Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and Aestivating Therapsid Share Burrow

PubMed Central

Fernandez, Vincent; Abdala, Fernando; Carlson, Kristian J.; Cook, Della Collins; Rubidge, Bruce S.; Yates, Adam; Tafforeau, Paul

2013-01-01

Fossorialism is a beneficial adaptation for brooding, predator avoidance and protection from extreme climate. The abundance of fossilised burrow casts from the Early Triassic of southern Africa is viewed as a behavioural response by many tetrapods to the harsh conditions following the Permo-Triassic mass-extinction event. However, scarcity of vertebrate remains associated with these burrows leaves many ecological questions unanswered. Synchrotron scanning of a lithified burrow cast from the Early Triassic of the Karoo unveiled a unique mixed-species association: an injured temnospondyl amphibian (Broomistega) that sheltered in a burrow occupied by an aestivating therapsid (Thrinaxodon). The discovery of this rare rhinesuchid represents the first occurrence in the fossil record of a temnospondyl in a burrow. The amphibian skeleton shows signs of a crushing trauma with partially healed fractures on several consecutive ribs. The presence of a relatively large intruder in what is interpreted to be a Thrinaxodon burrow implies that the therapsid tolerated the amphibian’s presence. Among possible explanations for such unlikely cohabitation, Thrinaxodon aestivation is most plausible, an interpretation supported by the numerous Thrinaxodon specimens fossilised in curled-up postures. Recent advances in synchrotron imaging have enabled visualization of the contents of burrow casts, thus providing a novel tool to elucidate not only anatomy but also ecology and biology of ancient tetrapods. PMID:23805181

Evaluation of aestival diapause in hemlock woolly adelgid

Treesearch

Scott M. Salom; Warren T. Mays; John Neal; Alexei Sharov

2000-01-01

Hemlock woolly adelgid, Adelges tsugae Annand (Homoptera: Adelgidae), has two generations/year that feed and reproduce on hemlock, Tsugae spp. The spring generation, present from March to June, is called progrediens. The next generation, present from June until the following March, is called sistens (McClure 1987, Gray and Salom...

Observations of cocooned Hydrobaenus (Diptera: Chironomidae) larvae in Lake Michigan

USGS Publications Warehouse

Tucker, Taaja R.; Hudson, Patrick L.; Riley, Stephen

2016-01-01

Larvae of the family Chironomidae have developed a variety of ways to tolerate environmental stress, including the formation of cocoons, which allows larvae to avoid unfavorable temperature conditions, drought, or competition with other chironomids. Summer cocoon formation by younger instars of the genus Hydrobaenus Fries allows persistence through increased temperatures and/or intermittent dry periods in arid regions or temporary habitats, but this behavior was not observed in the Great Lakes until the current study. Cocoon-aestivating Hydrobaenus sp. larvae were found in benthic grab samples collected in 2010–2013 near Sleeping Bear Dunes National Lakeshore in northern Lake Michigan with densities up to 7329/m2. The aestivating species was identified as Hydrobaenus johannseni (Sublette, 1967), and the associated chironomid community was typical for an oligotrophic nearshore system. Hydrobaenus cocoon formation in the Great Lakes was likely previously unnoticed due to the discrepancies between the genus' life history and typical benthos sampling procedures which has consequences for describing chironomid communities where Hydrobaenus is present.

Alternative life cycle strategies in the West African reed frog Hyperolius nitidulus: the answer to an unpredictable environment?

PubMed

Lampert, Kathrin P; Linsenmair, Eduard K

2002-02-01

The West African reed frog Hyperolius nitidulus, mainly known for its extraordinary aestivation behaviour and physiology, is able to vary its reproductive strategy in response to environmental conditions. We found indirect as well as direct evidence for individuals not following the generally assumed one year-one generation life cycle including an extended aestivation phase during the dry season, but leading very short lives for only a part of that rainy season in which the frogs were born. Second-generation frogs (males and females that reproduced in the season in which they were born) were significantly smaller than all other adults and their egg diameter was reduced. As the pattern and amount of rainfall and thus the span of time suitable for reproduction in H. nitidulus varies strongly between years in this savannah region, a flexible reproductive strategy may be highly adaptive for risk spreading. Alternative reproduction strategies probably contribute to the great success of H. nitidulus in terms of the extension of its geographical range and its often very high local abundance.

Persistence of Branchinecta paludosa (Anostraca) in Southern Wyoming, with notes on zoogeography

Treesearch

James F. Saunders; Denton Belk; Richard Dufford

1993-01-01

The fairy shrimp Branchinecta paludosa is a persistent resident of aestival ponds at high elevation in the Medicine Bow Mountains of southern Wyoming. These populations are far removed from the Arctic tundra habitat that typifies the distribution of the species, and appear to represent the southern margin of the range in North America. All of the records for the...

Age and seasonal differences in the synthesis and metabolism of testosterone by testicular tissue and pineal HIOMT activity of Uinta ground squirrels (Spermophilus armatus)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, L.C.; Balph, D.F.

Male Uinta ground squirrels (Spermophilus armatus) were sacrificed from a free-living population during the breeding season, which immediately followed emergence from hibernation; after the reproductive season; and just prior to aestivation/hibernation. HIOMT activity of the pineal gland was assayed and related to the ability of the gonads to synthesize and metabolize testosterone. Older squirrels had higher HIOMT activity than did the younger animals. The activity of this enzyme was lowest in squirrels during the breeding season. HIOMT activity increased after the breeding season to its highest level just before the squirrels enter aestivation/hibernation. At this time, testicular weight increased concomitantmore » with an apparent increase in HIOMT activity. Testicular size and weight were largest at the time of emergence of the animals from hibernation. Androgen synthesis was also greatest during the breeding season. As would be expected, both decreased rapidly thereafter. The testes formed little 17..cap alpha..,20..cap alpha..-dihydroxyprogesterone during or after the breeding season, contrary to what has been reported for rats and house sparrows. The older squirrels demonstrated a greater capacity for testosterone metabolism during the breeding season than did the younger animals.« less

Income breeding allows an aquatic snake Seminatrix pygaea to reproduce normally following prolonged drought-induced aestivation.

