species. PMID:23145328

  16. Phylogeny Estimation of the Radiation of Western North American Chipmunks (Tamias) in the Face of Introgression Using Reproductive Protein Genes

    PubMed Central

    Reid, Noah; Demboski, John R.; Sullivan, Jack

    2012-01-01

    The causes and consequences of rapid radiations are major unresolved issues in evolutionary biology. This is in part because phylogeny estimation is confounded by processes such as stochastic lineage sorting and hybridization. Because these processes are expected to be heterogeneous across the genome, comparison among marker classes may provide a means of disentangling these elements. Here we use introns from nuclear-encoded reproductive protein genes expected to be resistant to introgression to estimate the phylogeny of the western chipmunks (Tamias: subgenus: Neotamias), a rapid radiation that has experienced introgressive hybridization of mitochondrial DNA (mtDNA). We analyze the nuclear loci using coalescent-based species-tree estimation methods and concatenation to estimate a species tree and we use parametric bootstraps and coalescent simulations to differentiate between phylogenetic error, coalescent stochasticity and introgressive hybridization. Results indicate that the mtDNA gene tree reflects several introgression events that have occurred between taxa of varying levels of divergence and at different time points in the tree. T. panamintinus and T. speciosus appear to be fixed for ancient mitochondrial introgressions from T. minimus. A southern Rocky Mountains clade appears well sorted (i.e., species are largely monophyletic) at multiple nuclear loci, while five of six taxa are nonmonophyletic based on cytochrome b. Our simulations reject phylogenetic error and coalescent stochasticity as causes. The results represent an advance in our understanding of the processes at work during the radiation of Tamias and suggest that sampling reproductive-protein genes may be a viable strategy for phylogeny estimation of rapid radiations in which reproductive isolation is incomplete. However, a genome-scale survey that can statistically compare heterogeneity of genealogical process at many more loci will be necessary to test this conclusion. PMID:21878471

  17. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  18. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  19. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  20. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  1. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  2. 8 CFR 244.4 - Ineligible aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Ineligible aliens. 244.4 Section 244.4 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 244.4 Ineligible aliens. An alien is ineligible for...

  3. 8 CFR 236.13 - Ineligible aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Ineligible aliens. 236.13 Section 236.13 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED Family Unity Program §...

  4. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  5. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  6. 8 CFR 236.13 - Ineligible aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Ineligible aliens. 236.13 Section 236.13 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED Family Unity Program §...

  7. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  8. 8 CFR 236.13 - Ineligible aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Ineligible aliens. 236.13 Section 236.13 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED Family Unity Program §...

  9. 8 CFR 244.4 - Ineligible aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Ineligible aliens. 244.4 Section 244.4 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 244.4 Ineligible aliens. An alien is ineligible for...

  10. 8 CFR 236.13 - Ineligible aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Ineligible aliens. 236.13 Section 236.13 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED Family Unity Program §...

  11. 8 CFR 236.13 - Ineligible aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Ineligible aliens. 236.13 Section 236.13 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED Family Unity Program §...

  12. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  13. 8 CFR 244.4 - Ineligible aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Ineligible aliens. 244.4 Section 244.4 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 244.4 Ineligible aliens. An alien is ineligible for...

  14. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  15. 8 CFR 244.4 - Ineligible aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Ineligible aliens. 244.4 Section 244.4 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 244.4 Ineligible aliens. An alien is ineligible for...

  16. 8 CFR 244.4 - Ineligible aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Ineligible aliens. 244.4 Section 244.4 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 244.4 Ineligible aliens. An alien is ineligible for...

  17. The alien hand syndrome

    PubMed Central

    Panikkath, Deepa; Mojumder, Deb; Nugent, Kenneth

    2014-01-01

    A 77-year-old woman presented with the complaint of observing her left hand moving without her knowledge while watching television. Her left hand stroked her face and hair as if somebody was controlling it. These movements lasted only half an hour but on recovery, she had left hemiparesis. Alien hand syndrome as the presentation of cardioembolic stroke is extremely rare but can be terrifying to patients. PMID:24982566

  18. Captured by Aliens

    NASA Astrophysics Data System (ADS)

    Achenbach, Joel

    2000-03-01

    Captured by Aliens is a long and twisted voyage from science to the supernatural and back again. I hung out in Roswell, N.M., spent time with the Mars Society, met a guy who was figuring out the best way to build a spaceship to go to Alpha Centauri. I visited the set of the X-Files and talked to Mulder and Scully. One day over breakfast I was told by NASA administrator Dan Goldin, We live in a fog, man! He wants the big answers to the big questions. I spent a night in the base of a huge radio telescope in the boondocks of West Virginia, awaiting the signal from the aliens. I was hypnotized in a hotel room by someone who suspected that I'd been abducted by aliens and that this had triggered my interest in the topic. In the last months of his life, I talked to Carl Sagan, who believed that the galaxy riots with intelligent civilizations. He's my hero, for his steadfast adherence to the scientific method. What I found in all this is that the big question that needs immediate attention is not what's out THERE, but what's going on HERE, on Earth, and why we think the way we do, and how we came to be here in the first place.

  19. Alienation, authenticity and the self.

    PubMed

    Rae, Gavin

    2010-01-01

    While many commentators have held that the concept "alienation" is of crucial importance when attempting to understand human existence, others have held that it is an inherently empty concept that we should abandon. In this article, I refute the latters' charge by showing that each conception of "alienation" is underpinned by a normative ontological conception of the preferable, or authentic, self and show that the concept "alienation" has ethical, existential and socio-political uses. From this I conclude that, when properly understood, the concept "alienation" can provide us with vital insights into human existence.

  20. Historical and current introgression in a Mesoamerican hummingbird species complex: a biogeographic perspective

    PubMed Central

    Jiménez, Rosa Alicia

    2016-01-01

    The influence of geologic and Pleistocene glacial cycles might result in morphological and genetic complex scenarios in the biota of the Mesoamerican region. We tested whether berylline, blue-tailed and steely-blue hummingbirds, Amazilia beryllina, Amazilia cyanura and Amazilia saucerottei, show evidence of historical or current introgression as their plumage colour variation might suggest. We also analysed the role of past and present climatic events in promoting genetic introgression and species diversification. We collected mitochondrial DNA (mtDNA) sequence data and microsatellite loci scores for populations throughout the range of the three Amazilia species, as well as morphological and ecological data. Haplotype network, Bayesian phylogenetic and divergence time inference, historical demography, palaeodistribution modelling, and niche divergence tests were used to reconstruct the evolutionary history of this Amazilia species complex. An isolation-with-migration coalescent model and Bayesian assignment analysis were assessed to determine historical introgression and current genetic admixture. mtDNA haplotypes were geographically unstructured, with haplotypes from disparate areas interdispersed on a shallow tree and an unresolved haplotype network. Assignment analysis of the nuclear genome (nuDNA) supported three genetic groups with signs of genetic admixture, corresponding to: (1) A. beryllina populations located west of the Isthmus of Tehuantepec; (2) A. cyanura populations between the Isthmus of Tehuantepec and the Nicaraguan Depression (Nuclear Central America); and (3) A. saucerottei populations southeast of the Nicaraguan Depression. Gene flow and divergence time estimates, and demographic and palaeodistribution patterns suggest an evolutionary history of introgression mediated by Quaternary climatic fluctuations. High levels of gene flow were indicated by mtDNA and asymmetrical isolation-with-migration, whereas the microsatellite analyses found evidence

  1. Historical and current introgression in a Mesoamerican hummingbird species complex: a biogeographic perspective.

    PubMed

    Jiménez, Rosa Alicia; Ornelas, Juan Francisco

    2016-01-01

    The influence of geologic and Pleistocene glacial cycles might result in morphological and genetic complex scenarios in the biota of the Mesoamerican region. We tested whether berylline, blue-tailed and steely-blue hummingbirds, Amazilia beryllina, Amazilia cyanura and Amazilia saucerottei, show evidence of historical or current introgression as their plumage colour variation might suggest. We also analysed the role of past and present climatic events in promoting genetic introgression and species diversification. We collected mitochondrial DNA (mtDNA) sequence data and microsatellite loci scores for populations throughout the range of the three Amazilia species, as well as morphological and ecological data. Haplotype network, Bayesian phylogenetic and divergence time inference, historical demography, palaeodistribution modelling, and niche divergence tests were used to reconstruct the evolutionary history of this Amazilia species complex. An isolation-with-migration coalescent model and Bayesian assignment analysis were assessed to determine historical introgression and current genetic admixture. mtDNA haplotypes were geographically unstructured, with haplotypes from disparate areas interdispersed on a shallow tree and an unresolved haplotype network. Assignment analysis of the nuclear genome (nuDNA) supported three genetic groups with signs of genetic admixture, corresponding to: (1) A. beryllina populations located west of the Isthmus of Tehuantepec; (2) A. cyanura populations between the Isthmus of Tehuantepec and the Nicaraguan Depression (Nuclear Central America); and (3) A. saucerottei populations southeast of the Nicaraguan Depression. Gene flow and divergence time estimates, and demographic and palaeodistribution patterns suggest an evolutionary history of introgression mediated by Quaternary climatic fluctuations. High levels of gene flow were indicated by mtDNA and asymmetrical isolation-with-migration, whereas the microsatellite analyses found evidence

  2. Genomewide Variation in an Introgression Line of Rice-Zizania Revealed by Whole-Genome re-Sequencing

    PubMed Central

    Bai, Yan; Zhang, Yun-Hong; Liu, Ying; Wu, Ying; Lin, Xiu-Yun; Wen, Jia-Wei; Xu, Chun-Ming; Li, Lin-Feng; Liu, Bao

    2013-01-01

    Background Hybridization between genetically diverged organisms is known as an important avenue that drives plant genome evolution. The possible outcomes of hybridization would be the occurrences of genetic instabilities in the resultant hybrids. It remained under-investigated however whether pollination by alien pollens of a closely related but sexually "incompatible" species could evoke genomic changes and to what extent it may result in phenotypic novelties in the derived progenies. Methodology/Principal Findings In this study, we have re-sequenced the genomes of Oryza sativa ssp. japonica cv. Matsumae and one of its derived introgressant RZ35 that was obtained from an introgressive hybridization between Matsumae and Zizanialatifolia Griseb. in general, 131 millions 90 base pair (bp) paired-end reads were generated which covered 13.2 and 21.9 folds of the Matsumae and RZ35 genomes, respectively. Relative to Matsumae, a total of 41,724 homozygous single nucleotide polymorphisms (SNPs) and 17,839 homozygous insertions/deletions (indels) were identified in RZ35, of which 3,797 SNPs were nonsynonymous mutations. Furthermore, rampant mobilization of transposable elements (TEs) was found in the RZ35 genome. The results of pathogen inoculation revealed that RZ35 exhibited enhanced resistance to blast relative to Matsumae. Notably, one nonsynonymous mutation was found in the known blast resistance gene Pid3/Pi25 and real-time quantitative (q) RT-PCR analysis revealed constitutive up-regulation of its expression, suggesting both altered function and expression of Pid3/Pi25 may be responsible for the enhanced resistance to rice blast by RZ35. Conclusions/Significance Our results demonstrate that introgressive hybridization by Zizania has provoked genomewide, extensive genomic changes in the rice genome, and some of which have resulted in important phenotypic novelties. These findings suggest that introgressive hybridization by alien pollens of even a sexually incompatible

  3. The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and Subspecific introgression in Central America.

    PubMed

    Nunney, Leonard; Ortiz, Beatriz; Russell, Stephanie A; Ruiz Sánchez, Rebeca; Stouthamer, Richard

    2014-01-01

    The bacterium Xylella fastidiosa is a plant pathogen with a history of economically damaging introductions of subspecies to regions where its other subspecies are native. Genetic evidence is presented demonstrating the introduction of two new taxa into Central America and their introgression into the native subspecies, X. fastidiosa subsp. fastidiosa. The data are from 10 genetic outliers detected by multilocus sequence typing (MLST) of isolates from Costa Rica. Six (five from oleander, one from coffee) defined a new sequence type (ST53) that carried alleles at six of the eight loci sequenced (five of the seven MLST loci) diagnostic of the South American subspecies Xylella fastidiosa subsp. pauca which causes two economically damaging plant diseases, citrus variegated chlorosis and coffee leaf scorch. The two remaining loci of ST53 carried alleles from what appears to be a new South American form of X. fastidiosa. Four isolates, classified as X. fastidiosa subsp. fastidiosa, showed a low level of introgression of non-native DNA. One grapevine isolate showed introgression of an allele from X. fastidiosa subsp. pauca while the other three (from citrus and coffee) showed introgression of an allele with similar ancestry to the alleles of unknown origin in ST53. The presence of X. fastidiosa subsp. pauca in Central America is troubling given its disease potential, and establishes another route for the introduction of this economically damaging subspecies into the US or elsewhere, a threat potentially compounded by the presence of a previously unknown form of X. fastidiosa.

  4. Introgression and dispersal among spotted owl (Strix occidentalis) subspecies

    PubMed Central

    Funk, W Chris; Forsman, Eric D; Mullins, Thomas D; Haig, Susan M

    2008-01-01

    Abstract Population genetics plays an increasingly important role in the conservation and management of declining species, particularly for defining taxonomic units. Subspecies are recognized by several conservation organizations and countries and receive legal protection under the US Endangered Species Act (ESA). Two subspecies of spotted owls, northern (Strix occidentalis caurina) and Mexican (S. o. lucida) spotted owls, are ESA-listed as threatened, but the California (S. o. occidentalis) spotted owl is not listed. Thus, determining the boundaries of these subspecies is critical for effective enforcement of the ESA. We tested the validity of previously recognized spotted owl subspecies by analysing 394 spotted owls at 10 microsatellite loci. We also tested whether northern and California spotted owls hybridize as suggested by previous mitochondrial DNA studies. Our results supported current recognition of three subspecies. We also found bi-directional hybridization and dispersal between northern and California spotted owls centered in southern Oregon and northern California. Surprisingly, we also detected introgression of Mexican spotted owls into the range of northern spotted owls, primarily in the northern part of the subspecies’ range in Washington, indicating long-distance dispersal of Mexican spotted owls. We conclude with a discussion of the conservation implications of our study. PMID:25567499

  5. Molecular evidence for the introgression between Hylobates lar and H. pileatus in the wild.

    PubMed

    Matsudaira, Kazunari; Reichard, Ulrich H; Malaivijitnond, Suchinda; Ishida, Takafumi

    2013-01-01

    Inter-specific hybrid zones for Hylobates gibbons are known in Southeast Asia. Among these, one hybrid zone between Hylobates lar and H. pileatus is located in Khao Yai National Park, Thailand. To find molecular evidence for the natural hybridization of the gibbons in this region, we studied mitochondrial DNA (mtDNA) of 68 gibbons of the H. lar phenotype living adjacent to the hybrid zone. Nucleotide sequencing of a fragment of mtDNA spanning hyper variable segment I showed that nine gibbons had an mtDNA haplotype of H. pileatus, and that seven of these nine gibbons belonged to a single maternal lineage over three generations. It is thus confirmed that introgression between H. lar and H. pileatus exists and the initial hybridization took place ages ago.

  6. Evidence for historical introgression along a contact zone between two species of char (Pisces: Salmonidae) in northwestern North America.

    PubMed

    Redenbach, Z; Taylor, Eric B

    2002-05-01

    Phylogeographic analyses can yield valuable insights into the geographic and historical contexts of contact and hybridization between taxa. Two species of char (Salmonidae), Dolly Varden (Salvelinus malma) and bull trout (S. confluentus) have largely parapatric distributions in watersheds of northwestern North America. They are, however, sympatric in several localities and hybridization and some introgression occurs across a broad area of contact. We conducted a comparative phylogenetic analysis of Dolly Varden and bull trout to gain a historical perspective of hybridization between these species and to test for footprints of historical introgression. We resolved two major Dolly Varden mitochondrial DNA (mtDNA) clades (with 1.4-2.2% sequence divergence between haplotypes) that had different geographical distributions. Clade N is distributed across most of the range of Dolly Varden, from southern British Columbia through to the Kuril Islands in Asia. Clade S had a much more limited distribution, from Washington state, at the southern limit of the Dolly Varden range, to the middle of Vancouver Island. The distribution and inferred ages of the mtDNA clades suggested that Dolly Varden survived the Wisconsinan glaciation in a previously unsuspected refuge south of the ice sheet, and that Dolly Varden and bull trout were probably in continuous contact over most of the last 100,000 years. When bull trout were included in the phylogenetic analysis, however, the mtDNA of neither species was monophyletic: Clade S Dolly Varden clustered within the bull trout mtDNA clade. This pattern was discordant with two nuclear phylogenies produced (growth hormone 2 and rRNA internal transcribed sequence 1), in which Dolly Varden and bull trout were reciprocally monophyletic. This discordance between mtDNA- and nDNA-based phylogenies indicates that historical introgression of bull trout mtDNA into Dolly Varden occurred. Percent sequence divergence within these introgressed Dolly Varden

  7. Adaptive introgression across species boundaries in Heliconius butterflies.

    PubMed

    Pardo-Diaz, Carolina; Salazar, Camilo; Baxter, Simon W; Merot, Claire; Figueiredo-Ready, Wilsea; Joron, Mathieu; McMillan, W Owen; Jiggins, Chris D

    2012-01-01

    It is widely documented that hybridisation occurs between many closely related species, but the importance of introgression in adaptive evolution remains unclear, especially in animals. Here, we have examined the role of introgressive hybridisation in transferring adaptations between mimetic Heliconius butterflies, taking advantage of the recent identification of a gene regulating red wing patterns in this genus. By sequencing regions both linked and unlinked to the red colour locus, we found a region that displays an almost perfect genotype by phenotype association across four species, H. melpomene, H. cydno, H. timareta, and H. heurippa. This particular segment is located 70 kb downstream of the red colour specification gene optix, and coalescent analysis indicates repeated introgression of adaptive alleles from H. melpomene into the H. cydno species clade. Our analytical methods complement recent genome scale data for the same region and suggest adaptive introgression has a crucial role in generating adaptive wing colour diversity in this group of butterflies.

  8. Adaptive Introgression across Species Boundaries in Heliconius Butterflies

    PubMed Central

    Pardo-Diaz, Carolina; Salazar, Camilo; Baxter, Simon W.; Merot, Claire; Figueiredo-Ready, Wilsea; Joron, Mathieu; McMillan, W. Owen; Jiggins, Chris D.

    2012-01-01

    It is widely documented that hybridisation occurs between many closely related species, but the importance of introgression in adaptive evolution remains unclear, especially in animals. Here, we have examined the role of introgressive hybridisation in transferring adaptations between mimetic Heliconius butterflies, taking advantage of the recent identification of a gene regulating red wing patterns in this genus. By sequencing regions both linked and unlinked to the red colour locus, we found a region that displays an almost perfect genotype by phenotype association across four species, H. melpomene, H. cydno, H. timareta, and H. heurippa. This particular segment is located 70 kb downstream of the red colour specification gene optix, and coalescent analysis indicates repeated introgression of adaptive alleles from H. melpomene into the H. cydno species clade. Our analytical methods complement recent genome scale data for the same region and suggest adaptive introgression has a crucial role in generating adaptive wing colour diversity in this group of butterflies. PMID:22737081

  9. Desperately seeking aliens.

    PubMed

    Aldiss, B W

    2001-02-22

    Belief that intelligent life is commonplace in the Universe was taken for granted by scholars and scientists until well into the nineteenth century. Space travel since the late 1950s reignited the debate, which even now attracts discussion by serious, professional scientists. And although statisticians might lobby that life must surely exist somewhere in the Universe, the evolution of what we perceive as 'intelligent life' seems utterly improbable--elsewhere as well as on Earth. Can we free ourselves of our animist fantasies and accept that all alien forms of intelligent life are, and always have been, imaginary?

  10. Desperately seeking aliens

    NASA Astrophysics Data System (ADS)

    Aldiss, Brian W.

    2001-02-01

    Belief that intelligent life is commonplace in the Universe was taken for granted by scholars and scientists until well into the nineteenth century. Space travel since the late 1950s reignited the debate, which even now attracts discussion by serious, professional scientists. And although statisticians might lobby that life must surely exist somewhere in the Universe, the evolution of what we perceive as 'intelligent life' seems utterly improbable - elsewhere as well as on Earth. Can we free ourselves of our animist fantasies and accept that all alien forms of intelligent life are, and always have been, imaginary?

  11. Monitoring an Alien Invasion: DNA Barcoding and the Identification of Lionfish and Their Prey on Coral Reefs of the Mexican Caribbean

    PubMed Central

    Valdez-Moreno, Martha; Quintal-Lizama, Carolina; Gómez-Lozano, Ricardo; García-Rivas, María del Carmen

    2012-01-01

    Background In the Mexican Caribbean, the exotic lionfish Pterois volitans has become a species of great concern because of their predatory habits and rapid expansion onto the Mesoamerican coral reef, the second largest continuous reef system in the world. This is the first report of DNA identification of stomach contents of lionfish using the barcode of life reference database (BOLD). Methodology/Principal Findings We confirm with barcoding that only Pterois volitans is apparently present in the Mexican Caribbean. We analyzed the stomach contents of 157 specimens of P. volitans from various locations in the region. Based on DNA matches in the Barcode of Life Database (BOLD) and GenBank, we identified fishes from five orders, 14 families, 22 genera and 34 species in the stomach contents. The families with the most species represented were Gobiidae and Apogonidae. Some prey taxa are commercially important species. Seven species were new records for the Mexican Caribbean: Apogon mosavi, Coryphopterus venezuelae, C. thrix, C. tortugae, Lythrypnus minimus, Starksia langi and S. ocellata. DNA matches, as well as the presence of intact lionfish in the stomach contents, indicate some degree of cannibalism, a behavior confirmed in this species by the first time. We obtained 45 distinct crustacean prey sequences, from which only 20 taxa could be identified from the BOLD and GenBank databases. The matches were primarily to Decapoda but only a single taxon could be identified to the species level, Euphausia americana. Conclusions/Significance This technique proved to be an efficient and useful method, especially since prey species could be identified from partially-digested remains. The primary limitation is the lack of comprehensive coverage of potential prey species in the region in the BOLD and GenBank databases, especially among invertebrates. PMID:22675470

  12. Alienation and the Negotiation Process.

    ERIC Educational Resources Information Center

    Adams, Charles F.

    The author makes three assumptions in discussing the effect of collective negotiations on teachers' sense of alienation: first, alienation is a multidimensional concept that, in this context, is taken to derive from within the organizational setting of the school system; second, school systems are organized as bureaucracies containing more or less…

  13. Characteristics of successful alien plants.

    PubMed

    van Kleunen, M; Dawson, W; Maurel, N

    2015-05-01

    Herbert Baker arguably initiated the search for species characteristics determining alien plant invasion success, with his formulation of the 'ideal weed'. Today, a profusion of studies has tested a myriad of traits for their importance in explaining success of alien plants, but the multiple, not always appropriate, approaches used have led to some confusion and criticism. We argue that a greater understanding of the characteristics explaining alien plant success requires a refined approach that respects the multistage, multiscale nature of the invasion process. We present a schema of questions we can ask regarding the success of alien species, with the answering of one question in the schema being conditional on the answer of preceding questions (thus acknowledging the nested nature of invasion stages). For each question, we identify traits and attributes of species we believe are likely to be most important in explaining species success, and we make predictions as to how we expect successful aliens to differ from natives and from unsuccessful aliens in their characteristics. We organize the findings of empirical studies according to the questions in our schema that they have addressed, to assess the extent to which they support our predictions. We believe that research on plant traits of alien species has already told us a lot about why some alien species become successful after introduction. However, if we ask the right questions at the appropriate scale and use appropriate comparators, research on traits may tell us whether they are really important or not, and if so under which conditions.

  14. Extensive trans-species mitochondrial polymorphisms in the carabid beetles Carabus subgenus Ohomopterus caused by repeated introgressive hybridization.

    PubMed

    Sota, T; Ishikawa, R; Ujiie, M; Kusumoto, F; Vogler, A P

    2001-12-01

    To study the potential importance of introgressive hybridization to the evolutionary diversification of a carabid beetle lineage, we studied intraspecific and trans-species polymorphisms in the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequence (1083 bp) in four species of the subgenus Ohomopterus (genus Carabus) in central and eastern Honshu, Japan. Of the four species, C. insulicola is parapatric with the other three, and can hybridize naturally with at least two. This species possesses two haplotypes of remote lineages. We classified ND5 haplotypes using polymerase chain reaction-restriction fragment length polymorphism with TaqI endonuclease for 524 specimens, and sequenced 143 samples. Analysis revealed that each species was polyphyletic in its mitochondrial DNA phylogeny, representing a marked case of trans-species polymorphism. Recent one-way introgression of mitochondria from C. arrowianus nakamurai to C. insulicola, and from C. insulicola to C. esakii, was inferred from the frequency of identical sequences between these species and from direct evidence of hybridization in their contact zones. Other intraspecific polymorphisms in the four species may be due to undetected introgressive hybridization (e.g. C. insulicola to C. maiyasanus) or from stochastic lineage sorting of ancestral polymorphisms. This beetle group has a genital lock-and-key system, with species-specific or subspecies-specific genital morphology that may act as a barrier to hybridization. However, our results demonstrate that introgressive hybridization has occurred multiple times, at least for mitochondria, despite differences among, and stability within, morphological characters that distinguish local populations. Thus, hybridization and introgression could have been key processes in the evolutionary diversification of Ohomopterus.

  15. Crossability of Triticum urartu and Triticum monococcum Wheats, Homoeologous Recombination, and Description of a Panel of Interspecific Introgression Lines

    PubMed Central

    Fricano, Agostino; Brandolini, Andrea; Rossini, Laura; Sourdille, Pierre; Wunder, Joerg; Effgen, Sigi; Hidalgo, Alyssa; Erba, Daniela; Piffanelli, Pietro; Salamini, Francesco

    2014-01-01

    Triticum monococcum (genome Am) and T. urartu (genome Au) are diploid wheats, with the first having been domesticated in the Neolithic Era and the second being a wild species. In a germplasm collection, rare wild T. urartu lines with the presence of T. monococcum alleles were found. This stimulated our interest to develop interspecific introgression lines of T. urartu in T. monococcum, a breeding tool currently implemented in several crop species. Moreover, the experiments reported were designed to reveal the existence in nature of Am/Au intermediate forms and to clarify whether the two species are at least marginally sexually compatible. From hand-made interspecific crosses, almost-sterile F1 plants were obtained when the seed-bearing parent was T. monococcum. A high degree of fertility was, however, evident in some advanced generations, particularly when T. urartu donors were molecularly more related to T. monococcum. Analysis of the marker populations demonstrated chromosome pairing and recombination in F1 hybrid plants. Forty-six introgression lines were developed using a line of T. monococcum with several positive agronomic traits as a recurrent parent. Microsatellite markers were tested on Au and Am genomes, ordered in a T. monococcum molecular map, and used to characterize the exotic DNA fragments present in each introgression line. In a test based on 28 interspecific introgression lines, the existence of genetic variation associated with T. urartu chromosome fragments was proven for the seed content of carotenoids, lutein, β-cryptoxanthin, and zinc. The molecular state of available introgression lines is summarized. PMID:25147190

  16. Crossability of Triticum urartu and Triticum monococcum wheats, homoeologous recombination, and description of a panel of interspecific introgression lines.

    PubMed

    Fricano, Agostino; Brandolini, Andrea; Rossini, Laura; Sourdille, Pierre; Wunder, Joerg; Effgen, Sigi; Hidalgo, Alyssa; Erba, Daniela; Piffanelli, Pietro; Salamini, Francesco

    2014-08-21

    Triticum monococcum (genome A(m)) and T. urartu (genome A(u)) are diploid wheats, with the first having been domesticated in the Neolithic Era and the second being a wild species. In a germplasm collection, rare wild T. urartu lines with the presence of T. monococcum alleles were found. This stimulated our interest to develop interspecific introgression lines of T. urartu in T. monococcum, a breeding tool currently implemented in several crop species. Moreover, the experiments reported were designed to reveal the existence in nature of A(m)/A(u) intermediate forms and to clarify whether the two species are at least marginally sexually compatible. From hand-made interspecific crosses, almost-sterile F1 plants were obtained when the seed-bearing parent was T. monococcum. A high degree of fertility was, however, evident in some advanced generations, particularly when T. urartu donors were molecularly more related to T. monococcum. Analysis of the marker populations demonstrated chromosome pairing and recombination in F1 hybrid plants. Forty-six introgression lines were developed using a line of T. monococcum with several positive agronomic traits as a recurrent parent. Microsatellite markers were tested on A(u) and A(m) genomes, ordered in a T. monococcum molecular map, and used to characterize the exotic DNA fragments present in each introgression line. In a test based on 28 interspecific introgression lines, the existence of genetic variation associated with T. urartu chromosome fragments was proven for the seed content of carotenoids, lutein, β-cryptoxanthin, and zinc. The molecular state of available introgression lines is summarized.

