The impact of climate change on western Plethodon salamanders' distribution

Abstract

Aim: Given that salamanders have experienced large shifts in their distributions over time, we determined how each species of Plethodon in the Pacific Northwest would respond to climate change. We incorporated several greenhouse scenarios both on a species-by-species basis, and also using phylogenetic groups, with the aim to determine the best course of action in managing land area to conserve diversity in this group.

Location: Pacific Northwest of the United States (northern CA, OR, WA, ID, and MT).

Major taxa studied: Western Plethodon salamanders.

Methods: Species distribution models were estimated using MaxEnt for the current time period and for several future climate scenarios using bioclimatic data layers. We used several methods to quantify the change in habitat suitability over time from the models. We explored aspects of the climate layers to determine whether we can expect a concerted response to climate change due to similarity in ecological niche or independent responses that could be harder to manage.

Results: The distribution of western Plethodon salamander species is strongly influenced by precipitation and less so by temperature. Species responses to climate change resulted in both increases and decreases in predicted suitable habitat, though most species ranges do not contract, especially when taken as a phylogenetic group.

Main conclusions: While some established habitats may become more or less climatically suitable, the overall distribution of species in this group is unlikely to be significantly affected. Clades of Plethodon species are unlikely to be in danger of extirpation despite the possibility that individual species may be threatened as a result of limited distributions. Grouping species into lineages with similar geographic ranges can be a viable method of determining conservation needs. More biotic and dispersal information is needed to determine the true impact that changes in climate will have on the distribution of Plethodon species.

Keywords: Pacific Northwest; Plethodon; climate change; conservation; phylogenetic diversity; species distribution model.

FIGURE 1

Species localities and phylogenetic relationship based on mtDNA. Localities for each species are representative of the distribution for each species. (a) Localities for Plethodon asupak, elongatus, and stormi in CA and OR. (b) Localities for Plethodon idahoensis, larselli, and vandykei in OR, WA, ID, MT, and BC. (c) Localities for Plethodon dunni and vehiculum in OR, WA, and BC. (d) Phylogenetic tree for all PNW Plethodon species. Only the species tips are shown here because all species were monophyletic. For the full tree, see Figure S25

FIGURE 2

Current and future species distribution models. (a) P. elongatus‐stormi‐asupak. (b) P. larselli‐vandykei. (c) P. idahoensis. (d) P. dunni‐vehiculum. The future models depicted here are averaged by year and include CCSM4 and MIROC5 models and both the rpc4.5 and rpc8.5 climate scenarios. All other current and future models can be found as Figures S9–S24