Ambystoma Laterale Research Articles

Historical Demography and Climate Driven Range Shifts in the Blue-spotted Salamander Under the Climate Change Scenarios

This study integrates phylogeography with distributional analysis to understand the demographic history and range dynamics of a limited dispersal capacity amphibian species, Blue-spotted Salamander (Ambystoma laterale), under several climate change scenarios. For this we used an ecological niche modeling approach, together with Bayesian based demographic analysis, to develop inferences regarding this species' demographic history and range dynamics. The current model output was mostly congruent with the present distribution of the Blue-spotted Salamander. However, under both the Last Interglacial and the Last Glacial Maximum bioclimatic conditions, the model predicted a substantially narrower distribution than the present. These predictions showed almost no suitable area in the current distribution range of the species during almost the last 22.000 y before present (ybp). The predictions indicated that the distribution of this species shifted from eastern coast of northern North America to the southern part of the current distribution range of the species. The Bayesian Skyline Plot analysis, which provided good resolution of the effective population size changes over the Blue-spotted Salamander history, was mostly congruent with ecological niche modeling predictions for this species. This study provides the first investigation of the Blue-spotted Salamander’s late-Quaternary history based on ecological niche modeling and Bayesian-based demographic analysis. In terms of the main result of this study, we found that the species' present genetic structure has been substantially affected by past climate changes, and this species has reached current distribution range almost from nothing since the Last Glacial Maximum.

Environmental drivers of juvenile dispersal and adult non-breeding movements in Ambystoma salamanders

Understanding the environmental drivers of species’ dispersal and migration patterns is needed to accurately predict climate change impacts on populations. For pond-breeding amphibians, adult movements associated with the breeding period are well studied but major gaps exist in our knowledge of the drivers of adult and juvenile non-breeding movements. Here, we assess environmental drivers of adult and juvenile Ambystoma maculatum (Shaw, 1802), Ambystoma jeffersonianum (Green, 1827), and their unisexual dependants’ ( Ambystoma laterale–jeffersonianum (Uzzell, 1964)) summer and fall non-breeding movements using data from pitfall trapping and radio telemetry tracking. We used generalized linear models to assess the influence of precipitation, minimum temperature, day of year, and days since last precipitation on salamander movements. Juvenile summer dispersal movements were related to days since last precipitation in Jefferson Salamander complex individuals and 24 h precipitation in Spotted Salamanders. Adult and juvenile fall movements were driven by minimum temperature, 24 h precipitation, and days since last precipitation, and the effect of these environmental factors varied slightly between species and between Jefferson bisexuals and unisexuals. Our work indicates that changes in both temperature and precipitation will likely impact non-breeding dispersal and migration in these species and, overall, improves our understanding of ecological patterns throughout their entire life cycle.

Environmental Drivers of Amphibian Breeding Phenology across Multiple Sites

A mechanistic understanding of phenology, the seasonal timing of life history events, is important for understanding species’ interactions and the potential responses of ecological communities to a rapidly changing climate. We present analysis of a seven-year dataset on the breeding phenology of wood frogs (Rana sylvatica), tiger salamanders (Ambystoma tigrinum), blue-spotted salamanders (Ambystoma laterale), and associated unisexual Ambystoma salamanders from six wetlands in Southeast Michigan, USA. We assess whether the ordinal date of breeding migrations varies among species, sexes, and individual wetlands, and we describe the specific environmental conditions associated with breeding migrations for each species/sex. Breeding date was significantly affected by species/sex identity, year, wetland, and the interactions between species/sex and year as well as wetland and year. There was a great deal of variation among years, with breeding occurring nearly synchronously among groups in some years but widely spaced between groups in other years. Specific environmental triggers for movement varied for each species and sex and changed as the breeding season progressed. In general, salamanders responded to longer temperature lags (more warmer days in a row) than wood frogs, whereas wood frogs required longer precipitation lags (more rainy days in a row) than salamanders. Wood frogs were more likely to migrate around the time of a new moon, whereas in contrast, Ambystoma salamander migration was not associated with a moon phase. Ordinal day was an important factor in all models, suggesting that these amphibians require a latency period or similar mechanism to avoid breeding too early in the year, even when weather conditions appear favorable. Male wood frogs migrated earlier than female wood frogs, and male blue-spotted salamanders migrated earlier than female A. laterale and associated unisexual females. Larger unisexual salamanders migrated earlier than smaller individuals. Differences in species’ responses to environmental cues led to wood frogs and A. laterale breeding later than tiger salamanders in colder years but not in warmer years. This suggests that, as the climate warms, wood frog and A. laterale larvae may experience less predation from tiger salamander larvae due to reduced size differences when they breed simultaneously. Our study is one of few to describe the proximate drivers of amphibian breeding migrations across multiple species, wetlands, and years, and it can inform models predicting how climate change may shift ecological interactions among pond-breeding amphibian species.

