Desert Researcher Magazine Issue 1

JUMPING SPIDERS REVEAL A WEB OF CONNECTEDNESS BETWEEN DESERT OASES

By Susana Rinderle As part of the Mojave drainage basin, Anza-Borrego Desert State Park has undergone multiple dramatic ecological shifts over the eons.

By turns, it's been inland sea, desert, An adult Habronattus tarsalis male riparian habitat, and from Anza-Borrego Desert State Park desert again. It's therefore a natural lab for studying evolutionary dynamics in animals due to the natural isolation that occurs when a group of organisms is isolated by its ecosystem – into desert oases.

Brendan Rajah-Boyer, MS, MEd and his colleagues at the Hedin Lab at San Diego State University, saw an opportunity to explore these dynamics through a common, yet important group of jumping spiders known as the Habronattus tarsalis species complex. These spiders have been subject to separation and isolation over space and time by the appearance and disappearance of bodies of water in the desert. This can offer insight not only into the ecological history of Anza-Borrego Desert State Park, but the broader processes of how organisms change and evolve in relation to geography, and when periodically separated into oases by the ebb and flow of water.

Brendan and his colleagues posed two questions: (1) What patterns of diversification can be observed among desert populations of Habronattus tarsalis through genetic, morphological, and geographic data? (2) What genetic lineages exist within the Habronattus tarsalis species complex, and how do these lineages compare to those established in previous literature?

Using genetic and morphological data, the researchers analyzed geographic patterns and esthimated the relationships between different