  17. 28 CFR 21.3 - Aliens.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Aliens. 21.3 Section 21.3 Judicial Administration DEPARTMENT OF JUSTICE WITNESS FEES § 21.3 Aliens. (a) Aliens entitled to payment of $30 per day. The following aliens are entitled to witness fees and allowances provided in § 21.4: (1)...

  18. 8 CFR 1244.4 - Ineligible aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Ineligible aliens. 1244.4 Section 1244.4 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.4 Ineligible aliens. An...

  19. 28 CFR 21.3 - Aliens.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Aliens. 21.3 Section 21.3 Judicial Administration DEPARTMENT OF JUSTICE WITNESS FEES § 21.3 Aliens. (a) Aliens entitled to payment of $30 per day. The following aliens are entitled to witness fees and allowances provided in § 21.4: (1)...

  20. 8 CFR 245a.32 - Ineligible aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Ineligible aliens. 245a.32 Section 245a.32 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS ADJUSTMENT OF STATUS TO... IMMIGRATION AND NATIONALITY ACT LIFE Act Amendments Family Unity Provisions § 245a.32 Ineligible aliens....

  1. 8 CFR 1244.4 - Ineligible aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Ineligible aliens. 1244.4 Section 1244.4 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.4 Ineligible aliens. An...

  2. 8 CFR 245a.32 - Ineligible aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Ineligible aliens. 245a.32 Section 245a.32 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS ADJUSTMENT OF STATUS TO... IMMIGRATION AND NATIONALITY ACT LIFE Act Amendments Family Unity Provisions § 245a.32 Ineligible aliens....

  3. 28 CFR 21.3 - Aliens.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Aliens. 21.3 Section 21.3 Judicial Administration DEPARTMENT OF JUSTICE WITNESS FEES § 21.3 Aliens. (a) Aliens entitled to payment of $30 per day. The following aliens are entitled to witness fees and allowances provided in § 21.4: (1)...

  4. 8 CFR 245a.32 - Ineligible aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Ineligible aliens. 245a.32 Section 245a.32 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS ADJUSTMENT OF STATUS TO... IMMIGRATION AND NATIONALITY ACT LIFE Act Amendments Family Unity Provisions § 245a.32 Ineligible aliens....

  5. 28 CFR 21.3 - Aliens.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Aliens. 21.3 Section 21.3 Judicial Administration DEPARTMENT OF JUSTICE WITNESS FEES § 21.3 Aliens. (a) Aliens entitled to payment of $30 per day. The following aliens are entitled to witness fees and allowances provided in § 21.4: (1)...

  6. 8 CFR 245a.32 - Ineligible aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Ineligible aliens. 245a.32 Section 245a.32 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS ADJUSTMENT OF STATUS TO... IMMIGRATION AND NATIONALITY ACT LIFE Act Amendments Family Unity Provisions § 245a.32 Ineligible aliens....

  7. 8 CFR 1244.4 - Ineligible aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Ineligible aliens. 1244.4 Section 1244.4 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.4 Ineligible aliens. An...

  8. 8 CFR 1244.4 - Ineligible aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Ineligible aliens. 1244.4 Section 1244.4 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.4 Ineligible aliens. An...

  9. 8 CFR 245a.32 - Ineligible aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Ineligible aliens. 245a.32 Section 245a.32 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS ADJUSTMENT OF STATUS TO... IMMIGRATION AND NATIONALITY ACT LIFE Act Amendments Family Unity Provisions § 245a.32 Ineligible aliens....

  10. 8 CFR 1244.4 - Ineligible aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Ineligible aliens. 1244.4 Section 1244.4 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.4 Ineligible aliens. An...

  11. 28 CFR 21.3 - Aliens.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Aliens. 21.3 Section 21.3 Judicial Administration DEPARTMENT OF JUSTICE WITNESS FEES § 21.3 Aliens. (a) Aliens entitled to payment of $30 per day. The following aliens are entitled to witness fees and allowances provided in § 21.4: (1)...

  12. The Strength of Selection against Neanderthal Introgression

    PubMed Central

    Juric, Ivan

    2016-01-01

    Hybridization between humans and Neanderthals has resulted in a low level of Neanderthal ancestry scattered across the genomes of many modern-day humans. After hybridization, on average, selection appears to have removed Neanderthal alleles from the human population. Quantifying the strength and causes of this selection against Neanderthal ancestry is key to understanding our relationship to Neanderthals and, more broadly, how populations remain distinct after secondary contact. Here, we develop a novel method for estimating the genome-wide average strength of selection and the density of selected sites using estimates of Neanderthal allele frequency along the genomes of modern-day humans. We confirm that East Asians had somewhat higher initial levels of Neanderthal ancestry than Europeans even after accounting for selection. We find that the bulk of purifying selection against Neanderthal ancestry is best understood as acting on many weakly deleterious alleles. We propose that the majority of these alleles were effectively neutral—and segregating at high frequency—in Neanderthals, but became selected against after entering human populations of much larger effective size. While individually of small effect, these alleles potentially imposed a heavy genetic load on the early-generation human–Neanderthal hybrids. This work suggests that differences in effective population size may play a far more important role in shaping levels of introgression than previously thought. PMID:27824859

  13. The Strength of Selection against Neanderthal Introgression.

    PubMed

    Juric, Ivan; Aeschbacher, Simon; Coop, Graham

    2016-11-01

    Hybridization between humans and Neanderthals has resulted in a low level of Neanderthal ancestry scattered across the genomes of many modern-day humans. After hybridization, on average, selection appears to have removed Neanderthal alleles from the human population. Quantifying the strength and causes of this selection against Neanderthal ancestry is key to understanding our relationship to Neanderthals and, more broadly, how populations remain distinct after secondary contact. Here, we develop a novel method for estimating the genome-wide average strength of selection and the density of selected sites using estimates of Neanderthal allele frequency along the genomes of modern-day humans. We confirm that East Asians had somewhat higher initial levels of Neanderthal ancestry than Europeans even after accounting for selection. We find that the bulk of purifying selection against Neanderthal ancestry is best understood as acting on many weakly deleterious alleles. We propose that the majority of these alleles were effectively neutral-and segregating at high frequency-in Neanderthals, but became selected against after entering human populations of much larger effective size. While individually of small effect, these alleles potentially imposed a heavy genetic load on the early-generation human-Neanderthal hybrids. This work suggests that differences in effective population size may play a far more important role in shaping levels of introgression than previously thought.

  14. The Genomic Signature of Crop-Wild Introgression in Maize

    PubMed Central

    Hufford, Matthew B.; Lubinksy, Pesach; Pyhäjärvi, Tanja; Devengenzo, Michael T.; Ellstrand, Norman C.; Ross-Ibarra, Jeffrey

    2013-01-01

    The evolutionary significance of hybridization and subsequent introgression has long been appreciated, but evaluation of the genome-wide effects of these phenomena has only recently become possible. Crop-wild study systems represent ideal opportunities to examine evolution through hybridization. For example, maize and the conspecific wild teosinte Zea mays ssp. mexicana (hereafter, mexicana) are known to hybridize in the fields of highland Mexico. Despite widespread evidence of gene flow, maize and mexicana maintain distinct morphologies and have done so in sympatry for thousands of years. Neither the genomic extent nor the evolutionary importance of introgression between these taxa is understood. In this study we assessed patterns of genome-wide introgression based on 39,029 single nucleotide polymorphisms genotyped in 189 individuals from nine sympatric maize-mexicana populations and reference allopatric populations. While portions of the maize and mexicana genomes appeared resistant to introgression (notably near known cross-incompatibility and domestication loci), we detected widespread evidence for introgression in both directions of gene flow. Through further characterization of these genomic regions and preliminary growth chamber experiments, we found evidence suggestive of the incorporation of adaptive mexicana alleles into maize during its expansion to the highlands of central Mexico. In contrast, very little evidence was found for adaptive introgression from maize to mexicana. The methods we have applied here can be replicated widely, and such analyses have the potential to greatly inform our understanding of evolution through introgressive hybridization. Crop species, due to their exceptional genomic resources and frequent histories of spread into sympatry with relatives, should be particularly influential in these studies. PMID:23671421

  15. Alien Hand Syndrome.

    PubMed

    Hassan, Anhar; Josephs, Keith A

    2016-08-01

    Alien hand syndrome (AHS) is a rare disorder of involuntary limb movement together with a sense of loss of limb ownership. It most commonly affects the hand, but can occur in the leg. The anterior (frontal, callosal) and posterior variants are recognized, with distinguishing clinical features and anatomical lesions. Initial descriptions were attributed to stroke and neurosurgical operations, but neurodegenerative causes are now recognized as most common. Structural and functional imaging and clinical studies have implicated the supplementary motor area, pre-supplementary motor area, and their network connections in the frontal variant of AHS, and the inferior parietal lobule and connections in the posterior variant. Several theories are proposed to explain the pathophysiology. Herein, we review the literature to update advances in the understanding of the classification, pathophysiology, etiology, and treatment of AHS.

  16. Marker-Assisted Introgression in Backcross Breeding Programs

    PubMed Central

    Visscher, P. M.; Haley, C. S.; Thompson, R.

    1996-01-01

    The efficiency of marker-assisted introgression in backcross populations derived from inbred lines was investigated by simulation. Background genotypes were simulated assuming that a genetic model of many genes of small effects in coupling phase explains the observed breed difference and variance in backcross populations. Markers were efficient in introgression backcross programs for simultaneously introgressing an allele and selecting for the desired genomic background. Using a marker spacing of 10-20 cM gave an advantage of one to two backcross generations selection relative to random or phenotypic selection. When the position of the gene to be introgressed is uncertain, for example because its position was estimated from a trait gene mapping experiment, a chromosome segment should be introgressed that is likely to include the allele of interest. Even for relatively precisely mapped quantitative trait loci, flanking markers or marker haplotypes should cover ~10-20 cM around the estimated position of the gene, to ensure that the allele frequency does not decline in later backcross generations. PMID:8978075

  17. The search for alien life

    NASA Astrophysics Data System (ADS)

    Meyer, M.

    Life on Earth relies exclusively on the complex coordination among DNA, RNA, proteins, and an encompassing cell membrane. This level of complexity has been amenable to new molecular techniques with extreme specificity and sensitivity, enabling spectacular advances in cell biology and microbial ecology. Armed with molecular techniques, the last few decades of research have revealed the surprising extent of life on our own planet, expanding the habitable range of salinity, pressure, temperature, and radiation of our world. Given the relatively recent discoveries about life on Earth, how then can we expect to look for alien life that may use completely different sets of molecules for structure and activity? Astrobiology has taken on the challenge of developing the intellectual basis, target identification, instrument capabilities, and operational procedures for the search for life elsewhere. The research aims to develop general principles of how life maintains itself, how life interacts with its environment, and how the signatures of life may be preserved and recognized. The approach has been to move from the laboratory, to the environment, to robotic exploration of planetary analogs. To date, generic evidence for life can be perceived through life's creation and utilization of disequilibria, multiple uses of a relatively few sets of molecules, a preference for chiral compounds, and a predilection for lighter isotopes. It is through application of life detection instrumentation in environmental extremes that we hope to develop a catalogue of generic biosignatures, robust instrumentation capable of revealing the unexpected, and effective exploration strategies for robotic platforms in the search for signs of life. In 2009, Mars Science Laboratory and ExoMars may be the first beneficiaries of this approach.

  18. Introgression of A- and B-genome of tetraploid triticale chromatin into tetraploid rye.

    PubMed

    Wiśniewska, H; Kwiatek, M; Kulak-Książczyk, S; Apolinarska, B

    2013-11-01

    An improvement of rye is one of the mainstream goals of current breeding. Our study is concerned with the introduction of the tetraploid triticale (ABRR) into the 4x rye (RRRR) using classical methods of distant crossing. One hundred fifty BC1F9 hybrid plants [(4x rye × 4x triticales) × 4x rye] obtained from a backcrossing program were studied. The major aim of this work was to verify the presence of an introgressed A- and B- genome chromatin of triticale in a collection of the 4x rye-tiritcale hybrids and to determine their chromosome compositions. In the present study, karyotypes of the previously reported BC1F2s and BC1F3s were compared with that of the BC1F9 generation as obtained after several subsequent open pollinations. The genomic in situ hybridisation (GISH) allowed us to identify 133 introgression forms in which chromosome numbers ranged between 26 and 32. Using four DNA probes (5S rDNA, 25S rDNA, pSc119.2 and pAs1), the fluorescence in situ hybridisation (FISH) was carried out to facilitate an exact chromosome identification in the hybrid plants. The combination of the multi-colour GISH with the repetitive DNA FISH singled out five types of translocated chromosomes: 2A.2R, 4A.4R, 5A.5R, 5B.5R and 7A.7R among the examined BC1F9s. The reported translocation lines could serve as valuable sources of wheat chromatin suitable for further improvements of rye.

  19. Genetic characterization of hybridization and introgression between anadromous rainbow trout (Oncorhynchus mykiss irideus) and coastal cutthroat trout (O. clarki clarki).

    PubMed

    Young, W P; Ostberg, C O; Keim, P; Thorgaard, G H

    2001-04-01

    Interspecific hybridization represents a dynamic evolutionary phenomenon and major conservation problem in salmonid fishes. In this study we used amplified fragment length polymorphisms (AFLP) and mitochondrial DNA (mtDNA) markers to describe the extent and characterize the pattern of hybridization and introgression between coastal rainbow trout (Oncorhynchus mykiss irideus) and coastal cutthroat trout (O. clarki clarki). Hybrid individuals were initially identified using principle coordinate analysis of 133 polymorphic AFLP markers. Subsequent analysis using 23 diagnostic AFLP markers revealed the presence of F1, rainbow trout backcross, cutthroat trout backcross and later-generation hybrids. mtDNA analysis demonstrated equal numbers of F1 hybrids with rainbow and cutthroat trout mtDNA indicating reciprocal mating of the parental types. In contrast, rainbow and cutthroat trout backcross hybrids always exhibited the mtDNA from the recurrent parent, indicating a male hybrid mating with a pure female. This study illustrates the usefulness of the AFLP technique for generating large numbers of species diagnostic markers. The pattern of hybridization raises many questions concerning the existence and action of reproductive isolating mechanisms between these two species. Our findings are consistent with the hypothesis that introgression between anadromous populations of coastal rainbow and coastal cutthroat trout is limited by an environment-dependent reduction in hybrid fitness.

  20. Genetic characterization of hybridization and introgression between anadromous rainbow trout (oncorhynchus mykiss irideus) and coastal cutthroat trout (o. clarki clarki)

    USGS Publications Warehouse

    Young, W.P.; Ostberg, C.O.; Keim, P.; Thorgaard, G.H.

    2001-01-01

    Interspecific hybridization represents a dynamic evolutionary phenomenon and major conservation problem in salmonid fishes. In this study we used amplified fragment length polymorphisms (AFLP) and mitochondrial DNA (mtDNA) markers to describe the extent and characterize the pattern of hybridization and introgression between coastal rainbow trout (Oncorhynchus mykiss irideus) and coastal cutthroat trout (O. clarki clarki). Hybrid individuals were initially identified using principle coordinate analysis of 133 polymorphic AFLP markers. Subsequent analysis using 23 diagnostic AFLP markers revealed the presence of F1, rainbow trout backcross, cutthroat trout backcross and later-generation hybrids. mtDNA analysis demonstrated equal numbers of F1 hybrids with rainbow and cutthroat trout mtDNA indicating reciprocal mating of the parental types. In contrast, rainbow and cutthroat trout backcross hybrids always exhibited the mtDNA from the recurrent parent, indicating a male hybrid mating with a pure female. This study illustrates the usefulness of the AFLP technique for generating large numbers of species diagnostic markers. The pattern of hybridization raises many questions concerning the existence and action of reproductive isolating mechanisms between these two species. Our findings are consistent with the hypothesis that introgression between anadromous populations of coastal rainbow and coastal cutthroat trout is limited by an environment-dependent reduction in hybrid fitness.

  1. Cytonuclear genetic architecture in mosquitofish populations and the possible roles of introgressive hybridization

    USGS Publications Warehouse

    Scribner, Kim T.; Avise, John C.

    1993-01-01

    Spatial genetic structure in populations of mosquitofish (Gambusia) sampled throughout the south-eastern United States was characterized using mitochondrial (mt) DNA and allozyme markers. Both sets of data revealed a pronounced genetic discontinuity (along a broad path extending from south-eastern Mississippi to north-eastern Georgia) that corresponds to a recently recognized distinction between the nominal forms G. affinis to the west and G. holbrookito the east. However, several populations from the general contact region exhibited unusual allelic associations in high frequency, suggestive of evolutionary processes within a zone of introgressive hybridization. These involve: (i) cytonuclear profiles representing combinations of nuclear and mitochondrial genotypes that tended to be more nearly species-specific and concordant elsewhere; and (ii) significant nuclear gametic disequilibria, perhaps attributable to positive assortative mating and/or differential fitnesses of homospecific vs. recombinant genotypes. However, outside this suspected hybrid region, ‘heterospecific’ genetic markers also appeared in low frequency, thus complicating interpretations. These discordant alleles on a broader geographic scale may reflect: (a) the retention of polymorphisms from an ancestral gene pool; (b) occasional evolutionary convergence (especially with respect to electrophoretic mobility of allozyme alleles); (c) the ‘footprints’ of a moving hybrid zone; or (d) differential introgressive penetrance across the current hybrid region.

  2. Historic hybridization and introgression between two iconic Australian anemonefish and contemporary patterns of population connectivity.

    PubMed

    van der Meer, M H; Jones, G P; Hobbs, J-P A; van Herwerden, L

    2012-07-01

    Endemic species on islands are considered at risk of extinction for several reasons, including limited dispersal abilities, small population sizes, and low genetic diversity. We used mitochondrial DNA (D-Loop) and 17 microsatellite loci to explore the evolutionary relationship between an endemic anemonefish, Amphiprion mccullochi (restricted to isolated locations in subtropical eastern Australia) and its more widespread sister species, A. akindynos. A mitochondrial DNA (mtDNA) phylogram showed reciprocal monophyly was lacking for the two species, with two supported groups, each containing representatives of both species, but no shared haplotypes and up to 12 species, but not location-specific management units (MUs). Population genetic analyses suggested evolutionary connectivity among samples of each species (mtDNA), while ecological connectivity was only evident among populations of the endemic, A. mccullochi. This suggests higher dispersal between endemic anemonefish populations at both evolutionary and ecological timeframes, despite separation by hundreds of kilometers. The complex mtDNA structure results from historical hybridization and introgression in the evolutionary past of these species, validated by msat analyses (NEWHYBRIDS, STRUCTURE, and DAPC). Both species had high genetic diversities (mtDNA h > 0.90, π = 4.0%; msat genetic diversity, gd > 0.670). While high gd and connectivity reduce extinction risk, identifying and protecting populations implicated in generating reticulate structure among these species should be a conservation priority.

  3. A haplotype at STAT2 Introgressed from neanderthals and serves as a candidate of positive selection in Papua New Guinea.

    PubMed

    Mendez, Fernando L; Watkins, Joseph C; Hammer, Michael F

    2012-08-10

    Signals of archaic admixture have been identified through comparisons of the draft Neanderthal and Denisova genomes with those of living humans. Studies of individual loci contributing to these genome-wide average signals are required for characterization of the introgression process and investigation of whether archaic variants conferred an adaptive advantage to the ancestors of contemporary human populations. However, no definitive case of adaptive introgression has yet been described. Here we provide a DNA sequence analysis of the innate immune gene STAT2 and show that a haplotype carried by many Eurasians (but not sub-Saharan Africans) has a sequence that closely matches that of the Neanderthal STAT2. This haplotype, referred to as N, was discovered through a resequencing survey of the entire coding region of STAT2 in a global sample of 90 individuals. Analyses of publicly available complete genome sequence data show that haplotype N shares a recent common ancestor with the Neanderthal sequence (~80 thousand years ago) and is found throughout Eurasia at an average frequency of ~5%. Interestingly, N is found in Melanesian populations at ~10-fold higher frequency (~54%) than in Eurasian populations. A neutrality test that controls for demography rejects the hypothesis that a variant of N rose to high frequency in Melanesia by genetic drift alone. Although we are not able to pinpoint the precise target of positive selection, we identify nonsynonymous mutations in ERBB3, ESYT1, and STAT2-all of which are part of the same 250 kb introgressive haplotype-as good candidates.

  4. Reintroduction of a Homocysteine Level-Associated Allele into East Asians by Neanderthal Introgression.

    PubMed

    Hu, Ya; Ding, Qiliang; He, Yungang; Xu, Shuhua; Jin, Li

    2015-12-01

    In this study, we present an analysis of Neanderthal introgression at the dipeptidase 1 gene, DPEP1. A Neanderthal origin for the putative introgressive haplotypes was demonstrated using an established three-step approach. This introgression was under positive natural selection, reached a frequency of >50%, and introduced a homocysteine level- and pigmentation-associated allele (rs460879-T) into East Asians. However, the same allele was also found in non-East Asians, but not from Neanderthal introgression. It is likely that rs460879-T was lost in East Asians and was reintroduced subsequently through Neanderthal introgression. Our findings suggest that Neanderthal introgression could reintroduce an important previously existing allele into populations where the allele had been lost. This study sheds new light on understanding the contribution of Neanderthal introgression to the adaptation of non-Africans.

  5. 8 CFR 1214.2 - Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration proceedings. 1214.2 Section 1214.2 Aliens and... NONIMMIGRANT CLASSES § 1214.2 Review of alien victims of severe forms of trafficking in persons; aliens...

  6. 8 CFR 1214.2 - Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration proceedings. 1214.2 Section 1214.2 Aliens and... NONIMMIGRANT CLASSES § 1214.2 Review of alien victims of severe forms of trafficking in persons; aliens...

  7. 8 CFR 1214.2 - Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration proceedings. 1214.2 Section 1214.2 Aliens and... NONIMMIGRANT CLASSES § 1214.2 Review of alien victims of severe forms of trafficking in persons; aliens...

  8. 8 CFR 1214.2 - Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration proceedings. 1214.2 Section 1214.2 Aliens and... NONIMMIGRANT CLASSES § 1214.2 Review of alien victims of severe forms of trafficking in persons; aliens...

  9. 8 CFR 1214.2 - Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Review of alien victims of severe forms of trafficking in persons; aliens in pending immigration proceedings. 1214.2 Section 1214.2 Aliens and... NONIMMIGRANT CLASSES § 1214.2 Review of alien victims of severe forms of trafficking in persons; aliens...

  10. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    PubMed

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach.

  11. Graffiti and "Film School" Culture: Displaying Alienation.

    ERIC Educational Resources Information Center

    Scheibel, Dean

    1994-01-01

    Examines graffiti created by students in "film school" as an organizational document. Finds themes related to alienation and the discourse that counters the sources of that alienation. Shows how the humorous communicative style of graffiti creates tension among cultural meanings that mediates between alienation and liberation. (SR)

  12. 43 CFR 3102.2 - Aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Aliens. 3102.2 Section 3102.2 Public Lands... INTERIOR MINERALS MANAGEMENT (3000) OIL AND GAS LEASING Qualifications of Lessees § 3102.2 Aliens. Leases or interests therein may be acquired and held by aliens only through stock ownership, holding...

  13. 22 CFR 62.27 - Alien physicians.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Alien physicians. 62.27 Section 62.27 Foreign... Provisions § 62.27 Alien physicians. (a) Purpose. Pursuant to the Mutual Educational and Cultural Exchange... Foreign Medical Graduates must sponsor alien physicians who wish to pursue programs of graduate...

  14. 22 CFR 62.27 - Alien physicians.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Alien physicians. 62.27 Section 62.27 Foreign... Provisions § 62.27 Alien physicians. (a) Purpose. Pursuant to the Mutual Educational and Cultural Exchange... Foreign Medical Graduates must sponsor alien physicians who wish to pursue programs of graduate...

  15. 33 CFR 125.25 - Aliens.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Aliens. 125.25 Section 125.25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) WATERFRONT....25 Aliens. Alien registration records together with other papers and documents which indicated...

  16. 22 CFR 62.27 - Alien physicians.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Alien physicians. 62.27 Section 62.27 Foreign... Provisions § 62.27 Alien physicians. (a) Purpose. Pursuant to the Mutual Educational and Cultural Exchange... Foreign Medical Graduates must sponsor alien physicians who wish to pursue programs of graduate...

  17. 33 CFR 125.25 - Aliens.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Aliens. 125.25 Section 125.25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) WATERFRONT....25 Aliens. Alien registration records together with other papers and documents which indicated...

  18. 33 CFR 125.25 - Aliens.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Aliens. 125.25 Section 125.25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) WATERFRONT....25 Aliens. Alien registration records together with other papers and documents which indicated...

  19. 43 CFR 3102.2 - Aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Aliens. 3102.2 Section 3102.2 Public Lands... INTERIOR MINERALS MANAGEMENT (3000) OIL AND GAS LEASING Qualifications of Lessees § 3102.2 Aliens. Leases or interests therein may be acquired and held by aliens only through stock ownership, holding...

  20. 33 CFR 125.25 - Aliens.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Aliens. 125.25 Section 125.25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) WATERFRONT....25 Aliens. Alien registration records together with other papers and documents which indicated...

  1. 33 CFR 125.25 - Aliens.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Aliens. 125.25 Section 125.25 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) WATERFRONT....25 Aliens. Alien registration records together with other papers and documents which indicated...

  2. 43 CFR 3102.2 - Aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Aliens. 3102.2 Section 3102.2 Public Lands... INTERIOR MINERALS MANAGEMENT (3000) OIL AND GAS LEASING Qualifications of Lessees § 3102.2 Aliens. Leases or interests therein may be acquired and held by aliens only through stock ownership, holding...

  3. Adolescent Alienation: Assessment and Application.

    ERIC Educational Resources Information Center

    Fetro, Joyce V.

    Adolescents struggle to establish their own identities and become independent in making the transition from childhood to adulthood. Adolescent alienation can result from changes in family structure from traditional two-parent families to one-parent families, decreased family stability, increased mobility of society, population increases,…

  4. The Mexican "Illegal Alien" Commute.

    ERIC Educational Resources Information Center

    Decker, Phil

    1986-01-01

    A photo report of the following three treks by illegal aliens across the border from Mexico to work in Arizona reveals the dangers and disappointments the migrants are exposed to: (1) a "carpool" from Southern Mexico; (2) a train ride from Sinaloa; and (3) a 40-mile hike through the Arizona desert. (PS)

  5. Can we Communicate with Aliens?

    NASA Astrophysics Data System (ADS)

    Csányi, V.; Kampis, Gy.

    The subject of this paper is: what answer can be given if the aliens are neither animals nor humans of an unknown culture, but specimens of an extraterrestrial intelligence? If we generalize this question, we may ask, how and to what extent is communication possible among intelligent beings?

  6. ALIENS IN WESTERN STREAM ECOSYSTEMS

    EPA Science Inventory

    The USEPA's Environmental Monitoring and Assessment Program conducted a five year probability sample of permanent mapped streams in 12 western US states. The study design enables us to determine the extent of selected riparian invasive plants, alien aquatic vertebrates, and some ...

  7. Population structure of honey bees in the Carpathian Basin (Hungary) confirms introgression from surrounding subspecies.

