https://padlet.com/k_ashbrook/gfanwp6u0u1o Give your name and copy and paste the journal article's name and abstract onto the Padlet. en-us 2017-01-31 16:39:58 UTC 2025-10-03 03:15:46 UTC hello@padlet.com k_ashbrook https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/150595127 Love is blind: indiscriminate female mating responses to male courtship pheromones in newts (Salamandridae)

 Internal fertilization without copulation or prolonged physical contact is a rare reproductive mode among vertebrates. In many newts (Salamandridae), the male deposits a spermatophore on the substrate in the water, which the female subsequently takes up with her cloaca. Because such an insemination requires intense coordination of both sexes, male newts have evolved a courtship display, essentially consisting of sending pheromones under water by tail-fanning towards their potential partner. Behavioral experiments until now mostly focused on an attractant function, i.e. showing that olfactory cues are able to bring both sexes together. However, since males start their display only after an initial contact phase, courtship pheromones are expected to have an alternative function. Here we developed a series of intraspecific and interspecific two-female experiments with alpine newt (Ichthyosaura alpestris) and palmate newt (Lissotriton helveticus) females, comparing behavior in male courtship water and control water. We show that male olfactory cues emitted during tail-fanning are pheromones that can induce all typical features of natural female mating behavior. Interestingly, females exposed to male pheromones of their own species show indiscriminate mating responses to conspecific and heterospecific females, indicating that visual cues are subordinate to olfactory cues during courtship. ]]> 2017-01-31 16:46:47 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/150595127 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/151965825 GLUCOSE CONCENTRATION REGULATES FREEZETOLERANCE IN THE WOOD FROG RANA SYLVATICA
 In spring, the lowest temperature during freezing that can be survived by wood frogs (Rana sylvatica) from southern Ohio is approximately 23 ˚C. We investigated whether the thermal limit of freeze tolerance in these frogs is regulated by tissue levels of glucose, a putative cryoprotectant that is distributed to tissues during freezing. Frogs receiving exogenous glucose injections prior to freezing showed dose-dependent increases in glucose within the heart, liver, skeletal muscle and blood. Tissue glucose concentrations were further elevated during freezing by the production of endogenous glucose. Most glucose-loaded frogs survived freezing to 25 ˚C, whereas all control (saline-injected) frogs succumbed. Further, we investigated some mechanisms by which glucose might function as a cryoprotectant in R. sylvatica. Organ dehydration, a normal, beneficial response that reduces freezing injury to tissues, occurred independently of tissue glucose concentrations. However, elevated glucose levels reduced both body ice content and in vivo erythrocyte injury. These results not only provided conclusive evidence for glucose’s cryoprotective role in R. sylvatica, but also revealed that tissue glucose level is a critical determinant of freeze tolerance capacity in this species. 

]]> 2017-02-06 20:20:41 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/151965825 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/152624798  Hibernation physiology, freezing adaptation and extreme freeze tolerance in a northern population of the wood frog
 We investigated hibernation physiology and freeze tolerance in a population of the wood frog, Rana sylvatica, indigenous to Interior Alaska, USA, near the northernmost limit of the species’ range. Winter acclimatization responses included a 233% increase in the hepatic glycogen depot that was subsidized by fat body and skeletal muscle catabolism, and a rise in plasma osmolality that reflected accrual of urea (to 106±10μmolml−1) and an unidentified solute (to ~73μmolml−1). In contrast, frogs from a cool-temperate population (southern Ohio, USA) amassed much less glycogen, had a lower uremia (28±5μmolml−1) and apparently lacked the unidentified solute. Alaskan frogs survived freezing at temperatures as low as –16°C, some 10–13°C below those tolerated by southern conspecifics, and endured a 2-month bout of freezing at –4°C. The profound freeze tolerance is presumably due to their high levels of organic osmolytes and bound water, which limits ice formation. Adaptive responses to freezing (–2.5°C for 48h) and subsequent thawing (4°C) included synthesis of the cryoprotectants urea and glucose, and dehydration of certain tissues. Alaskan frogs differed from Ohioan frogs in retaining a substantial reserve capacity for glucose synthesis, accumulating high levels of cryoprotectants in brain tissue, and remaining hyperglycemic long after thawing. The northern phenotype also incurred less stress during freezing/thawing, as indicated by limited cryohemolysis and lactate accumulation. Post-glacial colonization of high latitudes by R. sylvatica required a substantial increase in freeze tolerance that was at least partly achieved by enhancing their cryoprotectant system. ]]> 2017-02-08 21:09:28 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/152624798 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153053279

