Mechanisms of population differentiation in marbled murrelets: historical versus contemporary processes

Congdon, Bradley C., Piatt, John F., Martin, Kathy, and Friesen, Vicki L. (2000) Mechanisms of population differentiation in marbled murrelets: historical versus contemporary processes. Evolution, 54 (3). pp. 974-986.

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Mechanisms of population differentiation in highly vagile species such as seabirds are poorly understood. Previous studies of marbled murrelets (Brachyramphus marmoratus; Charadriiformes: Alcidae) found significant pop- ulation genetic structure, but could not determine whether this structure is due to historical vicariance (e.g., due to Pleistocene glaciers), isolation by distance, drift or selection in peripheral populations, or nesting habitat selection. To discriminate among these possibilities, we analyzed sequence variation in nine nuclear introns from 120 marbled murrelets sampled from British Columbia to the western Aleutian Islands. Mismatch distributions indicated that murrelets underwent at least one population expansion during the Pleistocene and probably are not in genetic equilibrium. Maximum-likelihood analysis of allele frequencies suggested that murrelets from "mainland" sites (from the Alaskan Peninsula east) are genetically different from those in the Aleutians and that these two lineages diverged prior to the last glaciation. Analyses of molecular variance, as well as estimates of gene flow derived using coalescent theory, indicate that population genetic structure is best explained by peripheral isolation of murrelets in the Aleutian Islands, rather than by selection associated with different nesting habitats. No isolation-by-distance effects could be detected. Our results are consistent with a rapid expansion of murrelets from a single refugium during the early-mid Pleistocene, subsequent isolation and divergence in two or more refugia during the final Pleistocene glacial advance, and secondary contact following retreat of the ice sheets. Population genetic structure now appears to be maintained by distance effects combined with small populations and a highly fragmented habitat in the Aleutian Islands.

Item ID: 27872
Item Type: Article (Research - C1)
ISSN: 1558-5646
Keywords: Brachyramphus marmoratus, coalescent theory, intron, marbled murrelet, population differentiation
Date Deposited: 02 Jul 2013 00:49
FoR Codes: 06 BIOLOGICAL SCIENCES > 0699 Other Biological Sciences > 069999 Biological Sciences not elsewhere classified @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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