    PubMed

    Péntek-Zakar, Erika; Oleksa, Andrzej; Borowik, Tomasz; Kusza, Szilvia

    2015-12-01

    Carniolan honey bees (Apis mellifera carnica) are considered as an indigenous subspecies in Hungary adapted to most of the ecological and climatic conditions in this area. However, during the last decades Hungarian beekeepers have recognized morphological signs of the Italian honey bee (Apis mellifera ligustica). As the natural distribution of the honey bee subspecies can be affected by the importation of honey bee queens or by natural gene flow, we aimed at determining the genetic structure and characteristics of the local honey bee population using molecular markers. All together, 48 Hungarian and 84 foreign (Italian, Polish, Spanish, Liberian) pupae and/or workers were used for mitochondrial DNA analysis. Additionally, 53 sequences corresponding to 10 subspecies and the Buckfast hybrid were downloaded from GenBank. For the nuclear analysis, 236 Hungarian and 106 foreign honey bees were genotyped using nine microsatellites. Heterozygosity values, population-specific alleles, FST values, principal coordinate analysis, assignment tests, structure analysis, and dendrograms were calculated. Haplotype and nucleotide diversity values showed moderate values. We found that one haplotype (H9) was dominant in Hungary. The presence of the black honey bee (Apis mellifera mellifera) was negligible, but a few individuals resembling other subspecies were identified. We proved that the Hungarian honey bee population is nearly homogeneous but also demonstrated introgression from the foreign subspecies. Both mitochondrial DNA and microsatellite analyses corroborated the observations of the beekeepers. Molecular analyses suggested that Carniolan honey bee in Hungary is slightly affected by Italian and black honey bee introgression. Genetic differences were detected between Polish and Hungarian Carniolan honey bee populations, suggesting the existence of at least two different gene pools within A. m. carnica.

  8. Introgressive Hybridization and the Evolution of Lake-Adapted Catostomid Fishes

    PubMed Central

    Dowling, Thomas E.; Markle, Douglas F.; Tranah, Greg J.; Carson, Evan W.; Wagman, David W.; May, Bernard P.

    2016-01-01

    Hybridization has been identified as a significant factor in the evolution of plants as groups of interbreeding species retain their phenotypic integrity despite gene exchange among forms. Recent studies have identified similar interactions in animals; however, the role of hybridization in the evolution of animals has been contested. Here we examine patterns of gene flow among four species of catostomid fishes from the Klamath and Rogue rivers using molecular and morphological traits. Catostomus rimiculus from the Rogue and Klamath basins represent a monophyletic group for nuclear and morphological traits; however, the Klamath form shares mtDNA lineages with other Klamath Basin species (C. snyderi, Chasmistes brevirostris, Deltistes luxatus). Within other Klamath Basin taxa, D. luxatus was largely fixed for alternate nuclear alleles relative to C. rimiculus, while Ch. brevirostris and C. snyderi exhibited a mixture of these alleles. Deltistes luxatus was the only Klamath Basin species that exhibited consistent covariation of nuclear and mitochondrial traits and was the primary source of mismatched mtDNA in Ch. brevirostris and C. snyderi, suggesting asymmetrical introgression into the latter species. In Upper Klamath Lake, D. luxatus spawning was more likely to overlap spatially and temporally with C. snyderi and Ch. brevirostris than either of those two with each other. The latter two species could not be distinguished with any molecular markers but were morphologically diagnosable in Upper Klamath Lake, where they were largely spatially and temporally segregated during spawning. We examine parallel evolution and syngameon hypotheses and conclude that observed patterns are most easily explained by introgressive hybridization among Klamath Basin catostomids. PMID:26959681

  9. Searching for Alien Life Having Unearthly Biochemistry

    NASA Technical Reports Server (NTRS)

    Jones, Harry

    2003-01-01

    The search for alien life in the solar system should include exploring unearth-like environments for life having an unearthly biochemistry. We expect alien life to conform to the same basic chemical and ecological constraints as terrestrial life, since inorganic chemistry and the laws of ecosystems appear to be universal. Astrobiologists usually assume alien life will use familiar terrestrial biochemistry and therefore hope to find alien life by searching near water or by supplying hydrocarbons. The assumption that alien life is likely to be based on carbon and water is traditional and plausible. It justifies high priority for missions to search for alien life on Mars and Europa, but it unduly restricts the search for alien life. Terrestrial carbon-water biochemistry is not possible on most of the bodies of our solar system, but all alien life is not necessarily based on terrestrial biochemistry. If alien life has a separate origin from Earth life, and if can survive in an environment extremely different from Earth's, then alien life may have unearthly biochemistry. There may be other solvents than water that support alien life and other elements than carbon that form complex life enabling chain molecules. Rather than making the exploration-restricting assumption that all life requires carbon, water, and terrestrial biochemistry, we should make the exploration-friendly assumption that indigenous, environmentally adapted, alien life forms might flourish using unearthly biochemistry in many places in the solar system. Alien life might be found wherever there is free energy and a physical/chemical system capable of using that energy to build living structures. Alien life may be discovered by the detection of some general non-equilibrium chemistry rather than of terrestrial biochemistry. We should explore all the potential abodes of life in the solar system, including those where life based on terrestrial biochemistry can not exist.

  10. Hybridization between alien species Rumex obtusifolius and closely related native vulnerable species R. longifolius in a mountain tourist destination

    PubMed Central

    Takahashi, Koichi; Hanyu, Masaaki

    2015-01-01

    Alien species expand their distribution by transportation network development. Hybridization between alien species Rumex obtusifolius and closely related native vulnerable species R. longifolius was examined in a mountain tourist destination in central Japan. The three taxa were morphologically identified in the field. Stem height and leaf area were greater in R. longifolius than R. obtusifolius; hybrids were intermediate between the two Rumex species. R. longifolius and the hybrids grew mainly in wet land and the river tributary; R. obtusifolius grew mainly at the roadside and in meadows. Hybrid germination rates of pollen and seeds were much lower than for the two Rumex species. Clustering analysis showed the three taxa each formed a cluster. Most hybrids were F1 generation; the possibility was low of introgression into the two Rumex species by backcross. This study clarified that (1) hybridization occurred between R. obtusifolius and R. longifolius because they occurred together in a small area, but grew in different water habitat conditions, and (2) hybridization was mostly F1 generation because hybrid pollen and seed fertility was low. However, we need caution about introgression into R. longifolius by R. obtusifolius in this area because of the slight possibility of F2 generation and backcrosses. PMID:26354180

  11. Hybridization between alien species Rumex obtusifolius and closely related native vulnerable species R. longifolius in a mountain tourist destination.

    PubMed

    Takahashi, Koichi; Hanyu, Masaaki

    2015-09-10

    Alien species expand their distribution by transportation network development. Hybridization between alien species Rumex obtusifolius and closely related native vulnerable species R. longifolius was examined in a mountain tourist destination in central Japan. The three taxa were morphologically identified in the field. Stem height and leaf area were greater in R. longifolius than R. obtusifolius; hybrids were intermediate between the two Rumex species. R. longifolius and the hybrids grew mainly in wet land and the river tributary; R. obtusifolius grew mainly at the roadside and in meadows. Hybrid germination rates of pollen and seeds were much lower than for the two Rumex species. Clustering analysis showed the three taxa each formed a cluster. Most hybrids were F1 generation; the possibility was low of introgression into the two Rumex species by backcross. This study clarified that (1) hybridization occurred between R. obtusifolius and R. longifolius because they occurred together in a small area, but grew in different water habitat conditions, and (2) hybridization was mostly F1 generation because hybrid pollen and seed fertility was low. However, we need caution about introgression into R. longifolius by R. obtusifolius in this area because of the slight possibility of F2 generation and backcrosses.

  12. Sexual selection drives asymmetric introgression in wall lizards.

    PubMed

    While, Geoffrey M; Michaelides, Sozos; Heathcote, Robert J P; MacGregor, Hannah E A; Zajac, Natalia; Beninde, Joscha; Carazo, Pau; Pérez I de Lanuza, Guillem; Sacchi, Roberto; Zuffi, Marco A L; Horváthová, Terézia; Fresnillo, Belén; Schulte, Ulrich; Veith, Michael; Hochkirch, Axel; Uller, Tobias

    2015-12-01

    Hybridisation is increasingly recognised as an important cause of diversification and adaptation. Here, we show how divergence in male secondary sexual characters between two lineages of the common wall lizard (Podarcis muralis) gives rise to strong asymmetries in male competitive ability and mating success, resulting in asymmetric hybridisation upon secondary contact. Combined with no negative effects of hybridisation on survival or reproductive characters in F1-hybrids, these results suggest that introgression should be asymmetric, resulting in the displacement of sexual characters of the sub-dominant lineage. This prediction was confirmed in two types of secondary contact, across a natural contact zone and in two introduced populations. Our study illustrates how divergence in sexually selected traits via male competition can determine the direction and extent of introgression, contributing to geographic patterns of genetic and phenotypic diversity.

  13. Source-sink estimates of genetic introgression show influence of hatchery strays on wild chum salmon populations in Prince William Sound, Alaska.

    PubMed

    Jasper, James R; Habicht, Christopher; Moffitt, Steve; Brenner, Rich; Marsh, Jennifer; Lewis, Bert; Creelman Fox, Elisabeth; Grauvogel, Zac; Rogers Olive, Serena D; Grant, W Stewart

    2013-01-01

    The extent to which stray, hatchery-reared salmon affect wild populations is much debated. Although experiments show that artificial breeding and culture influence the genetics of hatchery salmon, little is known about the interaction between hatchery and wild salmon in a natural setting. Here, we estimated historical and contemporary genetic population structures of chum salmon (Oncorhynchus keta) in Prince William Sound (PWS), Alaska, with 135 single nucleotide polymorphism (SNP) markers. Historical population structure was inferred from the analysis of DNA from fish scales, which had been archived since the late 1960's for several populations in PWS. Parallel analyses with microsatellites and a test based on Hardy-Weinberg proportions showed that about 50% of the fish-scale DNA was cross-contaminated with DNA from other fish. These samples were removed from the analysis. We used a novel application of the classical source-sink model to compare SNP allele frequencies in these archived fish-scales (1964-1982) with frequencies in contemporary samples (2008-2010) and found a temporal shift toward hatchery allele frequencies in some wild populations. Other populations showed markedly less introgression, despite moderate amounts of hatchery straying. The extent of introgression may reflect similarities in spawning time and life-history traits between hatchery and wild fish, or the degree that hybrids return to a natal spawning area. The source-sink model is a powerful means of detecting low levels of introgression over several generations.

  14. Transmission ratio distortion results in asymmetric introgression in Louisiana Iris

    PubMed Central

    2010-01-01

    Background Linkage maps are useful tools for examining both the genetic architecture of quantitative traits and the evolution of reproductive incompatibilities. We describe the generation of two genetic maps using reciprocal interspecific backcross 1 (BC1) mapping populations from crosses between Iris brevicaulis and Iris fulva. These maps were constructed using expressed sequence tag (EST)- derived codominant microsatellite markers. Such a codominant marker system allowed for the ability to link the two reciprocal maps, and compare patterns of transmission ratio distortion observed between the two. Results Linkage mapping resulted in markers that coalesced into 21 linkage groups for each of the reciprocal backcross maps, presumably corresponding to the 21 haploid chromosomes of I. brevicaulis and I. fulva. The composite map was 1190.0-cM long, spanned 81% of the I. brevicaulis and I. fulva genomes, and had a mean density of 4.5 cM per locus. Transmission ratio distortion (TRD) was observed in 138 (48.5%) loci distributed in 19 of the 21 LGs in BCIB, BCIF, or both BC1 mapping populations. Of the distorted markers identified, I. fulva alleles were detected at consistently higher-than-expected frequencies in both mapping populations. Conclusions The observation that I. fulva alleles are overrepresented in both mapping populations suggests that I. fulva alleles are favored to introgress into I. brevicaulis genetic backgrounds, while I. brevicaulis alleles would tend to be prevented from introgressing into I. fulva. These data are consistent with the previously observed patterns of introgression in natural hybrid zones, where I. fulva alleles have been consistently shown to introgress across species boundaries. PMID:20298609

  15. Admixture mapping identifies introgressed genomic regions in North American canids.

    PubMed

    vonHoldt, Bridgett M; Kays, Roland; Pollinger, John P; Wayne, Robert K

    2016-06-01

    Hybrid zones typically contain novel gene combinations that can be tested by natural selection in a unique genetic context. Parental haplotypes that increase fitness can introgress beyond the hybrid zone, into the range of parental species. We used the Affymetrix canine SNP genotyping array to identify genomic regions tagged by multiple ancestry informative markers that are more frequent in an admixed population than expected. We surveyed a hybrid zone formed in the last 100 years as coyotes expanded their range into eastern North America. Concomitant with expansion, coyotes hybridized with wolves and some populations became more wolflike, such that coyotes in the northeast have the largest body size of any coyote population. Using a set of 3102 ancestry informative markers, we identified 60 differentially introgressed regions in 44 canines across this admixture zone. These regions are characterized by an excess of exogenous ancestry and, in northeastern coyotes, are enriched for genes affecting body size and skeletal proportions. Further, introgressed wolf-derived alleles have penetrated into Southern US coyote populations. Because no wolves currently exist in this area, these alleles are unlikely to have originated from recent hybridization. Instead, they probably originated from intraspecific gene flow or ancient admixture. We show that grey wolf and coyote admixture has far-reaching effects and, in addition to phenotypically transforming admixed populations, allows for the differential movement of alleles from different parental species to be tested in new genomic backgrounds.

  16. Genetic and phenotypic consequences of introgression between humans and Neanderthals.

    PubMed

    Wills, Christopher

    2011-01-01

    Strong evidence for introgression of Neanderthal genes into parts of the modern human gene pool has recently emerged. The evidence indicates that some populations of modern humans have received infusions of genes from two different groups of Neanderthals. One of these Neanderthal groups lived in the Middle East and Central Europe and the other group (the Denisovans) is known to have lived in Central Asia and was probably more widespread. This review examines two questions. First, how were these introgressions detected and what does the genetic evidence tell us about their nature and extent? We will see that an unknown but possibly large fraction of the entire Neanderthal gene complement may have survived in modern humans. Even though each modern European and Asian carries only a few percent of genes that can be traced back to Neanderthals, different individuals carry different subgroups of these introgressed genes. Second, what is the likelihood that this Neanderthal genetic legacy has had phenotypic effects on modern humans? We examine evidence for and against the possibility that some of the surviving fragments of Neanderthal genomes have been preserved by natural selection, and we explore the ways in which more evidence bearing on this question will become available in the future.

  17. Genetic structure of Miscanthus sinensis and Miscanthus sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression

    SciTech Connect

    Clark, Lindsay V.; Stewart, J. Ryan; Nishiwaki, Aya; Toma, Yo; Kjeldsen, Jens Bonderup; Jorgensen, Uffe; Zhao, Hua; Peng, Junhua; Yoo, Ji Hye; Heo, Kweon; Yu, Chang Yeon; Yamada, Toshihiko; Sacks, Erik J.

    2015-01-24

    Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable high-density genotyping. Throughout Japan, tetraploid Miscanthus sacchariflorus and diploid Miscanthus sinensis are common, and occasionally hybridize. In this study, 667 M. sinensis and 78 M. sacchariflorus genotypes from Japan were characterized using 20 704 SNPs and ten plastid microsatellites. Similarity of SNP genotypes between diploid and tetraploid M. sacchariflorus indicated that the tetraploids originated through autopolyploidy. Structure analysis indicated a gradient of introgression from diploid M. sinensis into tetraploid M. sacchariflorus throughout Japan; most tetraploids had some M. sinensis DNA. Among phenotypically M. sacchariflorus tetraploids, M. sinensis ancestry averaged 7% and ranged from 1-39%, with introgression greatest in southern Japan. Unexpectedly, rare (~1%) diploid M. sinensis individuals from northern Japan were found with 6-27% M. sacchariflorus ancestry. Population structure of M. sinensis in Japan included three groups, and was driven primarily by distance, and secondarily by geographic barriers such as mountains and straits. Miscanthus speciation is a complex and dynamic process. In contrast to limited introgression between diploid M. sacchariflorus and M. sinensis in northern China, selection for adaptation to a moderate maritime climate probably favoured cross-ploidy introgressants in southern Japan. Ultimately, these results will help guide the selection of Miscanthus accessions for the breeding of biomass cultivars.

  18. 22 CFR 42.22 - Returning resident aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Returning resident aliens. 42.22 Section 42.22... Returning resident aliens. (a) Requirements for returning resident status. An alien shall be classifiable as... presented that: (1) The alien had the status of an alien lawfully admitted for permanent residence at...

  19. 8 CFR 236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Confined aliens, incompetents, and minors. 236.2 Section 236.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED...

  20. 8 CFR 236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Confined aliens, incompetents, and minors. 236.2 Section 236.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED...

  1. 8 CFR 1241.30 - Aliens ordered deported.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Aliens ordered deported. 1241.30 Section 1241.30 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Aliens in...

  2. 8 CFR 1241.30 - Aliens ordered deported.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Aliens ordered deported. 1241.30 Section 1241.30 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Aliens in...

  3. 8 CFR 236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Confined aliens, incompetents, and minors. 236.2 Section 236.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED...

  4. 22 CFR 42.22 - Returning resident aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Returning resident aliens. 42.22 Section 42.22... Returning resident aliens. (a) Requirements for returning resident status. An alien shall be classifiable as... presented that: (1) The alien had the status of an alien lawfully admitted for permanent residence at...

  5. 22 CFR 42.22 - Returning resident aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Returning resident aliens. 42.22 Section 42.22... Returning resident aliens. (a) Requirements for returning resident status. An alien shall be classifiable as... presented that: (1) The alien had the status of an alien lawfully admitted for permanent residence at...

  6. 8 CFR 236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Confined aliens, incompetents, and minors. 236.2 Section 236.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED...

  7. 8 CFR 1241.30 - Aliens ordered deported.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Aliens ordered deported. 1241.30 Section 1241.30 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Aliens in...

  8. 22 CFR 42.22 - Returning resident aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Returning resident aliens. 42.22 Section 42.22... Returning resident aliens. (a) Requirements for returning resident status. An alien shall be classifiable as... presented that: (1) The alien had the status of an alien lawfully admitted for permanent residence at...

  9. 22 CFR 42.22 - Returning resident aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Returning resident aliens. 42.22 Section 42.22... Returning resident aliens. (a) Requirements for returning resident status. An alien shall be classifiable as... presented that: (1) The alien had the status of an alien lawfully admitted for permanent residence at...

  10. 8 CFR 1241.30 - Aliens ordered deported.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Aliens ordered deported. 1241.30 Section 1241.30 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Aliens in...

  11. 8 CFR 236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Confined aliens, incompetents, and minors. 236.2 Section 236.2 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS; REMOVAL OF ALIENS ORDERED REMOVED...

  12. 8 CFR 1241.30 - Aliens ordered deported.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Aliens ordered deported. 1241.30 Section 1241.30 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Aliens in...

  13. Investigating temporal changes in hybridization and introgression in a predominantly bimodal hybridizing population of invasive sika (Cervus nippon) and native red deer (C. elaphus) on the Kintyre Peninsula, Scotland.

    PubMed

    Senn, H V; Barton, N H; Goodman, S J; Swanson, G M; Abernethy, K A; Pemberton, J M

    2010-03-01

    We investigated temporal changes in hybridization and introgression between native red deer (Cervus elaphus) and invasive Japanese sika (Cervus nippon) on the Kintyre Peninsula, Scotland, over 15 years, through analysis of 1513 samples of deer at 20 microsatellite loci and a mtDNA marker. We found no evidence that either the proportion of recent hybrids, or the levels of introgression had changed over the study period. Nevertheless, in one population where the two species have been in contact since approximately 1970, 44% of individuals sampled during the study were hybrids. This suggests that hybridization between these species can proceed fairly rapidly. By analysing the number of alleles that have introgressed from polymorphic red deer into the genetically homogenous sika population, we reconstructed the haplotypes of red deer alleles introduced by backcrossing. Five separate hybridization events could account for all the recently hybridized sika-like individuals found across a large section of the Peninsula. Although we demonstrate that low rates of F1 hybridization can lead to substantial introgression, the progress of hybridization and introgression appears to be unpredictable over the short timescales.

  14. Alien liquid detector and control

    SciTech Connect

    Potter, B.M.

    1980-09-02

    An alien liquid detector employs a monitoring element and an energizing circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. For this purpose an electronic circit controls a flow of heating current to the monitoring element. The presence of an alien liquid is detected by sensing a predetermined change in heating current flow to the monitoring element, e.g., to distinguish between water and oil. In preferred embodiments the monitoring element is a thermistor whose resistance is compared with a reference resistance and heating current through the thermistor is controlled in accordance with the difference. In one embodiment a bridge circuit senses the resistance difference; the difference may be sensed by an operational amplifier arrangement. Features of the invention include positioning the monitoring element at the surface of water, slightly immersed, so that the power required to maintain the thermistor temperature substantially above ambient temperature serves to detect presence of oil pollution at the surface.

  15. 'Would you eat an alien?'

    PubMed

    2016-12-10

    A novel way of exploring comparative cognition, animal welfare ethics and human-animal relations formed the basis of this year's Wooldridge Memorial Lecture, held during the BVA Congress at the London Vet Show last month. Christine Nicol, of the University of Bristol, shared her experiences of making the BBC Radio 4 series 'Would you eat an alien?' and gave an insight into the ethical dilemmas that formed the basis of the programme. Laura Honey reports.

  16. Soldier Alienation: A Measureable Concept

    DTIC Science & Technology

    1984-06-01

    to the general question, "Who is today’s soldier and hoW should she/he be treated in order to maximize performance?" The technology exists to perform...modify expectations (Meglino, Youngblood, Randolph, Mobly , and DeNise, 1979). The approach suggested, then, would involve longitudinal research aired...In W. H. Truitt & G. Lolomons (Eds.), Science, Technology and Freedom. Boston: Houghton Mifflin, 1974. Lee, A. M. An obituary for alienation, Social

  17. Chromosomal location and comparative genomics analysis of powdery mildew resistance gene Pm51 in a putative wheat-Thinopyrum ponticum introgression line.

    PubMed

    Zhan, Haixian; Li, Guangrong; Zhang, Xiaojun; Li, Xin; Guo, Huijuan; Gong, Wenping; Jia, Juqing; Qiao, Linyi; Ren, Yongkang; Yang, Zujun; Chang, Zhijian

    2014-01-01

    Powdery mildew (PM) is a very destructive disease of wheat (Triticum aestivum L.). Wheat-Thinopyrum ponticum introgression line CH7086 was shown to possess powdery mildew resistance possibly originating from Th. ponticum. Genomic in situ hybridization and molecular characterization of the alien introgression failed to identify alien chromatin. To study the genetics of resistance, CH7086 was crossed with susceptible genotypes. Segregation in F2 populations and F2:3 lines tested with Chinese Bgt race E09 under controlled conditions indicated that CH7086 carries a single dominant gene for powdery mildew resistance. Fourteen SSR and EST-PCR markers linked with the locus were identified. The genetic distances between the locus and the two flanking markers were 1.5 and 3.2 cM, respectively. Based on the locations of the markers by nullisomic-tetrasomic and deletion lines of 'Chinese Spring', the resistance gene was located in deletion bin 2BL-0.89-1.00. Conserved orthologous marker analysis indicated that the genomic region flanking the resistance gene has a high level of collinearity to that of rice chromosome 4 and Brachypodium chromosome 5. Both resistance specificities and tests of allelism suggested the resistance gene in CH7086 was different from previously reported powdery mildew resistance genes on 2BL, and the gene was provisionally designated PmCH86. Molecular analysis of PmCH86 compared with other genes for resistance to Bgt in the 2BL-0.89-1.00 region suggested that PmCH86 may be a new PM resistance gene, and it was therefore designated as Pm51. The closely linked flanking markers could be useful in exploiting this putative wheat-Thinopyrum translocation line for rapid transfer of Pm51 to wheat breeding programs.

  18. Possibilities of direct introgression from Brassica napus to B. juncea and indirect introgression from B. napus to related Brassicaceae through B. juncea

    PubMed Central

    Tsuda, Mai; Ohsawa, Ryo; Tabei, Yutaka

    2014-01-01

    The impact of genetically modified canola (Brassica napus) on biodiversity has been examined since its initial stage of commercialization. Various research groups have extensively investigated crossability and introgression among species of Brassicaceae. B. rapa and B. juncea are ranked first and second as the recipients of cross-pollination and introgression from B. napus, respectively. Crossability between B. napus and B. rapa has been examined, specifically in terms of introgression from B. napus to B. rapa, which is mainly considered a weed in America and European countries. On the other hand, knowledge on introgression from B. napus to B. juncea is insufficient, although B. juncea is recognized as the main Brassicaceae weed species in Asia. It is therefore essential to gather information regarding the direct introgression of B. napus into B. juncea and indirect introgression of B. napus into other species of Brassicaceae through B. juncea to evaluate the influence of genetically modified canola on biodiversity. We review information on crossability and introgression between B. juncea and other related Brassicaseae in this report. PMID:24987292

  19. Introgression Between Cultivars and Wild Populations of Momordica charantia L. (Cucurbitaceae) in Taiwan

    PubMed Central

    Liao, Pei-Chun; Tsai, Chi-Chu; Chou, Chang-Hung; Chiang, Yu-Chung

    2012-01-01

    The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM). Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes. PMID:22754378

  20. Introgression between cultivars and wild populations of Momordica charantia L. (Cucurbitaceae) in Taiwan.

    PubMed

    Liao, Pei-Chun; Tsai, Chi-Chu; Chou, Chang-Hung; Chiang, Yu-Chung

    2012-01-01

    The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM). Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes.

  1. Unauthorized Aliens in the United States

    DTIC Science & Technology

    2010-04-27

    some two-stage legalization proposals, such as the McCain- Kennedy bill introduced in the 109th Congress (S. 1033), unauthorized aliens would apply...Act of 2005 (S. 1438), also introduced in the 109th Congress, would have authorized DHS to grant a new status—Deferred Mandatory Departure ( DMD ...could have received DMD status. DHS could have granted an alien DMD status for a period of up to five years. Aliens in DMD status could not have

  2. Influence of Introgression and Geological Processes on Phylogenetic Relationships of Western North American Mountain Suckers (Pantosteus, Catostomidae)

    PubMed Central

    Unmack, Peter J.; Dowling, Thomas E.; Laitinen, Nina J.; Secor, Carol L.; Mayden, Richard L.; Shiozawa, Dennis K.; Smith, Gerald R.

    2014-01-01

    Intense geological activity caused major topographic changes in Western North America over the past 15 million years. Major rivers here are composites of different ancient rivers, resulting in isolation and mixing episodes between river basins over time. This history influenced the diversification of most of the aquatic fauna. The genus Pantosteus is one of several clades centered in this tectonically active region. The eight recognized Pantosteus species are widespread and common across southwestern Canada, western USA and into northern Mexico. They are typically found in medium gradient, middle-elevation reaches of rivers over rocky substrates. This study (1) compares molecular data with morphological and paleontological data for proposed species of Pantosteus, (2) tests hypotheses of their monophyly, (3) uses these data for phylogenetic inferences of sister-group relationships, and (4) estimates timing of divergence events of identified lineages. Using 8055 base pairs from mitochondrial DNA protein coding genes, Pantosteus and Catostomus are reciprocally monophyletic, in contrast with morphological data. The only exception to a monophyletic Pantosteus is P. columbianus whose mtDNA is closely aligned with C. tahoensis because of introgression. Within Pantosteus, several species have deep genetic divergences among allopatric sister lineages, several of which are diagnosed and elevated to species, bringing the total diversity in the group to 11 species. Conflicting molecular and morphological data may be resolved when patterns of divergence are shown to be correlated with sympatry and evidence of introgression. PMID:24619087

  3. Index of Alien Impact: A method for evaluating potential ecological impact of alien plant species

    EPA Science Inventory

    Alien plant species are stressors to ecosystems and indicators of reduced ecosystem integrity. The magnitude of the stress reflects not only the quantity of aliens present, but also the quality of their interactions with native ecosystems. We develop an Index of Alien Impact (IAI...

