Amphibians are facing an extinction crisis, and in many cases it has become necessary to conserve species in captivity. Unfortunately, our understanding of the nutritional requirements of amphibians in captivity is currently limited. There have been anecdotal reports that captive bred amphibians have duller skin colouration than wild members of the same species. Many amphibians use carotenoid pigments in skin colouration. Carotenoids are yellow-red pigments synthesised by photosynthetic tissues, however vertebrates cannot synthesise them de novo and rely entirely on dietary sources. Reduced colour in captive bred amphibians could therefore result from limited carotenoid availability in the diet. Limited access to carotenoids could have further negative consequences on health and reproductive success since carotenoids are known to function in the immune, antioxidant and reproductive systems of other vertebrate taxa. The role of carotenoids in amphibian fitness is currently unknown, and the aim of this PhD was to assess the importance of carotenoids to anuran amphibians. Skin colour may be influenced by carotenoid availability, and it was therefore important to establish a suitable method for quantifying skin colour in amphibians. In Chapter 1 I assessed two methods for colour quantification, including digital photography and spectrometry. Neither method was significantly more accurate than the other, however I chose to use photography for my studies for reasons of practicality. In Chapters 2 and 3 I assessed the role of carotenoids in the reproductive systems of wild frogs. I found that carotenoid-based skin colouration was involved in the breeding behaviour of wild Agalychnis moreletii frogs. I found positive assortative mating by colour in that frogs were found mating with individuals with similar carotenoid-based colouration. This assortative mating by colour may be driven by mutual mate choice, or may have evolved to prevent mismatched pairing with a sympatric and phenotypically similar species (A. callidryas). I then analysed the carotenoid composition of eggs produced by wild A. moreletii and Phyllomedusa trinitatis, which are tree frogs with similar reproductive ecology but different egg deposition strategies: Agalychnis moreletii deposits green eggs on the surface of leaves while P. trinitatis wraps pale cream eggs in leaves. The concentration and diversity of carotenoids was significantly higher in A. moreletii than P. trinitatis and potential ecological explanations for this are discussed. In Chapter 4 I investigated carotenoid availability in the diet of captive amphibians by analysing the carotenoid composition of commonly used feeder-invertebrates. I assessed interspecific variation in carotenoid accumulation in three feeder-cricket species (Gryllus bimaculatus, Gryllodes sigillatus and Acheta domesticus), which were all fed one of three diets (wheat-bran, fish-food based diet, fresh fruit and vegetables). All three cricket species were a poor source of carotenoids unless they were gut-loaded on a carotenoid-rich diet. Nutrient retention over a two-day period was poor across species. Finally, there were significant interspecific differences in gut-loading capacity, with G. bimaculatus having the greatest capacity. This study shows that carotenoid availability to captive amphibians will be limited unless they are fed specific feeder invertebrate species, recently gut-loaded on carotenoid-rich foods. In Chapters 5, 6 and 7 I assessed the influence of carotenoids on fitness related traits in captive anurans. I firstly assessed colour degradation in captive-reared A. moreletii frogs and looked at whether skin colour could be improved through increased carotenoid availability in the diet. I found that carotenoid-based skin colour degraded quickly in captivity but could be improved through dietary supplementation with carotenoids, however there was a critical period during post-metamorphic growth for deposition of carotenoids in the skin. Next, I investigated the effect of carotenoids on larval growth and development, and post-metamorphic growth, development, skin colour and reproductive success in captive A. callidryas frogs. I found no direct effect of carotenoids during larval stages, however there were carry-over effects on post-metamorphic growth and skin colour. Increased post-metamorphic carotenoid availability positively influenced growth, skin colour and reproductive success. Similarly to A. moreletii, there was a critical period during post-metamorphic growth for deposition of carotenoids in the skin. Finally, I examined the protective potential of carotenoids in Silurana (Xenopus) tropicalis tadpoles that were exposed to ultraviolet (UV) light. Exposure to UV light significantly reduced tadpole survival and there was no evidence that carotenoids afforded any protection. Nevertheless, in tadpoles that were not exposed to enhanced UV light, carotenoids increased survival. Furthermore, carotenoids had a significantly positive effect on the developmental rate of tadpoles in both UV limited and UV enhanced environments. The studies in this PhD show that carotenoid availability has important consequences on fitness related traits in anuran amphibians, which include effects on growth, skin colour, reproductive success and survival. Carotenoid availability to captive amphibians will, however, be low unless they are provided with feeder invertebrates that have been recently gut-loaded on carotenoid-rich foods. These findings should be considered when recommendations are made on the nutritional requirements of amphibians in captivity as they could significantly improve the fitness of captive-bred individuals, and thus increase the success of ex situ conservation programmes.

