Endangered Species Recovery Program

Documenting Ecological Change in Time and Space:
The San Joaquin Valley of California

Mammalian Diversification:
From Chromosomes to Phylogeography
University of California, Berkeley. 2005

Patrick A. Kelly, Scott E. Phillips, and Daniel F. Williams
California State University, Stanislaus
Endangered Species Recovery Program
Fresno, CA 93727

Contact for Correspondence:
Patrick Kelly
Email patrickk AT esrp DOT csustan DOT edu

Abstract

The collections and journal archives of the Museum of Vertebrate Zoology (MVZ) at the University of California, Berkeley provide a unique historical database that can be effectively mined using new technologies in genetics and spatial analysis to address serious challenges to the conservation of biological diversity. Through direct reference to the journal entries of Joseph Grinnell and other MVZ biologists of the early 1900s and quantitative analyses of land use changes, we document the tempo and scale of land conversion through the 20th century in the San Joaquin Valley of California. We discuss the impacts of landscape level habitat changes to populations of selected mammal species, most notably the endemic San Joaquin kangaroo rat (Dipodomys nitratoides). Of the three described subspecies, two (Tipton, D. n. nitratoides; Fresno, D. n. exilis) are listed as endangered under the California and U.S. endangered species acts, and the third (short-nosed, D. n. brevinasus) is a California species of special concern. Despite intensive field surveys since 1992, we have been unable to locate a population of Fresno kangaroo rats. This is particularly troubling because analysis of cyt-b DNA sequences, which were developed from museum specimen tissue samples, has shown that the Fresno kangaroo rat is unique and strongly differentiated from the other two subspecies. As the population of California continues to grow, the assault on biological diversity will continue. Analyses of the unique historical data provided by the MVZ and other natural history museums, using the tools of modern molecular genetics and spatial analysis, are essential to addressing these threats and halting or reversing the decline of biological diversity.