  4. Weak Population Structure in European Roe Deer (Capreolus capreolus) and Evidence of Introgressive Hybridization with Siberian Roe Deer (C. pygargus) in Northeastern Poland

    PubMed Central

    Olano-Marin, Juanita; Plis, Kamila; Sönnichsen, Leif; Borowik, Tomasz; Niedziałkowska, Magdalena; Jędrzejewska, Bogumiła

    2014-01-01

    We investigated contemporary and historical influences on the pattern of genetic diversity of European roe deer (Capreolus capreolus). The study was conducted in northeastern Poland, a zone where vast areas of primeval forests are conserved and where the European roe deer was never driven to extinction. A total of 319 unique samples collected in three sampling areas were genotyped at 16 microsatellites and one fragment (610 bp) of mitochondrial DNA (mtDNA) control region. Genetic diversity was high, and a low degree of genetic differentiation among sampling areas was observed with both microsatellites and mtDNA. No evidence of genetic differentiation between roe deer inhabiting open fields and forested areas was found, indicating that the ability of the species to exploit these contrasting environments might be the result of its phenotypic plasticity. Half of the studied individuals carried an mtDNA haplotype that did not belong to C. capreolus, but to a related species that does not occur naturally in the area, the Siberian roe deer (C. pygargus). No differentiation between individuals with Siberian and European mtDNA haplotypes was detected at microsatellite loci. Introgression of mtDNA of Siberian roe deer into the genome of European roe deer has recently been detected in eastern Europe. Such introgression might be caused by human-mediated translocations of Siberian roe deer within the range of European roe deer or by natural hybridization between these species in the past. PMID:25271423

  5. Weak population structure in European roe deer (Capreolus capreolus) and evidence of introgressive hybridization with Siberian roe deer (C. pygargus) in northeastern Poland.

    PubMed

    Olano-Marin, Juanita; Plis, Kamila; Sönnichsen, Leif; Borowik, Tomasz; Niedziałkowska, Magdalena; Jędrzejewska, Bogumiła

    2014-01-01

    We investigated contemporary and historical influences on the pattern of genetic diversity of European roe deer (Capreolus capreolus). The study was conducted in northeastern Poland, a zone where vast areas of primeval forests are conserved and where the European roe deer was never driven to extinction. A total of 319 unique samples collected in three sampling areas were genotyped at 16 microsatellites and one fragment (610 bp) of mitochondrial DNA (mtDNA) control region. Genetic diversity was high, and a low degree of genetic differentiation among sampling areas was observed with both microsatellites and mtDNA. No evidence of genetic differentiation between roe deer inhabiting open fields and forested areas was found, indicating that the ability of the species to exploit these contrasting environments might be the result of its phenotypic plasticity. Half of the studied individuals carried an mtDNA haplotype that did not belong to C. capreolus, but to a related species that does not occur naturally in the area, the Siberian roe deer (C. pygargus). No differentiation between individuals with Siberian and European mtDNA haplotypes was detected at microsatellite loci. Introgression of mtDNA of Siberian roe deer into the genome of European roe deer has recently been detected in eastern Europe. Such introgression might be caused by human-mediated translocations of Siberian roe deer within the range of European roe deer or by natural hybridization between these species in the past.

  6. Detecting introgressive hybridization between free-ranging domestic dogs and wild wolves (Canis lupus) by admixture linkage disequilibrium analysis.

    PubMed

    Verardi, A; Lucchini, V; Randi, E

    2006-09-01

    Occasional crossbreeding between free-ranging domestic dogs and wild wolves (Canis lupus) has been detected in some European countries by mitochondrial DNA sequencing and genotyping unlinked microsatellite loci. Maternal and unlinked genomic markers, however, might underestimate the extent of introgressive hybridization, and their impacts on the preservation of wild wolf gene pools. In this study, we genotyped 220 presumed Italian wolves, 85 dogs and 7 known hybrids at 16 microsatellites belonging to four different linkage groups (plus four unlinked microsatellites). Population clustering and individual assignments were performed using a Bayesian procedure implemented in structure 2.1, which models the gametic disequilibrium arising between linked loci during admixtures, aiming to trace hybridization events further back in time and infer the population of origin of chromosomal blocks. Results indicate that (i) linkage disequilibrium was higher in wolves than in dogs; (ii) 11 out of 220 wolves (5.0%) were likely admixed, a proportion that is significantly higher than one admixed genotype in 107 wolves found previously in a study using unlinked markers; (iii) posterior maximum-likelihood estimates of the recombination parameter r revealed that introgression in Italian wolves is not recent, but could have continued for the last 70 (+/- 20) generations, corresponding to approximately 140-210 years. Bayesian clustering showed that, despite some admixture, wolf and dog gene pools remain sharply distinct (the average proportions of membership to wolf and dog clusters were Q(w) = 0.95 and Q(d) = 0.98, respectively), suggesting that hybridization was not frequent, and that introgression in nature is counteracted by behavioural or selective constraints.

  7. Dynamics of hybridization and introgression in red wolves and coyotes.

    PubMed

    Fredrickson, Richard J; Hedrick, Philip W

    2006-08-01

    Hybridization and introgression are significant causes of endangerment in many taxa and are considered the greatest biological threats to the reintroduced population of red wolves (Canis rufus) in North Carolina (U.S.A.). Little is known, however, about these processes in red wolves and coyotes (C. latrans). We used individual-based simulations to examine the process of hybridization and introgression between these species. Under the range of circumstances we considered, red wolves in colonizing and established populations were quickly extirpated, persisted near the carrying capacity, or had intermediate outcomes. Sensitivity analyses suggested that the probabilities of quasi extinction and persistence of red wolves near the carrying capacity were most affected by the strength of two reproductive barriers: red wolf challenges and assortative mating between red wolves and coyotes. Because model parameters for these barriers may be difficult to estimate, we also sought to identify other predictors of red wolf population fate. The proportion of pure red wolves in the population was a strong predictor of the future probabilities of red wolf quasi extinction and persistence. Finally, we examined whether sterilization can be effective in minimizing introgression while allowing the reintroduced red wolfpopulation to grow. Our results suggest sterilization can be an effective short-term strategy to reduce the likelihood of extirpation in colonizing populations of red wolves. Whether red wolf numbers are increased by sterilization depends on the level of sterilization effort and the acting reproductive barriers. Our results provide an outline of the conditions likely required for successful reestablishment and long-term maintenance of populations of wild red wolves in the presence of coyotes. Our modeling approach may prove generally useful in providing insight into situations involving complex species interactions when data are few.

  8. Alcohol-preferring (AA) and alcohol-avoiding (ANA) lines of rats after introgression of alien genes.

    PubMed

    Hyytiä, P; Halkka, O; Sarviharju, M; Eriksson, K

    1987-01-01

    Outcrossing has been used as a method for introducing new genetic variability into the high-drinking AA and low-drinking ANA rat lines that had reached their selection limits and were suffering of poor fertility and decreased litter size. The response to the renewed selection for differential alcohol consumption, and the effect of outcrossing upon the components of productivity are reported.

  9. Molecular marker-assisted alien gene introgression of Sr39 for wheat stem rust resistance derived from Aegilops speltoides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In wheat (Triticum aestivum L.), stem rust resistance gene Sr39, derived from Aegilops speltoides, is highly effective against multiple stem rust races including Ug99. However, the gene has not been used in wheat breeding because it is located on a large 2S chromosomal segment in the current transl...

  10. Fanon and the Problem of Alienation.

    ERIC Educational Resources Information Center

    Kessous, Naaman

    1987-01-01

    The notion of alienation as presented in the writings of Frantz Fanon needs a theoretical analysis which considers its economic, racial and political aspects. Marx wrote on alienation in a similar way portraying it as a self-fulfilling prophecy which is fraught with violence and dehumanization. (VM)

  11. Alienating Students: Marxist Theory in Action

    ERIC Educational Resources Information Center

    Thiele, Megan; Pan, Yung-Yi Dian; Molina, Devin

    2016-01-01

    Karl Marx's revolutionary call, "Workers of the World Unite," resonates with many in today's society. This article describes and assesses an easily reproducible classroom activity that simulates both alienating, and perhaps more importantly, non-alienating states of production as described by Marx. This hands-on learning activity gives…

  12. Alienation and the Four Worlds of Childhood.

    ERIC Educational Resources Information Center

    Bronfenbrenner, Urie

    1986-01-01

    Outlines the four worlds of childhood and the ways that alienation in adolescents can be counteracted through the creation of interconnecting links. The risks of losing youths to alienating factors caused by institutions, the social structure, and the pressures under which schools and families function is the highest it has ever been. (MD)

  13. Black, White, and Brown Adolescent Alienation.

    ERIC Educational Resources Information Center

    Heussenstamm, F. K.; Hoepfner, Ralph

    This study, based on cultural stereotypes, seeks to determine the demographic characteristics which differentiate among young people and correlate with their levels of alienation. A preliminary version of an experimental scale, designed to determine the existence and extent of alienation manifested by in-school adolescents, was developed in a…

  14. Reducing Classroom Alienation: Applications from Theory.

    ERIC Educational Resources Information Center

    Keating, Barbara R.

    1987-01-01

    Provides advice on minimizing classroom alienation (powerlessness, meaninglessness, normlessness, isolation, and self-estrangement) through specific classroom strategies. Concludes that student alienation effects learning as well as evaluation. A conscious effort to increase student integration improves teaching, student learning, and the…

  15. Alienation, Mass Society and Mass Culture.

    ERIC Educational Resources Information Center

    Dam, Hari N.

    This monograph examines the nature of alienation in mass society and mass culture. Conceptually based on the "Gemeinschaft-Gesellschaft" paradigm of sociologist Ferdinand Tonnies, discussion traces the concept of alienation as it appears in the philosophies of Hegel, Marx, Kierkegaard, Sartre, and others. Dwight Macdonald's "A Theory of Mass…

  16. Efficient nonmeiotic allele introgression in livestock using custom endonucleases

    PubMed Central

    Tan, Wenfang; Carlson, Daniel F.; Lancto, Cheryl A.; Garbe, John R.; Webster, Dennis A.; Hackett, Perry B.; Fahrenkrug, Scott C.

    2013-01-01

    We have expanded the livestock gene editing toolbox to include transcription activator-like (TAL) effector nuclease (TALEN)- and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-stimulated homology-directed repair (HDR) using plasmid, rAAV, and oligonucleotide templates. Toward the genetic dehorning of dairy cattle, we introgressed a bovine POLLED allele into horned bull fibroblasts. Single nucleotide alterations or small indels were introduced into 14 additional genes in pig, goat, and cattle fibroblasts using TALEN mRNA and oligonucleotide transfection with efficiencies of 10–50% in populations. Several of the chosen edits mimic naturally occurring performance-enhancing or disease- resistance alleles, including alteration of single base pairs. Up to 70% of the fibroblast colonies propagated without selection harbored the intended edits, of which more than one-half were homozygous. Edited fibroblasts were used to generate pigs with knockout alleles in the DAZL and APC genes to model infertility and colon cancer. Our methods enable unprecedented meiosis-free intraspecific and interspecific introgression of select alleles in livestock for agricultural and biomedical applications. PMID:24014591

  17. Introgressive Hybridization between Anciently Diverged Lineages of Silene (Caryophyllaceae)

    PubMed Central

    Petri, Anna; Pfeil, Bernard E.; Oxelman, Bengt

    2013-01-01

    Hybridization has played a major role during the evolution of angiosperms, mediating both gene flow between already distinct species and the formation of new species. Newly formed hybrids between distantly related taxa are often sterile. For this reason, interspecific crosses resulting in fertile hybrids have rarely been described to take place after more than a few million years after divergence. We describe here the traces of a reproductively successful hybrid between two ancestral species of Silene, diverged for about six million years prior to hybridization. No extant hybrids between the two parental lineages are currently known, but introgression of the RNA polymerase gene NRPA2 provides clear evidence of a temporary and fertile hybrid. Parsimony reconciliation between gene trees and the species tree, as well as consideration of clade ages, help exclude gene paralogy and lineage sorting as alternative hypotheses. This may represent one of the most extreme cases of divergence between species prior to introgressive hybridization discovered yet, notably at a homoploid level. Although species boundaries are generally believed to be stable after millions of years of divergence, we believe that this finding may indicate that gene flow between distantly related species is merely largely undetected at present. PMID:23861793

  18. Genetic introgression and the survival of Florida panther kittens

    USGS Publications Warehouse

    Hostetler, Jeffrey A.; Onorato, David P.; Nichols, James D.; Johnson, Warren E.; Roelke, Melody E.; O'Brien, Stephen J.; Jansen, Deborah; Oli, Madan K.

    2010-01-01

    Estimates of survival for the young of a species are critical for population models. These models can often be improved by determining the effects of management actions and population abundance on this demographic parameter. We used multiple sources of data collected during 1982–2008 and a live-recapture dead-recovery modeling framework to estimate and model survival of Florida panther (Puma concolor coryi) kittens (age 0–1 year). Overall, annual survival of Florida panther kittens was 0.323 ± 0.071 (SE), which was lower than estimates used in previous population models. In 1995, female pumas from Texas (P. c. stanleyana) were released into occupied panther range as part of an intentional introgression program to restore genetic variability. We found that kitten survival generally increased with degree of admixture: F1 admixed and backcrossed to Texas kittens survived better than canonical Florida panther and backcrossed to canonical kittens. Average heterozygosity positively influenced kitten and older panther survival, whereas index of panther abundance negatively influenced kitten survival. Our results provide strong evidence for the positive population-level impact of genetic introgression on Florida panthers. Our approach to integrate data from multiple sources was effective at improving robustness as well as precision of estimates of Florida panther kitten survival, and can be useful in estimating vital rates for other elusive species with sparse data.

  19. Genetic Introgression and the Survival of Florida Panther Kittens.

    PubMed

    Hostetler, Jeffrey A; Onorato, David P; Nichols, James D; Johnson, Warren E; Roelke, Melody E; O'Brien, Stephen J; Jansen, Deborah; Oli, Madan K

    2010-11-01

    Estimates of survival for the young of a species are critical for population models. These models can often be improved by determining the effects of management actions and population abundance on this demographic parameter. We used multiple sources of data collected during 1982-2008 and a live recapture-dead recovery modeling framework to estimate and model survival of Florida panther (Puma concolor coryi) kittens (age 0 - 1 year). Overall, annual survival of Florida panther kittens was 0.323 ± 0.071 (SE), which was lower than estimates used in previous population models. In 1995, female pumas from Texas (P. c. stanleyana) were released into occupied panther range as part of an intentional introgression program to restore genetic variability. We found that kitten survival generally increased with degree of admixture: F(1) admixed and backcrossed to Texas kittens survived better than canonical Florida panther and backcrossed to canonical kittens. Average heterozygosity positively influenced kitten and older panther survival, whereas index of panther abundance negatively influenced kitten survival. Our results provide strong evidence for the positive population-level impact of genetic introgression on Florida panthers. Our approach to integrate data from multiple sources was effective at improving robustness as well as precision of estimates of Florida panther kitten survival, and can be useful in estimating vital rates for other elusive species with sparse data.

  20. Mitochondrial introgression suggests extensive ancestral hybridization events among Saccharomyces species.

    PubMed

    Peris, David; Arias, Armando; Orlić, Sandi; Belloch, Carmela; Pérez-Través, Laura; Querol, Amparo; Barrio, Eladio

    2017-03-01

    Horizontal gene transfer (HGT) in eukaryotic plastids and mitochondrial genomes is common, and plays an important role in organism evolution. In yeasts, recent mitochondrial HGT has been suggested between S. cerevisiae and S. paradoxus. However, few strains have been explored given the lack of accurate mitochondrial genome annotations. Mitochondrial genome sequences are important to understand how frequent these introgressions occur, and their role in cytonuclear incompatibilities and fitness. Indeed, most of the Bateson-Dobzhansky-Muller genetic incompatibilities described in yeasts are driven by cytonuclear incompatibilities. We herein explored the mitochondrial inheritance of several worldwide distributed wild Saccharomyces species and their hybrids isolated from different sources and geographic origins. We demonstrated the existence of several recombination points in mitochondrial region COX2-ORF1, likely mediated by either the activity of the protein encoded by the ORF1 (F-SceIII) gene, a free-standing homing endonuclease, or mostly facilitated by A+T tandem repeats and regions of integration of GC clusters. These introgressions were shown to occur among strains of the same species and among strains of different species, which suggests a complex model of Saccharomyces evolution that involves several ancestral hybridization events in wild environments.

  1. From speciation to introgressive hybridization: the phylogeographic structure of an island subspecies of termite, Reticulitermes lucifugus corsicus

    PubMed Central

    2008-01-01

    Background Although much research has been carried out into European Reticulitermes taxonomy in recent years, there is still much discussion about phylogenetic relationships. This study investigated the evolution from intra- to interspecific phylogeny in the island subspecies Reticulitermes lucifugus corsicus and threw new light on this phenomenon. An integrative approach based on microsatellites and mitochondrial and nuclear DNA sequences was used to analyze samples taken from a wide area around the Tyrrhenian sea and showed how the subspecies evolved from its origins to its most recent form on continental coasts. Results According to mitochondrial phylogeny and molecular clock calculations, island and continental taxa diverged significantly by vicariance in the Pleistocene glacial period. However, more recently, numerous migrations, certainly human-mediated, affected the structure of the populations. This study provided evidence of direct hybridization and multiple introgressions which occurred in several hybrid areas. Analysis using STRUCTURE based on microsatellite data identified a population in Provence (France) which differed considerably (Fst = 0.477) from populations on the island of Corsica and in Tuscany in the Italian peninsula. This new population, principally distributed in urban areas, is highly heterogeneous especially within the ITS2 regions where homogenization by concerted evolution does not appear to have been completed. Conclusion This study provides an unusual picture of genetic interaction between termite populations in the Tyrrhenian area and suggests that more attention should be paid to the role of introgression and human impact on the recent evolution of European termites. PMID:18248672

  2. Intersubgenomic heterosis in seed yield potential observed in a new type of Brassica napus introgressed with partial Brassica rapa genome.

    PubMed

    Qian, W; Chen, X; Fu, D; Zou, J; Meng, J

    2005-05-01

    This paper reports the observation on the intersubgenomic heterosis for seed yield among hybrids between natural Brassica napus (A(n)A(n)C(n)C(n)) and a new type of B. napus with introgressions of genomic components of Brassica rapa (A(r)A(r)). This B. napus was selected from the progeny of B. napus x B. rapa and (B. napus x B. rapa) x B. rapa based on extensive phenotypic and cytological observation. Among the 129 studied partial intersubgenomic hybrids, which were obtained by randomly crossing 13 lines of the new type of B. napus in F(3) or BC(1)F(3) to 27 cultivars of B. napus from different regions as tester lines, about 90% of combinations exceeded the yield of their respective tester lines, whereas about 75% and 25% of combinations surpassed two elite Chinese cultivars, respectively. This strong heterosis was further confirmed by reevaluating 2 out of the 129 combinations in a successive year and by surveying hybrids between 20 lines of the new type of B. napus in BC(1)F(5) and its parental B. napus in two locations. Some DNA segments from B. rapa were identified with significant effects on seed yield and yield components of the new type of B. napus in BC(1)F(5) and intersubgenomic hybrids in positive or negative direction. It seems that the genomic components introgressed from B. rapa contributed to improvement of seed yield of rapeseed.

  3. Interspecific Hybridization in Pilot Whales and Asymmetric Genetic Introgression in Northern Globicephala melas under the Scenario of Global Warming

    PubMed Central

    Miralles, Laura; Oremus, Marc; Silva, Mónica A.; Planes, Serge; Garcia-Vazquez, Eva

    2016-01-01

    Pilot whales are two cetacean species (Globicephala melas and G. macrorhynchus) whose distributions are correlated with water temperature and partially overlap in some areas like the North Atlantic Ocean. In the context of global warming, distribution range shifts are expected to occur in species affected by temperature. Consequently, a northward displacement of the tropical pilot whale G. macrorynchus is expected, eventually leading to increased secondary contact areas and opportunities for interspecific hybridization. Here, we describe genetic evidences of recurrent hybridization between pilot whales in northeast Atlantic Ocean. Based on mitochondrial DNA sequences and microsatellite loci, asymmetric introgression of G. macrorhynchus genes into G. melas was observed. For the latter species, a significant correlation was found between historical population growth rate estimates and paleotemperature oscillations. Introgressive hybridization, current temperature increases and lower genetic variation in G. melas suggest that this species could be at risk in its northern range. Under increasing environmental and human-mediated stressors in the North Atlantic Ocean, it seems recommendable to develop a conservation program for G. melas. PMID:27508496

  4. Development of β-carotene rich maize hybrids through marker-assisted introgression of β-carotene hydroxylase allele.

    PubMed

    Muthusamy, Vignesh; Hossain, Firoz; Thirunavukkarasu, Nepolean; Choudhary, Mukesh; Saha, Supradip; Bhat, Jayant S; Prasanna, Boddupalli M; Gupta, Hari S

    2014-01-01

    Development of vitamin A-rich cereals can help in alleviating the widespread problem of vitamin A deficiency. We report here significant enhancement of kernel β-carotene in elite maize genotypes through accelerated marker-assisted backcross breeding. A favourable allele (543 bp) of the β-carotene hydroxylase (crtRB1) gene was introgressed in the seven elite inbred parents, which were low (1.4 µg/g) in kernel β-carotene, by using a crtRB1-specific DNA marker for foreground selection. About 90% of the recurrent parent genome was recovered in the selected progenies within two backcross generations. Concentration of β-carotene among the crtRB1-introgressed inbreds varied from 8.6 to 17.5 µg/g - a maximum increase up to 12.6-fold over recurrent parent. The reconstituted hybrids developed from improved parental inbreds also showed enhanced kernel β-carotene as high as 21.7 µg/g, compared to 2.6 µg/g in the original hybrid. The reconstituted hybrids evaluated at two locations possessed similar grain yield to that of original hybrids. These β-carotene enriched high yielding hybrids can be effectively utilized in the maize biofortification programs across the globe.

  5. Importance of incomplete lineage sorting and introgression in the origin of shared genetic variation between two closely related pines with overlapping distributions.

    PubMed

    Zhou, Y; Duvaux, L; Ren, G; Zhang, L; Savolainen, O; Liu, J

    2017-03-01

    Genetic variation shared between closely related species may be due to retention of ancestral polymorphisms because of incomplete lineage sorting (ILS) and/or introgression following secondary contact. It is challenging to distinguish ILS and introgression because they generate similar patterns of shared genetic diversity, but this is nonetheless essential for inferring accurately the history of species with overlapping distributions. To address this issue, we sequenced 33 independent intron loci across the genome of two closely related pine species (Pinus massoniana Lamb. and Pinus hwangshanensis Hisa) from Southeast China. Population structure analyses revealed that the species showed slightly more admixture in parapatric populations than in allopatric populations. Levels of interspecific differentiation were lower in parapatry than in allopatry. Approximate Bayesian computation suggested that the most likely speciation scenario explaining this pattern was a long period of isolation followed by a secondary contact. Ecological niche modeling suggested that a gradual range expansion of P. hwangshanensis during the Pleistocene climatic oscillations could have been the cause of the overlap. Our study therefore suggests that secondary introgression, rather than ILS, explains most of the shared nuclear genomic variation between these two species and demonstrates the complementarity of population genetics and ecological niche modeling in understanding gene flow history. Finally, we discuss the importance of contrasting results from markers with different dynamics of migration, namely nuclear, chloroplast and mitochondrial DNA.

  6. Importance of incomplete lineage sorting and introgression in the origin of shared genetic variation between two closely related pines with overlapping distributions

    PubMed Central

    Zhou, Y; Duvaux, L; Ren, G; Zhang, L; Savolainen, O; Liu, J

    2017-01-01

    Genetic variation shared between closely related species may be due to retention of ancestral polymorphisms because of incomplete lineage sorting (ILS) and/or introgression following secondary contact. It is challenging to distinguish ILS and introgression because they generate similar patterns of shared genetic diversity, but this is nonetheless essential for inferring accurately the history of species with overlapping distributions. To address this issue, we sequenced 33 independent intron loci across the genome of two closely related pine species (Pinus massoniana Lamb. and Pinus hwangshanensis Hisa) from Southeast China. Population structure analyses revealed that the species showed slightly more admixture in parapatric populations than in allopatric populations. Levels of interspecific differentiation were lower in parapatry than in allopatry. Approximate Bayesian computation suggested that the most likely speciation scenario explaining this pattern was a long period of isolation followed by a secondary contact. Ecological niche modeling suggested that a gradual range expansion of P. hwangshanensis during the Pleistocene climatic oscillations could have been the cause of the overlap. Our study therefore suggests that secondary introgression, rather than ILS, explains most of the shared nuclear genomic variation between these two species and demonstrates the complementarity of population genetics and ecological niche modeling in understanding gene flow history. Finally, we discuss the importance of contrasting results from markers with different dynamics of migration, namely nuclear, chloroplast and mitochondrial DNA. PMID:27649619

  7. Adaptive divergence in wine yeasts and their wild relatives suggests a prominent role for introgressions and rapid evolution at non coding sites.

    PubMed

    Almeida, Pedro; Barbosa, Raquel; Bensasson, Douda; Gonçalves, Paula; Sampaio, José Paulo

    2017-02-23

    In Saccharomyces cerevisiae, the main yeast in wine fermentation, the opportunity to examine divergence at the molecular level between a domesticated lineage and its wild counterpart arose recently due to the identification of the closest relatives of wine strains, a wild population associated with Mediterranean oaks. Since genomic data is available for a considerable number of representatives belonging to both groups, we used population genomics to estimate the degree and distribution of nucleotide variation between wine yeasts and their closest wild relatives. We found widespread genome-wide divergence, particularly at non-coding sites, which, together with above average divergence in trans-acting DNA binding proteins, may suggest an important role for divergence at the level of transcriptional regulation. Nine outlier regions putatively under strong divergent selection were highlighted by a genome wide scan under stringent conditions. Several cases of introgressions originating in the sibling species S. paradoxus, were also identified in the Mediterranean oak population. FFZ1 and SSU1, mostly known for conferring sulphite resistance in wine yeasts, were among the introgressed genes, although not fixed. Because the introgressions detected in our study are not found in wine strains, we hypothesise that ongoing divergent ecological selection segregates the two forms between the different niches. Together, our results provide a first insight into the extent and kind of divergence between wine yeasts and their closest wild relatives. This article is protected by copyright. All rights reserved.

  8. 8 CFR 1236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Confined aliens, incompetents, and minors. 1236.2 Section 1236.2 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS;...

  9. 45 CFR 233.52 - Overpayment to aliens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false Overpayment to aliens. 233.52 Section 233.52... ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.52 Overpayment to aliens. A State Plan under title IV-A of the Social Security Act, shall provide that: (a) Any sponsor of an alien and the alien shall...

  10. 8 CFR 274a.3 - Continuing employment of unauthorized aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Continuing employment of unauthorized aliens. 274a.3 Section 274a.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employer Requirements § 274a.3 Continuing employment...

  11. 26 CFR 1.871-3 - Residence of alien seamen.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 9 2014-04-01 2014-04-01 false Residence of alien seamen. 1.871-3 Section 1.871... (CONTINUED) INCOME TAXES (CONTINUED) Nonresident Aliens and Foreign Corporations § 1.871-3 Residence of alien seamen. In order to determine whether an alien seaman is a resident of the United States for purposes...

  12. 8 CFR 1240.38 - Fingerprinting of excluded aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Fingerprinting of excluded aliens. 1240.38 Section 1240.38 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS PROCEEDINGS TO DETERMINE REMOVABILITY OF ALIENS IN THE UNITED STATES Exclusion...

  13. 45 CFR 233.52 - Overpayment to aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 2 2012-10-01 2012-10-01 false Overpayment to aliens. 233.52 Section 233.52... ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.52 Overpayment to aliens. A State Plan under title IV-A of the Social Security Act, shall provide that: (a) Any sponsor of an alien and the alien shall...

  14. 22 CFR 40.91 - Certain aliens previously removed.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Certain aliens previously removed. 40.91... IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.91 Certain aliens previously removed. (a) 5-year bar. An alien who has been found inadmissible, whether as a...

  15. 45 CFR 1626.5 - Alien status and eligibility.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Alien status and eligibility. 1626.5 Section 1626... RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.5 Alien status and eligibility. Subject to all other... may provide legal assistance to an alien who is present in the United States and who is within one...

  16. 26 CFR 1.871-3 - Residence of alien seamen.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 9 2011-04-01 2011-04-01 false Residence of alien seamen. 1.871-3 Section 1.871... (CONTINUED) INCOME TAXES (CONTINUED) Nonresident Aliens and Foreign Corporations § 1.871-3 Residence of alien seamen. In order to determine whether an alien seaman is a resident of the United States for purposes...

  17. 47 CFR 90.115 - Foreign government and alien eligibility.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Foreign government and alien eligibility. 90... government and alien eligibility. (a) No station authorization in the radio services governed by this part....9(c) of this chapter) if such entity is: (1) An alien or the representative of any alien; (2)...