PubMed

Winne, Christopher T; Willson, John D; Gibbons, J Whitfield

2006-11-01

1. Capital breeding is an ideal reproductive strategy for many ectotherms because it provides a disassociation between feeding and reproduction, a necessary requirement for animals that become anorexic during pregnancy. Among ectotherms, some viviparous snakes (e.g. Viperidae) exemplify the capital breeding strategy because many species (i) do not feed during pregnancy due to behavioural conflicts between reproduction and foraging, and (ii) take more than one season to accumulate sufficient energetic stores for reproduction. 2. Isolated wetlands often exhibit extreme annual fluctuations in environmental conditions with prolonged droughts periodically leaving wetlands completely dry and devoid of prey. Following droughts, however, wetlands can be extremely productive, rendering prey resources virtually unlimited for some species. 3. This study examines drought survival strategy and reproductive ecology of a small aquatic snake Seminatrix pygaea (Cope) in an isolated wetland. Seminatrix pygaea are atypical from most sympatric snake species in that (i) their small body size, reliance on aquatic prey, and high rates of evaporative water loss make them ill-suited to overland movement, and (ii) they may not be subject to costs typically associated with feeding during pregnancy. 4. We hypothesized that S. pygaea would survive periodic multiyear droughts by aestivating within the dried wetland, a survival strategy heretofore undocumented in snakes. Further, we hypothesized that if S. pygaea rely on 'typical' snake reproductive strategies of 'adaptive anorexia' and capital breeding, reproductive output would be reduced in the first wet year following drought. 5. By encircling a 10-ha wetland with a continuous drift fence before it refilled we were able to demonstrate that S. pygaea were present within the dried wetland prior to the onset of spring rains that refilled the wetland in 2003. Our results suggest that S. pygaea are capable of surviving multiyear droughts by aestivating within the dried wetland. 6. Despite having presumably depleted energy reserves during the drought, S. pygaea reproduced with the same frequency and fecundity during the first season following refilling of the wetland as in pre-drought years. 7. The ability of S. pygaea to rebound rapidly from the stresses of prolonged drought is due in part to their reproductive ecology. Seminatrix pygaea readily feed throughout pregnancy and consequently can rapidly translate high prey abundances into reproductive output through income breeding.

Heat shock proteins and survival strategies in congeneric land snails (Sphincterochila) from different habitats.

PubMed

Mizrahi, Tal; Heller, Joseph; Goldenberg, Shoshana; Arad, Zeev

2012-09-01

Polmunate land snails are subject to stress conditions in their terrestrial habitat, and depend on a range of behavioural, physiological and biochemical adaptations for coping with problems of maintaining water, ionic and thermal balance. The involvement of the heat shock protein (HSP) machinery in land snails was demonstrated following short-term experimental aestivation and heat stress, suggesting that land snails use HSPs as part of their survival strategy. As climatic variation was found to be associated with HSP expression, we tested whether adaptation of land snails to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desert species Sphincterochila zonata and a Mediterranean-type species Sphincterochila cariosa. Our study suggests that Sphincterochila species use HSPs as part of their survival strategy following desiccation and heat stress, and as part of the natural annual cycle of activity and aestivation. Our studies also indicate that adaptation to different habitats results in the development of distinct strategies of HSP expression in response to stress, namely the reduced expression of HSPs in the desert-inhabiting species. We suggest that these different strategies reflect the difference in heat and aridity encountered in the natural habitats, and that the desert species S. zonata relies on mechanisms and adaptations other than HSP induction thus avoiding the fitness consequences of continuous HSP upregulation.

Nitrergic cardiovascular regulation in the African lungfish, Protopterus aethiopicus.

PubMed

Filogonio, Renato; Joyce, William; Wang, Tobias

2017-05-01

As a ubiquitous signaling molecule, nitric oxide (NO) exerts various important effects on the cardiovascular system and is involved in the regulation of vascular tone and myocardial metabolism in vertebrates. Lungfishes are closely related to tetrapods and provide an interesting possibility to understand the transition from water to land. Lungfishes are endowed with both systemic and pulmonary circulations, and their incompletely divided ventricle allows for blood to bypass either circuit. Lungfishes inhabit ephemeral waterbodies that may enforce prolonged aestivation during drought, throughout which nitric oxide synthase (NOS) expression is upregulated. To better understand the physiological relevance of NO on cardiovascular regulation in this transitory group, we measured vascular reactivity to muscarinic agonist acetylcholine, α- and β-adrenergic agonists (phenylephrine and isoproterenol, respectively), or the NO donor, sodium nitroprusside (SNP) on four vessel segments-efferent branchial arteries, gill artery, ductus arteriosus and pulmonary artery-from the African lungfish, Protopterus aethiopicus. In a simultaneous study, we measured oxygen consumption and twitch force in myocardial preparations in the presence and absence of an NOS inhibitor (asymmetric dimethylarginine; ADMA). Only the ductus arteriosus vasodilated in response to SNP. Isoproterenol caused vasodilation, whereas acetylcholine and phenylephrine vasoconstricted all vessel segments. NOS inhibition decreased myocardial force relative to oxygen consumption, indicating a lowered efficiency. We provide novel evidence that NO affects the vasculature of lungfish that may be derived from perivascular nitrergic nerves limited to the ductus arteriosus. Our data also suggests that NO exerts a tonic dampening of myocardial oxygen consumption which may be particularly important during aestivation. Copyright © 2017 Elsevier Inc. All rights reserved.

Glandulocalyx upatoiensis, a fossil flower of Ericales (Actinidiaceae/Clethraceae) from the Late Cretaceous (Santonian) of Georgia, USA

PubMed Central

Schönenberger, Jürg; von Balthazar, Maria; Takahashi, Masamichi; Xiao, Xianghui; Crane, Peter R.; Herendeen, Patrick S.

2012-01-01

Background and Aims Ericales are a major group of extant asterid angiosperms that are well represented in the Late Cretaceous fossil record, mainly by flowers, fruits and seeds. Exceptionally well preserved fossil flowers, here described as Glandulocalyx upatoiensis gen. & sp. nov., from the Santonian of Georgia, USA, yield new detailed evidence of floral structure in one of these early members of Ericales and provide a secure basis for comparison with extant taxa. Methods The floral structure of several fossil specimens was studied by scanning electron microscopy (SEM), light microscopy of microtome thin sections and synchrotron-radiation X-ray tomographic microscopy (SRXTM). For direct comparisons with flowers of extant Ericales, selected floral features of Actinidiaceae and Clethraceae were studied with SEM. Key Results Flowers of G. upatoiensis have five sepals with quincuncial aestivation, five free petals with quincuncial aestivation, 20–28 stamens arranged in a single series, extrorse anther orientation in the bud, ventral anther attachment and a tricarpellate, syncarpous ovary with three free styles and numerous small ovules on axile, protruding-diffuse and pendant placentae. The calyx is characterized by a conspicuous indumentum of large, densely arranged, multicellular and possibly glandular trichomes. Conclusions Comparison with extant taxa provides clear evidence for a relationship with core Ericales comprised of the extant families Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae and Ericaceae. Within this group, the most marked similarities are with extant Actinidiaceae and, to a lesser degree, with Clethraceae. More detailed analyses of the relationships of Glandulocalyx and other Ericales from the Late Cretaceous will require an improved understanding of the morphological features that diagnose particular extant groups defined on the basis of molecular data. PMID:22442339

Movements of florida apple snails in relation to water levels and drying events

USGS Publications Warehouse

Darby, P.C.; Bennetts, R.E.; Miller, S.J.; Percival, H.F.