Temnospondyls are the most species-rich group of early amphibians, but species-level phylogenetic analyses of this large clade have so far only incompletely sampled the group. This study represents the largest and most comprehensive species-level phylogenetic study of Temnospondyli, sampling 99 taxa for 297 morphological characters from all seven continents through nearly 170 million years of their evolutionary history. Results of this analysis support the monophyly of several clades. Phylogenetic definitions are updated and three new clades names are proposed: Eutemnospondyli, Neostereospondyli, and Latipalata. Major splits within temnospondyl evolution are recovered at the base of Eutemnospondyli (Euskelia and Limnarchia) and Neostereospondyli (Capitosauria and Trematosauria). Archegosauriodea is recovered within Euskelia. Dendrerpeton is recovered as the immediate sister taxon of Dissorophoidea, not Eryopoidea. This arrangement suggests that for subclade-level analyses of dissorophoids, which bear on the `Temnospondyl Hypothesis' for a putative origin of Lissamphibia within dissorophoids, the convention of rooting on Dendrerpeton and including eyropoids in the ingroup should be re-evaluated in light of the new temnospondyl topology. Study of the tempo and mode of evolution within temnospondyl amphibians has been limited in the past by the availability of a clade-wide, species-level phylogenetic analysis. The phylogenetic dataset generated by this study has allowed for investigation into rates of origination and extinction amongst this long-lived group at a scale not previously available for exploration. Extinction rate and origination rate, when calculated strictly from stratigraphic data, showed a high correlation with the number of sampled localities, indicating a strong influence on this evolutionary signal by sampling and rock record biases. But when rates were augmented with phylogenetic data, four periods of increased lineage origination are discernible from the Pennsylvanian to the Early Triassic. The largest of these origination events coincides with the Permo-Triassic mass extinction, indicating that amphibians were taking advantage of favorable conditions during the largest biological crisis in the Phanerozoic record. Temnospondyl amphibians are the second most abundant fossil vertebrates in the Permo-Triassic Karoo Basin of South Africa. Paleohistological investigation of these amphibians was hampered by small sample size and taxa available for sampling. Incorporation of paleohistologic data from other analyses helped to alleviate this problem; however, Temnospondyli remains under sampled in paleohistological analyses. Results show cyclic growth and a lifespan of thirty years or more in basal stereospondyls, convergence to sustained, non-cyclic growth in terrestrial temnospondyls, support findings based on gross morphology that Lydekkerina is a terrestrial stereospondyl, and suggest that ribs are a viable source of skeletochronologic information in temnospondyls and should serve as preferred material when proximal limb diaphyses are not available. Sustained, azonal growth in Micropholis is unlike that of Apateon or extant caudatans, suggesting a possible adaptation to local conditions in the earliest Triassic of Gondwana.