  18. 45 CFR 233.52 - Overpayment to aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 2 2013-10-01 2012-10-01 true Overpayment to aliens. 233.52 Section 233.52 Public... ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.52 Overpayment to aliens. A State Plan under title IV-A of the Social Security Act, shall provide that: (a) Any sponsor of an alien and the alien shall...

  19. 47 CFR 90.115 - Foreign government and alien eligibility.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Foreign government and alien eligibility. 90... government and alien eligibility. (a) No station authorization in the radio services governed by this part....9(c) of this chapter) if such entity is: (1) An alien or the representative of any alien; (2)...

  20. 8 CFR 1236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Confined aliens, incompetents, and minors. 1236.2 Section 1236.2 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS;...

  1. 8 CFR 235.3 - Inadmissible aliens and expedited removal.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Inadmissible aliens and expedited removal. 235.3 Section 235.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS INSPECTION OF PERSONS APPLYING FOR ADMISSION § 235.3 Inadmissible aliens and expedited removal. (a)...

  2. 47 CFR 90.115 - Foreign government and alien eligibility.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Foreign government and alien eligibility. 90... government and alien eligibility. (a) No station authorization in the radio services governed by this part....9(c) of this chapter) if such entity is: (1) An alien or the representative of any alien; (2)...

  3. 8 CFR 1236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Confined aliens, incompetents, and minors. 1236.2 Section 1236.2 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS;...

  4. 8 CFR 274a.3 - Continuing employment of unauthorized aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Continuing employment of unauthorized aliens. 274a.3 Section 274a.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employer Requirements § 274a.3 Continuing employment...

  5. 7 CFR 273.4 - Citizenship and alien status.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 4 2014-01-01 2014-01-01 false Citizenship and alien status. 273.4 Section 273.4... Citizenship § 273.4 Citizenship and alien status. (a) Household members meeting citizenship or alien status... alien who has been subjected to a severe form of trafficking in persons and who is certified by...

  6. 28 CFR 0.47 - Alien property matters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Alien property matters. 0.47 Section 0.47....47 Alien property matters. The Office of Alien Property shall be a part of the Civil Division: (a... Alien Property: (1) Exercising or performing all the authority, rights, privileges, powers, duties,...

  7. 8 CFR 235.3 - Inadmissible aliens and expedited removal.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Inadmissible aliens and expedited removal. 235.3 Section 235.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS INSPECTION OF PERSONS APPLYING FOR ADMISSION § 235.3 Inadmissible aliens and expedited removal. (a)...

  8. 45 CFR 1626.7 - Verification of eligible alien status.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 4 2014-10-01 2014-10-01 false Verification of eligible alien status. 1626.7... CORPORATION RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.7 Verification of eligible alien status. (a) An alien seeking representation shall submit appropriate documents to verify eligibility, unless the...

  9. 28 CFR 0.47 - Alien property matters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Alien property matters. 0.47 Section 0.47....47 Alien property matters. The Office of Alien Property shall be a part of the Civil Division: (a... Alien Property: (1) Exercising or performing all the authority, rights, privileges, powers, duties,...

  10. 8 CFR 204.6 - Petitions for employment creation aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Petitions for employment creation aliens. 204.6 Section 204.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS IMMIGRANT PETITIONS Immigrant Visa Petitions § 204.6 Petitions for employment creation aliens. (a)...

  11. 28 CFR 0.47 - Alien property matters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Alien property matters. 0.47 Section 0.47....47 Alien property matters. The Office of Alien Property shall be a part of the Civil Division: (a... Alien Property: (1) Exercising or performing all the authority, rights, privileges, powers, duties,...

  12. 8 CFR 1240.38 - Fingerprinting of excluded aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Fingerprinting of excluded aliens. 1240.38 Section 1240.38 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS PROCEEDINGS TO DETERMINE REMOVABILITY OF ALIENS IN THE UNITED STATES Exclusion...

  13. 8 CFR 274a.3 - Continuing employment of unauthorized aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Continuing employment of unauthorized aliens. 274a.3 Section 274a.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employer Requirements § 274a.3 Continuing employment...

  14. 45 CFR 1626.7 - Verification of eligible alien status.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Verification of eligible alien status. 1626.7... CORPORATION RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.7 Verification of eligible alien status. (a) An alien seeking representation shall submit appropriate documents to verify eligibility, unless the...

  15. 8 CFR 1241.20 - Aliens ordered excluded.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Aliens ordered excluded. 1241.20 Section 1241.20 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded...

  16. 22 CFR 40.91 - Certain aliens previously removed.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Certain aliens previously removed. 40.91... IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.91 Certain aliens previously removed. (a) 5-year bar. An alien who has been found inadmissible, whether as a...

  17. 31 CFR 515.335 - Permanent resident alien.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States....

  18. 22 CFR 40.91 - Certain aliens previously removed.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Certain aliens previously removed. 40.91... IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.91 Certain aliens previously removed. (a) 5-year bar. An alien who has been found inadmissible, whether as a...

  19. 8 CFR 204.6 - Petitions for employment creation aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Petitions for employment creation aliens. 204.6 Section 204.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS IMMIGRANT PETITIONS Immigrant Visa Petitions § 204.6 Petitions for employment creation aliens. (a)...

  20. 22 CFR 40.91 - Certain aliens previously removed.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Certain aliens previously removed. 40.91... IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.91 Certain aliens previously removed. (a) 5-year bar. An alien who has been found inadmissible, whether as a...

  1. 8 CFR 274a.3 - Continuing employment of unauthorized aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Continuing employment of unauthorized aliens. 274a.3 Section 274a.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employer Requirements § 274a.3 Continuing employment...

  2. 26 CFR 1.871-3 - Residence of alien seamen.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 9 2010-04-01 2010-04-01 false Residence of alien seamen. 1.871-3 Section 1.871... (CONTINUED) INCOME TAXES Nonresident Aliens and Foreign Corporations § 1.871-3 Residence of alien seamen. In order to determine whether an alien seaman is a resident of the United States for purposes of the...

  3. 8 CFR 1240.38 - Fingerprinting of excluded aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Fingerprinting of excluded aliens. 1240.38 Section 1240.38 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS PROCEEDINGS TO DETERMINE REMOVABILITY OF ALIENS IN THE UNITED STATES Exclusion...

  4. 22 CFR 40.92 - Aliens unlawfully present.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Aliens unlawfully present. 40.92 Section 40.92... UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.92 Aliens unlawfully present. (a) 3-year bar. An alien described in INA 212(a)(9)(B)(i)(I) shall be ineligible for...

  5. 47 CFR 90.115 - Foreign government and alien eligibility.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Foreign government and alien eligibility. 90... government and alien eligibility. (a) No station authorization in the radio services governed by this part....9(c) of this chapter) if such entity is: (1) An alien or the representative of any alien; (2)...

  6. 7 CFR 273.4 - Citizenship and alien status.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 4 2011-01-01 2011-01-01 false Citizenship and alien status. 273.4 Section 273.4... Citizenship § 273.4 Citizenship and alien status. (a) Household members meeting citizenship or alien status... alien who has been subjected to a severe form of trafficking in persons and who is certified by...

  7. 47 CFR 90.115 - Foreign government and alien eligibility.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Foreign government and alien eligibility. 90... government and alien eligibility. (a) No station authorization in the radio services governed by this part....9(c) of this chapter) if such entity is: (1) An alien or the representative of any alien; (2)...

  8. 8 CFR 1241.20 - Aliens ordered excluded.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Aliens ordered excluded. 1241.20 Section 1241.20 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded...

  9. 45 CFR 1626.5 - Alien status and eligibility.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 4 2011-10-01 2011-10-01 false Alien status and eligibility. 1626.5 Section 1626... RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.5 Alien status and eligibility. Subject to all other... may provide legal assistance to an alien who is present in the United States and who is within one...

  10. 8 CFR 1241.20 - Aliens ordered excluded.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Aliens ordered excluded. 1241.20 Section 1241.20 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded...

  11. 8 CFR 204.6 - Petitions for employment creation aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Petitions for employment creation aliens. 204.6 Section 204.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS IMMIGRANT PETITIONS Immigrant Visa Petitions § 204.6 Petitions for employment creation aliens. (a)...

  12. 7 CFR 273.4 - Citizenship and alien status.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 4 2012-01-01 2012-01-01 false Citizenship and alien status. 273.4 Section 273.4... Citizenship § 273.4 Citizenship and alien status. (a) Household members meeting citizenship or alien status... alien who has been subjected to a severe form of trafficking in persons and who is certified by...

  13. 8 CFR 1241.20 - Aliens ordered excluded.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Aliens ordered excluded. 1241.20 Section 1241.20 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded...

  14. 45 CFR 1626.7 - Verification of eligible alien status.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 4 2013-10-01 2013-10-01 false Verification of eligible alien status. 1626.7... CORPORATION RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.7 Verification of eligible alien status. (a) An alien seeking representation shall submit appropriate documents to verify eligibility, unless the...

  15. 8 CFR 1240.38 - Fingerprinting of excluded aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Fingerprinting of excluded aliens. 1240.38 Section 1240.38 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS PROCEEDINGS TO DETERMINE REMOVABILITY OF ALIENS IN THE UNITED STATES Exclusion...

  16. 31 CFR 515.335 - Permanent resident alien.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States....

  17. 26 CFR 1.6654-6 - Nonresident alien individuals.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 13 2013-04-01 2013-04-01 false Nonresident alien individuals. 1.6654-6 Section... Penalties § 1.6654-6 Nonresident alien individuals. (a) In general. A nonresident alien individual is... the gross income of a nonresident alien individual is such as to require making a payment of...

  18. 28 CFR 0.47 - Alien property matters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Alien property matters. 0.47 Section 0.47....47 Alien property matters. The Office of Alien Property shall be a part of the Civil Division: (a... Alien Property: (1) Exercising or performing all the authority, rights, privileges, powers, duties,...

  19. 45 CFR 1626.7 - Verification of eligible alien status.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Verification of eligible alien status. 1626.7... CORPORATION RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.7 Verification of eligible alien status. (a) An alien seeking representation shall submit appropriate documents to verify eligibility, unless the...

  20. 45 CFR 1626.7 - Verification of eligible alien status.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Verification of eligible alien status. 1626.7... CORPORATION RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.7 Verification of eligible alien status. (a) An alien seeking representation shall submit appropriate documents to verify eligibility, unless the...

  1. 45 CFR 233.52 - Overpayment to aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 2 2011-10-01 2011-10-01 false Overpayment to aliens. 233.52 Section 233.52... ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.52 Overpayment to aliens. A State Plan under title IV-A of the Social Security Act, shall provide that: (a) Any sponsor of an alien and the alien shall...

  2. 31 CFR 515.335 - Permanent resident alien.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States....

  3. 8 CFR 204.6 - Petitions for employment creation aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Petitions for employment creation aliens. 204.6 Section 204.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS IMMIGRANT PETITIONS Immigrant Visa Petitions § 204.6 Petitions for employment creation aliens. (a)...

  4. 26 CFR 1.6654-6 - Nonresident alien individuals.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Nonresident alien individuals. 1.6654-6 Section....6654-6 Nonresident alien individuals. (a) In general. A nonresident alien individual is required to... gross income of a nonresident alien individual is such as to require making a payment of...

  5. 8 CFR 1241.20 - Aliens ordered excluded.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Aliens ordered excluded. 1241.20 Section 1241.20 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded...

  6. 22 CFR 40.91 - Certain aliens previously removed.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Certain aliens previously removed. 40.91... IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.91 Certain aliens previously removed. (a) 5-year bar. An alien who has been found inadmissible, whether as a...

  7. 31 CFR 515.335 - Permanent resident alien.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States....

  8. 26 CFR 1.6654-6 - Nonresident alien individuals.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 13 2012-04-01 2012-04-01 false Nonresident alien individuals. 1.6654-6 Section... Penalties § 1.6654-6 Nonresident alien individuals. (a) In general. A nonresident alien individual is... the gross income of a nonresident alien individual is such as to require making a payment of...

  9. 8 CFR 1240.38 - Fingerprinting of excluded aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Fingerprinting of excluded aliens. 1240.38 Section 1240.38 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS PROCEEDINGS TO DETERMINE REMOVABILITY OF ALIENS IN THE UNITED STATES Exclusion...

  10. 8 CFR 1236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Confined aliens, incompetents, and minors. 1236.2 Section 1236.2 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS;...

  11. 22 CFR 40.92 - Aliens unlawfully present.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Aliens unlawfully present. 40.92 Section 40.92... UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.92 Aliens unlawfully present. (a) 3-year bar. An alien described in INA 212(a)(9)(B)(i)(I) shall be ineligible for...

  12. 22 CFR 40.92 - Aliens unlawfully present.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Aliens unlawfully present. 40.92 Section 40.92... UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.92 Aliens unlawfully present. (a) 3-year bar. An alien described in INA 212(a)(9)(B)(i)(I) shall be ineligible for...

  13. 28 CFR 0.47 - Alien property matters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false Alien property matters. 0.47 Section 0.47....47 Alien property matters. The Office of Alien Property shall be a part of the Civil Division: (a... Alien Property: (1) Exercising or performing all the authority, rights, privileges, powers, duties,...

  14. 8 CFR 1236.2 - Confined aliens, incompetents, and minors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Confined aliens, incompetents, and minors. 1236.2 Section 1236.2 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF INADMISSIBLE AND DEPORTABLE ALIENS;...

  15. 26 CFR 1.871-3 - Residence of alien seamen.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 9 2013-04-01 2013-04-01 false Residence of alien seamen. 1.871-3 Section 1.871... (CONTINUED) INCOME TAXES (CONTINUED) Nonresident Aliens and Foreign Corporations § 1.871-3 Residence of alien seamen. In order to determine whether an alien seaman is a resident of the United States for purposes...

  16. 45 CFR 1626.5 - Alien status and eligibility.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Alien status and eligibility. 1626.5 Section 1626... RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.5 Alien status and eligibility. Subject to all other... may provide legal assistance to an alien who is present in the United States and who is within one...

  17. 26 CFR 1.871-3 - Residence of alien seamen.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 9 2012-04-01 2012-04-01 false Residence of alien seamen. 1.871-3 Section 1.871... (CONTINUED) INCOME TAXES (CONTINUED) Nonresident Aliens and Foreign Corporations § 1.871-3 Residence of alien seamen. In order to determine whether an alien seaman is a resident of the United States for purposes...

  18. 7 CFR 273.4 - Citizenship and alien status.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 4 2013-01-01 2013-01-01 false Citizenship and alien status. 273.4 Section 273.4... Citizenship § 273.4 Citizenship and alien status. (a) Household members meeting citizenship or alien status... alien who has been subjected to a severe form of trafficking in persons and who is certified by...

  19. 31 CFR 515.335 - Permanent resident alien.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States....

  20. 22 CFR 40.92 - Aliens unlawfully present.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Aliens unlawfully present. 40.92 Section 40.92... UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.92 Aliens unlawfully present. (a) 3-year bar. An alien described in INA 212(a)(9)(B)(i)(I) shall be ineligible for...

  1. 26 CFR 1.6654-6 - Nonresident alien individuals.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 13 2014-04-01 2014-04-01 false Nonresident alien individuals. 1.6654-6 Section... Penalties § 1.6654-6 Nonresident alien individuals. (a) In general. A nonresident alien individual is... the gross income of a nonresident alien individual is such as to require making a payment of...

  2. 8 CFR 204.6 - Petitions for employment creation aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Petitions for employment creation aliens. 204.6 Section 204.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS IMMIGRANT PETITIONS Immigrant Visa Petitions § 204.6 Petitions for employment creation aliens. (a)...

  3. 26 CFR 1.6654-6 - Nonresident alien individuals.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 13 2011-04-01 2011-04-01 false Nonresident alien individuals. 1.6654-6 Section... Penalties § 1.6654-6 Nonresident alien individuals. (a) In general. A nonresident alien individual is... the gross income of a nonresident alien individual is such as to require making a payment of...

  4. 8 CFR 274a.3 - Continuing employment of unauthorized aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Continuing employment of unauthorized aliens. 274a.3 Section 274a.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employer Requirements § 274a.3 Continuing employment...

  5. 22 CFR 40.92 - Aliens unlawfully present.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Aliens unlawfully present. 40.92 Section 40.92... UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Aliens Previously Removed § 40.92 Aliens unlawfully present. (a) 3-year bar. An alien described in INA 212(a)(9)(B)(i)(I) shall be ineligible for...

  6. 45 CFR 233.52 - Overpayment to aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 2 2014-10-01 2012-10-01 true Overpayment to aliens. 233.52 Section 233.52 Public... ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.52 Overpayment to aliens. A State Plan under title IV-A of the Social Security Act, shall provide that: (a) Any sponsor of an alien and the alien shall...

  7. 45 CFR 1626.5 - Alien status and eligibility.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Alien status and eligibility. 1626.5 Section 1626... RESTRICTIONS ON LEGAL ASSISTANCE TO ALIENS § 1626.5 Alien status and eligibility. Subject to all other... may provide legal assistance to an alien who is present in the United States and who is within one...

  8. DNA.

    ERIC Educational Resources Information Center

    Felsenfeld, Gary

    1985-01-01

    Structural form, bonding scheme, and chromatin structure of and gene-modification experiments with deoxyribonucleic acid (DNA) are described. Indicates that DNA's double helix is variable and also flexible as it interacts with regulatory and other molecules to transfer hereditary messages. (DH)

  9. Can we continue to neglect genomic variation in introgression rates when inferring the history of speciation? A case study in a Mytilus hybrid zone.

    PubMed

    Roux, C; Fraïsse, C; Castric, V; Vekemans, X; Pogson, G H; Bierne, N

    2014-08-01

    The use of molecular data to reconstruct the history of divergence and gene flow between populations of closely related taxa represents a challenging problem. It has been proposed that the long-standing debate about the geography of speciation can be resolved by comparing the likelihoods of a model of isolation with migration and a model of secondary contact. However, data are commonly only fit to a model of isolation with migration and rarely tested against the secondary contact alternative. Furthermore, most demographic inference methods have neglected variation in introgression rates and assume that the gene flow parameter (Nm) is similar among loci. Here, we show that neglecting this source of variation can give misleading results. We analysed DNA sequences sampled from populations of the marine mussels, Mytilus edulis and M. galloprovincialis, across a well-studied mosaic hybrid zone in Europe and evaluated various scenarios of speciation, with or without variation in introgression rates, using an Approximate Bayesian Computation (ABC) approach. Models with heterogeneous gene flow across loci always outperformed models assuming equal migration rates irrespective of the history of gene flow being considered. By incorporating this heterogeneity, the best-supported scenario was a long period of allopatric isolation during the first three-quarters of the time since divergence followed by secondary contact and introgression during the last quarter. By contrast, constraining migration to be homogeneous failed to discriminate among any of the different models of gene flow tested. Our simulations thus provide statistical support for the secondary contact scenario in the European Mytilus hybrid zone that the standard coalescent approach failed to confirm. Our results demonstrate that genomic variation in introgression rates can have profound impacts on the biological conclusions drawn from inference methods and needs to be incorporated in future studies.

  10. Genetic dissection of maize phenology using an intraspecific introgression library

    PubMed Central

    2011-01-01

    Background Collections of nearly isogenic lines where each line carries a delimited portion of a donor source genome into a common recipient genetic background are known as introgression libraries and have already shown to be instrumental for the dissection of quantitative traits. By means of marker-assisted backcrossing, we have produced an introgression library using the extremely early-flowering maize (Zea mays L.) variety Gaspé Flint and the elite line B73 as donor and recipient genotypes, respectively, and utilized this collection to investigate the genetic basis of flowering time and related traits of adaptive and agronomic importance in maize. Results The collection includes 75 lines with an average Gaspé Flint introgression length of 43.1 cM. The collection was evaluated for flowering time, internode length, number of ears, number of nodes (phytomeres), number of nodes above the ear, number and proportion of nodes below the ear and plant height. Five QTLs for flowering time were mapped, all corresponding to major QTLs for number of nodes. Three additional QTLs for number of nodes were mapped. Besides flowering time, the QTLs for number of nodes drove phenotypic variation for plant height and number of nodes below and above the top ear, but not for internode length. A number of apparently Mendelian-inherited phenotypes were also observed. Conclusions While the inheritance of flowering time was dominated by the well-known QTL Vgt1, a number of other important flowering time QTLs were identified and, thanks to the type of plant material here utilized, immediately isogenized and made available for fine mapping. At each flowering time QTL, early flowering correlated with fewer vegetative phytomeres, indicating the latter as a key developmental strategy to adapt the maize crop from the original tropical environment to the northern border of the temperate zone (southern Canada), where Gaspé Flint was originally cultivated. Because of the trait differences

  11. Marker development and characterisation of Hordeum bulbosum introgression lines: a resource for barley improvement.

    PubMed

    Johnston, Paul A; Timmerman-Vaughan, Gail M; Farnden, Kevin J F; Pickering, Richard

    2009-05-01

    A set of 110 diploid putative introgression lines (ILs) containing chromatin introgressed from the undomesticated species Hordeum bulbosum L. (bulbous barley grass) into cultivated barley (Hordeum vulgare L.) has been identified using a high-copy number retrotransposon-like PCR marker, pSc119.1, derived from rye (Secale cereale L.). To evaluate these lines, 92 EST-derived markers were developed by marker sequencing across four barley cultivars and four H. bulbosum genotypes. Single nucleotide polymorphisms and insertions/deletions conserved between the two species were then used to develop a set of fully informative cleaved amplified polymorphic sequence markers or size polymorphic insertion/deletion markers. Introgressed chromatin from H. bulbosum was confirmed and genetically located in 88 of these lines using 46 of the EST-derived PCR markers. A total of 96 individual introgressions were detected with most of them (94.8%) extending to the most distal marker for each respective chromosome arm. Introgressions were detected on all chromosome arms except chromosome 3HL. Interstitial or sub-distal introgressions also occurred, with two located on chromosome 2HL and one each on 3HS, 5HL and 6HS. Twenty-two putative ILs that were positive for H. bulbosum chromatin using pSc119.1 have not had introgressions detected with these single-locus markers. When all introgressions are combined, more than 36% of the barley genetic map has now been covered with introgressed chromatin from H. bulbosum. These ILs represent a significant germplasm resource for barley improvement that can be mined for diverse traits of interest to barley breeders and researchers.

  12. An HMM-Based Comparative Genomic Framework for Detecting Introgression in Eukaryotes

    PubMed Central

    Liu, Kevin J.; Dai, Jingxuan; Truong, Kathy; Song, Ying; Kohn, Michael H.; Nakhleh, Luay

    2014-01-01

    One outcome of interspecific hybridization and subsequent effects of evolutionary forces is introgression, which is the integration of genetic material from one species into the genome of an individual in another species. The evolution of several groups of eukaryotic species has involved hybridization, and cases of adaptation through introgression have been already established. In this work, we report on PhyloNet-HMM—a new comparative genomic framework for detecting introgression in genomes. PhyloNet-HMM combines phylogenetic networks with hidden Markov models (HMMs) to simultaneously capture the (potentially reticulate) evolutionary history of the genomes and dependencies within genomes. A novel aspect of our work is that it also accounts for incomplete lineage sorting and dependence across loci. Application of our model to variation data from chromosome 7 in the mouse (Mus musculus domesticus) genome detected a recently reported adaptive introgression event involving the rodent poison resistance gene Vkorc1, in addition to other newly detected introgressed genomic regions. Based on our analysis, it is estimated that about 9% of all sites within chromosome 7 are of introgressive origin (these cover about 13 Mbp of chromosome 7, and over 300 genes). Further, our model detected no introgression in a negative control data set. We also found that our model accurately detected introgression and other evolutionary processes from synthetic data sets simulated under the coalescent model with recombination, isolation, and migration. Our work provides a powerful framework for systematic analysis of introgression while simultaneously accounting for dependence across sites, point mutations, recombination, and ancestral polymorphism. PMID:24922281

  13. Hosts and parasites as aliens.

    PubMed

    Taraschewski, H

    2006-06-01

    Over the past decades, various free-living animals (hosts) and their parasites have invaded recipient areas in which they had not previously occurred, thus gaining the status of aliens or exotics. In general this happened to a low extent for hundreds of years. With variable frequency, invasions have been followed by the dispersal and establishment of non-indigenous species, whether host or parasite. In the literature thus far, colonizations by both hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways. As to those factors permitting invasive success and colonization strength, various hypotheses have been put forward depending on the scientific background of respective authors and on the conspicuousness of certain invasions. Researchers who have tried to analyse characteristic developmental patterns, the speed of dispersal or the degree of genetic divergence in populations of alien species have come to different conclusions. Among parasitologists, the applied aspects of parasite invasions, such as the negative effects on economically important hosts, have long been at the centre of interest. In this contribution, invasions by hosts as well as parasites are considered comparatively, revealing many similarities and a few differences. Two helminths, the liver fluke, Fasciola hepatica, of cattle and sheep and the swimbladder nematode, Anguillicola crassus, of eels are shown to be useful as model parasites for the study of animal invasions and environmental global change. Introductions of F. hepatica have been associated with imports of cattle or other grazing animals. In various target areas, susceptible lymnaeid snails serving as intermediate hosts were either naturally present and/or were introduced from the donor continent of the parasite (Europe) and/or from other regions which were not within the original range of the parasite, partly reflecting progressive stages of a global biota change. In several

  14. A genomic view of introgression and hybrid speciation

    PubMed Central

    Baack, Eric J.; Rieseberg, Loren H.

    2007-01-01

    Summary Hybridization in plants and animals is more common and has more complex outcomes than previously realized. Genome-wide analyses of introgression in organisms ranging from oaks to sunflowers to fruit flies show that a substantial fraction of their genomes are permeable to alleles from related species. Hybridization can lead to rapid genomic changes, including chromosomal rearrangements, genome expansion, differential gene expression, and gene silencing, some of which are mediated by transposable elements. These genomic changes may lead to beneficial new phenotypes, and selection for fertility and ecological traits may in turn alter genome structure. Dramatic increases in the availability of genomic tools will produce a new understanding of the genetic nature of species and will resolve a century-old debate over the basis of hybrid vigour, while the natural recombinants found in hybrid zones will permit genetic mapping of species differences and reproductive barriers in non-model organisms. PMID:17933508

  15. Undocumented Aliens: A Study of Mexican Families.

    ERIC Educational Resources Information Center

    Salcido, Ramon M.

    1979-01-01

    The personal histories described here confirm that the primary impetus of undocumented aliens to emigrate is the desire for jobs and better socioeconomic opportunities. Amnesty, aid to families with dependent children, and increased social services are recommended. (Author/BEF)

  16. Molecular analysis, cytogenetics and fertility of introgression lines from transgenic wheat to Aegilops cylindrica host.

    PubMed

    Schoenenberger, Nicola; Guadagnuolo, Roberto; Savova-Bianchi, Dessislava; Küpfer, Philippe; Felber, François

    2006-12-01

    Natural hybridization and backcrossing between Aegilops cylindrica and Triticum aestivum can lead to introgression of wheat DNA into the wild species. Hybrids between Ae. cylindrica and wheat lines bearing herbicide resistance (bar), reporter (gus), fungal disease resistance (kp4), and increased insect tolerance (gna) transgenes were produced by pollination of emasculated Ae. cylindrica plants. F1 hybrids were backcrossed to Ae. cylindrica under open-pollination conditions, and first backcrosses were selfed using pollen bags. Female fertility of F1 ranged from 0.03 to 0.6%. Eighteen percent of the sown BC1s germinated and flowered. Chromosome numbers ranged from 30 to 84 and several of the plants bore wheat-specific sequence-characterized amplified regions (SCARs) and the bar gene. Self fertility in two BC1 plants was 0.16 and 5.21%, and the others were completely self-sterile. Among 19 BC1S1 individuals one plant was transgenic, had 43 chromosomes, contained the bar gene, and survived glufosinate treatments. The other BC1S1 plants had between 28 and 31 chromosomes, and several of them carried SCARs specific to wheat A and D genomes. Fertility of these plants was higher under open-pollination conditions than by selfing and did not necessarily correlate with even or euploid chromosome number. Some individuals having supernumerary wheat chromosomes recovered full fertility.

  17. Assessment of hybridization and introgression in lava-colonizing Hawaiian Dubautia (Asteraceae: Madiinae) using RAPD markers.