Body and Tail Coordination in the Bluespot Salamander (Ambystoma laterale) During Limb Regeneration.

Animals are incredibly good at adapting to changes in their environment, a trait envied by most roboticists. Many animals use different gaits to seamlessly transition between land and water and move through non-uniform terrains. In addition to adjusting to changes in their environment, animals can adjust their locomotion to deal with missing or regenerating limbs. Salamanders are an amphibious group of animals that can regenerate limbs, tails, and even parts of the spinal cord in some species. After the loss of a limb, the salamander successfully adjusts to constantly changing morphology as it regenerates the missing part. This quality is of particular interest to roboticists looking to design devices that can adapt to missing or malfunctioning components. While walking, an intact salamander uses its limbs, body, and tail to propel itself along the ground. Its body and tail are coordinated in a distinctive wave-like pattern. Understanding how their bending kinematics change as they regrow lost limbs would provide important information to roboticists designing amphibious machines meant to navigate through unpredictable and diverse terrain. We amputated both hindlimbs of blue-spotted salamanders (Ambystoma laterale) and measured their body and tail kinematics as the limbs regenerated. We quantified the change in the body wave over time and compared them to an amphibious fish species, Polypterus senegalus. We found that salamanders in the early stages of regeneration shift their kinematics, mostly around their pectoral girdle, where there is a local increase in undulation frequency. Amputated salamanders also show a reduced range of preferred walking speeds and an increase in the number of bending waves along the body. This work could assist roboticists working on terrestrial locomotion and water to land transitions.

Post-emergence survival and dispersal of juvenile Jefferson salamander (Ambystoma jeffersonianum) and their unisexual dependents

Abstract Understanding population demography and dispersal of species at risk is integral for evaluating population viability, identifying causes of decline, and assessing the effectiveness of recovery actions. In pond-breeding amphibians, juvenile survival and dispersal are key components linked to population and metapopulation stability but little is known about this life stage. We use mark-recapture methods to estimate juvenile daily apparent survival, dispersal distance, and initial dispersal orientation during summer and fall dispersal of endangered Ambystoma jeffersonianum and their unisexual dependents (Ambystoma laterale – jeffersonianum). Over four years (2015-2018), 1018 juveniles (612 bisexual, 406 unisexual) were marked and 192 (19%) were recaptured at least once. Total captures varied widely between years, with the highest number of captures (88% of all individuals) occurring in 2017. Cormack-Jolly-Seber estimates of daily apparent survival were low in all years (0.76-0.95) but was higher for unisexuals than bisexuals. The majority of juveniles (71%) did not disperse further than 10-40 m after which movement appeared to cease. While most juveniles remained close to their natal pond, at least 2% of juveniles in 2017 travelled further than 100 m. Dispersal orientation varied by year and there was no difference in either dispersal orientation or distance between bisexual and unisexual individuals. This work is the first to estimate and compare juvenile survival and dispersal of sympatric A. jeffersonianum and A. laterale – jeffersonianum individuals, the results of which help inform population viability assessment and increase our understanding of juvenile dispersal dynamics and habitat use.

Estimating critical habitat based on year-round movements of the endangered Jefferson Salamander (Ambystoma jeffersonianum) and their unisexual dependents

Habitat protection is a key component of endangered species conservation, but critical habitat designations are often based on limited data or habitat use during only a portion of a species’ life cycle. Protected habitat around breeding pools for the endangered Jefferson Salamander (Ambystoma jeffersonianum (Green, 1827)) and their unisexual dependents (Ambystoma laterale – (2) jeffersonianum) is based upon limited movement data from primarily spring and summer seasons. Furthermore, despite their treatment as distinct species under Canada’s Species at Risk Act, differences in habitat use have not been directly compared in areas where they co-occur. We used radiotelemetry to track A. jeffersonianum (JJ) and A. laterale – jeffersonianum (LJJ and LJJJ) during fall migrations to overwintering sites. We used these data and summarized available movement data from past studies that tracked movements in other periods of the annual cycle to estimate year-round critical habitat. Ambystoma jeffersonianum travelled significantly longer distances to overwintering locations than unisexuals. Individuals were more likely to overwinter next to a similar genomotype individual than not. Critical habitat encompassing the entire annual cycle of A. jeffersonianum extends up to 400–450 m from breeding ponds indicating existing regulatory habitat protections in Canada do not currently protect sufficient habitat.

