![]() Range disjunctions that coincide with phylogeographic breaks are consistent with the effects of geological or physical processes (like glaciations) that limit dispersal, and implicate dispersal barriers in the origin of the disjunct range (e.g., Muñoz-Salazar et al. The concordance between the geographical distributions of populations (including patterns such as range disjunctions) and of population genetic variation (phylogeographic breaks) can be used to test biogeographic hypotheses ( Avise 2000). 2003 Marko 2004 Hickerson and Cunningham 2005 Crandall et al. However, this trend conflicts with a conspicuous minority of other studies that reveal strong phylogeographic breaks in spite of prolonged planktonic larval development, or large differences in population genetic structure between sympatric species with similar larval dispersal potential ( Benzie 1999 Swearer et al. 2002 Kelly and Eernisse 2007 Teske et al. Numerous lines of evidence suggest a correlation between the evolutionary gain or loss of planktonic larval development and the magnitude or geographical scale of neutral genetic differentiation among marine animal populations ( Arndt and Smith 1998 Bohonak 1999 Kyle and Boulding 2000 Grosberg and Cunningham 2001 Hellberg et al. Direct estimates of realized dispersal in species with planktotrophic development are restricted for logistical reasons to cases in which realized dispersal is limited to small spatial scales (e.g., Knowlton and Keller 1986), but inferences based on oceanography and larval duration suggest that realized dispersal can exceed 10 3–10 4 km per generation ( Scheltema 1986 Shanks et al. 1998) is arguably greatest among sessile and sedentary marine animals that have prolonged development of feeding planktonic (planktotrophic) larvae. The intrinsic potential of some organisms to traverse physical and geological features that are barriers to dispersal for other species (e.g., Lessios et al. ![]() Dispersal barriers such as mountain ranges or climatic effects associated with Pleistocene glacial cycles ( DeChaine and Martin 2006 Knowles and Carstens 2007) are well-known determinants of the geographical distribution both of populations and of genetic variation in animals and plants of the Northern Hemisphere ( Hewitt 1996 Riddle 1996 Byun et al. Such range disjunctions may be initiated and maintained by a complex combination of factors, encompassing extrinsic geological and climatic barriers to dispersal and colonization, and intrinsic biological properties of organisms including habitat preferences and dispersal capabilities ( Schwaninger 2008). ![]() The surprising and discordant spatial distribution of populations and alleles suggests that historical vicariance (possibly caused by glaciations) and contemporary dispersal barriers (possibly caused by oceanographic conditions) both shape population genetic structure in this species.Įxplaining the origin and persistence of large geographical discontinuities in species distributions, such as the antitropical distributions of many temperate-zone animals and plants, is one of the original goals of evolutionary ecology ( Darwin 1859 Ekman 1953 Briggs 1987 Wiley 1988 Lindberg 1991). Populations from Vancouver Island and California were undifferentiated with evidence of high gene flow or very recent separation across the range disjunction between them. Northern populations from Alaska and Haida Gwaii were strongly differentiated from all southern populations from Vancouver Island and California. However, this population genetic discontinuity does correspond to previously described phylogeographic breaks in other species. We found a strong phylogeographic break at Queen Charlotte Sound in British Columbia that was not in the location predicted by the geographical distribution of the populations. miniata range using multilocus sequence data (mtDNA, nuclear introns) and multilocus genotype data (microsatellites). We analyzed spatial genetic variation across the P. ![]() Patiria miniata, a broadcast-spawning sea star species with high dispersal potential, has a geographic range in the intertidal zone of the northeast Pacific Ocean from Alaska to California that is characterized by a large range gap in Washington and Oregon. ![]()
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