Genetic Insights into the Giant Keyhole Limpet (), an Eastern Pacific Coastal Endemic: Complete Mitogenome, Phylogenetics, Phylogeography, and Historical Demography.

Background: The giant keyhole limpet is a gastropod mollusk (Fissurella superfamily) that is endemic to the eastern Pacific coast from southern California, USA, to Baja California Sur, Mexico. is socioeconomically important as it produces a potent immune-stimulating protein, called Keyhole Limpet Hemocyanin, which is extracted in vivo and utilized for vaccine development. However, ecological studies are scarce and genetic knowledge of the species needs to be improved. Our objectives were to assemble and annotate the mitogenome of , and to assess its phylogenetic relationships with other marine gastropods and to evaluate its population genetic diversity and structure.

Methods: Samples were collected for mitogenome assembly ( = 3) spanning its geographic range, Puerto Canoas (PCA) and Punta Eugenia (PEU), Mexico, and California (CAL), USA. Total DNA was extracted from gills sequenced using Illumina paired-end 150-bp-read sequencing. Reads were cleaned, trimmed, assembled , and annotated. In addition, 125 samples from eight locations were analyzed for genetic diversity and structure analysis at the and genes.

Results: The mitogenomes had lengths of 16,788 bp (PCA) and 16,787 bp (PEU) and were composed of 13 protein-coding regions, 22 tRNAs, two rRNAs, and the D-Loop region. In terms of phylogeographic diversity and structure, we found a panmictic population that has experienced recent demographic expansion with low nucleotide diversity (0.002), high haplotypic diversity (0.915), and low (0.047).

Conclusions: Genetic insights into the giant keyhole limpet provides tools for its management and conservation by delimiting fishing regions with low genetic diversity and/or genetically discrete units.