2002-01-01

Florida apple snails (Pomacea Paludosa) apparently have only a limited tolerance to wetland drying events (although little direct evidence exists), but their populations routinely face dry downs under natural and managed water regimes. In this paper, we address speculation that apple snails respond to decreasing water levels and potential drying events by moving toward refugia that remain inundated. We monitored the movements of apple snails in central Florida, USA during drying events at the Blue Cypress Marsh (BC) and at Lake Kissimmee (LK). We monitored the weekly movements of 47 BC snails and 31 LK snails using radio-telemetry. Snails tended to stop moving when water depths were 10 cm. Snails moved along the greatest positive depth gradient (i.e., towards deeper water) when they encountered water depths between 10 and 20 cm. Snails tended to move toward shallower water in water depths ???50 cm, suggesting that snails were avoiding deep water areas such as canals and sloughs. Of the 11 BC snails originally located in the area that eventually went dry, three (27%) were found in deep water refugia by the end of the study. Only one of the 31 LK snails escaped the drying event by moving to deeper water. Our results indicate that some snails may opportunistically escape drying events through movement. The tendency to move toward deeper water was statistically significant and indicates that this behavioral trait might enhance survival when the spatial extent of a dry down is limited. However, as water level falls below 10 cm, snails stop moving and become stranded. As the spatial extent of a dry down increases, we predict that the number of snails stranded would increase proportionally. Stranded Pomacea paludosa must contend with dry marsh conditions, possibly by aestivation. Little more than anecdotal information has been published on P. paludosa aestivation, but it is a common adaptation among other apple snails (Caenogastropoda: Ampullaridae). ?? 2002, The Society of Wetland Scientists.

Water balance of field-excavated aestivating Australian desert frogs, the cocoon-forming Neobatrachus aquilonius and the non-cocooning Notaden nichollsi (Amphibia: Myobatrachidae).

PubMed

Cartledge, Victoria A; Withers, Philip C; McMaster, Kellie A; Thompson, Graham G; Bradshaw, S Don

2006-09-01

Burrowed aestivating frogs of the cocoon-forming species Neobatrachus aquilonius and the non-cocooning species Notaden nichollsi were excavated in the Gibson Desert of central Australia. Their hydration state (osmotic pressure of the plasma and urine) was compared to the moisture content and water potential of the surrounding soil. The non-cocooning N. nichollsi was consistently found in sand dunes. While this sand had favourable water potential properties for buried frogs, the considerable spatial and temporal variation in sand moisture meant that frogs were not always in positive water balance with respect to the surrounding soil. The cocoon-forming N. aquilonius was excavated from two distinct habitat types, a claypan in which frogs had a well-formed cocoon and a dune swale where frogs did not have a cocoon. Cocoons of excavated frogs ranged in thickness from 19.4 microm to 55.61 microm and consisted of 81-229 layers. Cocooned claypan N. aquilonius were nearing exhaustion of their bladder water reserves and had a urine osmolality approaching that of the plasma. By contrast, non-cocooned N. aquilonius from the dune swale were fully hydrated, although soil moisture levels were not as high as calculated to be necessary to maintain water balance. Both species had similar plasma arginine vasotocin (AVT) concentrations ranging from 9.4 to 164 pg ml(-1), except for one cocooned N. aquilonius with a higher concentration of 394 pg ml(-1). For both species, AVT showed no relationship with plasma osmolality over the lower range of plasma osmolalities but was appreciably increased at the highest osmolality recorded. This study provides the first evidence that cocoon formation following burrowing is not obligatory in species that are capable of doing so, but that cocoon formation occurs when soil water conditions are more desiccating than for non-cocooned frogs.

Effects of seasonal variation on oxidative stress physiology in natural population of toad Bufo melanostictus; clues for analysis of environmental pollution.

PubMed

Samanta, Luna; Paital, Biswaranjan

2016-11-01

Natural population of Bufo melanostictus in response to environmental cues shows several physiologic changes such as reproductive activity, hibernation, aestivation and metabolic depression in different seasons. We investigated the effects of seasonal fluctuations on oxidative stress (OS) physiology biomarkers, such as endogenous (ELPx) and induced (ILPx) lipid peroxidation, front-line redox regulatory enzymes (superoxide dismutase: SOD and catalase) and two non-enzyme antioxidant metabolites (ascorbic acid and reduced glutathione) in liver, gonad and cerebral hemisphere of toads collected from the Bhubaneswar area of India, where temperature fluctuates considerably rising to the highest in summer (∼46 °C) and being lowest in winter (<10 °C). Soil and air of the sampling site, although varying seasonally, were mostly found to be unpolluted, except for suspended particulate matter and respiratory particulate matter that were above recommended value. The magnitude of both ELPx and ILPx levels in most of the tissues, for example, ELPx in liver, cerebral hemisphere and ovary, and ILPx in liver of males and ovary, were found to be higher in rainy season in comparison to the other seasons. Nevertheless, levels of both ELPx and ILPx were low in testes in rainy season in comparison to the other two seasons. No correlation was observed between temperature and the studied OS parameters except a positive correlation with SOD and negative correlations with non-enzymatic small redox regulatory molecules in some selected tissues. Conversely, discriminant function analysis reveals a clear impact of the changing season on OS physiology of the toad. It implies that season considerably modulates OS physiology which be a reflection of the toads to abiotic pollutants alone and/or as results of metabolic changes under hibernation, aestivation and due to reproductive activities. Therefore, seasonal changes in OS physiological responses in poikilothermic models especially in toads must be cautiously used as indicators to assess environmental impact, mainly soil pollution. Results of the present study may be used as baseline data for any future analyses of the physiological impacts of environmental changes using toads as model organism.

An Overview of Seasonal Changes in Oxidative Stress and Antioxidant Defence Parameters in Some Invertebrate and Vertebrate Species.

PubMed

Chainy, Gagan Bihari Nityananda; Paital, Biswaranjan; Dandapat, Jagneswar

2016-01-01

Antioxidant defence system, a highly conserved biochemical mechanism, protects organisms from harmful effects of reactive oxygen species (ROS), a by-product of metabolism. Both invertebrates and vertebrates are unable to modify environmental physical factors such as photoperiod, temperature, salinity, humidity, oxygen content, and food availability as per their requirement. Therefore, they have evolved mechanisms to modulate their metabolic pathways to cope their physiology with changing environmental challenges for survival. Antioxidant defences are one of such biochemical mechanisms. At low concentration, ROS regulates several physiological processes, whereas at higher concentration they are toxic to organisms because they impair cellular functions by oxidizing biomolecules. Seasonal changes in antioxidant defences make species able to maintain their correct ROS titre to take various physiological functions such as hibernation, aestivation, migration, and reproduction against changing environmental physical parameters. In this paper, we have compiled information available in the literature on seasonal variation in antioxidant defence system in various species of invertebrates and vertebrates. The primary objective was to understand the relationship between varied biological phenomena seen in different animal species and conserved antioxidant defence system with respect to seasons.