    PubMed

    Caraway, V; Carr, G D; Morden, C W

    2001-09-01

    Hybridization between Dubautia ciliolata and D. scabra occurring on a mosaic of lava flows of 1855 and 1935 on the island of Hawai'i was examined using random amplified polymorphic DNA (RAPD) markers. The RAPD data indicate that D. ciliolata plants, nearly restricted to the 1855 lava flow, contain higher levels of genetic variation than do D. scabra plants occurring on the 1935 lava flow. Seventy-one markers were specific to D. ciliolata and 60 to D. scabra; 40 of these were "constant" (found in all individuals) in one or the other species. Hybrids sampled were determined to represent F(1), filial hybrids beyond the F(1), and backcross progeny. All backcrosses were unidirectional with D. ciliolata acting as the recurrent parent. No hybrid, including an artificially produced F(1), had all 40 constant markers, suggesting that at least some loci for these markers were heterozygous in the parents. However, several hybrids exhibited a loss of many of the species markers, suggesting that they were later filial hybrid generation plants. The apparent occurrence of unidirectional introgression at the study site may be providing D. ciliolata plants with genetic plasticity to colonize the new lava flow previously occupied only by D. scabra.

  18. Undocumented aliens and uncompensated care: whose responsibility?

    PubMed Central

    Siddharthan, K; Alalasundaram, S

    1993-01-01

    Undocumented aliens concentrated in metropolitan areas and certain Sunbelt states can financially burden local health agencies and may interfere with access to health care for indigent populations that are legally resident. Data collected from Jackson Memorial Hospital, which provides the bulk of indigent medical services in Dade County, Florida, are used to investigate the problem of providing uncompensated care to undocumented aliens. Policy alternatives concerning immigration issues and reimbursement are discussed. PMID:8031329

  19. Undocumented aliens and uncompensated care: whose responsibility?

    PubMed

    Siddharthan, K; Alalasundaram, S

    1993-03-01

    Undocumented aliens concentrated in metropolitan areas and certain Sunbelt states can financially burden local health agencies and may interfere with access to health care for indigent populations that are legally resident. Data collected from Jackson Memorial Hospital, which provides the bulk of indigent medical services in Dade County, Florida, are used to investigate the problem of providing uncompensated care to undocumented aliens. Policy alternatives concerning immigration issues and reimbursement are discussed.

  20. Adaptive introgression between Anopheles sibling species eliminates a major genomic island but not reproductive isolation

    PubMed Central

    Clarkson, Chris S.; Weetman, David; Essandoh, John; Yawson, Alexander E.; Maslen, Gareth; Manske, Magnus; Field, Stuart G.; Webster, Mark; Antão, Tiago; MacInnis, Bronwyn; Kwiatkowski, Dominic; Donnelly, Martin J.

    2014-01-01

    Adaptive introgression can provide novel genetic variation to fuel rapid evolutionary responses, though it may be counterbalanced by potential for detrimental disruption of the recipient genomic background. We examine the extent and impact of recent introgression of a strongly selected insecticide-resistance mutation (Vgsc-1014F) located within one of two exceptionally large genomic islands of divergence separating the Anopheles gambiae species pair. Here we show that transfer of the Vgsc mutation results in homogenization of the entire genomic island region (~1.5% of the genome) between species. Despite this massive disruption, introgression is clearly adaptive with a dramatic rise in frequency of Vgsc-1014F and no discernable impact on subsequent reproductive isolation between species. Our results show (1) how resilience of genomes to massive introgression can permit rapid adaptive response to anthropogenic selection and (2) that even extreme prominence of genomic islands of divergence can be an unreliable indicator of importance in speciation. PMID:24963649

  1. Adaptive introgression between Anopheles sibling species eliminates a major genomic island but not reproductive isolation.

    PubMed

    Clarkson, Chris S; Weetman, David; Essandoh, John; Yawson, Alexander E; Maslen, Gareth; Manske, Magnus; Field, Stuart G; Webster, Mark; Antão, Tiago; MacInnis, Bronwyn; Kwiatkowski, Dominic; Donnelly, Martin J

    2014-06-25

    Adaptive introgression can provide novel genetic variation to fuel rapid evolutionary responses, though it may be counterbalanced by potential for detrimental disruption of the recipient genomic background. We examine the extent and impact of recent introgression of a strongly selected insecticide-resistance mutation (Vgsc-1014F) located within one of two exceptionally large genomic islands of divergence separating the Anopheles gambiae species pair. Here we show that transfer of the Vgsc mutation results in homogenization of the entire genomic island region (~1.5% of the genome) between species. Despite this massive disruption, introgression is clearly adaptive with a dramatic rise in frequency of Vgsc-1014F and no discernable impact on subsequent reproductive isolation between species. Our results show (1) how resilience of genomes to massive introgression can permit rapid adaptive response to anthropogenic selection and (2) that even extreme prominence of genomic islands of divergence can be an unreliable indicator of importance in speciation.

  2. Propagule pressure and stream characteristics influence introgression: cutthroat and rainbow trout in British Columbia.

    PubMed

    Bennett, Stephen N; Olson, John R; Kershner, Jeffrey L; Corbett, Peter

    2010-01-01

    Hybridization and introgression between introduced and native salmonids threaten the continued persistence of many inland cutthroat trout species. Environmental models have been developed to predict the spread of introgression, but few studies have assessed the role of propagule pressure. We used an extensive set of fish Stocking records and geographic information system (GIS) data to produce a spatially explicit index of potential propagule pressure exerted by introduced rainbow trout in the Upper Kootenay River, British Columbia, Canada. We then used logistic regression and the information-theoretic approach to test the ability of a set of environmental and spatial variables to predict the level of introgression between native westslope cutthroat trout and introduced rainbow trout. Introgression was assessed using between four and seven co-dominant, diagnostic nuclear markers at 45 sites in 31 different streams. The best model for predicting introgression included our GIS propagule pressure index and an environmental variable that accounted for the biogeoclimatic zone of the site (r2=0.62). This model was 1.4 times more likely to explain introgression than the next-best model, which consisted of only the propagule pressure index variable. We created a composite model based on the model-averaged results of the seven top models that included environmental, spatial, and propagule pressure variables. The propagule pressure index had the highest importance weight (0.995) of all variables tested and was negatively related to sites with no introgression. This study used an index of propagule pressure and demonstrated that propagule pressure had the greatest influence on the level of introgression between a native and introduced trout in a human-induced hybrid zone.

  3. Propagule pressure and stream characteristics influence introgression: Cutthroat and rainbow trout in British Columbia

    USGS Publications Warehouse

    Bennett, S.N.; Olson, J.R.; Kershner, J.L.; Corbett, P.

    2010-01-01

    Hybridization and introgression between introduced and native salmonids threaten the continued persistence of many inland cutthroat trout species. Environmental models have been developed to predict the spread of introgression, but few studies have assessed the role of propagule pressure. We used an extensive set of fish stocking records and geographic information system (GIS) data to produce a spatially explicit index of potential propagule pressure exerted by introduced rainbow trout in the Upper Kootenay River, British Columbia, Canada. We then used logistic regression and the information-theoretic approach to test the ability of a set of environmental and spatial variables to predict the level of introgression between native westslope cutthroat trout and introduced rainbow trout. Introgression was assessed using between four and seven co-dominant, diagnostic nuclear markers at 45 sites in 31 different streams. The best model for predicting introgression included our GIS propagule pressure index and an environmental variable that accounted for the biogeoclimatic zone of the site (r2 = 0.62). This model was 1.4 times more likely to explain introgression than the next-best model, which consisted of only the propagule pressure index variable. We created a composite model based on the model-averaged results of the seven top models that included environmental, spatial, and propagule pressure variables. The propagule pressure index had the highest importance weight (0.995) of all variables tested and was negatively related to sites with no introgression. This study used an index of propagule pressure and demonstrated that propagule pressure had the greatest influence on the level of introgression between a native and introduced trout in a human-induced hybrid zone. ?? 2010 by the Ecological Society of America.

  4. Does genetic introgression improve female reproductive performance? A test on the endangered Florida panther.

    PubMed

    Hostetler, Jeffrey A; Onorato, David P; Bolker, Benjamin M; Johnson, Warren E; O'Brien, Stephen J; Jansen, Deborah; Oli, Madan K

    2012-01-01

    Genetic introgression has been suggested as a management tool for mitigating detrimental effects of inbreeding depression, but the role of introgression in species conservation has been controversial, partly because population-level impacts of genetic introgressions are not well understood. Concerns about potential inbreeding depression in the endangered Florida panther (Puma concolor coryi) led to the release of eight female Texas pumas (P. c. stanleyana) into the Florida panther population in 1995. We used long-term reproductive data (1995-2008) collected from 61 female Florida panthers to estimate and model reproduction probability (probability of producing a litter) and litter size, and to investigate the influence of intentional genetic introgression on these parameters. Overall, 6-month probability of reproduction (±1SE) was 0.232 ± 0.021 and average litter size was 2.60 ± 0.09. Although F(1) admixed females had a lower reproduction probability than females with other ancestries, this was most likely because kittens born to F(1) females survive better; consequently, these females are unavailable for breeding until kittens are independent. There was no evidence for the effect of ancestry on litter size or of heterozygosity on probability of reproduction or litter size. In contrast, earlier studies have shown that genetic introgression positively affected Florida panther survival. Our results, along with those of earlier studies, clearly suggest that genetic introgression can have differential effects on components of fitness and highlight the importance of examining multiple demographic parameters when evaluating the effects of management actions.

  5. Alien abduction: a medical hypothesis.

    PubMed

    Forrest, David V

    2008-01-01

    In response to a new psychological study of persons who believe they have been abducted by space aliens that found that sleep paralysis, a history of being hypnotized, and preoccupation with the paranormal and extraterrestrial were predisposing experiences, I noted that many of the frequently reported particulars of the abduction experience bear more than a passing resemblance to medical-surgical procedures and propose that experience with these may also be contributory. There is the altered state of consciousness, uniformly colored figures with prominent eyes, in a high-tech room under a round bright saucerlike object; there is nakedness, pain and a loss of control while the body's boundaries are being probed; and yet the figures are thought benevolent. No medical-surgical history was apparently taken in the above mentioned study, but psychological laboratory work evaluated false memory formation. I discuss problems in assessing intraoperative awareness and ways in which the medical hypothesis could be elaborated and tested. If physicians are causing this syndrome in a percentage of patients, we should know about it; and persons who feel they have been abducted should be encouraged to inform their surgeons and anesthesiologists without challenging their beliefs.

  6. DNA

    ERIC Educational Resources Information Center

    Stent, Gunther S.

    1970-01-01

    This history for molecular genetics and its explanation of DNA begins with an analysis of the Golden Jubilee essay papers, 1955. The paper ends stating that the higher nervous system is the one major frontier of biological inquiry which still offers some romance of research. (Author/VW)

  7. The genetic legacy of the 19th-century decline of the British polecat: evidence for extensive introgression from feral ferrets.

    PubMed

    Costa, M; Fernandes, C; Birks, J D S; Kitchener, A C; Santos-Reis, M; Bruford, M W

    2013-10-01

    In the 19th century, the British polecat suffered a demographic contraction, as a consequence of direct persecution, reaching its lowest population in the years that preceded the First World War. The polecat is now recovering and expanding throughout Britain, but introgressive hybridization with feral ferrets has been reported, which could be masking the true range of the polecat and introducing domestic genes into the species. We used a fragment of the mitochondrial DNA control region and 11 microsatellite loci to characterize the frequency and extent of hybridization and introgression between the two species and assess whether the 19th-century decline corresponded to a genetic bottleneck in the polecat. The proportion of admixture detected in the wild was high (31%) and hybrids were more frequently found outside Wales, suggesting that hybridization is more likely to occur along the eastern edge of the polecat's range expansion. The patterns observed in the mitochondrial and nuclear DNA data show that introgression was mediated by crosses between male polecats and female ferrets, whose offspring backcrossed with polecats. No first-generation (F1 ) hybrids were identified, and the broad range of observed admixture proportions agrees with a scenario of past extensive hybridization between the two species. Using several different methods to investigate demographic history, we did not find consistent evidence for a genetic bottleneck in the British polecat, a result that could be interpreted as a consequence of hybridization with ferrets. Our results highlight the importance of the Welsh polecat population for the conservation and restoration of the genetic identity of the British polecat.

  8. ALIEN SPECIES: THEIR ROLE IN AMPHIBIAN POPULATION DECLINES AND RESTORATION

    EPA Science Inventory

    Alien species (also referred to as exotic, invasive, introduced, or normative species) have been implicated as causal agents in population declines of many amphibian species. Herein, we evaluate the relative contributions of alien species and other factors in adversely affecting ...

  9. Using effect size benchmarks to assess when alien impacts are actually alien.

    PubMed

    Smith, Helen M; Dickman, Chris R; Banks, Peter B

    2017-01-27

    Alien predators have on average twice the impact on native prey populations than do native predators, and are a severe threat to wildlife globally. Manipulation experiments can be used to quantify the impact of an alien predator on its prey population/s, but unless the results are compared to benchmarks, it is unclear whether this impact is indeed greater than that of a native predator. Here we use the Australian garden skink Lampropholis delicata and alien black rat Rattus rattus to test if black rats are an additive source of predation for the skink, and to judge whether the effect size of rat-impact on the skink represents that of an alien or native predator. We used replicated experiments to exclude black rats at local and landscape scales to test how rats affect skink activity and trapping frequency. Both manipulations had positive effects on skinks, however, the population-level effect size was lower than that described for alien predators but similar to that expected for native predators. We suggest that Australian skinks may respond appropriately to predatory alien rats because they coevolved with endemic Rattus species. This adds novel insights into the varying levels of impact that alien predators have on native prey.

  10. Using effect size benchmarks to assess when alien impacts are actually alien

    PubMed Central

    Smith, Helen M.; Dickman, Chris R.; Banks, Peter B.

    2017-01-01

    Alien predators have on average twice the impact on native prey populations than do native predators, and are a severe threat to wildlife globally. Manipulation experiments can be used to quantify the impact of an alien predator on its prey population/s, but unless the results are compared to benchmarks, it is unclear whether this impact is indeed greater than that of a native predator. Here we use the Australian garden skink Lampropholis delicata and alien black rat Rattus rattus to test if black rats are an additive source of predation for the skink, and to judge whether the effect size of rat-impact on the skink represents that of an alien or native predator. We used replicated experiments to exclude black rats at local and landscape scales to test how rats affect skink activity and trapping frequency. Both manipulations had positive effects on skinks, however, the population-level effect size was lower than that described for alien predators but similar to that expected for native predators. We suggest that Australian skinks may respond appropriately to predatory alien rats because they coevolved with endemic Rattus species. This adds novel insights into the varying levels of impact that alien predators have on native prey. PMID:28128305

  11. Effects of suppressing the DNA mismatch repair system on homeologous recombination in tomato.

    PubMed

    Tam, Sheh May; Hays, John B; Chetelat, Roger T

    2011-12-01

    In plant breeding, the ability to manipulate genetic (meiotic) recombination would be beneficial for facilitating gene transfer from wild relatives of crop plants. The DNA mismatch repair (MMR) system helps maintain genetic integrity by correcting base mismatches that arise via DNA synthesis or damage, and antagonizes recombination between homeologous (divergent) DNA sequences. Previous studies have established that the genomes of cultivated tomato (Solanum lycopersicum) and the wild relative S. lycopersicoides are substantially diverged (homeologous) such that recombination between their chromosomes is strongly reduced. Here, we report the effects on homeologous recombination of suppressing endogenous MMR genes in S. lycopersicum via RNAi-induced silencing of SlMSH2 and SlMSH7 or overexpressing dominant negatives of Arabidopsis MSH2 (AtMSH2-DN) in an alien substitution line (SL-8) of S. lycopersicoides in tomato. We show that certain inhibitions of MMR (RNAi of SlMSH7, AtMSH2-DN) are associated with modest increases in homeologous recombination, ranging from 3.8 to 29.2% (average rate of 17.8%) compared to controls. Unexpectedly, only the AtMSH2-DN proteins but not RNAi-induced silencing of MSH2 was found to increase homeologous recombination. The ratio of single to double crossovers (SCO:DCO ratio) decreased by approximately 50% in progeny of the AtMSH2-DN parents. An increase in the frequency of heterozygous SL-8 plants was also observed in the progeny of the SlMSH7-RNAi parents. Our findings may contribute to acceleration of introgression in cultivated tomato.

  12. Intentional genetic introgression influences survival of adults and subadults in a small, inbred felid population.

    PubMed

    Benson, John F; Hostetler, Jeffrey A; Onorato, David P; Johnson, Warren E; Roelke, Melody E; O'Brien, Stephen J; Jansen, Deborah; Oli, Madan K

    2011-09-01

    1. Inbreeding and low genetic diversity can cause reductions in individual fitness and increase extinction risk in animal populations. Intentional introgression, achieved by releasing genetically diverse individuals into inbred populations, has been used as a conservation tool to improve demographic performance in endangered populations. 2. By the 1980s, Florida panthers (Puma concolor coryi) had been reduced to a small, inbred population that appeared to be on the brink of extinction. In 1995, female pumas from Texas (P. c. stanleyana) were released in occupied panther range as part of an intentional introgression programme to restore genetic variability and improve demographic performance of panthers. 3. We used 25 years (1981-2006) of continuous radiotelemetry and genetic data to estimate and model subadult and adult panther survival and cause-specific mortality to provide rigorous sex and age class-specific survival estimates and evaluate the effect of the introgression programme on these parameters. 4. Genetic ancestry influenced annual survival of subadults and adults after introgression, as F(1) generation admixed panthers ( = 0·98) survived better than pre-introgression type panthers ( = 0·77) and other admixed individuals ( = 0·82). Furthermore, heterozygosity was higher for admixed panthers relative to pre-introgression type panthers and positively influenced survival. 5. Our results are consistent with hybrid vigour; however, extrinsic factors such as low density of males in some areas of panther range may also have contributed to higher survival of F(1) panthers. Regardless, improved survival of F(1) subadults and adults likely contributed to the numerical increase in panthers following introgression, and our results indicate that intentional admixture, achieved here by releasing individuals from another population, appears to have been successful in improving demographic performance in this highly endangered population.

  13. Alienation: A Concept for Understanding Low-Income, Urban Clients

    ERIC Educational Resources Information Center

    Holcomb-McCoy, Cheryl

    2004-01-01

    The author examines the concept of alienation and how it can be used to understand low-income, urban clients. A description is presented of 4 dimensions of alienation: powerlessness, meaninglessness, normlessness, and social isolation. Case illustrations are provided, and recommendations are made for counseling alienated clients. This article…

  14. 22 CFR 41.24 - International organization aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false International organization aliens. 41.24... aliens. (a) Definition of international organization. “International organization” means: (1) Any public...)(27)(I), INTELSAT or any successor or separated entity thereof. (b) Aliens coming to...

  15. 42 CFR 436.330 - Coverage for certain aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 4 2011-10-01 2011-10-01 false Coverage for certain aliens. 436.330 Section 436... Coverage of the Medically Needy § 436.330 Coverage for certain aliens. If an agency provides Medicaid to... condition, as defined in § 440.255(c) of this chapter to those aliens described in § 436.406(c) of...

  16. 32 CFR 1602.3 - Aliens and nationals.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Aliens and nationals. 1602.3 Section 1602.3 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.3 Aliens and nationals. (a) The term alien means any person who is not a citizen or national of...

  17. 8 CFR 1235.3 - Inadmissible aliens and expedited removal.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Inadmissible aliens and expedited removal. 1235.3 Section 1235.3 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS INSPECTION OF PERSONS APPLYING FOR ADMISSION § 1235.3 Inadmissible...

  18. 42 CFR 436.330 - Coverage for certain aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 4 2012-10-01 2012-10-01 false Coverage for certain aliens. 436.330 Section 436... Coverage of the Medically Needy § 436.330 Coverage for certain aliens. If an agency provides Medicaid to... condition, as defined in § 440.255(c) of this chapter to those aliens described in § 436.406(c) of...

  19. 22 CFR 41.24 - International organization aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false International organization aliens. 41.24... aliens. (a) Definition of international organization. “International organization” means: (1) Any public...)(27)(I), INTELSAT or any successor or separated entity thereof. (b) Aliens coming to...

  20. 32 CFR 1602.3 - Aliens and nationals.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Aliens and nationals. 1602.3 Section 1602.3 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.3 Aliens and nationals. (a) The term alien means any person who is not a citizen or national of...

  1. 8 CFR 1235.3 - Inadmissible aliens and expedited removal.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Inadmissible aliens and expedited removal. 1235.3 Section 1235.3 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS INSPECTION OF PERSONS APPLYING FOR ADMISSION § 1235.3 Inadmissible...

  2. 42 CFR 435.139 - Coverage for certain aliens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Coverage for certain aliens. 435.139 Section 435... Aliens § 435.139 Coverage for certain aliens. The agency must provide services necessary for the treatment of an emergency medical condition, as defined in § 440.255(c) of this chapter, to those...

  3. 20 CFR 404.1036 - Certain nonresident aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Certain nonresident aliens. 404.1036 Section... Employment § 404.1036 Certain nonresident aliens. (a) Foreign students. (1) Foreign students (nonimmigrant aliens) may be temporarily in the United States under subparagraph (F) of section 101(a)(15) of...

  4. 32 CFR 1630.46 - Class 4-T: Treaty alien.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Class 4-T: Treaty alien. 1630.46 Section 1630.46 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.46 Class 4-T: Treaty alien. In Class 4-T shall be placed any registrant who is an alien...

  5. 43 CFR 426.8 - Nonresident aliens and foreign entities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Nonresident aliens and foreign entities..., DEPARTMENT OF THE INTERIOR ACREAGE LIMITATION RULES AND REGULATIONS § 426.8 Nonresident aliens and foreign... reclamation law or these regulations, a nonresident alien or foreign entity that directly holds land in...

  6. 32 CFR 1630.46 - Class 4-T: Treaty alien.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Class 4-T: Treaty alien. 1630.46 Section 1630.46 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.46 Class 4-T: Treaty alien. In Class 4-T shall be placed any registrant who is an alien...

  7. 22 CFR 41.24 - International organization aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false International organization aliens. 41.24... aliens. (a) Definition of international organization. “International organization” means: (1) Any public...)(27)(I), INTELSAT or any successor or separated entity thereof. (b) Aliens coming to...

  8. 42 CFR 436.128 - Coverage for certain qualified aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 4 2012-10-01 2012-10-01 false Coverage for certain qualified aliens. 436.128... Mandatory Coverage of the Categorically Needy § 436.128 Coverage for certain qualified aliens. The agency... § 440.255(c) of this chapter to those aliens described in § 436.406(c) of this subpart....

  9. 20 CFR 404.1036 - Certain nonresident aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Certain nonresident aliens. 404.1036 Section... Employment § 404.1036 Certain nonresident aliens. (a) Foreign students. (1) Foreign students (nonimmigrant aliens) may be temporarily in the United States under subparagraph (F) of section 101(a)(15) of...

  10. 22 CFR 40.9 - Classes of inadmissible aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Classes of inadmissible aliens. 40.9 Section 40.9 Foreign Relations DEPARTMENT OF STATE VISAS REGULATIONS PERTAINING TO BOTH NONIMMIGRANTS AND... inadmissible aliens. Subparts B through L describe classes of inadmissible aliens who are ineligible to...

  11. 45 CFR 233.51 - Eligibility of sponsored aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 2 2013-10-01 2012-10-01 true Eligibility of sponsored aliens. 233.51 Section 233... CONDITIONS OF ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.51 Eligibility of sponsored aliens... affidavit(s) of support or similar agreement on behalf of an alien (who is not the child of the sponsor...

  12. 32 CFR 1602.3 - Aliens and nationals.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Aliens and nationals. 1602.3 Section 1602.3 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.3 Aliens and nationals. (a) The term alien means any person who is not a citizen or national of...

  13. 45 CFR 233.51 - Eligibility of sponsored aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 2 2012-10-01 2012-10-01 false Eligibility of sponsored aliens. 233.51 Section... CONDITIONS OF ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.51 Eligibility of sponsored aliens... affidavit(s) of support or similar agreement on behalf of an alien (who is not the child of the sponsor...

  14. 32 CFR 1630.46 - Class 4-T: Treaty alien.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Class 4-T: Treaty alien. 1630.46 Section 1630.46 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.46 Class 4-T: Treaty alien. In Class 4-T shall be placed any registrant who is an alien...

  15. 22 CFR 41.58 - Aliens in religious occupations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Aliens in religious occupations. 41.58 Section... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.58 Aliens in religious occupations. (a) Requirements for “R” classification. An alien shall be classifiable under the provisions of...

  16. 22 CFR 40.9 - Classes of inadmissible aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Classes of inadmissible aliens. 40.9 Section 40.9 Foreign Relations DEPARTMENT OF STATE VISAS REGULATIONS PERTAINING TO BOTH NONIMMIGRANTS AND... inadmissible aliens. Subparts B through L describe classes of inadmissible aliens who are ineligible to...

  17. 42 CFR 436.330 - Coverage for certain aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 4 2013-10-01 2013-10-01 false Coverage for certain aliens. 436.330 Section 436... Coverage of the Medically Needy § 436.330 Coverage for certain aliens. If an agency provides Medicaid to... condition, as defined in § 440.255(c) of this chapter to those aliens described in § 436.406(c) of...

  18. 22 CFR 41.58 - Aliens in religious occupations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Aliens in religious occupations. 41.58 Section... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.58 Aliens in religious occupations. (a) Requirements for “R” classification. An alien shall be classifiable under the provisions of...

  19. 45 CFR 233.51 - Eligibility of sponsored aliens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 2 2010-10-01 2010-10-01 false Eligibility of sponsored aliens. 233.51 Section... CONDITIONS OF ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.51 Eligibility of sponsored aliens... affidavit(s) of support or similar agreement on behalf of an alien (who is not the child of the sponsor...

  20. 43 CFR 426.8 - Nonresident aliens and foreign entities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Nonresident aliens and foreign entities..., DEPARTMENT OF THE INTERIOR ACREAGE LIMITATION RULES AND REGULATIONS § 426.8 Nonresident aliens and foreign... reclamation law or these regulations, a nonresident alien or foreign entity that directly holds land in...

  1. 20 CFR 404.1036 - Certain nonresident aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Certain nonresident aliens. 404.1036 Section... Employment § 404.1036 Certain nonresident aliens. (a) Foreign students. (1) Foreign students (nonimmigrant aliens) may be temporarily in the United States under subparagraph (F) of section 101(a)(15) of...

  2. 42 CFR 436.128 - Coverage for certain qualified aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 4 2014-10-01 2014-10-01 false Coverage for certain qualified aliens. 436.128... Mandatory Coverage of the Categorically Needy § 436.128 Coverage for certain qualified aliens. The agency... § 440.255(c) of this chapter to those aliens described in § 436.406(c) of this subpart....

  3. 22 CFR 41.55 - Aliens with extraordinary ability.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Aliens with extraordinary ability. 41.55... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.55 Aliens with extraordinary ability. (a) Requirements for O classification. An alien shall be classifiable under the provisions of INA...

  4. 42 CFR 435.139 - Coverage for certain aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 4 2011-10-01 2011-10-01 false Coverage for certain aliens. 435.139 Section 435... Aliens § 435.139 Coverage for certain aliens. The agency must provide services necessary for the treatment of an emergency medical condition, as defined in § 440.255(c) of this chapter, to those...

  5. 22 CFR 41.55 - Aliens with extraordinary ability.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Aliens with extraordinary ability. 41.55... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.55 Aliens with extraordinary ability. (a) Requirements for O classification. An alien shall be classifiable under the provisions of INA...

  6. 22 CFR 41.24 - International organization aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false International organization aliens. 41.24... aliens. (a) Definition of international organization. “International organization” means: (1) Any public...)(27)(I), INTELSAT or any successor or separated entity thereof. (b) Aliens coming to...

  7. 22 CFR 41.55 - Aliens with extraordinary ability.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Aliens with extraordinary ability. 41.55... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.55 Aliens with extraordinary ability. (a) Requirements for O classification. An alien shall be classifiable under the provisions of INA...

  8. 32 CFR 1630.46 - Class 4-T: Treaty alien.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Class 4-T: Treaty alien. 1630.46 Section 1630.46 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.46 Class 4-T: Treaty alien. In Class 4-T shall be placed any registrant who is an alien...

  9. 43 CFR 426.8 - Nonresident aliens and foreign entities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Nonresident aliens and foreign entities..., DEPARTMENT OF THE INTERIOR ACREAGE LIMITATION RULES AND REGULATIONS § 426.8 Nonresident aliens and foreign... reclamation law or these regulations, a nonresident alien or foreign entity that directly holds land in...

