Climate-driven genetic divergence of limpets with different life histories across a southeast African marine biogeographic disjunction: different processes, same outcome

Peter Teske, Iliane Papadopoulos, Karum Mmonwa, T Matumba, Christopher McQuaid, Nigel Barker, Luciano Beheregaray

    Research output: Contribution to journalArticle

    28 Citations (Scopus)

    Abstract

    Genetic divergence among populations of marine broadcast spawners in the absence of past geological barriers presents an intriguing challenge to understanding speciation in the sea. To determine how differences in life history affect genetic divergence and demographic histories across incomplete dispersal barriers, we conducted a comparative phylogeographic study of three intertidal limpets (Siphonaria spp.) represented on either side of a biogeographic disjunction separating tropical and subtropical marine provinces in southeastern Africa. Using a combination of mitochondrial and nuclear sequence data, we identified two distinct evolutionary lineages each in both Siphonaria concinna (a planktonic disperser) and S. nigerrima (a direct developer), and panmixia in a second planktonic disperser, S. capensis. Although phylogeographic breaks were present in two species, how these became established differed depending on their life histories. In the direct developer, lack of gene flow following divergence, and demographic expansion from a small initial size in the species' subtropical population, point to a single colonisation event. In contrast, the evolutionary lineages of the planktonic disperser split into two genetic lineages with much larger initial population sizes and southward gene flow continued at least periodically, indicating that divergence in this species may have been driven by a combination of reduced larval dispersal and divergent selection. These findings help explain why the presence or absence of phylogeographic breaks often appears to be independent of species' dispersal potential.

    Original languageEnglish
    Pages (from-to)5025-5041
    Number of pages17
    JournalMolecular Ecology
    Volume20
    Issue number23
    DOIs
    Publication statusPublished - Dec 2011

    Keywords

    • comparative phylogeography
    • direct developer
    • divergent selection
    • ocean current intensity
    • phylogeographic break
    • planktonic larvae

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