SDSU Biologists Discover Several New Trapdoor Spider Species in California

Contact:
Lorena Nava
San Diego State University
(619) 594-3952 office
lnava@mail.sdsu.edu

SAN DIEGO (Thursday, Feb.1, 2007)-- Using both nuclear and mitochondrial DNA sequences, San Diego State University biology professor Marshal Hedin and former SDSU student James Starrett recently discovered several new trapdoor spider species in regions of Northern California.

Photo: SDSU Professor Marshall Hedin discovered five new trapdoor spider species

“The discovery of five distinct species in our study provides novel insight into how we perceive the evolution and diversity of trapdoor spiders in California,” Hedin said. “It also demonstrates how California is a ‘hot spot’ for biological diversity – there are more native plant and animal species here than in any other comparable region in North America.”

The study, co-written with Starrett, an SDSU graduate now conducting Ph.D. research at the University of California, Riverside, was published in the February issue of Molecular Ecology. The National Science Foundation funded the research, including an NSF Research Experience for Undergraduates grant, which supports active research participation by undergraduate students and which funded Starrett’s work.

Hedin, who specializes in evolutionary biology and arachnid systematics, focused on the diversity and biogeographical history of the mygalomorph spider Antrodiaetus riversi for this study. Mygalomorph spiders include tarantulas, trapdoor spiders and purseweb spiders and exhibit remarkable levels of species diversity in California.

“We've discovered that this single species (A. riversi) is actually a complex of genetically divergent species,” Hedin said. “No one has looked closely at how the different species differ from one another functionally, simply because all populations were treated as ‘one thing’ in the past.”

Photo: A turrett houses the trapdoor spider

The trapdoors spiders examined in the study were chosen based on several factors, including their long life span, with many living longer than 10 years, their sedentary lifestyle and their specialized habitat. Starrett and Hedin collected samples from 32 sites in northern California, including the northern coast, the Central Valley, the Bay Area, near Monterey and in the Sierra Nevada mountains.

“When we analyzed the samples, we were surprised to find deep, geographically distinct differences,” Hedin said. “We discovered four clades, or groups of organisms that share a common ancestor, and we named them based upon where they were found.” 
Conservation biologists may be interested in the Monterey population, as researchers found it to be highly unique in its restricted range in the immediate vicinity of Monterey, Hedin said.

Hedin and Starrett predict that further DNA-based studies of poorly known animal groups from California will continue to reveal previously unrecognized species diversity. 

Hedin suggested that “study of this diversity will allow researchers to piece together a complete picture of the history and evolutionary diversity that makes California such a rich and special place."

Photo: SDSU graduate James Starrett attempts to capture a spider for his study.

San Diego State University is the oldest and largest higher education institution in the San Diego region. Since it was founded in 1897, the university has grown to offer bachelors degrees in 81 areas, masters degrees in 73 areas and doctorates in 16 areas. SDSUs more than 34,000 students participate in an academic curriculum distinguished by direct contact with faculty and an increasing international emphasis that prepares them for a global future. For more information, visit www.sdsu.edu.

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