Phylogeography of the Night Lizard, Xantusia henshawi, from Southern California

The granite night lizard, Xantusia henshawi, is a highly specialized crevice dwelling lizard found in the Peninsular Ranges of southern California, United States and northern Baja California, Mexico. Generally, little morphological variation is seen in this species over a variety of habitats throughout its range, from elevations near sea level to approximately 2000 meters, and from Mediterranean habitats near the Pacific coast to arid desert habitat in the Colorado Desert of California. One exception is the variation seen in the subspecies X h. gracilis, which differs from X h. henshawi in morphology, allozymes, ecology, and natural history. In this study, intraspecific variation within Xantusia henshawi was analyzed by constructing a genealogy using mitochondrial DNA (mtDNA) sequence data. A 379 base pair region of mtDNA (cytochrome b) was amplified and sequenced for lizards representing 13 localities across their known range in southern California. •The resulting gene tree was compared to the known geologic history of the area comprising the range of this species. Three (3) haploclades were found in the maximum parsimony (MP) analyses that were separated geographically from one another by two major geologic fault zones. It is believed that the unstable nature of habitat surrounding these faults has led to the unique evolution of the three haploclades. Using the evolutionary species concept, results of this study in combination with those of previous studies warrant the elevation of the subspecies Xantusia henshawi gracilis to full species, Xantusia gracilis. This study has assisted in identifying unknown barriers to gene flow that have contributed to the evolution of these species

Phylogeography and Conservation of the Arroyo Toad (Bufo californicus)

The Arroyo Toad (Bufo cakfomicus) is an endangered species found in rivers of southern California, USA and northern Baja California, Mexico. It has experienced population declines throughout its range, as a result of urbanization, hydrologic alterations, and overall habitat loss. As part of the Recovery Plan for this species, it was determined that more research was needed to assist in management decisions. One of those research needs was to better understand the intraspecific genetic variation within the Arroyo Toad. I conducted a range wide genetic study of the Arroyo Toad to uncover lineages and genetic variation among and between all major watersheds. This information is essential to our understanding of the species by providing data to determine recovery units independent of geographic location, delimit metapopulations, identify closely related populations for the potential augmentation of declining or extinct populations, assess dispersal between watersheds, and quantify genetic diversity throughout its distribution. In the course of this project, I also identified a more precise range of the species in Baja California, Mexico, along with the issues and challenges facing its conservation in the poorly known southern portion of its range

Surface-dwelling and Subterranean Invertebrate Fauna Associated with Giant Reed (Arundo donax Poaceae) in Southern California

In the southwestern United States giant reed, Arundo donax, is a nonnative invasive plant that has become widely established in moist places and forms its largest stands along riparian corridors. The most widely reported negative effects include competition with native species, increased rate of transpiration, increased potential for wildfires, and stream channel and bank alteration. However, little is known about the faunal communities associated with this plant and the potential effects on native fauna. In this study, we focused our efforts on determining the faunal composition specifically from rhizome clumps of A. donax from a site located along the Santa Margarita River in San Diego County, California. A total of 2590 individual macro-invertebrates were collected and identified, and represented 64 species from 7 classes. No sensitive species and few vertebrates were found to be in association with A. donax rhizome clumps. Four non-native invertebrate species made up 43% of the total number of captured invertebrates, and 31% of the sampled invertebrates were confirmed as native species. This study demonstrates that A. donax rhizome clumps, and the soils associated with them, provide habitat for several native macro-invertebrate species, but can be dominated by a greater abundance of non-native species