]]> 2017-02-10 14:10:10 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153053279 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153219087  Global climates have been changing, sometimes rapidly and dramatically, throughout the evolutionary history of amphibians. Therefore, existing amphibian species have been derived from those that have survived major climatic disturbances. Although recent global climate change has resulted in warming in many regions, temperatures in some areas to date have not changed measurably, or have even cooled. Declines of some amphibian populations have been correlated with climate events, but demonstrations of direct causal relationships need further research. Data are available indicating some indirect effect of climate change on the initiation of breeding activities of some amphibians that occur earlier than in previous springs, but the costs and benefits of these changes are just beginning to be investigated. Climate may also play an indirect role in facilitating epidemics of infectious disease. Regardless of the role that climate changes may have played in past and current amphibian declines, future shifts in climate, should they prove as dramatic as predicted, will certainly pose challenges for surviving amphibian populations and for successful recovery efforts of species that have suffered declines. ]]> 2017-02-11 13:37:29 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153219087 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153398010 Environmental conditions at the edge of a species’ ecological optimum can exert great ecological or evolutionary pressure at local populations. For ectotherms like amphibians temperature is one of the most important abiotic factors of their environment as it influences directly their metabolism and sets limits to their distribution. Amphibians have evolved three ways to cope with sub-zero temperatures: freeze tolerance, freeze protection, freeze avoidance. The aim of this study was to assess which strategy common frogs at mid and high elevation use to survive and thrive in cold climates. In particular we (1) tested for the presence of physiological freeze protection, (2) evaluated autumnal activity and overwintering behaviour with respect to freeze avoidance and (3) assessed the importance of different high-elevation microhabitats for behavioural thermoregulation. Common frogs did not exhibit any signs of freeze protection when experiencing temperatures around 0 °C. Instead they retreated to open water for protection and overwintering. High elevation common frogs remained active for around the same period of time than their conspecifics at lower elevation. Our results suggest that at mid and high elevation common frogs use freeze avoidance alone to survive temperatures below 0 °C. The availability of warm microhabitats, such as rock or pasture, provides high elevation frogs with the opportunity of behavioural thermoregulation and thus allows them to remain active at temperatures at which common frogs at lower elevation cease activity. ]]> 2017-02-13 12:41:23 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153398010 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153757500 Climate change and amphibians.— Amphibian life histories are exceedingly sensitive to temperature and precipitation, and there is good evidence that recent climate change has already resulted in a shift to breeding earlier in the year for some species. There are also suggestions that the recent increase in the occurrence of El Niño events has caused declines of anurans in Central America and is linked to elevated mortality of amphibian embryos in the northwestern United States. However, evidence linking amphibian declines in Central America to climate relies solely on correlations, and the mechanisms underlying the declines are not understood. Connections between embryo mortality and declines in abundance have not been demonstrated. Analyses of existing data have generally failed to find a link between climate and amphibian declines. It is likely, however, that future climate change will cause further declines of some amphibian species. Reduced soil moisture could reduce prey species and eliminate habitat. Reduced snowfall and increased summer evaporation could have dramatic effects on the duration or occurrence of seasonal wetlands, which are primary habitat for many species of amphibians. Climate change may be a relatively minor cause of current amphibian declines, but it may be the biggest future challenge to the persistence of many species.

]]> 2017-02-14 15:53:14 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153757500 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153815072 Hyperolius viridiflavus nitidulus inhabits parts of the seasonally very hot and dry West African savanna. During the long lasting dry season, the small frog is sitting unhidden on mostly dry plants and has to deal with high solar radiation load (SRL), evaporative water loss (EWL)
and small energy reserves. It seems to be very badly equipped to survive such harsh climatic conditions (unfavorable surface to volume ratio, very limited capacity to store energy and water). Therefore, it must have developed extraordinary efficient mechanisms to solve the mentioned
problems. Some of these mechanisms are to be looked for within the skin of the animal (e.g. protection against fast desiccation, deleterious effects of UV radiation and overheating). The morphology ofthe wet season skin is, in most aspects, that of a "normal" anuran skin. It differs in the organization of the processes of the melanophores and in the arrangement of the chromatophores in the stratum spongiosum, forming no "Dermal Chromatophore Unit". During the adaptation to dry season conditions the number of iridophores in dorsal and ventral skin is increased 4-6 times compared to wet season skin. This increase is accompanied by a very conspicuous change of the wet season color pattern. Now, at air temperatures below 35° C the color becomes brownish white or grey and changes to a brilliant white at air temperatures near and over 40° C. Thus, in dry season state the frog retains its ability for rapid color change. In wet season state the platelets of the iridophores are irregularly distributed. In dry season state many platelets become arranged almost parallel to the surface. These purine crystals probably act as quarter-wavelength interference reflectors, reducing SRL by reflecting a considerable amount of the radiated energy input. EWL is as low as that of much larger xeric reptilians. The impermeability of the skin seems to be the result of several mechanisms (ground substance, iridophores, lipids, mucus) supplementing each other. The light red skin at the pelvic region and inner sides ofthe limbs is specialized for rapid uptake ofwater allowing the frog to replenish the unavoidable EWL by using single drops of dew or rain, available for only very short periods.