<p>In the Anthropocene, amphibians must not only cope with natural stressors but also a suite of human-made stressors that have been experienced relatively recently within their evolutionary history. Because it has become increasingly common for natural and anthropogenic stressors to co-occur in aquatic ecosystems, the study of their separate and combined effects on ecosystems and their component species is increasingly necessary. This is especially important for amphibians, which have experienced global declines and can be highly sensitive to both natural and anthropogenic stressors. Pesticides and parasites are two commonly co-occurring stressors that can have complex individual and synergistic detrimental effects in amphibian populations. Here, I conducted three studies to broadly assess the separate and interactive effects of pesticides and parasites on amphibians. More specifically, I explored: 1) the underlying physiological mechanism allowing amphibians to induce increased tolerance to a pesticide within a single generation, 2) the effects of exposure timing to two functionally similar cryptic parasite species on infection outcomes, and 3) population-level variation in susceptibility to parasites and whether prior exposure to pesticides influenced the outcome of host-parasite interactions. First, to test the hypothesis that induced pesticide tolerance is the result of a generalized stress response, I exposed tadpoles to an anthropogenic stressor (sublethal pesticide dose), a natural stressor (cues from a caged predator), or a simulated stressor via exogenous exposure to the stress hormone corticosterone (CORT). I then exposed the larvae to a lethal carbaryl treatment to assess how the stressor exposures influenced survival. I found that prior exposure to exogenous CORT and predator cues induced tolerance to a lethal concentration of carbaryl, providing evidence that pesticide tolerance can be induced by a generalized stress response both in the presence and absence (exogenous CORT) of specific cues. Second, I explored how the timing of host exposure to two co-occurring cryptic echinostome species influences infection outcomes. I found that echinostome infection success in larval anurans can differ significantly based on the parasite species makeup, density, and exposure timing. I also found that priority effects can occur even between functionally similar cryptic species, with an early exposure to <i>Echinoparyphium </i>lineage 3 reducing the infection success of <i>Echinostoma trivolvis </i>three days later. Finally, I assessed the influence of pesticide exposure on host-parasite interactions and population-level variation in these responses. This was accomplished by exposing wood frog larvae from eight populations to one of two treatments (a sublethal carbaryl concentration or a pesticide-free control) followed by controlled parasite exposures to either echinostome trematodes or ranavirus. Then, I assessed how pesticide exposure influenced infection loads, infection prevalence, and survival in each population. I found significant population-level variation in infection outcomes. Interestingly, however, I found no significant effects of pesticide exposure on disease outcomes. Together, these three studies demonstrate the wide-ranging and surprising outcomes that can result from interactions among and between natural and anthropogenic stressors.</p>

The giant bullfrog, Pyxicephalus adspersus, is a large, explosive-breeding anuran from southern Africa, which spends most of the year buried in a state of torpor. In South Africa this species is considered to be Near-Threatened by habitat loss and other factors, especially in the densely human populated Gauteng Province. The aim of this thesis was to obtain essential outstanding information about the ecology of P. adspersus to contribute towards improved conservation management of this species. A model was used to predict the geographic range of P. adspersus in southern Africa, and recent land cover data were used to determine the amount of suitable habitat remaining for this species in Gauteng. As a step towards identifying P. adspersus conservation management units, genetic structure and gene flow for populations from 23 localities in Gauteng and seven additional localities in the north-eastern interior of South Africa was quantified using 708 base pairs of the mitochondrial gene cytochrome b. To investigate the unpredictable activity and unknown spatial habitat requirements of P. adspersus, a population’s spawning and non-breeding activity was monitored, and the movements of 70 adult frogs were radio- or spool-tracked during five summers at a site in Diepsloot, Gauteng. Using skeletohronology, the age distribution of breeding P. adspersus at this and two other peri-urban sites near Johannesburg, Gauteng, was examined. Bioclimatic conditions were predicted to be suitable for P. adspersus in the temperate to semi-arid interior, but not the low-lying eastern subtropical and arid western sides of southern Africa. Limited genetic data suggested that P. adspersus was common in the north-eastern interior of South Africa, and that populations in the Free State Province represent an evolutionary significant unit of this species. In central Gauteng, where P. adspersus may have declined by > 90%, populations < 20 km apart exhibited significant genetic differentiation, possibly as a result of genetic drift. At Diepsloot, both annual numbers of spawning events and numbers of spawning males were positively correlated with rainfall, although other meteorological variables also affected the activity of P. adspersus. Radio- or spool-tracked frogs showed high fidelity to their breeding site and burrows, which were situated up to 1 km away from the water. Male P. adspersus probably live 20 years in the wild, but at some peri-urban breeding sites adult life expectancy and body size may be declining. The geographic range of P. adspersus was predicted to be slightly smaller than that reported by other authors, and deserves phylogeographic validation. The main conservation priority for P. adspersus in South Africa should be the protection of terrestrial habitat for adult foraging and aestivation around, and for juvenile dispersal and gene flow between, breeding sites. In Gauteng, the conservation of a P. adspersus metapopulation is critical, and could most likely be achieved in the northern region of this province. Populations in the Free State Province deserve improved protection given their reported genetic uniqueness. At local spatial scales specific threats (e.g. pollution) should be ameliorated, and long-term monitoring should be implemented to detect real population trends. / Thesis (PhD)--University of Pretoria, 2012. / Zoology and Entomology / Unrestricted

No description available.

