Search Results

Photo of a [I]Batrachoseps major[/I] being screened for fungal disease at Los Angeles World Airways.
Photo of a Batrachoseps major being screened for fungal disease at Los Angeles World Airways.
Robert Fisher, U.S. Geological Survey
Papers & Reports Slender salamanders (genus Batrachoseps) reveal Southern California to be a center for the diversification, persistence, and introduction of salamander lineages
Click to copy
Authors: Jockusch E L, Hansen R W, Fisher R N, Wake D B | Date: 2020-08-14 | Outlet: PeerJ 8:e9599 | Format: .PDF
Background. The southern California biodiversity hotspot has had a complex geological history, with both plate tectonic forces and sea level changes repeatedly reconfiguring the region, and likely driving both lineage splittings and extinctions. Here we investigate patterns of genetic divergence in two species of slender salamanders (Plethodontidae: Batrachoseps) in this region. The complex geological history in combination with several organismal traits led us to predict that these species harbor multiple ancient mitochondrial lineages endemic to southern California. These species belong to a clade characterized by fine-scale mitochondrial structure, which has been shown to track ancient splits. Both focal species, Batrachoseps major and B. nigriventris, are relatively widely distributed in southern California, and estimated to have persisted there across millions of years. Recently several extralimital populations of Batrachoseps were found in the San Joaquin Valley of California, a former desert area that has been extensively modified for agriculture. The origins of these populations are unknown, but based on morphology, they are hypothesized to result from human-mediated introductions of B. major.
Methods. We sequenced the mitochondrial gene cytochrome b from a geographically comprehensive sampling of the mitochondrial lineages of B. major and B. nigriventris that are endemic to southern California. We used phylogenetic analyses to characterize phylogeographic structure and identify mitochondrial contact zones. We also included the San Joaquin Valley samples to test whether they resulted from introductions. We used a bootstrap resampling approach to compare the strength of isolation-by-distance in both Batrachoseps species and four other salamander species with which they co-occur in southern California.
Results. The northern lineage of B. major harbors at least eight deeply differentiated, geographically cohesive mitochondrial subclades. We identify geographic contact between many of these mtDNA lineages and some biogeographic features that are concordant with lineage boundaries. Batrachoseps nigriventris also has multiple deeply differentiated clades within the region. Comparative analyses highlight the smaller spatial scales over which mitochondrial divergence accumulates in Batrachoseps relative to most other salamander species in southern California. The extralimital populations of Batrachoseps from the San Joaquin Valley are assigned to B. major based on their mitochondrial haplotypes and are shown to result from at least two independent introductions from different source populations. We also suggest that B. major on Catalina Island, where it is considered native, may be the result of an introduction. Some of the same traits that facilitate the build-up of deep phylogeographic structure in Batrachoseps likely also contribute to its propensity for introductions, and we anticipate that additional introduced populations will be discovered.
A Cuban Treefrog ([I]Osteopilus septentrionalis[/I]) with striking green coloration
A Cuban Treefrog (Osteopilus septentrionalis) with striking green coloration
Brad M. Gloriso
Papers & Reports OSTEOPILUS SEPTENTRIONALIS (Cuban Treefrog)
Click to copy
Authors: Glorioso BM, Vanbergen P, Roy J, Walter M, Leonpacher L, Freistak M | Date: 2018 | Outlet: Herpetological Review 49(1):70-71 | Format: .PDF
