Journal Article

Applying stochastic and Bayesian integral projection modeling to amphibian population viability analysis

Clause, Adam G., Rollins, Hilary B., Trenham, Peter C., Searcy, Christopher A., Messerman, Arianne F., Shaffer, H. Bradley, Gray, Levi N., Krkošek, Martin

2023

Overview

Integral projection models (IPMs) can estimate the population dynamics of species for which both discrete life stages and continuous variables influence demographic rates. Stochastic IPMs for imperiled species, in turn, can facilitate population viability analyses (PVAs) to guide conservation decision-making. Biphasic amphibians are globally distributed, often highly imperiled, and ecologically well suited to the IPM approach. Herein, we present a stochastic size- and stage-structured IPM for a biphasic amphibian, the U.S. federally threatened California tiger salamander (CTS) (Ambystoma californiense). This Bayesian model reveals that CTS population dynamics show greatest elasticity to changes in juvenile and metamorph growth and that populations are likely to experience rapid growth at low density. We integrated this IPM with climatic drivers of CTS demography to develop a PVA and examined CTS extinction risk under the primary threats of habitat loss and climate change. The PVA indicated that long-term viability is possible with surprisingly high (20%–50%) terrestrial mortality but simultaneously identified likely minimum terrestrial buffer requirements of 600–1000 m while accounting for numerous parameter uncertainties through the Bayesian framework. These analyses underscore the value of stochastic and Bayesian IPMs for understanding both climate-dependent taxa and those with cryptic life histories (e.g., biphasic amphibians) in service of ecological discovery and biodiversity conservation. In addition to providing guidance for CTS recovery, the contributed IPM and PVA supply a framework for applying these tools to investigations of ecologically similar species.

• Publisher: John Wiley and Sons, Inc,John Wiley & Sons, Inc,Ecological Society of America
• Subject: Ambystoma californiense / Amphibians / Animals / Bayes Theorem / Bayesian analysis / Bayesian theory / Biodiversity / Biodiversity conservation / body size / Climate change / Conservation / conservation buffers / Continuity (mathematics) / Decision analysis / Decision making / Demographic variables / Demography / density dependence / Ecosystem / environmental stochasticity / extinction / habitat destruction / Habitat loss / juveniles / life stage / Mathematical models / mortality / Parameter uncertainty / pond‐breeding amphibian / Population / Population Dynamics / Population viability / population viability analysis / Projection model / Reptiles & amphibians / risk / Species extinction / Threatened species / viability / Wildlife conservation