Microsatellite Analysis of Population Structure in the Endangered Hawaiian Monk Seal |
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Authors: | Maria B Kretzmann †‡‡ Neil J Gemmell ‡§ Axel Meyer† |
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Affiliation: | Department of Biology, University of California, Santa Cruz, CA 95064, U.S.A.;Department of Ecology and Evolution, State University of New York, Stony Brook, NY 11794, U.S.A.;Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom;Department of Zoology, University of Canterbury, P.O. Box 4800, Christchurch, New Zealand;Department of Biology, University of Konstanz, 78457 Konstanz, Germany |
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Abstract: | Abstract: The endangered Hawaiian monk seal breeds at six locations in the northwestern Hawaiian Islands. To determine whether significant genetic differentiation exists among these sites, we used microsatellite loci to examine the monk seal population structure at the five largest breeding colonies. Of 27 loci isolated from other seal species, only 3 were polymorphic in an initial screening of one individual from each breeding site. Only two alleles were found at each of these 3 loci in samples of 46–108 individuals. This extremely low variation is consistent with other measures of genetic variability in this species and is probably the result of a recent severe population bottleneck, combined with a long-term history of small population sizes. Although the smallest monk seal subpopulation in this study ( Kure Atoll) showed some evidence of heterozygote deficit, possibly indicative of inbreeding, the next smallest ( Pearl and Hermes Reef) had an apparent excess of heterozygous individuals. Genetic differentiation was detected between the two subpopulations at extreme ends of the range ( Kure and French Frigate Shoals). This trend was significant only at the microsatellite locus for which we had the largest sample size ( Hg6.3: R ST = 0.206, p = 0.002; allelic goodness of fit G h = 15.412, p < 0.005). French Frigate Shoals is the source population for translocated animals that have been released primarily at Kure Atoll. Differentiation between these sites consisted of allele frequency differences (with the same allele predominant in each location at all three loci), rather than the preservation of alternative alleles. Although the translocations have had positive demographic effects, we recommend continued genetic monitoring of both the source and recipient populations because translocated individuals are now entering the breeding population. |
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