A note on the geographic distribution of the Cuban Treefrog (Osteopilus septentrionalis), describing new parish records in East Baton Rouge Parish and Lafayette Parish.
Hatchling western pond turtle found in the stomach of an invasive bullfrog in the San Luis Rey River, San Diego Co., CA
Hatchling western pond turtle found in the stomach of an invasive bullfrog in the San Luis Rey River, San Diego Co., CA
U.S. Geological Survey
Papers & Reports Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles
Click to copy
Authors: Nicholson E G, Manzo S, Devereux Z, Morgan T, Fisher R N, Brown C W, Dagit R, Scott P A, Shaffer H B | Date: 2020-06-12 | Outlet: PeerJ 8:e9248 DOI 10.7717/peerj.9248 | Format: .PDF
The western pond turtle (WPT), recently separated into two paripatrically distributed species (Emys pallida and Emys marmorata), is experiencing significant reductions in its range and population size. In addition to habitat loss, two potential causes of decline are female-biased road mortality and high juvenile mortality from non-native predatory bullfrogs (Rana catesbeiana). However, quantitative analyses of these threats have never been conducted for either species of WPT. We used a combination of historical museum samples and published and unpublished field studies shared with us through personal communications with WPT field researchers (B Shaffer, P Scott, R Fisher, C Brown, R Dagit, L Patterson, T Engstrom, 2019, personal communications) to quantify the effect of roads and bullfrogs on WPT populations along the west coast of the United States. Both species of WPT shift toward increasingly male biased museum collections over the last century, a trend consistent with increasing, female-biased road mortality. Recent WPT population studies revealed that road density and proximity were significantly associated with increasingly male-biased sex ratios, further suggesting female-biased road mortality. The mean body size of museum collections of E. marmorata, but not E. pallida, has increased over the last 100 years, consistent with reduced recruitment and aging populations that could be driven by invasive predators. Contemporary WPT population sites that co-occur with bullfrogs had significantly greater average body sizes than population sites without bullfrogs, suggesting strong bullfrog predation on small WPT hatchlings and juveniles. Overall, our findings indicate that both species of WPT face demographic challenges which would have been difficult to document without the use of both historical data from natural history collections and contemporary demographic field data. Although correlational, our analyses suggest that female-biased road mortality and predation on small turtles by non-native bullfrogs are occurring, and that conservation strategies reducing both may be important for WPT recovery.
A young Cuban Treefrog ([I]Osteopilus septentrionalis[/I]) on a palmetto frond
A young Cuban Treefrog (Osteopilus septentrionalis) on a palmetto frond
Brad M. Glorioso
Papers & Reports OSTEOPILUS SEPTENTRIONALIS (Cuban Treefrog)
Click to copy
Authors: Glorioso BM, Steece AP, Lemann ZK, Lazare R, Beck JW | Date: 2016 | Outlet: Herpetological Review 47(2):249 | Format: .PDF
A note on the geographic distribution of the Cuban Treefrog (Osteopilus septentrionalis), describing new parish records in St. Tammany Parish and Orleans Parish.
Cuban Treefrog ([I]Osteopilus septentrionalis[/I]) pictured as found resting on the trunk of a palm
Cuban Treefrog (Osteopilus septentrionalis) pictured as found resting on the trunk of a palm
Brad M. Glorioso
Papers & Reports OSTEOPILUS SEPTENTRIONALIS (Cuban Treefrog)
Click to copy
Authors: Glorioso BM, Macedo K, Maldonado BR, Hillard CJ, Morenc IN, Grimes ES | Date: 2018 | Outlet: Herpetological Review 49(4):709 | Format: .PDF
A note on the geographic distribution of the Cuban Treefrog (Osteopilus septentrionalis), describing a new parish record and probable establishment in St. Charles Parish.