Landscape and management factors influence the occupancy dynamics of sympatric salamanders in an urban preserve system

Conserving amphibian populations living in urban areas is challenging due to a lack of information about urban amphibian natural history, ecology, and responses to habitat management. To address these knowledge gaps, we used 10 years of monitoring data to investigate patterns of occupancy, detectability, and population turnover for sympatric Ambystoma laterale (Blue-spotted Salamanders) and A. tigrinum (Eastern Tiger Salamanders; hereafter Tiger Salamanders) inhabiting 26 suburban preserves in the third largest metropolitan area in the United States, Chicago. From 2009 to 2018 we conducted 2181 artificial cover object surveys at 158 randomly distributed monitoring points and detected Blue-spotted Salamanders 375 times and Tiger Salamanders 85 times. We constructed dynamic occupancy models and used an information theoretic approach to rank a priori candidate models containing landscape, survey, and management covariates. Blue-spotted Salamander occupancy was more than twice as high as Tiger Salamander occupancy. Detection probability for both species was substantially <1 and was influenced by both survey and landscape covariates. Prescribed fire was an important predictor of colonization for Blue-spotted Salamanders and both species exhibited higher rates of colonization at sites near breeding wetlands. Overall rates of turnover were low for both species. Our results reveal that salamander populations can persist in highly fragmented urban preserve systems. We recommend that urban land managers maintain a mosaic of forests and wetlands and consider the impacts of habitat management on non-target species (such as salamanders).

Post-Breeding Migration and Habitat of Unisexual Salamanders in Maine, USA

Abstract The behavioral phenotypes of hybrids vary in degree of similarity to their parent species. Unisexual salamanders (Ambystoma laterale sp.), the result of ancient hybridization, contain nuclear DNA of multiple sperm-host species whose habitat preferences differ from one another. We radio tracked unisexual salamanders from four vernal pools to quantify migration distances and post-breeding habitat selection and compared these to published accounts for Blue-Spotted Salamanders (A. laterale) and Jefferson Salamanders (Ambystoma jeffersonianum). Unisexual salamanders used sites with higher numbers of small mammal burrows, lower substrate temperatures, and lower cover by forest floor vegetation than available sites, similar to the sperm-hosts. Unisexual salamanders also migrated distances within the range reported for these sperm-hosts. Even so, individual migration distances were context specific. We implore managers to use caution when designating management zones around breeding pools by considering ...

Influence of genome and bio-ecology on the prevalence of genome exchange in unisexuals of the Ambystoma complex

BackgroundUnisexuals of the blue-spotted salamander complex are thought to reproduce by kleptogenesis. Genome exchanges associated with this sperm-dependent mode of reproduction are expected to result in a higher genetic variation and multiple ploidy levels compared to clonality. However, the existence of some populations exclusively formed of genetically identical individuals suggests that factors could prevent genome exchanges. This study aimed at assessing the prevalence of genome exchange among unisexuals of the Ambystoma laterale-jeffersonianum complex from 10 sites in the northern part of their distribution.ResultsA total of 235 individuals, including 207 unisexuals, were genotyped using microsatellite loci and AFLP. Unisexual individuals could be sorted in five genetically distinct groups, likely derived from the same paternal A. jeffersonianum haplome. One of these groups exclusively reproduced clonally, even when found in sympatry with lineages presenting signature of genome exchange. Genome exchange was site-dependent for another group. Genome exchange was detected at all sites for the three remaining groups.ConclusionPrevalence of genome exchange appears to be associated with ecological conditions such as availability of effective sperm donors. Intrinsic genomic factors may also affect this process, since different lineages in sympatry present highly variable rate of genome exchange. The coexistence of clonal and genetically diversified lineages opens the door to further research on alternatives to genetic variation.

Has the Eastern Red-backed Salamander (&lt;i&gt;Plethodon cinereus&lt;/i&gt;) Declined in Ontario?

