SREL Reprint #1919





Genetic structure in a wintering population of American Coots

McAlpine, S., O.E. Rhodes Jr., C.D. McCreedy, and I.L. Brisbin Jr.

American Coots (Fulica americana) wintering on the Savannah River Site (SRS), near Aiken, South Carolina, arrive in stages and exhibit temporally stable patterns of site fidelity. Site fidelity in colormarked coots was observed both throughout the winter and across years (Pottei- 1987) on various portions of Par Pond reservoir on the SRS. In addition, Brisbin et al. ( 1973) and Potter (1987) found that cesium-137 body burdens of coots differed significantly between birds from different sites on this reservoir and varied in accordance with the levels of contamination in those sites. These data led us to ask whether the birds from these sites represented distinct and stable population-specific or demographic cohorts which arrived at the reservoir in the same temporal sequence each year and, therefore, were structured on the reservoir with regard to population of origin.

If genetically differentiated breeding populations of coots occupy different sites within a given wintering area, then genetic analyses of the birds on the wintering area should elucidate this structure. Likewise, specific sex and/or age classes of birds from genetically differentiated breeding populations could be detected within a given wintering area. If such populations or sex/age cohorts of coots are mixed on Pat- Pond, the data should reflect this in two ways. First, there should be a heterozygote deficiency in the overall sample of' coots from the reservoir; this is known as the Wahlund (1928) effect. Second, when groups of birds from different breeding areas are categorized correctly on the wintering area, such as site-specific aggregations of birds or sex/age classes, F-statistics should indicate that a substantial amount of the total genetic variance is partitioned among these groups within the wintering population. Our objectives were to survey genetic variability in the Par Pond wintering population of American Coots and to use genetic techniques to assess spatial and demographic subsets of these wintering coots in an effort to understand the migratory behavior of this species.

SREL Reprint #1919

McAlpine, S., O.E. Rhodes Jr., C.D. McCreedy, and I.L. Brisbin Jr. 1994. Genetic structure in a wintering population of American Coots (Fulica americana). The Wilson Bulletin 106:738-743.

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