Papers & Reports Survival estimates for the invasive American Bullfrog
Click to copy
Authors: Howell PE, Muths E, Sigafus BH, Hossack BR | Outlet: Amphibia-Reptilia
We used five years of capture mark-recapture data to estimate annual apparent survival of post-metamorphic bullfrogs in a population on the Buenos Aires National Wildlife Refuge in their invaded range in Arizona, U.S.A.

Papers & Reports A statistical forecasting approach to metapopulation viability analysis
Click to copy
Authors: Howell PE, Hossack BR, Muths E, Sigafus BH, Chenevert-Steffler A, Chandler RB | Date: 2020 | Outlet: Ecological Applications 2020:e02038
Conservation of at-risk species is aided by reliable forecasts of the consequences of environmental change and management actions on population viability. Forecasts from conventional population viability analysis (PVA) are made using a two-step procedure in which parameters are estimated, or elicited from expert opinion, and then plugged into a stochastic population model without accounting for parameter uncertainty. Recently-developed statistical PVAs differ because forecasts are made conditional on models that are fitted to empirical data. The statistical forecasting approach allows for uncertainty about parameters, but it has rarely been applied in metapopulation contexts where spatially-explicit inference is needed about colonization and extinction dynamics and other forms of stochasticity that influence metapopulation viability. We conducted a statistical metapopulation viability analysis (MPVA) using 11 years of data on the federally-threatened Chiricahua leopard frog to forecast responses to landscape heterogeneity, drought, environmental stochasticity, and management. We evaluated several future environmental scenarios and pond restoration options designed to reduce extinction risk. Forecasts over a 50-yr time horizon indicated that metapopulation extinction risk was <8% for all scenarios, but uncertainty was high. Without pond restoration, extinction risk is forecasted to be 5.6% (95% CI: 0?60%) by year 2060. Restoring six ponds by increasing hydroperiod reduced extinction risk to 1.0% (0 ? 11%) in year 2060. We found little evidence that drought influences metapopulation viability when managers have the ability to maintain ponds that hold water throughout the year and are free of invasive species. Our study illustrates the utility of the spatially explicit statistical forecasting approach to MPVA in conservation planning efforts.

B Sigafus
Click to copy
Authors: Howell P, Sigafus B, Hossack B, Muths E | Outlet: Southwestern Naturalist 64:69-72
Invasive species are a major threat to the persistence of native species, particularly in systems where ephemeral aquatic habitats have been converted to or replaced by permanent water and predators such as fish have been introduced. Within the Altar Valley, Arizona, USA, the invasive American bullfrog (Lithobates [=Rana] catesbeianus) has been successfully eradicated to help recover Chiricahua leopard frogs (Lithobates chiricahuensis). However, other non-native predators including sunfish (Lepomis spp) are present in some permanent water bodies. During four consecutive years (2014-2017) we detected both the federally-threatened Chiricahua leopard frog and sunfish at one permanent water body in the Altar Valley. This suggests that despite the potential negative effect of predatory fish on amphibians, there may be conditions where the Chiricahua leopard frog may be able to co-occur with this non-native predator. A better understanding of rare situations of co-occurrence with non-native predators may contribute to our understanding of why co-occurrence happens in some but not all systems and whether conservation strategies can be developed in situations where complete eradication of non-native predators is infeasible.

Papers & Reports The relative efficiency of native and non-native aquatic species as predators of potential disease vectors: Invasive crayfish enhance the survival of mosquitoes
Click to copy
Authors: Bucciarelli G, Suh D, Davis A, Sharpton D, Roberts D, Shaffer HB, Fisher RN, Kats L | Date: 2018-08-06 | Outlet: Conservation Biology | Format: .PDF
The introductions of non-native predators often reduce biodiversity and affect natural predator-prey relationships. However, non-native predators may increase the abundance of potential disease vectors (e.g. mosquitoes) indirectly through competition or predation cascades. The Santa Monica
Mountains, situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of non-native species. We examined the effect that non-native crayfish (Procambarus clarkii) have on an existing native predator, dragonfly nymphs (Aeshna sp.) and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared to native dragonfly nymphs as well as a reduced efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient mosquito predators compared to crayfish and dragonfly
nymphs suffered reduced efficiency in the presence of crayfish. Analyses of field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly
nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency, and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.
Endangered fish in endangered frog habitat with several parasites from the pet trade.
Endangered fish in endangered frog habitat with several parasites from the pet trade.
Papers & Reports Introduced parasites of freshwater fish in southern California, U.S.A.
Click to copy
Authors: Kuperman BI, Matey VE, Warburton ML, Fisher RN | Date: 2002 | Outlet: pp. 407-411 in: Proceedings of the 10th International Congress of Parasitology - ICOPA X. Monduzzi Editore S.p.A. - MEDIMOND Inc., Bologna, Italy. 660 pp. | Format: .PDF