A novel method to calculate climatic niche similarity among species with restricted ranges—the case of terrestrial Lycian salamanders

Abstract

Within the framework of the present study we test whether climatic niche similarity can be identified in a monophyletic group of species inhabiting remarkably restricted ranges by pooling presence data of all species into a single concatenated data set and subsequently jackknifing single species. We expect that, when the jackknifed species differs markedly in its climatic niche from all other species, this approach will result in increased niche homogeneity, allowing assessments of niche divergence patterns. To test our novel jackknife approach, we developed species distribution models for all members of Lycian salamanders (genus Lyciasalamandra), native to Turkey and the adjacent Aegean islands using Maxent. Degrees of niche similarity among species were assessed using Schoener’s index. Significance of results was tested using null-models. The degree of niche similarity was generally high among all seven species, with only L. helverseni differing significantly from the others. Carstic lime stones providing specific microhabitat features may explain the high degree of niche similarity detected, since the variables with the highest explanative power in our models (i.e. mean temperature, and precipitation of the coldest quarter) corresponded well with salamander natural history observations, supporting the biologically plausibility of the results. We conclude that the jackknife approach presented here for the first time allows testing for niche similarity in species inhabiting restricted ranges and with few species records available. Our results strongly support the view that detailed natural history information and knowledge of microhabitats is crucial when assessing possible climate change impacts on species.