The eastern spadefoot (Scaphiopus holbrookii) is an ephemeral wetland breeding amphibian that ranges from southern Florida north and westward to southeastern Missouri and northward along the Atlantic coastal plain to Massachusetts. This species is listed as either "threatened" or "endangered" in the four states (Connecticut, Massachusetts, New York, and Rhode Island) in the northeastern United States where it is known to exist. Population declines and extirpations throughout the region over the past century have been documented and are largely believed to be the result of habitat loss and/or alteration. Very limited empirical results exist on many life history attributes of S. holbrookii anywhere in its range, including movement patterns, upland habitat selection, and breeding habitat preferences. These are critical information gaps that must be filled in order to effectively conserve and manage for this rare species in the northeastern U.S. While S. holbrookii is extremely rare throughout most of the Northeast, it is locally common in specific areas of Cape Cod National Seashore, most notably in an extensive sand-dune ecosystem known as the Province Lands located at the northern terminus of the Cape Cod peninsula. During 2005 and 2006, we conducted larval trapping surveys at 102 wetlands in the Province Lands primarily to: 1) identify breeding wetlands and 2) to assess breeding habitat use and preferences of S. holbrookii with respect to a suite of selected abiotic and biotic covariates. We captured S. holbrookii larvae at 140/652 (~21.5%) trap locations and 41/102 (~40.2%) wetlands sampled. Model results identified a number of additional habitat covariates that exhibited a statistically significant relationship with larval S. holbrookii abundance including: the percent cover of 1) cranberry (positive relationship), and 2) woody shrub (positive relationship) at a 4m radius from the trap location; 3) percent woody shrub cover at the wetland-scale (negative relationship); 4) percent canopy cover at the wetland-scale (positive relationship); 5) wetland pH (positive relationship); 6) distance to the closest paved road (positive relationship); and the kernel density cover of 7) deciduous shrubland edge (positive relationship), 8) deciduous shrubland (negative relationship), 9) pine (positive relationship), and 10) open dune (positive relationship) in the uplands surrounding the study wetlands. During 2006 and 2008 we radio-tracked adult S. holbrookii in the Province Lands using surgically implanted radio-transmitters to: 1) describe movement patterns and estimate home range sizes, and 2) assess upland habitat preferences of S. holbrookii. We tracked 19/20 individuals (11 males and 8 females) and 12/20 individuals (7 males and 5 females) for at least the first 30 and 100 days post-surgery, respectively, during 2006. During 2008 we successfully tracked 15/25 individuals (10 males and 5 females) and 5/25 individuals (3 males and 2 females) for at least the first 30 and 100 days post-surgery, respectively. In addition to results obtained on a suite of movement attributes we identified a number of upland habitat preferences for S. holbrookii. Use locations were: 1) closer to the nearest deciduous shrub edge, 2) had a greater percent cover of ground-running pitch pine branches at a 1 m scale, 3) had a greater percent cover of deciduous shrubs at a 1 m scale, and 4) had a greater percent cover of reindeer lichen at a 5 m scale. Results from this research provide much needed empirical results on these critical life history attributes related to the movement and breeding ecology of S. holbrookii. These results will aid biologists and Park management staff at Cape Cod National Seashore in more effectively employing conservation and management strategies aimed at enhancing the long-term persistence probability of this regionally rare species in the Province Lands.

