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.

LLU Discipline





Graduate School

First Advisor

Ronald Carter

Second Advisor

L. Lee Grismer

Third Advisor

William Hayes

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Xantusiidae -- California, Southern; Phylogeography; Phylogeny.



Page Count

v; 53

Digital Format


Digital Publisher

Loma Linda University Libraries

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This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


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Loma Linda University. Del E. Webb Memorial Library. University Archives

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