  10. 43 CFR 426.8 - Nonresident aliens and foreign entities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Nonresident aliens and foreign entities..., DEPARTMENT OF THE INTERIOR ACREAGE LIMITATION RULES AND REGULATIONS § 426.8 Nonresident aliens and foreign... reclamation law or these regulations, a nonresident alien or foreign entity that directly holds land in...

  11. 45 CFR 233.51 - Eligibility of sponsored aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 2 2014-10-01 2012-10-01 true Eligibility of sponsored aliens. 233.51 Section 233... CONDITIONS OF ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.51 Eligibility of sponsored aliens... affidavit(s) of support or similar agreement on behalf of an alien (who is not the child of the sponsor...

  12. 22 CFR 41.58 - Aliens in religious occupations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Aliens in religious occupations. 41.58 Section... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.58 Aliens in religious occupations. (a) Requirements for “R” classification. An alien shall be classifiable under the provisions of...

  13. 22 CFR 40.9 - Classes of inadmissible aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Classes of inadmissible aliens. 40.9 Section 40.9 Foreign Relations DEPARTMENT OF STATE VISAS REGULATIONS PERTAINING TO BOTH NONIMMIGRANTS AND... inadmissible aliens. Subparts B through L describe classes of inadmissible aliens who are ineligible to...

  14. 22 CFR 41.55 - Aliens with extraordinary ability.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Aliens with extraordinary ability. 41.55... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.55 Aliens with extraordinary ability. (a) Requirements for O classification. An alien shall be classifiable under the provisions of INA...

  15. 42 CFR 436.128 - Coverage for certain qualified aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 4 2013-10-01 2013-10-01 false Coverage for certain qualified aliens. 436.128... Mandatory Coverage of the Categorically Needy § 436.128 Coverage for certain qualified aliens. The agency... § 440.255(c) of this chapter to those aliens described in § 436.406(c) of this subpart....

  16. 20 CFR 404.1036 - Certain nonresident aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Certain nonresident aliens. 404.1036 Section... Employment § 404.1036 Certain nonresident aliens. (a) Foreign students. (1) Foreign students (nonimmigrant aliens) may be temporarily in the United States under subparagraph (F) of section 101(a)(15) of...

  17. 43 CFR 426.8 - Nonresident aliens and foreign entities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Nonresident aliens and foreign entities..., DEPARTMENT OF THE INTERIOR ACREAGE LIMITATION RULES AND REGULATIONS § 426.8 Nonresident aliens and foreign... reclamation law or these regulations, a nonresident alien or foreign entity that directly holds land in...

  18. 32 CFR 1602.3 - Aliens and nationals.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Aliens and nationals. 1602.3 Section 1602.3 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.3 Aliens and nationals. (a) The term alien means any person who is not a citizen or national of...

  19. 42 CFR 436.128 - Coverage for certain qualified aliens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Coverage for certain qualified aliens. 436.128... Mandatory Coverage of the Categorically Needy § 436.128 Coverage for certain qualified aliens. The agency... § 440.255(c) of this chapter to those aliens described in § 436.406(c) of this subpart....

  20. 42 CFR 436.330 - Coverage for certain aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 4 2014-10-01 2014-10-01 false Coverage for certain aliens. 436.330 Section 436... Coverage of the Medically Needy § 436.330 Coverage for certain aliens. If an agency provides Medicaid to... condition, as defined in § 440.255(c) of this chapter to those aliens described in § 436.406(c) of...

  1. 42 CFR 435.139 - Coverage for certain aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 4 2014-10-01 2014-10-01 false Coverage for certain aliens. 435.139 Section 435... ISLANDS, AND AMERICAN SAMOA Mandatory Coverage Mandatory Coverage of Certain Aliens § 435.139 Coverage for certain aliens. The agency must provide services necessary for the treatment of an emergency...

  2. 42 CFR 436.128 - Coverage for certain qualified aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 4 2011-10-01 2011-10-01 false Coverage for certain qualified aliens. 436.128... Mandatory Coverage of the Categorically Needy § 436.128 Coverage for certain qualified aliens. The agency... § 440.255(c) of this chapter to those aliens described in § 436.406(c) of this subpart....

  3. 45 CFR 233.51 - Eligibility of sponsored aliens.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 2 2011-10-01 2011-10-01 false Eligibility of sponsored aliens. 233.51 Section... CONDITIONS OF ELIGIBILITY IN FINANCIAL ASSISTANCE PROGRAMS § 233.51 Eligibility of sponsored aliens... affidavit(s) of support or similar agreement on behalf of an alien (who is not the child of the sponsor...

  4. 22 CFR 41.58 - Aliens in religious occupations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Aliens in religious occupations. 41.58 Section... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.58 Aliens in religious occupations. (a) Requirements for “R” classification. An alien shall be classifiable under the provisions of...

  5. 42 CFR 436.330 - Coverage for certain aliens.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Coverage for certain aliens. 436.330 Section 436... Coverage of the Medically Needy § 436.330 Coverage for certain aliens. If an agency provides Medicaid to... condition, as defined in § 440.255(c) of this chapter to those aliens described in § 436.406(c) of...

  6. 22 CFR 41.55 - Aliens with extraordinary ability.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Aliens with extraordinary ability. 41.55... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.55 Aliens with extraordinary ability. (a) Requirements for O classification. An alien shall be classifiable under the provisions of INA...

  7. 78 FR 69292 - TWIC Not Evidence of Resident Alien Status

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-19

    ... SECURITY Coast Guard 33 CFR Part 141 RIN 1625-AC09 TWIC Not Evidence of Resident Alien Status AGENCY: Coast... employment of personnel on the OCS to U.S. citizens or resident aliens. The TWIC reference incorrectly... status as a U.S. resident alien, as that term is defined. This rule clarifies the regulations....

  8. 22 CFR 41.24 - International organization aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false International organization aliens. 41.24... aliens. (a) Definition of international organization. “International organization” means: (1) Any public...)(27)(I), INTELSAT or any successor or separated entity thereof. (b) Aliens coming to...

  9. 20 CFR 404.1036 - Certain nonresident aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Certain nonresident aliens. 404.1036 Section... Employment § 404.1036 Certain nonresident aliens. (a) Foreign students. (1) Foreign students (nonimmigrant aliens) may be temporarily in the United States under subparagraph (F) of section 101(a)(15) of...

  10. 42 CFR 435.139 - Coverage for certain aliens.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 4 2013-10-01 2013-10-01 false Coverage for certain aliens. 435.139 Section 435... ISLANDS, AND AMERICAN SAMOA Mandatory Coverage Mandatory Coverage of Certain Aliens § 435.139 Coverage for certain aliens. The agency must provide services necessary for the treatment of an emergency...

  11. 32 CFR 1602.3 - Aliens and nationals.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Aliens and nationals. 1602.3 Section 1602.3 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.3 Aliens and nationals. (a) The term alien means any person who is not a citizen or national of...

  12. 22 CFR 40.9 - Classes of inadmissible aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Classes of inadmissible aliens. 40.9 Section 40.9 Foreign Relations DEPARTMENT OF STATE VISAS REGULATIONS PERTAINING TO BOTH NONIMMIGRANTS AND... inadmissible aliens. Subparts B through L describe classes of inadmissible aliens who are ineligible to...

  13. 32 CFR 1630.46 - Class 4-T: Treaty alien.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Class 4-T: Treaty alien. 1630.46 Section 1630.46 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.46 Class 4-T: Treaty alien. In Class 4-T shall be placed any registrant who is an alien...

  14. 42 CFR 435.139 - Coverage for certain aliens.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 4 2012-10-01 2012-10-01 false Coverage for certain aliens. 435.139 Section 435... Aliens § 435.139 Coverage for certain aliens. The agency must provide services necessary for the treatment of an emergency medical condition, as defined in § 440.255(c) of this chapter, to those...

  15. 22 CFR 40.9 - Classes of inadmissible aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Classes of inadmissible aliens. 40.9 Section 40.9 Foreign Relations DEPARTMENT OF STATE VISAS REGULATIONS PERTAINING TO BOTH NONIMMIGRANTS AND... inadmissible aliens. Subparts B through L describe classes of inadmissible aliens who are ineligible to...

  16. 22 CFR 41.58 - Aliens in religious occupations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Aliens in religious occupations. 41.58 Section... IMMIGRATION AND NATIONALITY ACT, AS AMENDED Business and Media Visas § 41.58 Aliens in religious occupations. (a) Requirements for “R” classification. An alien shall be classifiable under the provisions of...

  17. Socio-economic Predictors of Alienation among the Elderly.

    ERIC Educational Resources Information Center

    Durant, Thomas J., Jr.; Christian, Ollie

    1990-01-01

    Studied level of alienation and associations between socioeconomic variables and alienation in 200 older senior center clients. Found group isolation and powerlessness were more prevalent than personal isolation or normlessness; health, race, education, and income were strongest predictors of alienation; and older Blacks and those with lower…

  18. The in silico identification and characterization of a bread wheat/Triticum militinae introgression line.

    PubMed

    Abrouk, Michael; Balcárková, Barbora; Šimková, Hana; Komínkova, Eva; Martis, Mihaela M; Jakobson, Irena; Timofejeva, Ljudmilla; Rey, Elodie; Vrána, Jan; Kilian, Andrzej; Järve, Kadri; Doležel, Jaroslav; Valárik, Miroslav

    2017-02-01

    The capacity of the bread wheat (Triticum aestivum) genome to tolerate introgression from related genomes can be exploited for wheat improvement. A resistance to powdery mildew expressed by a derivative of the cross-bread wheat cv. Tähti × T. militinae (Tm) is known to be due to the incorporation of a Tm segment into the long arm of chromosome 4A. Here, a newly developed in silico method termed rearrangement identification and characterization (RICh) has been applied to characterize the introgression. A virtual gene order, assembled using the GenomeZipper approach, was obtained for the native copy of chromosome 4A; it incorporated 570 4A DArTseq markers to produce a zipper comprising 2132 loci. A comparison between the native and introgressed forms of the 4AL chromosome arm showed that the introgressed region is located at the distal part of the arm. The Tm segment, derived from chromosome 7G, harbours 131 homoeologs of the 357 genes present on the corresponding region of Chinese Spring 4AL. The estimated number of Tm genes transferred along with the disease resistance gene was 169. Characterizing the introgression's position, gene content and internal gene order should not only facilitate gene isolation, but may also be informative with respect to chromatin structure and behaviour studies.

  19. Reticulate evolutionary history and extensive introgression in mosquito species revealed by phylogenetic network analysis.

    PubMed

    Wen, Dingqiao; Yu, Yun; Hahn, Matthew W; Nakhleh, Luay

    2016-06-01

    The role of hybridization and subsequent introgression has been demonstrated in an increasing number of species. Recently, Fontaine et al. (Science, 347, 2015, 1258524) conducted a phylogenomic analysis of six members of the Anopheles gambiae species complex. Their analysis revealed a reticulate evolutionary history and pointed to extensive introgression on all four autosomal arms. The study further highlighted the complex evolutionary signals that the co-occurrence of incomplete lineage sorting (ILS) and introgression can give rise to in phylogenomic analyses. While tree-based methodologies were used in the study, phylogenetic networks provide a more natural model to capture reticulate evolutionary histories. In this work, we reanalyse the Anopheles data using a recently devised framework that combines the multispecies coalescent with phylogenetic networks. This framework allows us to capture ILS and introgression simultaneously, and forms the basis for statistical methods for inferring reticulate evolutionary histories. The new analysis reveals a phylogenetic network with multiple hybridization events, some of which differ from those reported in the original study. To elucidate the extent and patterns of introgression across the genome, we devise a new method that quantifies the use of reticulation branches in the phylogenetic network by each genomic region. Applying the method to the mosquito data set reveals the evolutionary history of all the chromosomes. This study highlights the utility of 'network thinking' and the new insights it can uncover, in particular in phylogenomic analyses of large data sets with extensive gene tree incongruence.

  20. Reticulate Speciation and Barriers to Introgression in the Anopheles gambiae Species Complex.

    PubMed

    Crawford, Jacob E; Riehle, Michelle M; Guelbeogo, Wamdaogo M; Gneme, Awa; Sagnon, N'Fale; Vernick, Kenneth D; Nielsen, Rasmus; Lazzaro, Brian P

    2015-11-28

    Speciation as a process remains a central focus of evolutionary biology, but our understanding of the genomic architecture and prevalence of speciation in the face of gene flow remains incomplete. The Anopheles gambiae species complex of malaria mosquitoes is a radiation of ecologically diverse taxa. This complex is well-suited for testing for evidence of a speciation continuum and genomic barriers to introgression because its members exhibit partially overlapping geographic distributions as well as varying levels of divergence and reproductive isolation. We sequenced 20 genomes from wild A. gambiae s.s., Anopheles coluzzii, Anopheles arabiensis, and compared these with 12 genomes from the "GOUNDRY" subgroup of A. gambiae s.l. Amidst a backdrop of strong reproductive isolation, we find strong evidence for a speciation continuum with introgression of autosomal chromosomal regions among species and subgroups. The X chromosome, however, is strongly differentiated among all taxa, pointing to a disproportionately large effect of X chromosome genes in driving speciation among anophelines. Strikingly, we find that autosomal introgression has occurred from contemporary hybridization between A. gambiae and A. arabiensis despite strong divergence (∼5× higher than autosomal divergence) and isolation on the X chromosome. In addition to the X, we find strong evidence that lowly recombining autosomal regions, especially pericentromeric regions, serve as barriers to introgression secondarily to the X. We show that speciation with gene flow results in genomic mosaicism of divergence and introgression. Such a reticulate gene pool connecting vector taxa across the speciation continuum has important implications for malaria control efforts.

  1. The psychosocial treatment of parental alienation.

    PubMed

    Darnall, Douglas

    2011-07-01

    Parental alienation occurs in divorces when one parent indoctrinates the child to dislike, fear, and avoid contact with the other parent. Mental health professionals who treat children and adolescents are likely to encounter victims of parental alienation in clinical practice, and it is important to identify and treat these youngsters earlier, when the condition is mild, rather than later, when the parental alienation is almost intractable. This article presents an overview of the treatment of parental alienation, which is called reunification therapy. All the parties involved in the case have a role in the prevention and treatment of parental alienation.

  2. Pathophysiology and Treatment of Alien Hand Syndrome

    PubMed Central

    Sarva, Harini; Deik, Andres; Severt, William Lawrence

    2014-01-01

    Background Alien hand syndrome (AHS) is a disorder of involuntary, yet purposeful, hand movements that may be accompanied by agnosia, aphasia, weakness, or sensory loss. We herein review the most reported cases, current understanding of the pathophysiology, and treatments. Methods We performed a PubMed search in July of 2014 using the phrases “alien hand syndrome,” “alien hand syndrome pathophysiology,” “alien hand syndrome treatment,” and “anarchic hand syndrome.” The search yielded 141 papers (reviews, case reports, case series, and clinical studies), of which we reviewed 109. Non-English reports without English abstracts were excluded. Results Accumulating evidence indicates that there are three AHS variants: frontal, callosal, and posterior. Patients may demonstrate symptoms of multiple types; there is a lack of correlation between phenomenology and neuroimaging findings. Most pathologic and functional imaging studies suggest network disruption causing loss of inhibition as the likely cause. Successful interventions include botulinum toxin injections, clonazepam, visuospatial coaching techniques, distracting the affected hand, and cognitive behavioral therapy. Discussion The available literature suggests that overlap between AHS subtypes is common. The evidence for effective treatments remains anecdotal, and, given the rarity of AHS, the possibility of performing randomized, placebo-controlled trials seems unlikely. As with many other interventions for movement disorders, identifying the specific functional impairments caused by AHS may provide the best guidance towards individualized supportive care. PMID:25506043

  3. 43 CFR 3102.2 - Aliens.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... INTERIOR MINERALS MANAGEMENT (3000) OIL AND GAS LEASING Qualifications of Lessees § 3102.2 Aliens. Leases... control in a present or potential lessee that is incorporated under the laws of the United States or of any State or territory thereof, and only if the laws, customs or regulations of their country do...

  4. Immigration: Terrorist Grounds for Exclusion of Aliens

    DTIC Science & Technology

    2005-03-30

    SEVIS ) are also used during secondary inspections. For more on NSEERS, see CRS Report RL31570, Immigration: Alien Registration, by Andorra Bruno. For...more on SEVIS , see CRS Report RL32188, Monitoring Foreign Students in the United States: The Student and Exchange Visitor Information System ( SEVIS

  5. Processes of Alienation: Marx, Orff and Kodaly

    ERIC Educational Resources Information Center

    Benedict, Cathy

    2009-01-01

    Using Marx as a lens through which to interrogate music methodology, in particular those espoused by Orff and Kodaly, this article suggests that rather than the free play and creativity Orff and Kodaly intended, the implementation of these methods in a strict and unmindful manner, often alienates both teacher and student from musicking. Thus these…

  6. Creating Aliens: The Ultimate Life Sciences Activity.

    ERIC Educational Resources Information Center

    Beltramo, Dan

    2001-01-01

    Describes a seven-week project completed by the author's eighth-grade science students (as they studied "the chemistry of living things") in which they designed an alien and its world using the scientific concepts that they learned in class. Compares class presentations using PowerPoint software to presentations using posterboard. (SR)

  7. Aliens Among Us : Are They Already Here ?

    NASA Astrophysics Data System (ADS)

    McGaha, J.

    2008-03-01

    Popular culture, science fiction and mainstream belief, says they are! What is the evidence? Astronomer, skeptic and retired USAF pilot James McGaha examines this "Space Age" Mythology. From years of investigation of the physical evidence of aliens and there spacecraft (UFO's) here on earth, McGaha presents the scientific facts.

  8. Invite an Alien to Astronomy Night

    ERIC Educational Resources Information Center

    Governor, Donna; Richwine, Pebble

    2007-01-01

    Dozens of inflatable aliens recently "descended" upon the authors' middle school to kick-off their first school-wide Astronomy night. With an estimated attendance of over 500, their eighth-grade students hosted over a dozen activity-rich sessions designed to entertain and educate students and their families about the wonders of the solar system…

  9. Neighborhood Disorder, Subjective Alienation, and Distress

    ERIC Educational Resources Information Center

    Ross, Catherine E.; Mirowsky, John

    2009-01-01

    Living in a threatening, noxious, and dangerous neighborhood may produce anxiety, anger, and depression because it is subjectively alienating. We hypothesize that neighborhood disorder represents ambient threat that elicits perceptions of powerlessness, normlessness, mistrust, and isolation. These perceptions in turn lead to anxious and angry…

  10. Student Drug Usage and Self-Alienation.

    ERIC Educational Resources Information Center

    Fischler, Michael L.

    Utilizing responses (a self administered, 15 item questionnaire) of a rural northeastern New England sample of junior high, senior high, and college students, correlation between legal and illegal drug use and perceived self-alienation was examined. Comparison was also made between users and nonusers. Legal users were defined as those who made at…

  11. The Lonely Consumer: Advertising and Alienation.

    ERIC Educational Resources Information Center

    Larson, Charles U.; Denton, Robert E.

    Advertising plays on the broad feelings of alienation (defined as an individual's frustrated or estranged responses to economic and sociological phenomena which affect that individual's place in society) which are endemic to the American consumer society and are, in Marxist views, symptomatic of any capitalist system. By generating anxieties and…

  12. Combatives for Alienated Youth: Problems and Prospects.

    ERIC Educational Resources Information Center

    Hellison, Don

    Combative activities (boxing, wrestling, kung fu, etc.) are seen as having a positive influence on alienated inner city youth. Potential contributions of such activities in a school curriculum or recreation program include involvement, security, self-concept, and self-realization. Participants may be able to free themselves from such stereotype…

  13. 22 CFR 62.27 - Alien physicians.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Examiners Examination, the Foreign Medical Graduate Examination in the Medical Sciences, the United States... physician will be under the direct supervision of a physician who is a U.S. citizen or resident alien and... activities involving direct patient care. Under these circumstances, the special eligibility...

  14. Alteration of wheat vernalization requirement by alien chromosome-mediated transposition of MITE

    PubMed Central

    Gorafi, Yasir Serag Alnor; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2016-01-01

    Under the changing climate, early flowering is advantageous to escape terminal heat and drought. Previously during evaluation of 14 chromosome introgression lines (ILs), we found three ILs that flowered a month earlier than their wheat background Chinese Spring (CS). This paper describes the cause of the early flowering in the ILs and provides insight into the evolution of spring wheat from the winter wheat. We used specific molecular markers for Vrn genes to determine its allelic composition. Phenotypic evaluations carried out under field conditions and in a growth chamber. Unlike the winter vrn-A1 allele of CS, the spring Vrn-A1 allele of the ILs had insertions of 222 and 131-bp miniature inverted-repeat transposable element (MITE) in the promoter region. Sequence analysis indicated that the 222-bp insertion is similar to an insertion in the spring genotype, Triple Dirk D. Our results ruled out any possibility of outcrossing or contamination. Without vernalization, Vrn-A1 is highly expressed in the ILs compared to CS. We attribute the early flowering of the ILs to the insertion of the MITE in the promoter of Vrn-A1. The alien chromosome might mediate this insertion. PMID:27162490

  15. Alteration of wheat vernalization requirement by alien chromosome-mediated transposition of MITE.

    PubMed

    Gorafi, Yasir Serag Alnor; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2016-03-01

    Under the changing climate, early flowering is advantageous to escape terminal heat and drought. Previously during evaluation of 14 chromosome introgression lines (ILs), we found three ILs that flowered a month earlier than their wheat background Chinese Spring (CS). This paper describes the cause of the early flowering in the ILs and provides insight into the evolution of spring wheat from the winter wheat. We used specific molecular markers for Vrn genes to determine its allelic composition. Phenotypic evaluations carried out under field conditions and in a growth chamber. Unlike the winter vrn-A1 allele of CS, the spring Vrn-A1 allele of the ILs had insertions of 222 and 131-bp miniature inverted-repeat transposable element (MITE) in the promoter region. Sequence analysis indicated that the 222-bp insertion is similar to an insertion in the spring genotype, Triple Dirk D. Our results ruled out any possibility of outcrossing or contamination. Without vernalization, Vrn-A1 is highly expressed in the ILs compared to CS. We attribute the early flowering of the ILs to the insertion of the MITE in the promoter of Vrn-A1. The alien chromosome might mediate this insertion.

  16. Mosquito genomics. Extensive introgression in a malaria vector species complex revealed by phylogenomics.

    PubMed

    Fontaine, Michael C; Pease, James B; Steele, Aaron; Waterhouse, Robert M; Neafsey, Daniel E; Sharakhov, Igor V; Jiang, Xiaofang; Hall, Andrew B; Catteruccia, Flaminia; Kakani, Evdoxia; Mitchell, Sara N; Wu, Yi-Chieh; Smith, Hilary A; Love, R Rebecca; Lawniczak, Mara K; Slotman, Michel A; Emrich, Scott J; Hahn, Matthew W; Besansky, Nora J

    2015-01-02

    Introgressive hybridization is now recognized as a widespread phenomenon, but its role in evolution remains contested. Here, we use newly available reference genome assemblies to investigate phylogenetic relationships and introgression in a medically important group of Afrotropical mosquito sibling species. We have identified the correct species branching order to resolve a contentious phylogeny and show that lineages leading to the principal vectors of human malaria were among the first to split. Pervasive autosomal introgression between these malaria vectors means that only a small fraction of the genome, mainly on the X chromosome, has not crossed species boundaries. Our results suggest that traits enhancing vectorial capacity may be gained through interspecific gene flow, including between nonsister species.

  17. Hybridization and Introgression in a Sympatric Pair of Oak Species (Fagaceae) Studied with Morphology and Chloroplast and Nuclear SSR Markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chloroplast and nuclear SSR markers and morphology were used to study hybridization and introgression between Quercus douglasii and Q. lobata, two sympatric oak species native to California. Chloroplast SSR markers provided strong evidence of gene exchange via ongoing introgression between these sp...

  18. Unidirectional diploid-tetraploid introgression among British birch trees with shifting ranges shown by restriction site-associated markers.

    PubMed

    Zohren, Jasmin; Wang, Nian; Kardailsky, Igor; Borrell, James S; Joecker, Anika; Nichols, Richard A; Buggs, Richard J A

    2016-06-01

    Hybridization may lead to introgression of genes among species. Introgression may be bidirectional or unidirectional, depending on factors such as the demography of the hybridizing species, or the nature of reproductive barriers between them. Previous microsatellite studies suggested bidirectional introgression between diploid Betula nana (dwarf birch) and tetraploid B. pubescens (downy birch) and also between B. pubescens and diploid B. pendula (silver birch) in Britain. Here, we analyse introgression among these species using 51 237 variants in restriction site-associated (RAD) markers in 194 individuals, called with allele dosages in the tetraploids. In contrast to the microsatellite study, we found unidirectional introgression into B. pubescens from both of the diploid species. This pattern fits better with the expected nature of the reproductive barrier between diploids and tetraploids. As in the microsatellite study, introgression into B. pubescens showed clear clines with increasing introgression from B. nana in the north and from B. pendula in the south. Unlike B. pendula alleles, introgression of B. nana alleles was found far from the current area of sympatry or allopatry between B. nana and B. pubescens. This pattern fits a shifting zone of hybridization due to Holocene reduction in the range of B. nana and expansion in the range of B. pubescens.

  19. Introgression from domestic goat generated variation at the major histocompatibility complex of Alpine ibex.

    PubMed

    Grossen, Christine; Keller, Lukas; Biebach, Iris; Croll, Daniel

    2014-06-01

    The major histocompatibility complex (MHC) is a crucial component of the vertebrate immune system and shows extremely high levels of genetic polymorphism. The extraordinary genetic variation is thought to be ancient polymorphisms maintained by balancing selection. However, introgression from related species was recently proposed as an additional mechanism. Here we provide evidence for introgression at the MHC in Alpine ibex (Capra ibex ibex). At a usually very polymorphic MHC exon involved in pathogen recognition (DRB exon 2), Alpine ibex carried only two alleles. We found that one of these DRB alleles is identical to a DRB allele of domestic goats (Capra aegagrus hircus). We sequenced 2489 bp of the coding and non-coding regions of the DRB gene and found that Alpine ibex homozygous for the goat-type DRB exon 2 allele showed nearly identical sequences (99.8%) to a breed of domestic goats. Using Sanger and RAD sequencing, microsatellite and SNP chip data, we show that the chromosomal region containing the goat-type DRB allele has a signature of recent introgression in Alpine ibex. A region of approximately 750 kb including the DRB locus showed high rates of heterozygosity in individuals carrying one copy of the goat-type DRB allele. These individuals shared SNP alleles both with domestic goats and other Alpine ibex. In a survey of four Alpine ibex populations, we found that the region surrounding the DRB allele shows strong linkage disequilibria, strong sequence clustering and low diversity among haplotypes carrying the goat-type allele. Introgression at the MHC is likely adaptive and introgression critically increased MHC DRB diversity in the genetically impoverished Alpine ibex. Our finding contradicts the long-standing view that genetic variability at the MHC is solely a consequence of ancient trans-species polymorphism. Introgression is likely an underappreciated source of genetic diversity at the MHC and other loci under balancing selection.

  20. Mapping the genomic architecture of adaptive traits with interspecific introgressive origin: a coalescent-based approach.

    PubMed

    Hejase, Hussein A; Liu, Kevin J

    2016-01-11

    Recent studies of eukaryotes including human and Neandertal, mice, and butterflies have highlighted the major role that interspecific introgression has played in adaptive trait evolution. A common question arises in each case: what is the genomic architecture of the introgressed traits? One common approach that can be used to address this question is association mapping, which looks for genotypic markers that have significant statistical association with a trait. It is well understood that sample relatedness can be a confounding factor in association mapping studies if not properly accounted for. Introgression and other evolutionary processes (e.g., incomplete lineage sorting) typically introduce variation among local genealogies, which can also differ from global sample structure measured across all genomic loci. In contrast, state-of-the-art association mapping methods assume fixed sample relatedness across the genome, which can lead to spurious inference. We therefore propose a new association mapping method called Coal-Map, which uses coalescent-based models to capture local genealogical variation alongside global sample structure. Using simulated and empirical data reflecting a range of evolutionary scenarios, we compare the performance of Coal-Map against EIGENSTRAT, a leading association mapping method in terms of its popularity, power, and type I error control. Our empirical data makes use of hundreds of mouse genomes for which adaptive interspecific introgression has recently been described. We found that Coal-Map's performance is comparable or better than EIGENSTRAT in terms of statistical power and false positive rate. Coal-Map's performance advantage was greatest on model conditions that most closely resembled empirically observed scenarios of adaptive introgression. These conditions had: (1) causal SNPs contained in one or a few introgressed genomic loci and (2) varying rates of gene flow - from high rates to very low rates where incomplete lineage

  1. Phylogeography of Silver Pheasant (Lophura nycthemera L.) across China: aggregate effects of refugia, introgression and riverine barriers.