Amphibians are known to be declining around the world. Although often only reported for frogs, declines among salamanders are also known to be occurring. In Ontario, for example, citizen science monitoring indicates the Eastern Red-backed Salamander (Plethodon cinereus) has not been found in the last 20 years in many areas where it was historically known to occur. To test whether this decline is real or the result of lack of recent observations, we conducted targeted surveys in 25 grid squares with no recent records of the species and confirmed the presence of the Eastern Red-backed Salamander in 84% of these squares. It made up 90% (183 of 202) of all six species of salamanders encountered and was also the first salamander species detected in 90% of the squares. The median number of cover objects needed to detect a species was 34 (range 1–145) for Eastern Red-backed Salamanders, 129.5 (range 34–204) for Blue-spotted Salamanders (Ambystoma laterale), and 154 (range 6–187) for Spotted Salamanders (Ambystoma maculatum), and these detection rates differed significantly (H = 9.46, P &lt; 0.01). Our study suggests that Eastern Red-backed Salamanders have not declined. We caution researchers using citizen science data that a lack of sightings of a “cryptic species” does not mean a species has declined.

Survivorship of Ploidy-variable UnisexualAmbystomaSalamanders Across Developmental Stages

Abstract: Populations of unisexual Ambystoma salamanders typically consist of ploidy-variable individuals (diploid through pentaploid) that differ in their proportional representation within the populations. These salamanders reproduce using a method that has been termed kleptogenesis: stealing genetic material from males of compatible bisexual Ambystoma species (e.g., Jefferson Salamanders [A. jeffersonianum] and Blue-spotted Salamanders [A. laterale]). Kleptogenesis can result in ploidy-variable embryos within an egg mass because the unisexual female might or might not incorporate the male genome. Little is known about the survivorship of individuals having different ploidy levels. Triploid individuals are most abundant, indicating that higher ploidy individuals (tetraploids and pentaploids) are either produced more rarely, or suffer higher mortality than triploids. We assessed the frequency of ploidy levels (determined by microsatellite analysis) across four life-history stages over 2 yr: adults, earl...

WOODLAND POND SALAMANDER ABUNDANCE IN RELATION TO FOREST MANAGEMENT AND ENVIRONMENTAL CONDITIONS IN NORTHERN WISCONSIN

Woodland ponds are important landscape features that help sustain populations of amphibians that require this aquatic habitat for successful reproduction. Species abundance patterns often reflect site-specific differences in hydrology, physical characteristics, and surrounding vegetation. Large-scale processes such as changing land cover and environmental conditions are other potential drivers influencing amphibian populations in the Upper Midwest, but little information exists on the combined effects of these factors. We used Blue-spotted (Ambystoma laterale Hallowell) and Spotted Salamander (A. maculatum Shaw) monitoring data collected at the same woodland ponds thirteen years apart to determine if changing environmental conditions and vegetation cover in surrounding landscapes influenced salamander movement phenology and abundance. Four woodland ponds in northern Wisconsin were sampled for salamanders in April 1992-1994 and 2005-2007. While Bluespotted Salamanders were more abundant than Spotted Salamanders in all ponds, there was no change in the numbers of either species over the years. However, peak numbers of Blue-spotted Salamanders occurred 11.7 days earlier (range: 9-14 days) in the 2000s compared to the 1990s; Spotted Salamanders occurred 9.5 days earlier (range: 3 - 13 days). Air and water temperatures (April 13- 24) increased, on average, 4.8 oC and 3.7 oC, respectively, between the decades regardless of pond. There were no discernible changes in canopy openness in surrounding forests between decades that would have warmed the water sooner (i.e., more light penetration). Our finding that salamander breeding phenology can vary by roughly 10 days in Wisconsin contributes to growing evidence that amphibian populations have responded to changing climate conditions by shifting life-cycle events. Managers can use this information to adjust monitoring programs and forest management activities in the surrounding landscape to avoid vulnerable amphibian movement periods. Considering direct and indirect stressors such as changing habitat and environmental conditions simultaneously to better understand trends in space and time can help improve monitoring programs for this taxa, which is at major risk of continued declines.

Spatial arrangement and metrics of freshwater coastal rock pools applied to amphibian conservation