An Overview of Seasonal Changes in Oxidative Stress and Antioxidant Defence Parameters in Some Invertebrate and Vertebrate Species

PubMed Central

Chainy, Gagan Bihari Nityananda; Paital, Biswaranjan; Dandapat, Jagneswar

2016-01-01

Antioxidant defence system, a highly conserved biochemical mechanism, protects organisms from harmful effects of reactive oxygen species (ROS), a by-product of metabolism. Both invertebrates and vertebrates are unable to modify environmental physical factors such as photoperiod, temperature, salinity, humidity, oxygen content, and food availability as per their requirement. Therefore, they have evolved mechanisms to modulate their metabolic pathways to cope their physiology with changing environmental challenges for survival. Antioxidant defences are one of such biochemical mechanisms. At low concentration, ROS regulates several physiological processes, whereas at higher concentration they are toxic to organisms because they impair cellular functions by oxidizing biomolecules. Seasonal changes in antioxidant defences make species able to maintain their correct ROS titre to take various physiological functions such as hibernation, aestivation, migration, and reproduction against changing environmental physical parameters. In this paper, we have compiled information available in the literature on seasonal variation in antioxidant defence system in various species of invertebrates and vertebrates. The primary objective was to understand the relationship between varied biological phenomena seen in different animal species and conserved antioxidant defence system with respect to seasons. PMID:27127682

Do ice nucleating agents limit the supercooling ability of the land snail Cornu aspersum?

PubMed

Ansart, A; Nicolai, A; Vernon, P; Madec, L

2010-01-01

The supercooling ability of adults and eggs of the partially freezing tolerant land snail Cornu aspersum remains limited to high subzero temperatures (ca. -5 degree C) whatever the conditions, suggesting the presence of ice nucleating agents (INAs). In this study, we investigated the nucleation activity of the digestive tract of adult snails, eggs and their direct environment: food, faeces and soil. The mucous ribbon always present in the distal intestine of adults exhibited a heat-sensitive (i.e. organic) nucleation activity, close to that of the entire snails during dormant states (aestivation and hibernation). However, a microbial nature of these INAs could not be established in inactive snails. The food provided to active snails contained ice nucleating bacteria, which followed the digestive tract to be found in the intestine and in the faeces, but with a decreasing concentration along the transit. Eggshells also presented a heat-sensitive nucleation activity, which could be related to its structure. Moreover, eggs are laid directly in the soil which contained both organic and mineral INAs. This study is the first to demonstrate the implication of organic INAs in the cold hardiness of a terrestrial gastropod.

Application of morphologic burrow interpretations to discern continental burrow architects: Lungfish or crayfish?

USGS Publications Warehouse

Hasiotis, Stephen T.; Mitchell, Charles E.; Dubiel, Russell R.

1993-01-01

A methodology for trace fossil identification using burrowing signatures is tested by evaluating ancient and modern lungfish and crayfish burrows and comparing them to previously undescribed burrows in a stratigraphic interval thought to contain both lungfish and crayfish burrows. Permian burrows that bear skeletal remains of the lungfish Gnathorhiza, from museum collections, were evaluated to identify unique burrow morphologies that could be used to distinguish lungfish from crayfish burrows when fossil remains are absent. The lungfish burrows were evaluated for details of the burrowing mechanism preserved in the burrow morphologies together forming burrowing signatures and were compared to new burrows in the Chinle Formation of western Colorado to test the methodology of using burrow signatures to identify unknown burrows.Permian lungfish aestivation burrows show simple, nearly vertical, unbranched architectures and relatively smooth surficial morphologies with characteristic quasi‐horizontal striae on the burrow walls and vertical striae on the bulbous terminus. Burrow lengths do not exceed 0.5 m. In contrast, modern and ancient crayfish burrows exhibit simple to highly complex architectures with highly textured surficial morphologies. Burrow lengths may reach 4 to 5 m.Burrow morphologies unlike those identified in Gnathorhiza aestivation burrows were found in four burrow groups from museum collections. Two of these groups exhibit simple architectures and horizontal striae that were greater in sinuosity and magnitude, respectively. One of these burrows contains the remains of Lysoro‐phus, but the burrow surface reveals no reliable surficial characteristics. It is not clear whether Lysorophustruly burrowed or merely occupied a pre‐existing structure. The other two groups exhibit surficial morphologies similar to those found on modern and ancient crayfish burrows and may provide evidence of freshwater crayfish in the Permian.Burrows from the Upper Triassic Chinle Formation in western Colorado exhibit simple to moderately complex architectural morphologies, ranging from predominantly vertical, unbranched, with little or no chamber development to predominantly vertical, few branches, and with minor chamber development. Surficial burrow morphologies are moderate to highly textured. The burrows have scrape marks, scratch marks, mud and lag‐liners, knobby surfaces, pleopod striae, and body impressions.Although no fossil remains of the burrowing organism were found within or associated with the Chinle burrows from western Colorado, the similarity of architectural and surficial burrow morphologies to those in the Chinle of Canyonlands, Utah and to modern crayfish burrows, clearly indicates that the Colorado burrows are the product of burrowing crayfish rather than lungfish. Evaluation of burrowing signatures preserved in the architectural and surficial burrow morphologies is a very useful tool to compare and contrast Chinle burrows from different regions on the Colorado Plateau. Documentation of crayfish burrows in the Chinle of Utah and Colorado strongly suggests that other large‐diameter Chinle burrows elsewhere on the Colorado Plateau and in stratigraphically equivalent units may also be the product of crayfish activity.

The effects of drought and fire in the extirpation of an abundant semi-aquatic turtle from a lacustrine environment in the southwestern USA

USGS Publications Warehouse

Lovich, Jeffrey E.; Quillman, Mari; Zitt, Brian; Schroeder, Adam; Green, David E.; Yackulic, Charles B.; Gibbons, Paul; Goode, Eric

2017-01-01

We documented a significant mortality event affecting a southwestern pond turtle (Actinemys pallida) population living in a lake in southern California, USA. The area around the lake was impacted by a large wildland fire in 2013 that occurred during a protracted drought. As the mortality event was still unfolding, we collected data in 2014 on water quality, demographic structure, and short-term survivorship of the population. Water quality was poor with low levels of dissolved oxygen and high salinity of up to 45.90 ppt. Many turtles were severely emaciated and coated with a pale mineralized layer on their shells and skin. Estimated survival rate was low leading to a projected 90% decline in 134 days and a high probability of extirpation within a year. The lake was dry in September 2015 with no evidence of live turtles. Necropsies and low volumetric body condition indices suggested death by starvation. Although this semi-aquatic species has the ability to aestivate in upland habitats during periods of low water or move to other nearby water bodies, it is unlikely that many were able to do so because of their extremely poor condition and the severity of the drought conditions throughout the area.