    PubMed

    Dong, Lu; Heckel, Gerald; Liang, Wei; Zhang, Yanyun

    2013-06-01

    The role of Pleistocene glacial cycles in forming the contemporary genetic structure of organisms has been well studied in China with a particular focus on the Tibetan Plateau. However, China has a complex topography and diversity of local climates, and how glacial cycles may have shaped the subtropical and tropical biota of the region remains mostly unaddressed. To investigate the factors that affected the phylogeography and population history of a widely distributed and nondeciduous forest species, we analysed morphological characters, mitochondrial DNA sequences and nuclear microsatellite loci in the Silver Pheasant (Lophura nycthemera). In a pattern generally consistent with phenotypic clusters, but not nominal subspecies, deeply divergent mitochondrial lineages restricted to different geographic regions were detected. Coalescent simulations indicated that the time of main divergence events corresponded to major glacial periods in the Pleistocene and gene flow was only partially lowered by drainage barriers between some populations. Intraspecific cytonuclear discordance was revealed in mitochondrial lineages from Hainan Island and the Sichuan Basin with evidence of nuclear gene flow from neighbouring populations into the latter. Unexpectedly, hybridization was revealed in Yingjiang between the Silver Pheasant and Kalij Pheasant (Lophura leucomelanos) with wide genetic introgression at both the mtDNA and nuclear levels. Our results highlight a novel phylogeographic pattern in a subtropical area generated from the combined effects of climate oscillation, partial drainage barriers and interspecific hybridization. Cytonuclear discordance combined with morphological differentiation implies that complex historical factors shaped the divergence process in this biodiversity hot spot area of southern China.

  2. Phylogeography of the mountain chickadee (Poecile gambeli): diversification, introgression, and expansion in response to Quaternary climate change.

    PubMed

    Spellman, Garth M; Riddle, Brett; Klicka, John

    2007-03-01

    Since the late 1990s, molecular techniques have fuelled debate about the role of Pleistocene glacial cycles in structuring contemporary avian diversity in North America. The debate is still heated; however, there is widespread agreement that the Pleistocene glacial cycles forced the repeated contraction, fragmentation, and expansion of the North American biota. These demographic processes should leave genetic 'footprints' in modern descendants, suggesting that detailed population genetic studies of contemporary species provide the key to elucidating the impact of the late Quaternary (late Pleistocene-Holocene). We present an analysis of mitochondrial DNA (mtDNA) variation in the mountain chickadee (Poecile gambeli) in an attempt to examine the genetic evidence of the impact of the late Quaternary glacial cycles. Phylogenetic analyses reveal two strongly supported clades of P. gambeli: an Eastern Clade (Rocky Mountains and Great Basin) and a Western Clade (Sierra Nevada and Cascades). Post-glacial introgression is apparent between these two clades in the Mono Lake region of Central California. Within the Eastern Clade there is evidence of isolation-by-distance in the Rocky Mountain populations, and of limited gene flow into and around the Great Basin. Coalescent analysis of genetic variation in the Western Clade indicates that northern (Sierra Nevada/Cascades) and southern (Transverse/Peninsular Ranges) populations have been isolated and evolving independently for nearly 60,000 years.

  3. Production and identification of wheat - Agropyron cristatum (1.4P) alien translocation lines.

    PubMed

    Liu, Wei-Hua; Luan, Yang; Wang, Jing-Chang; Wang, Xiao-Guang; Su, Jun-Ji; Zhang, Jin-Peng; Yang, Xin-Ming; Gao, Ai-Nong; Li, Li-Hui

    2010-06-01

    The P genome of Agropyron Gaertn., a wild relative of wheat, contains an abundance of desirable genes that can be utilized as genetic resources to improve wheat. In this study, wheat - Aegilops cylindrica Host gametocidal chromosome 2C addition lines were crossed with wheat - Agropyron cristatum (L.) Gaertn. disomic addition line accession II-21 with alien recombinant chromosome (1.4)P. We successfully induced wheat - A. cristatum alien chromosomal translocations for the first time. The frequency of translocation in the progeny was 3.75%, which was detected by molecular markers and genomic in situ hybridization (GISH). The translocation chromosomes were identified by dual-color GISH /fluorescence in situ hybridization (FISH). The P genomic DNA was used as probe to detect the (1.4)P chromosome fragment, and pHvG39, pAs1, or pSc119.2 repeated sequences were used as probes to identify wheat translocated chromosomes. The results showed that six types of translocations were identified in the three wheat - A. cristatum alien translocation lines, including the whole arm or terminal portion of a (1.4)P chromosome. The (1.4)P chromosome fragments were translocated to wheat chromosomes 1B, 2B, 5B, and 3D. The breakpoints were located at the centromeres of 1B and 2B, the pericentric locations of 5BS, and the terminals of 5BL and 3DS. In addition, we obtained 12 addition-deletion lines that contained alien A. cristatum chromosome (1.4)P in wheat background. All of these wheat - A. cristatum alien translocation lines and addition-deletion lines would be valuable for identifying A. cristatum chromosome (1.4)P-related genes and providing genetic resources and new germplasm accessions for the genetic improvement of wheat. The specific molecular markers of A. cristatum (1.4)P chromosome have been developed and used to track the (1.4)P chromatin.

  4. [Unidirectional Hybridization of Kaluga Acipenser dauricus Georgi, 1775 and Amur Sturgeon Acipenser schrenckii Brandt, 1869, Inferred from the Mitochondrial DNA Genotyping of Their Natural Hybrids].

    PubMed

    Shedko, S V; Shedko, M B

    2016-03-01

    In 2009 through 2011, among 730 individuals of kaluga and Amur sturgeon collected in the lower reaches of the Amur River and the Amursky Liman, 17 morphologically intermediate individuals (hybrids) with the body length of 56 to 202 cm (median, 81 cm) were identified, including 11 individuals (4.6%) found in 2009, three individuals (1.6%) found in 2010, and three individuals (1.1%), in 2011. In 16 hybrids 819 bp of the mtDNA control regions were sequences and 11 haplotypes were identified. Since all these haplotypes were from the mtDNA lineages of kaluga, it was concluded that hybridization occurred in one direction, kaluga (♀) x Amur sturgeon (♂). This asymmetry could be caused by the large difference in sizes of these species. Since the earlier examined morphologically typical Amur sturgeons showed the absence of alien haplotypes (Shedko, et al., 2015), the absence of the mtDNA introgression is claimed. This can be caused by low viability or sterility of the backcross females (kaluga (♀) x Amur sturgeon (♂)) x Amur sturgeon (♂). The samples of hybrids and typical kaluga individuals demonstrated no differences in the frequency spectra of the mtDNA haplotypes. However, haplotype and nucleotide diversity in the first sample was somewhat higher than in the second one (0.950 versus 0.927 and 0.0054 versus 0.0044, respectively). The data obtained will be useful for population monitoring of kaluga and Amur sturgeon, Amur River endemics, which are classified as critically endangered by the IUCN Red List of Threatened Species.

  5. Unexpected population genetic structure of European roe deer in Poland: an invasion of the mtDNA genome from Siberian roe deer.

    PubMed

    Matosiuk, Maciej; Borkowska, Anetta; Świsłocka, Magdalena; Mirski, Paweł; Borowski, Zbigniew; Krysiuk, Kamil; Danilkin, Aleksey A; Zvychaynaya, Elena Y; Saveljev, Alexander P; Ratkiewicz, Mirosław

    2014-05-01

    Introgressive hybridization is a widespread evolutionary phenomenon which may lead to increased allelic variation at selective neutral loci and to transfer of fitness-related traits to introgressed lineages. We inferred the population genetic structure of the European roe deer (Capreolus capreolus) in Poland from mitochondrial (CR and cyt b) and sex-linked markers (ZFX, SRY, DBY4 and DBY8). Analyses of CR mtDNA sequences from 452 individuals indicated widespread introgression of Siberian roe deer (C. pygargus) mtDNA in the European roe deer genome, 2000 km from the current distribution range of C. pygargus. Introgressed individuals constituted 16.6% of the deer studied. Nearly 75% of them possessed haplotypes belonging to the group which arose 23 kyr ago and have not been detected within the natural range of Siberian roe deer, indicating that majority of present introgression has ancient origin. Unlike the mtDNA results, sex-specific markers did not show signs of introgression. Species distribution modelling analyses suggested that C. pygargus could have extended its range as far west as Central Europe after last glacial maximum. The main hybridization event was probably associated with range expansion of the most abundant European roe deer lineage from western refugia and took place in Central Europe after the Younger Dryas (10.8-10.0 ka BP). Initially, introgressed mtDNA variants could have spread out on the wave of expansion through the mechanism of gene surfing, reaching high frequencies in European roe deer populations and leading to observed asymmetrical gene flow. Human-mediated introductions of C. pygargus had minimal effect on the extent of mtDNA introgression.

  6. The Global Distribution and Drivers of Alien Bird Species Richness

    PubMed Central

    Dyer, Ellie E.; Cassey, Phillip; Redding, David W.; Collen, Ben; Franks, Victoria; Gaston, Kevin J.; Jones, Kate E.; Kark, Salit; Orme, C. David L.; Blackburn, Tim M.

    2017-01-01

    Alien species are a major component of human-induced environmental change. Variation in the numbers of alien species found in different areas is likely to depend on a combination of anthropogenic and environmental factors, with anthropogenic factors affecting the number of species introduced to new locations, and when, and environmental factors influencing how many species are able to persist there. However, global spatial and temporal variation in the drivers of alien introduction and species richness remain poorly understood. Here, we analyse an extensive new database of alien birds to explore what determines the global distribution of alien species richness for an entire taxonomic class. We demonstrate that the locations of origin and introduction of alien birds, and their identities, were initially driven largely by European (mainly British) colonialism. However, recent introductions are a wider phenomenon, involving more species and countries, and driven in part by increasing economic activity. We find that, globally, alien bird species richness is currently highest at midlatitudes and is strongly determined by anthropogenic effects, most notably the number of species introduced (i.e., “colonisation pressure”). Nevertheless, environmental drivers are also important, with native and alien species richness being strongly and consistently positively associated. Our results demonstrate that colonisation pressure is key to understanding alien species richness, show that areas of high native species richness are not resistant to colonisation by alien species at the global scale, and emphasise the likely ongoing threats to global environments from introductions of species. PMID:28081142

  7. The Global Distribution and Drivers of Alien Bird Species Richness.

    PubMed

    Dyer, Ellie E; Cassey, Phillip; Redding, David W; Collen, Ben; Franks, Victoria; Gaston, Kevin J; Jones, Kate E; Kark, Salit; Orme, C David L; Blackburn, Tim M

    2017-01-01

    Alien species are a major component of human-induced environmental change. Variation in the numbers of alien species found in different areas is likely to depend on a combination of anthropogenic and environmental factors, with anthropogenic factors affecting the number of species introduced to new locations, and when, and environmental factors influencing how many species are able to persist there. However, global spatial and temporal variation in the drivers of alien introduction and species richness remain poorly understood. Here, we analyse an extensive new database of alien birds to explore what determines the global distribution of alien species richness for an entire taxonomic class. We demonstrate that the locations of origin and introduction of alien birds, and their identities, were initially driven largely by European (mainly British) colonialism. However, recent introductions are a wider phenomenon, involving more species and countries, and driven in part by increasing economic activity. We find that, globally, alien bird species richness is currently highest at midlatitudes and is strongly determined by anthropogenic effects, most notably the number of species introduced (i.e., "colonisation pressure"). Nevertheless, environmental drivers are also important, with native and alien species richness being strongly and consistently positively associated. Our results demonstrate that colonisation pressure is key to understanding alien species richness, show that areas of high native species richness are not resistant to colonisation by alien species at the global scale, and emphasise the likely ongoing threats to global environments from introductions of species.

  8. 8 CFR 241.24 - Notice to transportation line of alien's exclusion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Notice to transportation line of alien's exclusion. 241.24 Section 241.24 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings Commenced Prior to April 1, 1997) §...

  9. 8 CFR 241.9 - Notice to transportation line of alien's removal.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Notice to transportation line of alien's removal. 241.9 Section 241.9 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Post-hearing Detention and Removal § 241.9 Notice to transportation line of alien's...

  10. 8 CFR 241.9 - Notice to transportation line of alien's removal.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Notice to transportation line of alien's removal. 241.9 Section 241.9 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Post-hearing Detention and Removal § 241.9 Notice to transportation line of alien's...

  11. 8 CFR 241.24 - Notice to transportation line of alien's exclusion.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Notice to transportation line of alien's exclusion. 241.24 Section 241.24 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings Commenced Prior to April 1, 1997) §...

  12. 8 CFR 241.24 - Notice to transportation line of alien's exclusion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Notice to transportation line of alien's exclusion. 241.24 Section 241.24 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for...

  13. 8 CFR 274a.12 - Classes of aliens authorized to accept employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Classes of aliens authorized to accept employment. 274a.12 Section 274a.12 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employment Authorization § 274a.12 Classes of aliens authorized...

  14. 8 CFR 1212.5 - Parole of aliens into the United States.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Parole of aliens into the United States. 1212.5 Section 1212.5 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF... INADMISSIBLE ALIENS; PAROLE § 1212.5 Parole of aliens into the United States. Procedures and standards for...

  15. 8 CFR 1212.5 - Parole of aliens into the United States.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Parole of aliens into the United States. 1212.5 Section 1212.5 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF... INADMISSIBLE ALIENS; PAROLE § 1212.5 Parole of aliens into the United States. Procedures and standards for...

  16. 8 CFR 1212.5 - Parole of aliens into the United States.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Parole of aliens into the United States. 1212.5 Section 1212.5 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF... INADMISSIBLE ALIENS; PAROLE § 1212.5 Parole of aliens into the United States. Procedures and standards for...

  17. 8 CFR 241.21 - Stay of deportation of excluded alien.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Stay of deportation of excluded alien. 241.21 Section 241.21 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings...

  18. 8 CFR 241.21 - Stay of deportation of excluded alien.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Stay of deportation of excluded alien. 241.21 Section 241.21 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings...

  19. 8 CFR 274a.12 - Classes of aliens authorized to accept employment.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Classes of aliens authorized to accept employment. 274a.12 Section 274a.12 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employment Authorization § 274a.12 Classes of aliens authorized...

  20. 8 CFR 274a.12 - Classes of aliens authorized to accept employment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Classes of aliens authorized to accept employment. 274a.12 Section 274a.12 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employment Authorization § 274a.12 Classes of aliens authorized...

  1. 8 CFR 241.21 - Stay of deportation of excluded alien.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Stay of deportation of excluded alien. 241.21 Section 241.21 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings...

  2. 8 CFR 1212.5 - Parole of aliens into the United States.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Parole of aliens into the United States. 1212.5 Section 1212.5 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF... INADMISSIBLE ALIENS; PAROLE § 1212.5 Parole of aliens into the United States. Procedures and standards for...

  3. 8 CFR 1212.5 - Parole of aliens into the United States.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Parole of aliens into the United States. 1212.5 Section 1212.5 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF... INADMISSIBLE ALIENS; PAROLE § 1212.5 Parole of aliens into the United States. Procedures and standards for...

  4. 8 CFR 241.21 - Stay of deportation of excluded alien.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Stay of deportation of excluded alien. 241.21 Section 241.21 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings...

  5. 8 CFR 241.24 - Notice to transportation line of alien's exclusion.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Notice to transportation line of alien's exclusion. 241.24 Section 241.24 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for...

  6. 8 CFR 241.21 - Stay of deportation of excluded alien.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Stay of deportation of excluded alien. 241.21 Section 241.21 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS APPREHENSION AND DETENTION OF ALIENS ORDERED REMOVED Deportation of Excluded Aliens (for Hearings...

  7. 8 CFR 274a.12 - Classes of aliens authorized to accept employment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Classes of aliens authorized to accept employment. 274a.12 Section 274a.12 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROL OF EMPLOYMENT OF ALIENS Employment Authorization § 274a.12 Classes of aliens authorized...

  8. Single R Gene Introgression Lines for Accurate Dissection of the Brassica - Leptosphaeria Pathosystem

    PubMed Central

    Larkan, Nicholas J.; Yu, Fengqun; Lydiate, Derek J.; Rimmer, S. Roger; Borhan, M. Hossein

    2016-01-01

    Seven blackleg resistance (R) genes (Rlm1, Rlm2, Rlm3, Rlm4, LepR1, LepR2 & LepR3) were each introgressed into a common susceptible B. napus doubled-haploid (DH) line through reciprocal back-crossing, producing single-R gene introgression lines (ILs) for use in the pathological and molecular study of Brassica—Leptosphaeria interactions. The genomic positions of the R genes were defined through molecular mapping and analysis with transgenic L. maculans isolates was used to confirm the identity of the introgressed genes where possible. Using L. maculans isolates of contrasting avirulence gene (Avr) profiles, we preformed extensive differential pathology for phenotypic comparison of the ILs to other B. napus varieties, demonstrating the ILs can provide for the accurate assessment of Avr-R gene interactions by avoiding non-Avr dependant alterations to resistance responses which can occur in some commonly used B. napus varieties. Whole-genome SNP-based assessment allowed us to define the donor parent introgressions in each IL and provide a strong basis for comparative molecular dissection of the pathosystem. PMID:27965684

  9. Neppiness in an Introgressed Population of Cotton: Genotypic Variation and Genotypic Correlation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neps and seed coat fragments are two types of impurities in ginned fibers causing severe problems in textile processing during spinning and dyeing. The study was designed to investigate the genotypic variation for neps and seed coat fragments remaining in ginned fibers in an introgressed population ...

  10. Revisiting a classic case of introgression: hybridization and gene flow in Californian sunflowers.

    PubMed

    Owens, Gregory L; Baute, Gregory J; Rieseberg, Loren H

    2016-06-01

    During invasion, colonizing species can hybridize with native species, potentially swamping out native genomes. However, theory predicts that introgression will often be biased into the invading species. Thus, empirical estimates of gene flow between native and invasive species are important to quantify the actual threat of hybridization with invasive species. One classic example of introgression occurs in California, where Helianthus bolanderi was thought to be a hybrid between the serpentine endemic Helianthus exilis and the congeneric invader Helianthus annuus. We used genotyping by sequencing to look for signals of introgression and population structure. We find that H. bolanderi and H. exilis form one genetic clade, with weak population structure that is associated with geographic location rather than soil composition and likely represent a single species, not two. Additionally, while our results confirmed early molecular analysis and failed to support the hybrid origin of H. bolanderi, we did find evidence for introgression mainly into the invader H. annuus, as predicted by theory.

  11. Evaluating the Use of ABBA–BABA Statistics to Locate Introgressed Loci

    PubMed Central

    Martin, Simon H.; Davey, John W.; Jiggins, Chris D.

    2015-01-01

    Several methods have been proposed to test for introgression across genomes. One method tests for a genome-wide excess of shared derived alleles between taxa using Patterson’s D statistic, but does not establish which loci show such an excess or whether the excess is due to introgression or ancestral population structure. Several recent studies have extended the use of D by applying the statistic to small genomic regions, rather than genome-wide. Here, we use simulations and whole-genome data from Heliconius butterflies to investigate the behavior of D in small genomic regions. We find that D is unreliable in this situation as it gives inflated values when effective population size is low, causing D outliers to cluster in genomic regions of reduced diversity. As an alternative, we propose a related statistic f^d, a modified version of a statistic originally developed to estimate the genome-wide fraction of admixture. f^d is not subject to the same biases as D, and is better at identifying introgressed loci. Finally, we show that both D and f^d outliers tend to cluster in regions of low absolute divergence (dXY), which can confound a recently proposed test for differentiating introgression from shared ancestral variation at individual loci. PMID:25246699

  12. Analysis of wild-species introgressions in tomato inbreds uncovers ancestral origins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Decades of intensive tomato breeding using wild germplasm has resulted in genomes of domesticated accessions (Solanum lycopersicum) to be intertwined with introgressions from their wild relatives. Here we present the first whole genome sequences of two tomato inbreds Gh13 and BTI87, both carrying a ...

  13. Mistaken Identity: Another Bias in the Use of Relative Genetic Divergence Measures for Detecting Interspecies Introgression

    PubMed Central

    Ritz, Kathryn R.; Noor, Mohamed A. F.

    2016-01-01

    Measures of genetic divergence have long been used to identify evolutionary processes operating within and between species. However, recent reviews have described a bias in the use of relative divergence measures towards incorrectly identifying genomic regions that are seemingly immune to introgression. Here, we present a novel and opposite bias of relative divergence measures: misidentifying regions of introgression between sister species. We examine two distinct haplotypes of intermediate frequency within Drosophila pseudoobscura at the DPSX009 locus. One of these haplotypes had lower relative divergence than another to sister species D. persimilis. Although we and others initially presumed one haplotype have spread via introgression between D. pseudoobscura and D. persimilis, absolute divergence measures and individual sequence analysis suggest that haplotype structuring occurred as the result of within-species processes. The potential for this type of misinference may occur with any haplotype that recently spread within a species. We conclude that absolute measures of genetic divergence are necessary for confirming putative regions of introgression. PMID:27760228

  14. Synergism of natural selection and introgression in the origin of a new species.

    PubMed

    Grant, Peter R; Grant, B Rosemary

    2014-05-01

    This article explores how introgressive hybridization enhances the evolutionary effects of natural selection and how, reciprocally, natural selection can enhance the evolutionary effects of introgression. Both types of interaction were observed during a 40-year study of Darwin's finches (Geospiza) on the small Galápagos island of Daphne Major. Hybrids, produced rarely by Geospiza fortis (medium ground finch) breeding with Geospiza scandens (cactus finch) and Geospiza fuliginosa (small ground finch), survived and bred as well as the parental species in the past 3 decades. By backcrossing, they increased the standing genetic variation and thereby the evolutionary responsiveness of the populations to natural selection. Natural selection occurred in droughts and oscillated in direction as a result of climatically induced fluctuations in food composition. Introgressive hybridization has led to the formation of a new lineage. It was initiated by a large, introgressed, hybrid male with a unique song and genetic marker that immigrated from the nearby island of Santa Cruz and bred with local hybrids and with G. fortis. All members of the lineage died in the 2003-2005 drought except a brother and a sister, who then bred with each other. Subsequent increase in the lineage was facilitated by selective mortality of the largest G. fortis. Breeding endogamously, the lineage is behaving as a biological species.

  15. Phenotypic and ionome profiling of Triticum aestivum x Aegiolps tauschii introgression lines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eighty-four single homozygous introgressions of the Aegilops tauschii D-genome in the ‘Chinese Spring’ genetic background were used to study phenotypic and ionome profiles during two years of field experiments. An augmented design was used with a repeated check of a local bread wheat cultivar was im...

  16. Adaptive introgression of anticoagulant rodent poison resistance by hybridization between Old World mice

    PubMed Central

    Song, Ying; Endepols, Stefan; Klemann, Nicole; Richter, Dania; Matuschka, Franz-Rainer; Shih, Ching-Hua; Nachman, Michael W.; Kohn, Michael H.

    2011-01-01

    Summary It is known that evolution by selection on new or standing single nucleotide polymorphisms (SNPs) in the vitamin K 2,3-epoxide reductase subcomponent 1 (vkorc1) of house mice (Mus musculus domesticus) can cause resistance to anticoagulant rodenticides such as warfarin [1–3]. Here we report an introgression in European M. m. domesticus spanning as much as ~20.3 megabases (Mb) and including vkorc1, the molecular target of anticoagulants [1–4], that stems from hybridization with the Algerian mouse (M. spretus). We show that in the laboratory the homozygous complete vkorc1 allele of M. spretus confers resistance when introgressed into M. m. domesticus. Consistent with selection on the introgression after the introduction of rodenticides in the 1950s we document historically adaptive population genetics of vkorc1 in M. m. domesticus. Furthermore, we detected adaptive protein evolution of vkorc1 in the M. spretus lineage (Ka/Ks=1.54–1.93) resulting in radical amino-acid substitutions that apparently have anticoagulant tolerance of M. spretus as pleiotropic effect. Thus, positive selection produced an adaptive, divergent and pleiotropic vkorc1 allele in the donor species, M. spretus, which crossed a species barrier where it is expressed as adaptive trait in the recipient species, M. m. domesticus. Resistant house mice originated from selection on new or standing vkorc1 polymorphisms and from selection on vkorc1 polymorphisms acquired by adaptive introgressive hybridization. PMID:21782438

  17. Introgression of Clearfield(TM) rice crop traits into weedy red rice outcrosses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies were conducted to determine the impact of introgression of crop alleles into weedy rice populations. Seeds of 89 weedy rice accessions collected from Arkansas fields in 11 counties, with a history of Clearfield(TM) rice production, were planted in 2011 and treated with two applications of im...

  18. Adaptive introgression of abiotic tolerance traits in the sunflower Helianthus annuus.

    PubMed

    Whitney, Kenneth D; Randell, Rebecca A; Rieseberg, Loren H

    2010-07-01

    *Adaptive trait introgression is increasingly recognized as common. However, it is unclear whether adaptive genetic exchanges typically affect only a single trait, or instead affect multiple aspects of the phenotype. Here, we examine introgression of abiotic tolerance traits between two hybridizing North American sunflower species, Helianthus annuus and Helianthus debilis. *In two common gardens in the hybrid range, we measured 10 ecophysiological, phenological, and architectural traits for parents and their natural and artificial hybrids, and examined how fitness covaried with trait values. *Eight of the 10 traits showed patterns consistent with introgression from H. debilis into H. annuus, and suggested that H. debilis-like traits allowing rapid growth and reproduction before summer heat and drought have been favored in the hybrid range. Natural selection currently favors BC(1) hybrids with H. debilis-like branching traits. *We demonstrate that introgression has altered multiple aspects of the H. annuus phenotype in an adaptive manner, has affected traits relevant to both biotic and abiotic environments, and may have aided expansion of the H. annuus range into central Texas, USA.

  19. Metabolic Profiling and Physiological Analysis of a Novel Rice Introgression Line with Broad Leaf Size

    PubMed Central

    Zhao, Xiuqin; Zhang, Guilian; Wang, Yun; Zhang, Fan; Wang, Wensheng; Zhang, Wenhao; Fu, Binying; Xu, Jianlong; Li, Zhikang

    2015-01-01

    A rice introgression line, NIL-SS1, and its recurrent parent, Teqing, were used to investigate the influence of the introgression segment on plant growth. The current research showed NIL-SS1 had an increased flag leaf width, total leaf area, spikelet number per panicle and grain yield, but a decreased photosynthetic rate. The metabolite differences in NIL-SS1 and Teqing at different developmental stages were assessed using gas chromatography—mass spectrometry technology. Significant metabolite differences were observed across the different stages. NIL-SS1 increased the plant leaf nitrogen content, and the greatest differences between NIL-SS1 and Teqing occurred at the booting stage. Compared to Teqing, the metabolic phenotype of NIL-SS1 at the booting stage has closer association with those at the flowering stage. The introgression segment induced more active competition for sugars and organic acids (OAs) from leaves to the growing young spikes, which resulted in more spikelet number per plant (SNP). The results indicated the introgression segment could improve rice grain yield by increasing the SNP and total leaf area per plant, which resulted from the higher plant nitrogen content across growth stages and stronger competition for sugars and OAs of young spikes at the booting stage. PMID:26713754

  20. Evolutionary objections to "alien design" models.

    NASA Astrophysics Data System (ADS)

    Coffey, E. J.

    A previous paper demonstrated that the principal supporters of SETI have ignored the biological and evolutionary consequences of a creature's body form. In fact, the supporting evidence they provide actually contradicts their view. The approach they employ is that of the engineer: the process of "designing" a hypothetical creature to a specification irrespective of biological or evolutionary considerations. The principal types of "alien designs" which have been employed shall be discussed, and the evolutionary objections to them given.