Exact Enumeration of Sires in the Polyandrous Nurse Shark (Ginglymostoma cirratum)
Polyandry has been demonstrated in a number of shark species. Studies based on a small number of loci typically estimate the minimum number of sires, which may be much lower than the actual number of sires due to the sharing of alleles by parents. We genotyped three litters of Nurse Shark (Ginglymostoma cirratum) ranging in size from 29 to 39 pups at 12 DNA microsatellite loci to determine the number of sires for each litter. We analyzed the genotypes using two analytical methods, both of which indicated that each litter had five to seven sires with one to 17 pups per sire. Previous analyses of these litters based on MHC loci indicated a minimum of four sires. Because G. cirratum are not capable of long-term sperm storage and ovulate over several weeks, they may require multiple inseminations to fertilize an entire litter. The varying levels of developmental stage among embryos found within a single litter may reflect multiple fertilizations over a prolonged period. Exact enumeration of sires as demonstrated here can provide valuable information for understanding reproductive ecology of live-bearing vertebrates.Abstract
Assignment to full-sib groups for the 29-pup series as described in the text. Individual pup numbers are along either axis. Kinship-derived significance flags (“▪” = P < 0.5, “▪▪” = P < 0.01, “▪▪▪” = P < 0.001) are provided for the null hypothesis (half sib) against the alternate hypothesis (full sib). Shaded boxes indicate presumptive full-sib groups. The matrix is symmetrical around the diagonal. The dotted line connecting pup 2 with pups 3, 11, 25, and 20 indicates a full-sib group assigned by Colony but not by Kinship.
Assignment to full-sib groups for the 32-pup series of Saville et al. (2002) as described in the text. Individual pup numbers are along either axis. Kinship-derived significance flags (“▪” = P < 0.5, “▪▪” = P < 0.01, “▪▪▪” = P < 0.001) are provided for the null hypothesis (half sib) against the alternate hypothesis (full sib). Shaded boxes indicate presumptive full-sib groups. The matrix is symmetrical around the diagonal.
Assignment to full-sib groups for the 39-pup series of Ohta et al. (2000) as described in the text. Individual pup numbers are along either axis. Kinship-derived significance flags (“▪” = P < 0.5, “▪▪” = P < 0.01, “▪▪▪” = P < 0.001) are provided for the null hypothesis (half sib) against the alternate hypothesis (full sib). Shaded boxes indicate presumptive full-sib groups. The matrix is symmetrical around the diagonal.
Contributor Notes
Associate Editor: J. W. Snodgrass.