Elements of cold hardiness in a littoral population of the land snail Helix aspersa (Gastropoda: Pulmonata).

PubMed

Ansart, A; Vernon, P; Daguzan, J

2002-10-01

The land snail Helix aspersa can be considered partially tolerant to freezing, in the sense it can survive some ice formation within its body for a limited time, and possesses a limited ability to supercool. This study aimed at understanding what factors are responsible for the variation of the temperature of crystallization ( Tc) in a littoral temperate population. The ability to supercool was maximal (ca. -5 degrees C) during dormancy periods (hibernation and aestivation) and minimal (ca. -3 degrees C) during spring and autumn, in relation with the decrease of water mass and the increase of osmolality. Tc decreased in October to remain stable through late autumn and winter; it increased quickly with the awakening of animals in April. Snails with an epiphragm had a significantly higher ability to supercool (ca. -4.8 degrees C) than snails which did not form an epiphragm (ca. -4.2 degrees C). The animals' size had a weak but significant influence on the realization of the Tc. It appeared that there was not a real cold-hardiness strategy in this population; rather a sum of parameters, varying in consequences of the external conditions and of the activity cycle, which are responsible for the enhancement of the supercooling ability during winter.

Climate matching as a tool for predicting potential North American spread of Brown Treesnakes

USGS Publications Warehouse

Rodda, Gordon H.; Reed, Robert N.; Jarnevich, Catherine S.; Witmer, G.W.; Pitt, W. C.; Fagerstone, K.A.

2007-01-01

Climate matching identifies extralimital destinations that could be colonized by a potential invasive species on the basis of similarity to climates found in the species’ native range. Climate is a proxy for the factors that determine whether a population will reproduce enough to offset mortality. Previous climate matching models (e.g., Genetic Algorithm for Rule-set Prediction [GARP]) for brown treesnakes (Boiga irregularis) were unsatisfactory, perhaps because the models failed to allow different combinations of climate attributes to influence a species’ range limits in different parts of the range. Therefore, we explored the climate space described by bivariate parameters of native range temperature and rainfall, allowing up to two months of aestivation in the warmer portions of the range, or four months of hibernation in temperate climes. We found colonization area to be minimally sensitive to assumptions regarding hibernation temperature thresholds. Although brown treesnakes appear to be limited by dry weather in the interior of Australia, aridity rarely limits potential distribution in most of the world. Potential colonization area in North America is limited primarily by cold. Climatically suitable portions of the United States (US) mainland include the Central Valley of California, mesic patches in the Southwest, and the southeastern coastal plain from Texas to Virginia.

Drought survival and reproduction impose contrasting selection pressures on maximum body size and sexual size dimorphism in a snake, Seminatrix pygaea.

PubMed

Winne, Christopher T; Willson, John D; Whitfield Gibbons, J

2010-04-01

The causes and consequences of body size and sexual size dimorphism (SSD) have been central questions in evolutionary ecology. Two, often opposing selective forces are suspected to act on body size in animals: survival selection and reproductive (fecundity and sexual) selection. We have recently identified a system where a small aquatic snake species (Seminatrix pygaea) is capable of surviving severe droughts by aestivating within dried, isolated wetlands. We tested the hypothesis that the lack of aquatic prey during severe droughts would impose significant survivorship pressures on S. pygaea, and that the largest individuals, particularly females, would be most adversely affected by resource limitation. Our findings suggest that both sexes experience selection against large body size during severe drought when prey resources are limited, as nearly all S. pygaea are absent from the largest size classes and maximum body size and SSD are dramatically reduced following drought. Conversely, strong positive correlations between maternal body size and reproductive success in S. pygaea suggest that females experience fecundity selection for large size during non-drought years. Collectively, our study emphasizes the dynamic interplay between selection pressures that act on body size and supports theoretical predictions about the relationship between body size and survivorship in ectotherms under conditions of resource limitation.

Spiral phyllotaxis underlies constrained variation in Anemone (Ranunculaceae) tepal arrangement.

PubMed

Kitazawa, Miho S; Fujimoto, Koichi

2018-05-01

Stabilization and variation of floral structures are indispensable for plant reproduction and evolution; however, the developmental mechanism regulating their structural robustness is largely unknown. To investigate this mechanism, we examined positional arrangement (aestivation) of excessively produced perianth organs (tepals) of six- and seven-tepaled (lobed) flowers in six Anemone species (Ranunculaceae). We found that the tepal arrangement that occurred in nature varied intraspecifically between spiral and whorled arrangements. Moreover, among the studied species, variation was commonly limited to three types, including whorls, despite five geometrically possible arrangements in six-tepaled flowers and two types among six possibilities in seven-tepaled flowers. A spiral arrangement, on the other hand, was unique to five-tepaled flowers. A spiral phyllotaxis model with stochasticity on initiating excessive primordia accounted for these limited variations in arrangement in cases when the divergence angle between preexisting primordia was less than 144°. Moreover, interspecific differences in the frequency of the observed arrangements were explained by the change of model parameters that represent meristematic growth and differential organ growth. These findings suggest that the phyllotaxis parameters are responsible for not only intraspecific stability but interspecific difference of floral structure. Decreasing arrangements from six-tepaled to seven-tepaled Anemone flowers demonstrate that the stabilization occurs as development proceeds to increase the component (organ) number, in contrast from the intuition that the variation will be larger due to increasing number of possible states (arrangements).

Effects of ultraviolet radiation on 25-hydroxyvitamin D3 synthesis in red-eared slider turtles (Trachemys scripta elegans).

PubMed

Acierno, Mark J; Mitchell, Mark A; Roundtree, Marlana K; Zachariah, Trevor T

2006-12-01

To determine whether there are increased concentrations of 25-hydroxyvitaminn D(3) in red-eared slider turtles (Trachemys scripta elegans) after exposure to UV radiation. 12 yearling turtles recently removed from aestivation. Turtles were randomly allocated to 2 groups (6 turtles/group). An initial blood sample was collected from all turtles for measurement of 25-hydroxyvitamin D(3) concentrations. Turtles of 1 group were then provided no supplemental lighting, whereas turtles of the other group were exposed to full-spectrum coil bulbs at a distance of 22.86 cm. The UV-A and UV-B radiation generated by the supplemental lighting was measured by use of a radiometer-photometer at weekly intervals. Measurements were collected 2.54 and 22.86 cm from the bulb surface. The study was continued for a 4-week period. At the end of the study, a second blood sample was collected from all turtles for measurement of 25-hydroxyvitamin D(3). Mean +/- SD 25-hydroxyvitamin D(3) concentrations differed significantly between turtles provided supplemental UV radiation (71.7 +/- 46.9 nmol/L) and those not provided UV radiation (31.4 +/- 13.2 nmol/L). Appropriate husbandry recommendations for raising and maintaining red-eared slider turtles should include use of sunlight that is unobstructed by UV-B filtering material or provision of an artificial source of UV-B radiation.

