Niche differentiation in the bank vole: Maxent input and output data

Species-level environmental niche modelling has been crucial in efforts to
understand how species respond to climate variation and change. However,
species often exhibit local adaptation and intraspecific niche differences
that may be important to consider in predicting responses to climate.
Here, we explore if phylogeographic lineages of the bank vole originating
from different glacial refugia (Carpathian, Western, Eastern and Southern)
show niche differentiation, which would suggest a role for local
adaptation in biogeography of this widespread Eurasian small mammal. We
first model the environmental requirements for the bank vole using
species-wide occurrences (210 filtered records) and then model each
lineage separately to examine niche overlap and test for niche
differentiation in geographical and environmental space. We then use the
models to estimate past [Last Glacial Maximum (LGM) and mid-Holocene]
habitat suitability to compare to previously hypothesized glacial refugia
for this species. Environmental niches are statistically significantly
different from each other for all pairs of lineages in geographical as
well as environmental space and these differences cannot be explained by
habitat availability within their respective ranges. Together with the
inability of most of the lineages to correctly predict the distributions
of other lineages, these result support intraspecific ecological
differentiation in the bank vole. Model projections of habitat suitability
during the LGM support glacial survival of the bank vole in the
Mediterranean region as well as in central and western Europe. Niche
differences between lineages and the resulting spatial segregation of
habitat suitability suggest ecological differentiation has played a role
in determining the present phylogeographic patterns in the bank vole. Our
study illustrates that models pooling lineages within a species may
obscure the potential for different response to climate change among
populations.