Coastal habitats are an ecotone between aquatic and terrestrial ecosystems. Depressions on volcanic bedrock shores of Lake Superior form small pool habitats that are influenced to various degrees by their spatial context and that relate to differences in mechanisms of disturbance. A total of 71,931 coastal pools were mapped and measured, and amphibian occupants were identified along 48 km of shoreline at Isle Royale National Park, where coastal rock pool habitats were abundant. Generally, mean depth of pools was 0.11 m, with a mean surface area of 0.6 m 2 , although maximum measurements were 1.5 m and 378 m 2 , respectively. Three strongly defined zones occurred, with bedrock near the lake having a low slope and more numerous, smaller, and shallower pools; bedrock near the forest edge had a steeper slope and fewer, larger, and deeper pools; and a median zone occurring between. A single offshore location, Passage Island, had nearly 63% of all pool abundance. Two amphibian species were typical of coastal pools, the chorus frog ( Pseudacris triseriata ) and blue-spotted salamander ( Ambystoma laterale ), while spring peeper ( Pseudacris crucifer ) was uncommon and probably incidental to coastal habitats. These three species were significantly more abundant in mid-shore pools. Four other amphibian species were only rarely detected. Both coastal habitat density and chorus frog abundance were highest at localities directly adjacent to an international shipping lane. As a result of intriguing spatial distributions and potential for impacts from coastal pollution, chorus frog in particular reveals that coastal ecology can be unique from inland contexts and have important management implications at the land–water interface.

Postbreeding Habitat Use of the Rare, Pure-Diploid Blue-spotted Salamander (Ambystoma laterale)

Abstract The pure-diploid Blue-spotted Salamander (Ambystoma laterale) is among the rarest amphibians in northeastern North America, and data on its ecology are sparse. We assessed the movement ecology and terrestrial habitat use of A. laterale using radio- and passive integrated transponder (PIT) tag- telemetry. We radio-tracked 22 A. laterale for a median of 54 days (range 6–126 days) in the spring and summer of 2009 and 2010. Using a modified PIT tag reader, we conducted 34 in situ surveys during the spring and summer of 2009 through 2011, resulting in 42 relocations. We detected salamanders at a median straight-line distance of 67 m (range 7–281 m) from their breeding wetland. The life zone (i.e., critical terrestrial habitat), encompassing 95% of observed salamander movements, extended 152 m from the edge of the breeding wetland. Eighteen radio-tracked salamanders migrated to upland forest, three to a wet meadow, and one to a red maple (Acer rubrum) swamp. Salamanders used upland forest and wet meado...

Development of 31 new microsatellite loci for two mole salamanders (Ambystoma laterale and A. jeffersonianum)

Ambystoma salamanders are amphibians that due to limited dispersal abilities and reliance on wetlands for breeding are susceptible to population declines and local extinctions (Blaustein et al. 2011). Species identification within Ambystoma is especially difficult due to the presence of unisexual Ambystoma that consist of multiple all-female lineages in which clones can have between two and five nuclear genomes from up to five other Ambystoma species (Bogart et al. 2007). The majority of these unisexual Ambystoma are composed of nuclear genomes from two species, A. laterale (Blue Spotted Salamander) and A. jeffersonianum (Jefferson Salamander). We developed species-specific microsatellite markers for these two species as a tool for the identification and investigation of the genetic interactions between sexual and unisexual groups in areas where either sexual species is endangered or of special conservation concern (Ohio, Indiana, and Ontario).

Effect of Sub-Canopy on Habitat Selection in the Blue-spotted Salamander (Ambystoma laterale-jeffersonianum unisexual complex)

Elucidating the mechanisms that influence spatial distribution patterns is vital to understanding how populations persist. We examined distribution in one of the most common salamanders in southeastern Michigan, the Blue-spotted Salamander (Ambystoma laterale-jeffersonianum unisexual complex). Three major tree species dominate the sub-canopy in the study site and form monospecific patches, which may have an effect on the distribution of terrestrial phases of local amphibian species. To examine this, we tested whether adult salamanders are significantly associated negatively or positively with patches of particular tree species. We then examined two potential causal factors: habitat quality, using leaf litter macroinvertebrate biomass as a proxy, and behavioral site choice in the Blue-spotted Salamander. We found that this species is positively associated with patches of red maple and negatively associated with patches of black cherry. We also found that, when presented with a choice, salamanders choose red maple leaf litter over black cherry leaf litter. In the absence of differences in physical leaf litter characteristics between patches of red maple and black cherry, we suggest that the Blue-spotted Salamander may be utilizing chemical cues to select habitat. Our findings imply that salamander populations may be affected not only by habitat loss, but also by changes in forest composition. These results provide evidence for a more complex model than the traditional amphibian metapopulation concept, where even fully forested habitat may form a matrix of optimal and sub-optimal, or even intolerable, patches.