I studied the ecology and distribution of the Florida bog frog (Rana okaloosae) and flatwoods salamander (Ambystoma cingulatum) on Eglin Air Force Base in northwest Florida. I report data on the breeding ecology, population dynamics, home ranges, microhabitat, and distribution of the endemic bog frog and make comparisons to its closest relative, the bronze frog (Rana clamitans clamitans). Bog and bronze frogs occur in the same habitats and are suspected to hybridize. I investigated the potential for auditory and visual mate recognition errors between R. okaloosae and R. clamitans. I also described the vocal repertoire of the bog frog and observed the response of resident males to the playback of unfamiliar conspecific and heterospecific (R. clamitans) calls. The advertisement calls of bog frogs vary among individuals, and individual voice recognition is possible. I exposed tadpoles of bog frogs, bronze frogs, and leopard frogs (R. sphenocephala) to chemical cues from 2 predators, the banded water snake (Colubridae: Nerodia fasciata) and the red fin pickerel (Esocidae: Esox americanus) to evaluate whether swimming behavior or habitat selection differed among tadpole species. The time spent swimming differed among tadpole species and predator treatments, differences which potentially could affect growth rates, survivorship rates, and distribution patterns. Lastly, I discuss the relationship between fire and the federallyâ threatened flatwoods salamander (Ambystoma cingulatum). I compared 13 breeding wetlands with different fire histories in addition to burned and unburned halves of a partiallyâ burned wetland. In general, areas that burned more recently had more open canopies, higher dissolved oxygen concentrations, higher water temperatures, more understory vegetation, and were shallower than unburned areas. Rangewide surveys indicate that prescribed fires typically are applied in winter and early spring in areas inhabited by flatwoods salamanders. Based on what is known about the natural history of the species, the historical burning regime of the longleaf ecosystem, and the effects of fires on ephemeral wetlands, I suggest that land mangers diversify their fireâ management strategy to increase the likelihood of burning the breeding wetlands of flatwoods salamanders. / Ph. D.

We compared techniques for assessing nutritional condition in 3 groups of terrestrial salamanders. We measured variability in species richness and relative abundance before harvest at 5 sites in the Jefferson National Forest of southwest Virginia and compared the effects of 7 silvicultural treatments on terrestrial salamander richness and relative abundance at 1 site. / Master of Science

Because the ancestry of extant amphibians remains highly controversial, under traditional perspectives, amphibians and amniotes often are distinguished by differences in developmental mode rather than their evolutionary relationships. Resolution of relationships is important, however, because phylogeny affects interpretations of biology, including the evolution of development. To address those issues, I documented the growth and development of two extinct lepospondyls, Microbrachis pelikani and Hyloplesion longicostatum, and compared the patterns in those taxa to data from other tetrapods. I quantified allometry in the skeleton using both measurement-based and geometric morphometric analyses. I applied Ontogenetic Sequence Analysis (OSA), a size-independent method, to the reconstruction of ossification sequences based on fossils. I also documented skeletal morphogenesis and used Parsimov Analysis and Parsimov-based Genetic Inference of ossification sequence data to evaluate the three hypotheses of extant amphibian ancestry, the Lepospondyl (LH), Temnospondyl (TH), and Polyphyletic (PH) hypotheses. Skeletal growth in Microbrachis pelikani and Hyloplesion longicostatum is primarily isometric. Comparisons with data from other Paleozoic taxa suggest that isometry was the ancestral pattern of growth in tetrapods. All regression analyses had a linear fit indicating lack of an abrupt metamorphosis. Absence of metamorphosis is also supported by the possession of lateral lines in both taxa throughout ontogeny, and Microbrachis pelikani additionally retained gills. However, ossification of the skeleton was completed at small body size. The greatest resolution in ossification sequence reconstruction was achieved with OSA, but results from all reconstruction methods indicated advanced ossification of the pubis and delayed ossification of the scapula in the lepospondyls. In terms of total number of sequence shifts optimized across each hypothesis of amphibian relationships, the TH had the shortest tree length. However, the values for the three hypotheses did not differ significantly, demonstrating that none was supported strongly. Based on my synthesis of new developmental data, I propose that Microbrachis pelikani and Hyloplesion longicostatum expressed a mosaic pattern of skeletal development. That pattern included a gradual transition to an adult morphology, and a lack of an amphibian-like metamorphosis. A similar pattern is common to most early tetrapods and Eusthenopteron, supporting the hypothesis that metamorphosis is not ancestral for Tetrapoda. / text

