Harlequin Duck Recovery from the Exxon Valdez Oil Spill: A Population Genetics Perspective

Abstract

ABSTR^CT.--Concerns about Harlequin Duck (Histrionicus histrionicus) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds located in different molting and wintering areas belong to genetically distinct and, thus, demographically independent populations. Owing to the lack of direct observations of movements among marine areas, three classes of genetic markers that differed in mode of inheritance were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound (PWS) and the Alaska Peninsula and Kodiak Archipelago (APKA). We could not reject the null hypothesis that the wintering aggregations within each region are composed of a single genetically panmictic population. Differences in genotype frequencies among wintering locations within PWS and APKA were low and nonsignificant for all three classes of markers. Furthermore, we saw no evidence for deviations in Hardy-Weinberg equilibrium or gametic disequilibrium between loci within a winter collection site as would be expected if these locales were composed of individuals from reproductively isolated (and genetically distinct) breeding locales. Finally, no evidence for significant structuring was noted between PWS and APKA. Lack of spatial genetic structuring could be due to the cumulative effects of low levels of gene flow over long time periods, low levels of gene flow by immature birds moving between marine habitats, or to episodic dispersal caused by habitat alteration (e.g. volcanic eruptions). Harlequin Ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from non-affected areas.Demographic studies suggest, however, that levels of movements are low, and that population recovery by emigration is a long-term process.

Where east meets west: Phylogeography of the high Arctic North American brant goose

“…Therefore, to determine the fragment we amplified was of mitochondria in origin, we followed procedures in Sorenson and Quinn ( 1998 ) and Lanctot et al. ( 1999 ). Precautions taken to avoid amplification of nuclear inserts included amplifying tissues with low‐quality DNA such as feathers (54 samples for YKD, 42 for NS, and 77 from wintering samples not included in this study for reference mtDNA haplotypes; see Sonsthagen et al., 2024 ) as well as comparing sequences from mtDNA‐rich tissues such as heart muscle to blood to feathers from the same individual.…”

“…and Lanctot et al (1999). Precautions taken to avoid amplification of nuclear inserts included amplifying tissues with low-quality DNA such as feathers (54…”