Abstract
Climatic changes can affect species distributions, population abundance,
and evolution. Such organismal responses could be determined by the
amount and quality of available habitats, which can vary independently.
In this study, we assessed changes in habitat quantity and quality
independently to generate explicit predictions of the species’ responses
to climatic changes between Last Glacial Maximum (LGM) and present day.
We built ecological niche models and distribution models for 21 reptile,
mammal, and plant taxa from the Baja California peninsula inhabiting
lowland or highland environments. Geological data suggests the CCSM
global circulation model is a better representation of LGM climate for
the Baja California peninsula. Significant niche divergence was detected
for all clades within species, along with significant differences in the
niche breadth and area of distribution between northern and southern
clades. Most clades showed a reduction in distribution area towards LGM.
Further, niche marginality (used as a measure of habitat quality) was
higher during LGM for most clades, except for northern highland species.
Our results suggest that changes in habitat quantity and quality can
affect organismal response independently. This allows the prediction of
genomic signatures associated with changes in effective population size
and selection pressure that could be explicitly tested to support our
models.