Predicting long-term population viability for an imperiled salamander under future climate changes

Abstract

Climate change has a variety of effects on amphibians breeding in ephemeral wetlands, altering both demographic processes and underlying environmental conditions. These changes can threaten the long-term viability of populations and limit the effectiveness of ongoing management programs. The reticulated flatwoods salamander (Ambystoma bishopi) is an endangered amphibian endemic to the southeastern United States, an area experiencing shifts in temperature and precipitation patterns. To examine the response of flatwoods salamander populations to climate change, we incorporated climate projections into a stochastic integral projection model developed using 10 years (2010–2020) of data from 2 breeding sites. We examined 6 climate change scenarios, combining 3 general circulation models (GCMs) under 2 emission scenarios to estimate extinction probability from 2030–2100. Using just wetland hydroperiod as a metric of reproductive success, 1 and 2 out of 6 climate scenarios indicated a high probability of local extinction in the 2 wetland sites (probability of quasi-extinction >90%). When accounting for potential interactions between salamander phenology and wetland hydrology that can reduce breeding success, extinction probability increased from near 0 to above 25% in 2 and 3 scenarios across the 2 populations. This is the first study combining a stochastic integral projection model with GCM-derived climate forecasts to predict population viability in an endangered amphibian, and this methodology is broadly applicable to other imperiled amphibian species. Overall, our results indicate that there is a relatively high probability that these 2 flatwoods salamander populations will go extinct by the end of the century under some climate scenarios, mostly driven by severe droughts and repeated reproductive failure. Conservation and management actions should focus on maintaining high adult survival, managing habitat to extend wetland hydroperiod, and promoting clusters of breeding wetlands that can undergo natural extinction and colonization dynamics, especially when larger, longer hydroperiod wetlands are closely associated with multiple small wetlands.