| environment-dependent admixture dynamics in a tiger salamander hybrid zone. | after an estimated five million years of independent evolution, the barred tiger salamander (ambystoma tigrinum mavortium) was introduced by bait dealers into the native range of the california tiger salamander (a. californiense). hybridization and backcrossing have been occurring in central california for 50-60 years, or an estimated 15-30 generations. we studied genetic and ecological factors influencing admixture of these two divergent gene pools by analyzing frequencies of hybrid genotypes i ... | 2004 | 15266977 |
| rapid fixation of non-native alleles revealed by genome-wide snp analysis of hybrid tiger salamanders. | hybrid zones represent valuable opportunities to observe evolution in systems that are unusually dynamic and where the potential for the origin of novelty and rapid adaptation co-occur with the potential for dysfunction. recently initiated hybrid zones are particularly exciting evolutionary experiments because ongoing natural selection on novel genetic combinations can be studied in ecological time. moreover, when hybrid zones involve native and introduced species, complex genetic patterns prese ... | 2009 | 19630983 |
| larval hannemania sp. infestations of spea spp. in the southern high plains, texas, usa. | we describe a case history of larval hannemania sp. (acari: trombiculidae) infestations in two spadefoot toads (spea spp. anura: pelobatidae) captured from playa wetlands in the southern high plains, texas. hannemania sp. larvae were superficially attached to the skin, not encysted, and dermal changes were not observed. gross field examinations revealed a presumed occurrence of hannemania sp. in spea spp. at four of 24 wetlands in 2003 and 2004. although other species of amphibians were present ... | 2007 | 17984273 |
| hybrid vigor between native and introduced salamanders raises new challenges for conservation. | hybridization between differentiated lineages can have many different consequences depending on fitness variation among hybrid offspring. when introduced organisms hybridize with natives, the ensuing evolutionary dynamics may substantially complicate conservation decisions. understanding the fitness consequences of hybridization is an important first step in predicting its evolutionary outcome and conservation impact. here, we measured natural selection caused by differential viability of hybrid ... | 2007 | 17884982 |
| helminth and leech community structure in tadpoles and caudatan larvae of two amphibian species from western nebraska. | currently no comparative studies exist on helminth and leech community structure among sympatric anuran tadpoles and salamander larvae. during june-august 2007-2009, we examined 50 bullfrog tadpoles, rana catesbeiana , 50 barred tiger salamander larvae, ambystoma mavortium , and 3 species of snails from nevens pond, keith county, nebraska for helminth and leech infections. the helminth and leech compound community of this larval amphibian assemblage consisted of at least 7 species, 4 in bullfrog ... | 2012 | 22059380 |
| introduction history and habitat variation explain the landscape genetics of hybrid tiger salamanders. | genetic introgression from introduced species into native populations is a growing challenge for biological conservation, and one that raises unique practical and ethical issues. here, we describe the extent of introgression between native california tiger salamanders (ambystoma californiense) and introduced barred tiger salamanders (a. tigrinum mavortium) relative to habitat, distance from introduction sites, and watershed boundaries. we used ancestry informative markers (aims) to characterize ... | 2007 | 17489263 |
| ecological equivalency as a tool for endangered species management. | the use of taxon substitutes for extinct or endangered species is a controversial conservation measure. we use the example of the endangered california tiger salamander (ambystoma californiense; cts), which is being replaced by hybrids with the invasive barred tiger salamander (ambystoma mavortium), to illustrate a strategy for evaluating taxon substitutes based on their position in a multivariate community space. approximately one-quarter of cts's range is currently occupied by "full hybrids" w ... | 2016 | 27039512 |
| morphology and escape performance of tiger salamander larvae (ambystoma tigrinum mavortium). | the ability of an individual to escape predators is an important component of fitness. several adaptive explanations of body shape variation in amphibians hypothesize relationships between swimming performance and morphology, but these ideas have rarely been tested. here we investigate bivariate and multivariate relationships between natural variation in morphology and performance. we used high-speed video to examine fast-starts associated with escape responses in small tiger salamander larvae ( ... | 2003 | 12945751 |
| metacercariae of clinostomum attenuatum in ambystoma tigrinum mavortium, bufo cognatus and spea multiplicata from west texas. | tissues from barred tiger salamanders (ambystoma tigrinum mavortium), great plains toads (bufo cognatus) and new mexico spadefoots (spea multiplicata) collected from 16 playa wetlands in texas during 1999 and 2000 were examined by light microscopy. digenean cysts were primarily distributed subcutaneously throughout the specimens and occasionally coelomic invasion was noted. the parasites within the cysts were 1.5-2 mm in diameter, with a thin (c. 10 microm wide) eosinophilic-staining tegument, t ... | 2004 | 15575998 |
| invasive hybrid tiger salamander genotypes impact native amphibians. | although the ecological consequences of species invasions are well studied, the ecological impacts of genetic introgression through hybridization are less understood. this is particularly true of the impacts of hybridization on "third party" community members not genetically involved in hybridization. we also know little about how direct interactions between hybrid and parental individuals influence fitness. here, we examined the ecological effects of hybridization between the native, threatened ... | 2009 | 19564601 |
| lethal effects of water quality on threatened california salamanders but not on co-occurring hybrid salamanders. | biological invasions and habitat alteration are often detrimental to native species, but their interactions are difficult to predict. interbreeding between native and introduced species generates novel genotypes and phenotypes, and human land use alters habitat structure and chemistry. both invasions and habitat alteration create new biological challenges and opportunities. in the intensively farmed salinas valley, california (u.s.a.), threatened california tiger salamanders (ambystoma californi ... | 2013 | 23140535 |
| specific dynamic action of ambystomatid salamanders and the effects of meal size, meal type, and body temperature. | the past decade has witnessed a dramatic increase in studies of amphibian and reptile specific dynamic action (sda). these studies have demonstrated that sda, the summed energy expended on meal digestion and assimilation, is affected significantly by meal size, meal type, and body size and to some extent by body temperature. while much of this attention has been directed at anuran and reptile sda, we investigated the effects of meal size, meal type, and body temperature on the postprandial metab ... | 2006 | 16826498 |
| mortality rates differ among amphibian populations exposed to three strains of a lethal ranavirus. | infectious diseases are a growing threat to biodiversity, in many cases because of synergistic effects with habitat loss, environmental contamination, and climate change. emergence of pathogens as new threats to host populations can also arise when novel combinations of hosts and pathogens are unintentionally brought together, for example, via commercial trade or wildlife relocations and reintroductions. chytrid fungus (batrachochytrium dendrobatidis) and amphibian ranaviruses (family iridovirid ... | 2010 | 20143127 |