Estimating the Genetic Variability and Spatial Structure of Wood Frogs in Rocky Mountain National Park
Wood frog embryos in an icy wetland. Photo by Mark Roth, USGS Gallery.
We investigated genetic structure and levels of genetic diversity in wood frogs in Rocky Mountain National Park, where recent disturbances have altered hydrologic processes and fragmented amphibian habitat. We estimated migration rates among subpopulations, tested for a pattern of isolation-by-distance, and looked for evidence of a recent population bottleneck. We found two subpopulations corresponding to northern and southern areas. Estimates of migration rates among the two subpopulations were low, as were estimates of genetic variability. Conservation of the population of wood frogs may be improved by increasing the spatial distribution of the population and improving gene flow between the subpopulations. Construction or restoration of wetlands in the landscape between the clusters has the potential to address each of these objectives. This research was in collaboration with Colorado State University
Modeling habitat connectivity to inform translocation efforts: a case study with the Chiricahua leopard frog
Jarchow, C.J., B.R. Hossack, B.H. Sigafus, C.R. Schwalbe, and E. Muths
Though a third of amphibian species worldwide are thought to be imperiled, existing assessments simply categorize extinction risk, providing little information on the rate of population losses. We conducted the first analysis of the rate of change in the probability that amphibians occupy ponds and other comparable habitat features across the United States. We found that overall occupancy by amphibians declined 3.7% annually from 2002 to 2011. Species that are Red-listed by the International Union for Conservation of Nature (IUCN) declined an average of 11.6% annually. All subsets of data examined had a declining trend including species in the IUCN Least Concern category. This analysis suggests that amphibian declines may be more widespread and severe than previously realized.
The state of amphibians in the United States
Muths, E., M.J. Adams, E.H.C. Grant, D. Miller, P.S. Corn, and L.C. Ball
More than 25 years ago, scientists began to identify unexplained declines in amphibian populations around the world. Much has been learned since then, but amphibian declines have not abated and the interactions among the various threats to amphibians are not clear. Amphibian decline is a problem of local, national, and international scope that can affect ecosystem function, biodiversity, and commerce. This fact sheet provides a snapshot of the state of the amphibians and introduces examples to illustrate the range of issues in the United States.
Effects of hydroperiod duration on survival, developmental rate, and size at metamorphosis in Boreal Chorus Frog tadpoles (Pseudacris maculata)
Equivalence testing and corresponding confidence interval estimates are used to provide more enlightened statistical statements about parameter estimates by relating them to intervals of effect sizes deemed to be of scientific or practical importance rather than just to an effect size of zero. Equivalence tests and confidence interval estimates are based on a null hypothesis that a parameter estimate is either outside (inequivalence hypothesis) or inside (equivalence hypothesis) an equivalence region, depending on the question of interest and assignment of risk...
Amphibian Research and Monitoring Initiative: Rocky Mountain Region
The Department of Interior's Amphibian Research and Monitoring Initiative (ARMI) is designed to determine where populations of amphibians are present; to monitor specific sentinel populations and to investigate potential causes of decline and deformity. The Rocky Mountain Region of ARMI encompasses Montana, Wyoming, Colorado, and New Mexico. Two USGS-Biological Resource Division Centers initiate and develop ARMI projects in this region.
Survey and assessment of amphibian populations in Rocky Mountain National Park