Second North American Sea Duck Conference - Patuxent Wildlife ...

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SECOND NORTH AMERICAN SEA DUCK CONFERENCE DEFINING POPULATION UNITS FOR CONSERVATION OF SEA DUCKS: CONTRASTING GENETIC AND DEMOGRAPHIC CRITERIA John Pearce¹, Sam Iverson², Daniel Esler², and Sandy Talbot¹ ¹Alaska Science Center, U.S. Geological Survey; john_pearce@usgs.gov ²Anchorage, AK 2Centre for Wildlife Ecology, Simon Fraser University, Burnaby, BC Several tools can be used to examine population differentiation and identify appropriate conservation units, including genetic and demographic analyses. In this presentation, we discuss the benefits and challenges associated with independent and combined uses of these approaches. Many of the challenges stem from a frequent misunderstanding or misinterpretation of data that is obtained through genetic and demographic methods. Additionally, many are often frustrated when study results from one marker type is markedly different than obtained with a second marker type. In this talk, we review how genetics and demographics can be used to measure spatial and temporal variation in population differentiation. For example, if population segments show evidence of genetic differentiation, one can strongly infer that these segments also are demographically independent. Conversely, failing to reject a hypothesis of panmixia using neutral genetic markers cannot be interpreted as evidence for lack of short-term demographic independence. Because genetic data reflect both historical and contemporary exchange, genetic signatures can persist over long temporal scales. Thus, direct measurements of movement (using bands, radios, stable isotopes, etc.) can be particularly useful for disentangling historic gene flow from more contemporary levels of movement. Managers should not be surprised if genetic and demographic data show different patterns, because of the different temporal scales to which they apply. Indeed, this is a common occurrence in ornithological studies. We review recent cases that highlight the benefit of a combined marker approach, and offer some suggestions on how best to interpret studies in which only a single marker type is used. For example, one shortcoming of demographic data is the cost and methodological challenges associated with accurately quantifying movements of individuals across multiple years and study sites. Yet such data is often very useful for interpreting population genetic data. Thus, we recommend a multiple marker approach for a better understanding of population demography and delineation. 28 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
SECOND NORTH AMERICAN SEA DUCK CONFERENCE POPULATION STRUCTURE AND PHYLOGEOGRAPHY OF COMMON EIDERS Sarah Sonsthagen¹, Sandra Talbot², Kim Scribner³, Richard Lanctot 4 , and Kevin McCracken¹ 1Institute of Arctic Biology, University Alaska Fairbanks, Fairbanks, AK; ftsas@uaf.edu, fnkgm@uaf.edu 2U. S. Geological Survey, Alaska Science Center, Anchorage, AK; sandy_talbot@usgs.gov 3Department of Fish and Wildlife, Michigan State University, East Lansing, MI; scribne3@msu.edu 4U. S. Fish and Wildlife Service, Anchorage, AK; Richard_Lanctot@fws.gov Common eider (Somateria mollissima) populations have been declining throughout most of their range. Since little is known about their breeding biology, this demonstrates a need to define population structure and assess genetic variability of common eiders. Studies indicate that female common eiders exhibit high levels of breeding and natal philopatry, which may restrict dispersal among populations. However, pair formation occurs on the wintering grounds, providing a potential avenue for gene flow among populations via male dispersal. However, male dispersal among populations may be limited as molecular and banding data from the European subspecies indicates that non-random mating is occurring on wintering grounds such that males are more likely to mate with females from the same colony. Using microsatellite genotypes and sequence information from mitochondrial control region and nuclear DNA introns, we assessed population structure of common eiders breeding throughout North America and Scandinavia. Common eiders are exhibiting high levels of population structure at the mitochondrial DNA marker and moderate to low levels of differentiation at the nuclear markers. In addition to the high levels of population subdivision, we observed two haplotype and allele groups, which indicate that common eiders were separated in two separate glacial refugia during the Pleistocene. Along with the genetic structuring among populations and cline in haplotype and allelic frequencies across their distribution, there was likely a step-wise post glacial colonization of North America and Scandinavia by common eiders. Nuclear DNA data support current subspecies taxonomy, as microsatellite and intron data have the most significant pairwise population comparisons occurring among subspecies. This is consistent with the breeding biology of common eiders, as male mediated gene flow has likely had a homogenizing effect on the nuclear genome. However, mtDNA variation is better accounted for by grouping populations by geographic proximity supporting a stepwise-postglacial colonization of North America and Scandinavia. NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA 29
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