Genotypic and Phenotypic Diversity in Endangered Populations of the Callippe Silverspot Butterfly (Speyeria callippe) in the Greater Bay Area

Grave Covell

Speyeria callippe callippe is on the federal endangered species list and is restricted to populations surrounding the heavily urbanized Bay Area. Destruction of appropriate habitat that includes adult and larval food resources has caused extinctions of many populations in the hills of the San Francisco Bay Area. Despite its endangered status no research into the size or genetic diversity of the remaining populations has been done. This is critical information for management because current populations may be suffering reduced genetic variation and reduced gene flow that can lead to further extinctions. One problem that has hampered traditional mark-recapture studies for estimating population sizes is that two other subspecies of Speyeria are present in the Bay Area (S.c. comstocki and S.c. liliana). These subspecies are difficult to distinguish because their color patterns broadly overlap. Thus, our study examined two questions: 1) do S. callippe populations in the Bay Area show any signs of reduced genetic diversity or gene flow? And 2) do color pattern traits used in describing subspecies correlate with genetic diversity? To answer these questions we analysed 884 bp of mitochondrial DNA for 191 individuals from nine populations, and scored each specimen for two wing pattern traits. Our results indicated that 1) there is striking genetic differentiation among S. callippe populations in the Bay Area, 2) the main endangered species population has no variation in the analyzed gene, and 3) four mtDNA haplogroups were identified that only weakly correlate with the three subspecies.