On whose shoulders we stand – the pioneering entomological discoveries of Károly Sajó *

PubMed Central

Vig, Károly

2011-01-01

Abstract The excellence of Károly Sajó as a researcher into Hungary’s natural history has been undeservedly neglected. Yet he did lasting work, especially in entomology, and a number of his discoveries and initiatives were before their time. Born in 1851 in Győr, he received his secondary education there and went to Pest University. He taught in a grammar school in 1877–88 before spending seven years as an entomologist at the National Phylloxera Experimental Station, later the Royal Hungarian State Entomological Station. Pensioned off at his own request in 1895, he moved to Őrszentmiklós, where he continued making entomological observations on his own farm and wrote the bulk of his published materials: almost 500 longer or shorter notes, articles and books, mainly on entomological subjects. Sajó was among the first in the world to publish in 1896 a study of how the weather affects living organisms, entitled Living Barometers. His Sleep in Insects, which appeared in the same year, described his discovery, from 1895 observations of the red turnip beetle, Entomoscelis adonidis (Pallas, 1771), of aestivation in insects – in present-day terms diapause. It was a great loss to universal entomology when Sajó ceased publishing about 25 years before his death. His unpublished notes, with his library and correspondence, were destroyed in the World War II. His surviving insect collection is now kept in the Hungarian Natural History Museum, Budapest. PMID:22303108

The plurennial life cycles of the European Tettigoniidae (Insecta: Orthoptera) : 2. The effect of photoperiod on the induction of an initial diapause.

PubMed

Ingrisch, Sigfrid

1986-11-01

In eggs of European Tettigoniidae species, an initial diapause can occur just after blastoderm formation and a final diapause close to the end of embryonic development. The effect of photoperiod experienced maternally on the induction of the initial diapause was studied, using 13 species from Central and Southeastern Europe. In Conocephalus dorsalis and Platycleis albopunctata there was no initial diapause induced by photoperod, while, in Tettigonia-and Saga-species and in Metrioptera saussuriana it occurred independently of day length. In Metrioptera roeseli, M. bicolor, Leptophyes punctatissima, Eupholidoptera smyrnensis, and Decticus verrucivorus, oviposition at short day induced an initial diapause, while after oviposition at long day, the eggs developed directly until final diapause. On the other hand, in up to 1/4 of the eggs of Pholidoptera griseoaptera an initial diapause was induced by long day length. Populations of D. verrucivorus from different latitudes differed with respect to the critical day length. For E. smyrnensis and M. roeseli, a photoperiodic response curve was calculated.In the Rhodian population of E. smyrnensis, the dormancy sequence of initial and final embryonic diapause can be used for aestivation and hibernation within an annual life cycle, while enabling hibernation in successive years for the Central European species. The population of D. verrucivorus near Aachen has an "obligatory" plurennial life cycle, since the critical day length for development without initial diapause is above the range of day length occurring in the field.

On whose shoulders we stand - the pioneering entomological discoveries of Károly Sajó.

PubMed

Vig, Károly

2011-01-01

The excellence of Károly Sajó as a researcher into Hungary's natural history has been undeservedly neglected. Yet he did lasting work, especially in entomology, and a number of his discoveries and initiatives were before their time.Born in 1851 in Győr, he received his secondary education there and went to Pest University. He taught in a grammar school in 1877-88 before spending seven years as an entomologist at the National Phylloxera Experimental Station, later the Royal Hungarian State Entomological Station. Pensioned off at his own request in 1895, he moved to Őrszentmiklós, where he continued making entomological observations on his own farm and wrote the bulk of his published materials: almost 500 longer or shorter notes, articles and books, mainly on entomological subjects.Sajó was among the first in the world to publish in 1896 a study of how the weather affects living organisms, entitled Living Barometers. His Sleep in Insects, which appeared in the same year, described his discovery, from 1895 observations of the red turnip beetle, Entomoscelis adonidis (Pallas, 1771), of aestivation in insects - in present-day terms diapause.It was a great loss to universal entomology when Sajó ceased publishing about 25 years before his death. His unpublished notes, with his library and correspondence, were destroyed in the World War II. His surviving insect collection is now kept in the Hungarian Natural History Museum, Budapest.

Feltia submontana (Noctuidae, Noctuinae): Redescription, Taxonomy, Life Cycle, and Spatial Distribution of a Neglected South American Potential Pest Species.

PubMed

Dias, F M S; Specht, A; Roque-Specht, V F; San Blas, G; Casagrande, M M; Mielke, O H H

2018-06-06

Feltia submontana (Köhler, 1961) is redescribed based on specimens from Northwestern Argentina and Central and Southeastern Brazil. Taxonomic comments, photographs of the adults, characters of taxonomic importance, and illustrations of structures of the labial palpus, legs, and male and female genitalia are provided. The species is compared with similar-looking and supposedly closely related species, such as F. hispidula (Guenée, 1852) and F. lilacina (Zerny, 1916). The species, originally described for Argentina, is reported for Brazil for the first time. Most Brazilian specimens come from the "Cerrado" but also from Southeastern Atlantic Forests. The life cycle of F. submontana specimens collected in Planaltina, Distrito Federal, Brazil, is described; the species probably has only a single generation per year and imagines are on the wing in the late autumn and early winter months; the last instar prepupa and pupa pass through aestival diapause. The abundance of F. submontana relative to other species of Agrotis Ochsenheimer, 1816, and Feltia Walker, 1856, in the above-cited locality is accessed through 4 years of standardized collecting with light trap; the species is the second most abundant species of these genera in the area, with about one fifth of the captures, second only to A. ipsilon (Hufnagel, 1766), with about two thirds of the captures, and about two times more abundant than F. subterranea (Fabricius, 1794); the latter two are regarded as important pest species in South America.

The plurennial life cycles of the European Tettigoniidae (Insecta: Orthoptera) : 1. The effect of temperature on embryonic development and hatching.

PubMed

Ingrisch, Sigfrid

1986-11-01

The effect of temperature on embryonic development, voltinism, and hatching was studied in the laboratory in eggs of 21 Central and Southeastern European Tettigoniidae species. In most species, the embryo has to arrive at a postkatatrepsis stage prior to the onset of cold to be able to hatch in the following spring. The rate of embryonic development differs: quickly developing species need 4 weeks at 24°C (prior to cold) and almost all eggs hatch after the first cold treatment, slowly developing species would need 8-12 weeks to do the same. In Central Europe, warmth is not enough for the slowly developing species to have an univoltine life cycle, but they could have it in southern Europe. Most species make use of a dormancy sequence to pass successive winters as follows: an initial embryonic dormancy (either quiscence or diapause in embryonic stage 4) and a final diapause in embryonic stage 23/24. Additionally, 3 forms of aestivation or summer dormancy were observed facultatively: an initial diapause in embryonic stage 4 (induced and terminated at 30°C), a median dormancy shortly before or after katatrepsis (at 30°C), and a penultimate diapause in embryonic stage 20 (at 24°C).The life cycles of the European Tettigoniidae species can follow one of 3 types: 1. annual life cycle (no initial embryonic dormancy); 2. annual or biennial depending on whether laid early or late; 3. biennial or many year life cycle (up to 8 years due to a prolonged initial diapause).

