Present address: Natural Sciences Division, Limestone College, 1115 College Drive, Gaffney SC 29340-3799, USA.
Divergence genetics analysis reveals historical population genetic processes leading to contrasting phylogeographic patterns in co-distributed species
Article first published online: 12 OCT 2010
© 2010 Blackwell Publishing Ltd
Volume 19, Issue 22, pages 5043–5060, November 2010
How to Cite
McGOVERN, T. M., KEEVER, C. C., SASKI, C. A., HART, M. W. and MARKO, P. B. (2010), Divergence genetics analysis reveals historical population genetic processes leading to contrasting phylogeographic patterns in co-distributed species. Molecular Ecology, 19: 5043–5060. doi: 10.1111/j.1365-294X.2010.04854.x
- Issue published online: 3 NOV 2010
- Article first published online: 12 OCT 2010
- Received 2 March 2010; revision received 5 July 2010; accepted 7 July 2010
- ancestral polymorphism;
- divergence time;
- gene flow;
- larval development;
Coalescent samplers are computational time machines for inferring the historical demographic genetic processes that have given rise to observable patterns of spatial genetic variation among contemporary populations. We have used traditional characterizations of population structure and coalescent-based inferences about demographic processes to reconstruct the population histories of two co-distributed marine species, the frilled dog whelk, Nucella lamellosa, and the bat star, Patiria miniata. Analyses of population structure were consistent with previous work in both species except that additional samples of N. lamellosa showed a larger regional genetic break on Vancouver Island (VI) rather than between the southern Alexander Archipelago as in P. miniata. Our understanding of the causes, rather than just the patterns, of spatial genetic variation was dramatically improved by coalescent analyses that emphasized variation in population divergence times. Overall, gene flow was greater in bat stars (planktonic development) than snails (benthic development) but spatially homogeneous within species. In both species, these large phylogeographic breaks corresponded to relatively ancient divergence times between populations rather than regionally restricted gene flow. Although only N. lamellosa shows a large break on VI, population separation times on VI are congruent between species, suggesting a similar response to late Pleistocene ice sheet expansion. The absence of a phylogeographic break in P. miniata on VI can be attributed to greater gene flow and larger effective population size in this species. Such insights put the relative significance of gene flow into a more comprehensive historical biogeographic context and have important implications for conservation and landscape genetic studies that emphasize the role of contemporary gene flow and connectivity in shaping patterns of population differentiation.