Masters Thesis

A Test of Diagnostic Shell Differences of the Limpets Lottia Conus and Lottia Scabra Identified with a Pcr-based Assay.Identified with a Pcr-based Assay.

Rocky intertidal grazers with similar morphologies and ecological habitats likely compete for food and space. Two intertidal limpets Lottia scabra and L. conus (Gastropoda: Lottidae), are alike in their morphology and overlap in range in southern California. Despite both species being common in this region, little has been published on L. conus since it was described in 1945, thus comparisons of L. conus to L. scabra are minimal. Limited descriptions and dorsal shell plasticity contribute to inaccurate identifications; therefore any potential interactions between these species remain unstudied. I evaluated published and unpublished shell differences between L. conus and L. scabra to determine whether shell diagnoses could distinguish between species. To ensure accurate identifications, species-specific mitochondrial 16S ribosomal DNA primers were successfully designed and applied using a PCR-based assay. Sequencing of selected individuals with nuclear (ITS-1) DNA confirmed that the mitochondrial and nuclear markers agree in their identification. Measured shell features were significantly different between L. conus and L. scabra, however, the range in these characteristics overlapped considerably, which contributed to misidentifications. Qualitative diagnoses also contradicted published distinctions. My results indicated that L. conus has a wider range of morphologies than previously recognized, some of which are indistinguishable from L. scabra, and can only be reliably identified with molecular techniques. Furthermore, I found that non-lethal sampling of foot mucus could be used in the field for iii species identification for future studies on the potential ecological interactions between L. scabra and L. conus. This technique has considerable potential for a variety of molluscan studies while reducing organism mortality.

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