Heat shock proteins and resistance to desiccation in congeneric land snails.

PubMed

Mizrahi, Tal; Heller, Joseph; Goldenberg, Shoshana; Arad, Zeev

2010-07-01

Land snails are subject to daily and seasonal variations in temperature and in water availability and depend on a range of behavioral and physiological adaptations for coping with problems of maintaining water, ionic, and thermal balance. Heat shock proteins (HSPs) are a multigene family of proteins whose expression is induced by a variety of stress agents. We used experimental desiccation to test whether adaptation to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desiccation-resistant, desert species Sphincterochila zonata, and a Mediterranean-type, desiccation-sensitive species Sphincterochila cariosa. We examined the HSP response in the foot, hepatopancreas, and kidney tissues of snails exposed to normothermic desiccation. Our findings show variations in the HSP response in both timing and magnitude between the two species. The levels of endogenous Hsp72 in S. cariosa were higher in all the examined tissues, and the induction of Hsp72, Hsp74, and Hsp90 developed earlier than in S. zonata. In contrary, the induction of sHSPs (Hsp25 and Hsp30) was more pronounced in S. zonata compared to S. cariosa. Our results suggest that land snails use HSPs as part of their survival strategy during desiccation and as important components of the aestivation mechanism in the transition from activity to dormancy. Our study underscores the distinct strategy of HSP expression in response to desiccation, namely the delayed induction of Hsp70 and Hsp90 together with enhanced induction of sHSPs in the desert-dwelling species, and suggests that evolution in harsh environments will result in selection for reduced Hsp70 expression.

The consequences of seasonal fasting during the dormancy of tegu lizards (Salvator merianae) on their postprandial metabolic response.

PubMed

Gavira, Rodrigo S B; Sartori, Marina R; Gontero-Fourcade, Manuel N; Gomes, Bruna F; Abe, Augusto S; Andrade, Denis V

2018-04-19

Tegu lizards ( Salvator merianae ) aestivate for up to 5 months during Brazil's winter, when they retreat to burrows and halt most activities. Dormant tegus reduce their gastrointestinal (GI) mass, which allows a substantial energy economy. This strategy, however, implies that the first post-dormancy digestion would be more costly than subsequent feeding episodes as a result of GI atrophy. To address this, we determined the postprandial metabolic response (SDA) of the first (M1), second (M2) and several (RM) feeding episodes after tegus' dormancy. Another group of tegus (PF) was subjected to an extra 50 day fasting period after arousal. Glucose, triglycerides and uric acid levels were checked before and after feeding. M1 digestion lasted twice as long and cost twofold more when compared with M2 or RM, in agreement with the idea that GI atrophy inflates digestion cost at the first post-dormancy meal. The SDA response was similar in M2 and RM, suggesting that the GI tract was fully reorganized after the first feeding. The SDA cost was equal in PF and RM, implying that the change in state per se (dormant to arousal) triggers the regrowth of GI, independently of feeding. Fasting tegus at M1 presented higher triglyceride and lower uric acid levels than fed tegus, indicating that fasting is mainly sustained by fat storage. Our results show that seasonal fasting imposes an extra digestion cost to tegus following their next feeding, which is fully paid during their first digestion. This surplus cost, however, is negligible compared with the overall energetic savings from GI tract atrophy during the dormancy period. © 2018. Published by The Company of Biologists Ltd.

What parts of the US mainland are climatically suitable for invasive alien pythons spreading from Everglades National Park?

USGS Publications Warehouse

Rodda, G.H.; Jarnevich, C.S.; Reed, R.N.

2009-01-01

The Burmese Python (Python molurus bivittatus) is now well established in southern Florida and spreading northward. The factors likely to limit this spread are unknown, but presumably include climate or are correlated with climate. We compiled monthly rainfall and temperature statistics from 149 stations located near the edge of the python's native range in Asia (Pakistan east to China and south to Indonesia). The southern and eastern native range limits extend to saltwater, leaving unresolved the species' climatic tolerances in those areas. The northern and western limits are associated with cold and aridity respectively. We plotted mean monthly rainfall against mean monthly temperature for the 149 native range weather stations to identify the climate conditions inhabited by pythons in their native range, and mapped areas of the coterminous United States with the same climate today and projected for the year 2100. We accounted for both dry-season aestivation and winter hibernation (under two scenarios of hibernation duration). The potential distribution was relatively insensitive to choice of scenario for hibernation duration. US areas climatically matched at present ranged up the coasts and across the south from Delaware to Oregon, and included most of California, Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Florida, Georgia, and South and North Carolina. By the year 2100, projected areas of potential suitable climate extend northward beyond the current limit to include parts of the states of Washington, Colorado, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, New Jersey, and New York. Thus a substantial portion of the mainland US is potentially vulnerable to this ostensibly tropical invader. ?? 2008 Springer Science+Business Media B.V.

Flower development of Goniorrhachis marginata reveals new insights into the evolution of the florally diverse detarioid legumes.

PubMed

Prenner, Gerhard; Cardoso, Domingos

2017-02-01

The study of floral morphology and ontogeny and the re-investigation of existing data help to uncover potential synapomorphic characters and foster our understanding of phylogenetic relationships that rely primarily on molecular analyses. Goniorrhachis marginata is a monotypic caesalpinioid legume (Leguminosae) that shows some interesting floral features, such as a long hypanthium and regular Rosaceae-like flowers. We studied the ontogeny and morphology of the flowers in detail and present our results in a broad phylogenetic context. Flower buds were collected in the field, fixed in 70 % ethanol and investigated using scanning electron microscopy. Older buds in spirit were carefully opened to investigate the direction of style bending. Characters of the style from 131 taxa from the main legume lineages were analysed and mapped on a Bayesian molecular phylogeny. The tetramerous calyx is the result of complete loss of one sepal. The formation of the radially symmetrical corolla starts in a typical caesalpinioid pattern with the adaxial petal innermost (ascending aestivation). The young style bends in the abaxial direction, which is a character found exclusively in all studied detarioid legumes and therefore a newly described synapomorphy for the clade. We show that investigation of unstudied taxa and reinvestigation of published data can uncover new, previously overlooked and important characters. Curvature of the style can be detected in young buds with a hand lens and therefore is an important character for field botanists. Our study reveals the importance of including poorly studied and/or phylogenetically enigmatic taxa in molecular phylogenies and in detailed morphological and ontogenetic analyses. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Flower development of Goniorrhachis marginata reveals new insights into the evolution of the florally diverse detarioid legumes

