California Sea Grant College Program

I isolated and developed primers for 17 microsatellite loci in the anomuran crab Petrolisthes cinctipes as a prelude to a comprehensive analysis of genetic structure in this species. I excluded from subsequent analyses any loci that 1) produced unscorable multiband amplification products; 2) showed evidence of null alleles; 3) failed Slatkin's (1994, 1996) exact test for a fit to the Ewens sampling distribution for selectively neutral alleles; 4) did not amplify a product of the expected size; 5) failed to amplify any product from DNA extracted from the original crab from which the library was developed; or 6) exhibited non-Mendelian patterns of inheritance. Non-Mendelian inheritance was assessed by comparing the genotypes of brooded embryos to their mothers. Amplification of two loci (Pcl60b, and Pc36L) from brooded embryos revealed heterozygous amplification products that did not match either apparent allele amplified from the mother. On the basis of these criteria, 15 of the 17 loci isolated in this study are excluded. The data generated from testing for non-Mendelian inheritance also allows an inference about the mating structure of this crab. Using the two remaining loci, I found that eight often broods analyzed show evidence of multiple paternity. This result suggests that multiple paternity of broods is widespread in Petrolisthes cinctipes.