Population Status and Conservation of the Black Toad, Bufo Exsul

Murphy, John F.; Simandle, Eric T.; Becker, Dawne E.

doi:10.1894/0038-4909(2003)048<0054:psacot>2.0.co;2

Cited by 8 publications

(18 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The estimates of effective population size are lower for the two populations showing greatest evidence for having undergone a population bottleneck, Bog Mound and Antelope springs ( N e = 7–16). Although they are somewhat higher in Corral and Buckhorn springs ( N e = 23–30), these estimates are very small for naturally occurring populations and are two orders of magnitude lower than census size estimates (Sherman 1980; Murphy et al. 2003), which range from ∼5000 to 17 000 adults at Corral Springs.…”

Section: Discussionmentioning

confidence: 66%

“…Low effective population sizes can result from demographic bottlenecks, substantial reproductive skew among breeding adults, or uneven sex ratios (Beebee 2005). During field surveys, Murphy et al. (2003) found that almost two‐thirds of adult B. exsul at Corral Springs were female, and this may contribute to the very low effective population sizes in this species.…”

Section: Discussionmentioning

confidence: 99%

“…I parameterized the TPM used in m‐ratio by assigning an 80% rate of single‐step mutations and a mean of 2.8 repeats to the size change of multiple‐step mutations, based upon empirical estimates of microsatellite evolution (Garza & Williamson 2001), and used a mutation rate of 5 × 10 −4 (Goldstein & Schlotterer 1999). Census size estimates in black toads range from 5000 to 17 000 individuals per spring (Sherman 1980; Murphy et al. 2003).…”

Section: Methodsmentioning

confidence: 99%

“…Bufo exsul inhabits four spring systems in Deep Springs Valley, a high desert basin in the Inyo‐White Mountains of California, and has never been reported more than 12 m from any water source (Schuierer 1961; Lannoo 2005). Three of the four springs border Deep Springs Lake, a seasonal salt lake, and all four are separated from each other by arid desert scrub habitat (Schuierer 1961, 1962; Murphy et al. 2003).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fine‐scale population structure in a desert amphibian: landscape genetics of the black toad (Bufo exsul)

Wang

2009

Molecular Ecology

View full text Add to dashboard Cite

Environmental variables can strongly influence a variety of intra- and inter-population processes, including demography, population structure and gene flow. When environmental conditions are particularly harsh for a certain species, investigating these effects is important to understanding how populations persist under difficult conditions. Furthermore, species inhabiting challenging environments present excellent opportunities to examine the effects of complex landscapes on population processes because these effects will often be more pronounced. In this study, I use 16 microsatellite loci to examine population structure, gene flow and demographic history in the black toad, Bufo exsul, which has one of the most restricted natural ranges of any amphibian. Bufo exsul inhabits four springs in the Deep Springs Valley high desert basin and has never been observed more than several meters from any source of water. My results reveal limited gene flow and moderately high levels of population structure (F(ST) = 0.051-0.063) between all but the two closest springs. I found that the geographic distance across the arid scrub habitat between springs is significantly correlated with genetic structure when distance accounts for topography and barriers to dispersal. I also found very low effective population sizes (N(e) = 7-30) and substantial evidence for historical population bottlenecks in all four populations. Together, these results suggest that the desert landscape and B. exsul's high habitat specificity contribute significantly to population structure and demography in this species and emphasize the importance of considering behavioural and landscape data in conservation genetic studies of natural systems.

show abstract

Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fine‐scale population structure in a desert amphibian: landscape genetics of the black toad (Bufo exsul)

Wang

2009

Molecular Ecology

View full text Add to dashboard Cite

show abstract

“…At present, this species does not seem to be highly threatened, being classified as VU because of its small area of occupancy. However, its current (relatively favorable) threat status is ensured by habitat protection, including a fenced area to exclude livestock and manipulation of irrigation water to minimize impacts on breeding toads, eggs and larvae (Murphy et al 2003). While this protection is so far proving adequate, the species would likely become more seriously threatened if such measures were removed.…”

Section: Recommendation: Continue Ongoing Effortsmentioning

confidence: 99%

Identification and gap analysis of key biodiversity areas: targets for comprehensive protected area systems

Langhammer¹

2007

157

View full text Add to dashboard Cite

Hot, wet and rare: modelling the occupancy dynamics of the narrowly distributed Dixie Valley toad

2022

View full text Add to dashboard Cite

Context. Small population sizes and no possibility of metapopulation rescue put narrowly distributed endemic species under elevated risk of extinction from anthropogenic change. Desert spring wetlands host many endemic species that require aquatic habitat and are isolated by the surrounding xeric terrestrial habitat. Aims. We sought to model the occupancy dynamics of the Dixie Valley toad (Anaxyrus williamsi), a recently described species endemic to a small desert spring wetland complex in Nevada, USA. Methods. We divided the species' range into 20 m × 20 m cells and surveyed for Dixie Valley toads at 60 cells during six primary periods from 2018 to 2021, following an occupancy study design. We analysed our survey data by using a multi-state dynamic occupancy model to estimate the probability of adult occurrence, colonisation, site survival, and larval occurrence and the relationship of each to environmental covariates. Key results. The detection probabilities of adult and larval toads were affected by survey length and time of day. Adult Dixie Valley toads were widely distributed, with detections in 75% of surveyed cells at some point during the 3-year study, whereas larvae were observed only in 20% of cells during the study. Dixie Valley toad larvae were more likely to occur in cells far from spring heads with a high coverage of surface water, low emergent vegetation cover, and water temperatures between 20°C and 28°C. Adult toads were more likely to occur in cells with a greater coverage of surface water and water depth >10 cm. Cells with more emergent vegetation cover and surface water were more likely to be colonised by adult toads. Conclusions. Our results showed that Dixie Valley toads are highly dependent on surface water in both spring and autumn. Adults and larvae require different environmental conditions, with larvae occurring farther from spring heads and in fewer cells. Implications. Disturbances to the hydrology of the desert spring wetlands in Dixie Valley could threaten the persistence of this narrowly distributed toad.

show abstract

Population Status and Conservation of the Black Toad, Bufo Exsul

Cited by 8 publications

References 3 publications

Fine‐scale population structure in a desert amphibian: landscape genetics of the black toad (Bufo exsul)

Fine‐scale population structure in a desert amphibian: landscape genetics of the black toad (Bufo exsul)

Identification and gap analysis of key biodiversity areas: targets for comprehensive protected area systems

Hot, wet and rare: modelling the occupancy dynamics of the narrowly distributed Dixie Valley toad

Contact Info

Product

Resources

About