PubMed Central

Prenner, Gerhard; Cardoso, Domingos

2017-01-01

Background and Aims The study of floral morphology and ontogeny and the re-investigation of existing data help to uncover potential synapomorphic characters and foster our understanding of phylogenetic relationships that rely primarily on molecular analyses. Goniorrhachis marginata is a monotypic caesalpinioid legume (Leguminosae) that shows some interesting floral features, such as a long hypanthium and regular Rosaceae-like flowers. We studied the ontogeny and morphology of the flowers in detail and present our results in a broad phylogenetic context. Methods Flower buds were collected in the field, fixed in 70 % ethanol and investigated using scanning electron microscopy. Older buds in spirit were carefully opened to investigate the direction of style bending. Characters of the style from 131 taxa from the main legume lineages were analysed and mapped on a Bayesian molecular phylogeny. Key Results The tetramerous calyx is the result of complete loss of one sepal. The formation of the radially symmetrical corolla starts in a typical caesalpinioid pattern with the adaxial petal innermost (ascending aestivation). The young style bends in the abaxial direction, which is a character found exclusively in all studied detarioid legumes and therefore a newly described synapomorphy for the clade. Conclusions We show that investigation of unstudied taxa and reinvestigation of published data can uncover new, previously overlooked and important characters. Curvature of the style can be detected in young buds with a hand lens and therefore is an important character for field botanists. Our study reveals the importance of including poorly studied and/or phylogenetically enigmatic taxa in molecular phylogenies and in detailed morphological and ontogenetic analyses. PMID:28025284

Natural variation in resistance to desiccation and heat shock protein expression in the land snail Theba pisana along a climatic gradient.

PubMed

Mizrahi, Tal; Goldenberg, Shoshana; Heller, Joseph; Arad, Zeev

2015-01-01

Land snails frequently encounter desiccating conditions, and their survival depends on a suite of morphological, physiological, and molecular adaptations to the specific microhabitat. Strategies of survival can be determined by integrating information from various levels of biological organization. In this study, we used a combination of physiological parameters related to water economy and molecular factors (stress protein expression) to investigate the strategies of survival adopted by seven populations of the Mediterranean-type land snail Theba pisana from different habitats. We analyzed water compartmentalization during aestivation and used experimental desiccation to compare desiccation resistance. We also measured the endogenous levels of heat shock proteins (HSPs) Hsp72, Hsp74, and Hsp90 under nonstress conditions and analyzed the HSP response to desiccation in two populations that differed mostly in their resistance to desiccation. We revealed significant intraspecific differences in resistance to desiccation that seem to be determined by the speed of recruitment of the water-preserving mechanisms. The ability to cope with desiccating conditions was correlated with habitat temperature but not with the rainfall gradient, implying that in the coastal region, temperature is likely to have a major impact on desiccation resistance rather than precipitation. Also, higher desiccation resistance was correlated with higher constitutive levels of Hsp74 in the foot tissue. HSPs were upregulated during desiccation, but the response was delayed and was milder in the most resistant population compared to the most susceptible one. Our study suggests that T. pisana populations from warmer habitats were more resistant to desiccation and developed distinct strategies of HSP expression for survival, namely, the maintenance of high constitutive levels of Hsp70 together with a delayed and limited response to stress.

Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes.

PubMed

Chew, S F; Ip, Y K

2014-03-01

With the development of air-breathing capabilities, some fishes can emerge from water, make excursions onto land or even burrow into mud during droughts. Air-breathing fishes have modified gill morphology and morphometry and accessory breathing organs, which would tend to reduce branchial ammonia excretion. As ammonia is toxic, air-breathing fishes, especially amphibious ones, are equipped with various strategies to ameliorate ammonia toxicity during emersion or ammonia exposure. These strategies can be categorized into (1) enhancement of ammonia excretion and reduction of ammonia entry, (2) conversion of ammonia to a less toxic product for accumulation and subsequent excretion, (3) reduction of ammonia production and avoidance of ammonia accumulation and (4) tolerance of ammonia at cellular and tissue levels. Active ammonia excretion, operating in conjunction with lowering of ambient pH and reduction in branchial and cutaneous NH₃ permeability, is theoretically the most effective strategy to maintain low internal ammonia concentrations. NH₃ volatilization involves the alkalization of certain epithelial surfaces and requires mechanisms to prevent NH₃ back flux. Urea synthesis is an energy-intensive process and hence uncommon among air-breathing teleosts. Aestivating African lungfishes detoxify ammonia to urea and the accumulated urea is excreted following arousal. Reduction in ammonia production is achieved in some air-breathing fishes through suppression of amino acid catabolism and proteolysis, or through partial amino acid catabolism leading to alanine formation. Others can slow down ammonia accumulation through increased glutamine synthesis in the liver and muscle. Yet, some others develop high tolerance of ammonia at cellular and tissue levels, including tissues in the brain. In summary, the responses of air-breathing fishes to ameliorate ammonia toxicity are many and varied, determined by the behaviour of the species and the nature of the environment in which it lives. © 2014 The Fisheries Society of the British Isles.

New observations - with older ones reviewed - on mass migrations in millipedes based on a recent outbreak on Hachijojima (Izu Islands) of the polydesmid diplopod (Chamberlinius hualienensis, Wang 1956): Nothing appears to make much sense.

PubMed

Meyer-Rochow, Victor Benno

2015-05-18

Mass aggregations and migrations of millipedes despite numerous attempts to find causes for their occurrences are still an enigma. They have been reported from both southern and northern hemisphere countries, from highlands and lowlands of both tropical and temperate regions and they can involve species belonging to the orders Julida and Spirobolida, Polydesmida and Glomerida. According to the main suggestions put forward in the past, mass occurrences in Diplopoda occur: (1) because of a lack of food and a population increase beyond sustainable levels; (2) for the purpose of reproduction and in order to locate suitable oviposition sites; (3) to find overwintering or aestivation sites; (4) because of habitat disruption and changes in the local environment; (5) as a consequence of weather conditions the year (or winter and spring) before. A recent outbreak (November 2014) of a mass migration of the polydesmid Chamberlinius hualienensis Wang 1956 on the Japanese Izu Island of Hachijojima 300 km to the south of Tokyo gave this author an opportunity to review the existing literature on millipede mass migrations and to carry out additional observations on the phenomenon in the field as well as the laboratory. Hitherto unreported heavy infestations with phoretic deutonymphs of the mite Histiostoma sp. as well as dense populations of internal rhabditid nematodes (Oscheius cf. necromena and an unidentified species of the genus Fictor), suggest that infestations of this kind could be necromenic and either have been a contributing factor for the mass migration or been a consequence of so many individuals occurring together at close proximity. It is concluded that mass migrations and aggregations in millipedes do not have one common cause, but represent phenomena that often are seasonally recurring events and appear identical in their outcome, but which have evolved as responses to different causes in different millipede taxa and therefore need to be examined on a case-to-case basis.