PROESTOU, D.A.: Microsatellite Markers Developed to Assess Paternity in Crepidula fornicata

Estimates of reproductive success are crucial for understanding the evolution and timing of sex change. In polyandrous species, individual male reproductive success can only be quantified through paternity analysis. Paternity analysis requires the development of polymorphic molecular markers. I constructed a partial genomic DNA library for Crepidula fornicata, a protandrous marine gastropod that forms semi-permanent stacks in order to mate, and screened it for the presence of dinucleotide (CT and GT) and trinucleotide (AGG) microsatellite repeats. Dinucleotide repeats were abundant in the C. fornicata genome, while trinucleotide repeats were sparse. Clones containing microsatellite loci were sequenced and sequence specific primers were designed. Of the twenty primer sets tested, ten exhibited a high degree of polymorphism, two were moderately variable, and eight did not amplify. The ten variable markers will be used to assess the paternity of offspring from field collected mating stacks. These data will provide estimates of individual male reproductive success and will be used to explain why and when protandrous hermaphrodites change sex.