AN ABSTRACT OF THE DISSERTATION OF GRETCHEN ELIZABETH PADGETT-FLOHR for the Doctor of Philosophy degree in Zoology, presented on March 5, 2009 at Southern Illinois University of Carbondale. TITLE: BATRACHOCHYTRIUM DENDROBATIDIS IN CENTRAL CALIFORNIA AMPHIBIANS MAJOR PROFESSOR: Eric Schauber Amphibian chytridiomycosis has been identified as a disease responsible for the decline and extinction of many amphibian taxa world wide, but little research has been conducted on the disease in Mediterranean climates. To address this gap in the data I studied the amphibian assemblage present across a ~6,475 ha site in central California and investigated the occurrence of the etiological agent, Batrachochytrium dendrobatidis (BD) from organismal, community, landscape and historical perspectives. I initially tested the accuracy and reliability of a proposed diagnostic screening test for BD in four larval species that occur on the site. The screening test proposed by Fellers et al. (2001) and Vredenburg and Summers (2001) consisted of examining larval amphibian mouthparts for abnormalities and or defects, based on their hypothesis that mouthpart defects are clinical signs of BD infection. Sensitivity and specificity of the diagnostic screening test were 76% and 58%, respectively, indicating that the proposed screening test was not a reliable diagnostic test for BD infection for the four species I examined. I conducted controlled laboratory experiments to examine the consequences of BD infection in the two threatened California species that occur on my study site: Rana draytonii and Ambystoma californiense. Both species were susceptible to infection, but all infected animals survived the 18-month study. Infected A. californiense sloughed skin at three times the rate of uninfected salamanders, a pattern that may have long-term energetic costs potentially leading to population-level consequences of sublethal infection by BD. I conducted a retrospective survey of the California Academy of Sciences' (San Francisco, California, USA) amphibian collection, testing for BD in four amphibian species collected from central California between 1897 and 2005 to assess whether the pathogen is novel versus endemic. The earliest detection of BD was in two Rana catesbeiana collected in 1961, and the data support the hypothesis that BD was a novel pathogen introduced into central California prior to 1961 that spread geographically and taxonomically from at least one point of introduction and is now endemic throughout most of central California. I analyzed how environmental factors, amphibian community composition, land use practices, and landscape structure affect the dynamics of the pathogen's distribution on my study site in central California. The distribution of BD in ponds within the landscape varied markedly between years and increases were associated with precipitation, mean minimum and maximum temperatures, and presence of particular species. Pseudacris regilla infection patterns were highly indicative of overall patterns of pond BD status. Fourteen ponds were identified as BD hotpots (BD-positive three of four years). Occurrences of the pathogen within the landscape were spatially autocorrelated and ponds in close proximity to BD hotspots were more likely to test positive. Local land use, (presence/absence of grazing or recreational activity and developed lands), apparently did not influence BD status of a pond. My studies show that BD was likely a novel pathogen introduced into California ca. 1961 that has since become established as an endemic pathogen throughout most of central California. The listed amphibian species that occur in central California can be infected with BD but appear to be resistant to manifesting amphibian chytridiomycosis, and the data from the studies herein could support one of two hypotheses: that natural selection acting over the past 48 years has selected for those individuals that were resistant to the disease; or that the species on my site have always been resistant to BD. The research I conducted further supports the hypothesis that BD is locally vectored by native amphibians (e.g. P. regilla) moving between ponds and that local ecological constraints likely limit vectoring of BD by non-native species. These findings contribute substantially to elucidating and understanding the responses of amphibian populations to disease/pathogen introduction and lay groundwork for future investigations into the host-pathogen-environment relationship as it relates to declining amphibian populations.