]]> 2017-02-14 18:11:01 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153815072 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153889949  The reproductive behaviour of the Smith Frog, Hyla faber, was studied in an artificial permanent pond in southeastern Brazil. Males built nests at the edges of this pond where eggs were laid. Reproductive activity continued from late October, 1988 through early March. 1989. Twenty five males and 20 females were marked at the pond. There was no sexual dimorphism in size and females did not choose the larger males. Mean male residency was 15.5 nights; only two females were observed for more than one night. Three different vocalizations were emitted during female attraction and courtship. Courtship behaviour was complex and nearly invariable. Male reproductive success varied between 1-7 matings and was not correlated with male size, but was positively correlated with length of residency. Only one female was observed mating more than once. Except for minor details, the reproductive behaviour of the Smith Frog is very similar to that observed for Hyla rosenbergi, an ecologically and phylogenetically related species ]]> 2017-02-14 23:11:22 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/153889949 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154056453 We studied sexual dimorphism, female reproduction and egg incubation of the oriental leaf-toed gecko (Hemidactylus bowringii) from a population in southern China. The largest male and female in our sample were 60 and 57 mm snout-vent length (SVL), respectively. Males are the larger sex; sexual dimorphism in head size and tail length (TL) is evident in juveniles and adults, with males having larger heads as well as longer tails than females. Oviposition occurred between late May and late July. Females switched from laying two eggs early in the breeding season to 1-2 eggs later in the season. Clutch mass and egg mass were both independent of female SVL, whereas relative clutch mass was negatively correlated with female SVL. The previous conclusion that female H. bowringii lay a single clutch of eggs per breeding season is unlikely to be true. Thermal environments experienced by H. bowringii eggs affect incubation length as well as morphological and locomotor phenotypes of hatchlings. Hatchlings from eggs incubated at 30 degrees C were larger (SVL, tail length and body mass) and performed better in the racetrack than their counterparts from eggs incubated at 24 degrees C. Temperatures suitable for embryonic development are relatively high in H. bowringii, primarily as a consequence of the adaptive response to warm environments in southern China.

]]> 2017-02-15 16:06:05 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154056453 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154103568 We present a modeling approach to assess the impact of different conservation management options on the population dynamics of the moor frog (Rana arvalis, Amphibia, Anura) in dynamic river floodplains. The model is targeted at supporting amphibian conservation actions within floodplain management efforts for human flood protection. FloMan-MF is an individual-based, spatially explicit simulation model that combines three aspects: the hydrological dynamics of the landscape influenced by floods, frog reproductive behavior modeled through migration and selection of suitable reproduction sites (ponds), and population structure and trajectory over time. We validated each of the three systems and applied the baseline scenario to a two-year case study conducted in the Middle Elbe River floodplain (Germany). The FloMan-MF model aims to identify suitable compositions of floodplain ponds and habitat characteristics to optimize the reproductive habitat for moor frogs in a degraded floodplain. Therefore, to show potential applications of the model, we simulated floodplain habitat degradation and five different management scenarios. The population responded differently to each of the simulated management actions, ranging from rapid extinction to recovery with low numbers of individuals. The partly unexpected results reveal complex interactions in species-habitat interactions over time. According to our results, the establishment of dynamic temporary ponds seems to be a basic condition for population persistence of this species and can be realized within floodplain management activities. Extending the rationale and basic design of FloMan-MF to other amphibian species living in floodplains is straightforward.]]> 2017-02-15 18:01:12 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154103568 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154183933 Studies on thermoregulation in the laboratory and field have come a long way from the early work done between 1940 and 1960. While some physiological studies on amphibians have progressed at the same rate as those on reptiles, field studies have been far behind. Laboratory studies have largely delt with thermal acclimation, evaporative water loss, and thermal and moisture gradient behavior. Field studies, following early summaries of body temperatures of field animals, have stressed behavioral thermoregulation; yet, detailed studies on behavioral thermoregulation in amphibians have been completed for only a handful of species. A few studies have placed behavioral and physiological thermoregulation into an ecological or energetic framework; these studies are reviewed, and suggestions are made for future work.]]> 2017-02-15 22:42:01 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/154183933 https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/155707348 The mating system of a population of bullfrogs, Rana catesbeiana, in New Jersey is resource defense polygyny. The sex ratio of the breeding population is skewed toward males. Males defend territories against conspecifics by stereotyped postures, vocalizations and physical combat. Females select mates and oviposit in the male's territory. This system presumably evolved in response to the prolonged breeding season, the temporally asynchronous arrival of females at the breeding pond, the skewed operational sex ratio and the ability of males to gain indirect access to females through defense of oviposition sites. This study is compared with previous reports of bullfrog social behavior. General characteristics of the mating system in different parts of the range are discussed. There are consistencies in social behavior within the species. However, there is a degree of behavioral plasticity previously unreported in anuran breeding behavior.]]> 2017-02-23 11:30:05 UTC https://padlet.com/k_ashbrook/gfanwp6u0u1o/wish/155707348