Collaborative Research: Nested Events and Embedded Phylogeographic Structure within the Southern Regional Deserts of North America

University Of Nevada Las Vegas, Las Vegas NV

Investigators

Abstract

A grant has been awarded to Dr. Brett Riddle at the University of Nevada Las Vegas to investigate detailed biogeographic structure in highly arid adapted small mammals (pocket mice, cactus mice, antelope ground squirrels, and Merriam's kangaroo rat) across the Peninsular, Sonoran, and Chihuahuan warm deserts in southwestern North America. These small mammal groups represent a total of 20 species that collectively contain in their genomes a signature of the events (including cycles of geographic isolation and dispersal) that record a long historical association between earth history and biotic diversification. These events include geological tectonic activities instrumental in the origination of regional deserts several millions of years ago, as well as cycles of climatic transformations within the most recent 2 million years (the Pleistocene epoch). We will use DNA sequences from the mitochondrial genome across some 1656 specimens to examine patterns of geographic distribution of evolutionary lineages embedded within these 20 species, and use comparative analytical tools to ask to what extent the diversification of this aridlands mammal biota is attributable to: 1) Neogene vicariant or dispersal events; 2) events associated with pluvial-interpluvial cycles of the Pleistocene; or 3) post-Pleistocene filter-barriers. Our analysis of small mammal biogeographic history will provide a general framework for addressing the evolutionary biology, ecology, and conservation biology of the southern regional deserts of North America and hence be applicable to other biotic groups that demonstrate similar distributional patterns and long-term adaptation within these aridlands. Elucidation of these historically derived patterns and processes of biological diversification will be critical to formulating the understanding of biodiversity required for conservation management planning in these increasingly impacted and threatened desert regions.