Further Observations of Blue-Spotted Salamanders Near Pinawa, Manitoba

Further Observations of Blue-Spotted Salamanders Near Pinawa, Manitoba

Ontogenetic and individual diet variation in amphibian larvae across an environmental gradient

Summary1. Variation among individuals within size or age classes can have profound effects on community dynamics and food‐web structure. We investigated the potential influence of habitat disturbance on intrapopulation niche variation.2. Amphibians occupy a range of lentic habitats from short‐hydroperiod intermittent ponds to long‐hydroperiod permanent ponds. We quantified ontogenetic diet variation and individual specialisation in wood frog tadpoles (Lithobates sylvaticus) and blue‐spotted salamander larvae (Ambystoma laterale) to investigate the influence of hydroperiod on population niche width across a natural hydroperiod gradient using stable isotope and gut content analyses. In one of the few tests using larval forms, we tested the niche variation hypothesis, which predicts that populations with larger niche widths also have increased individual variation.3. Our results support the niche variation hypothesis, indicating that more generalised populations exhibit higher within‐individual diet variation. We report gradual changes in the relative importance of diet items, decreased dietary overlap and increased trophic position in L. sylvaticus throughout development. A. laterale became more enriched in δ13C and increased in δ15N throughout its larval period. We did not find a relationship between hydroperiod and niche parameters, indicating that niches are conserved across heterogeneous habitats. In contrast to most documented cases, we estimated low levels of individual specialisation in amphibian larvae.4. Amphibians are an important link between aquatic and terrestrial ecosystems, whereby diet shifts can influence food‐web structure by altering energy flow pathways and the trophic position of higher consumers, ultimately changing food‐chain length.

Interactive effects of roads and weather on juvenile amphibian movements

We investigated whether paved roads adjacent to 16 ponds acted as barriers to movements of juvenile wood frogs (Lithobates sylvaticus), green frogs (Lithobates clamitans), mole salamanders (Ambystoma laterale, A. maculatum), and American toads (Anaxyrus americanus) in eastern New Brunswick, Canada. Using pitfall traps and drift fences, we recorded captures of juveniles dispersing away from their natal ponds into forest habitat (pondside fences) or across the road (roadside fences) over two field seasons. To explain variations in abundance of dispersers among sites, we measured several road-associated variables including traffic intensity and roadside habitat structure, pond quality, and weather variables. We estimated the activity patterns (across 4-day periods) and seasonal abundance of juveniles in transit between ponds and terrestrial habitat using generalized linear mixed models. For all groups, activity across 4-day periods increased with either total precipitation or minimum air temperature. However, road-associated variables were also important for some species. Mole salamander activity was lowest next to roads. Wood frog activity increased with minimum air temperature, but the effect was weakest at roadside fences (minimum air temperature × fence position interaction). Seasonal abundance of most groups varied with habitat structure or pond hydroperiod. Green frog abundance decreased with increasing traffic intensity, but abundance was higher at roadside fences than pondside fences. In contrast, wood frog seasonal abundance tended to be lowest at roadside fences. We conclude that road-associated disturbances are detectable at fine temporal scales and that amphibian responses to such variables can be influenced by weather variables.

Varying Responses of Northeastern North American Amphibians to the Chytrid Pathogen Batrachochytrium dendrobatidis

Chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is widespread among amphibians in northeastern North America. It is unknown, however, whether Bd has the potential to cause extensive amphibian mortalities in northeastern North America as have occurred elsewhere. In the laboratory, we exposed seven common northeastern North American amphibian species to Bd to assess the likelihood of population-level effects from the disease. We exposed larval wood frogs (Lithobates sylvaticus) and postmetamorphic frogs of six other species to two different strains of Bd, a northeastern strain (JEL404) and a strain that caused die-offs of amphibians in Panama (JEL423), under ideal in vitro growth conditions for Bd. Exposed American toads (Anaxyrus americanus) all died; thus, this species may be the most likely to die from Bd-caused disease in the wild. Both Bd strains were associated with mortalities of wood frogs, although half the metamorphs survived. The Bd strain from Panama killed metamorphic green frogs (L. clamitans), whereas the northeastern strain did not, which means novel strains of Bd may lead to death even when local strains may not. No mortality was observed in four species (bullfrogs [L. catesbeianus], northern leopard frogs [L. pipiens], spring peepers [Pseudacris crucifer], and blue-spotted salamanders [Ambystoma laterale]) and in some individuals of green frogs and wood frogs that we exposed. This finding suggests these six species may be Bd vectors. Our results show that systematic exposures of amphibian species to Bd in the laboratory may be a good first step in the identification of species susceptible to Bd-caused declines and in directing regional conservation efforts aimed at susceptible species.