Hybridization between genetically and morphologically divergent forms of Rhagada (Gastropoda: Camaenidae) snails at a zone of secondary contact

Z.R. Hamilton, Michael Johnson

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 348-362. Congeneric sympatry is rare in Australian camaenid land snails, and the reasons are poorly understood. As the first example of contact between species of the Western Australian genus Rhagada, we examined the parapatric zone between the coastally distributed Rhagadaconvicta and an undescribed inland species, which differ in size, shape, and banding of their shells and in their reproductive systems. Phylogenetic analysis of sequences of the mitochondrial 16S RNA gene indicated secondary contact between two distinct clades, with an average sequence divergence of 6.5%. Despite these substantial differences, the two forms hybridize in the narrow contact zone, resulting in intermediate phenotypes for shells and reproductive anatomy, and incongruence of the mitochondrial DNA (mtDNA) lineage and morphology. Hybridization appears to be asymmetric, however, as all morphological intermediates possessed the R.convicta mtDNA. Interbreeding between these deeply divergent forms challenges the use of reproductive structures as indicators of reproductive isolation in snail taxonomy. This is the first contact zone detected between mainland species of Rhagada and indicates that the widespread pattern of geographical replacement is not simply a result of allopatric divergence without subsequent contact. Instead, the perspective for understanding the radiation and geographical distributions must include interactions between the species.
    Original languageEnglish
    Pages (from-to)348-362
    JournalBiological Journal of the Linnean Society
    Volume114
    Issue number2
    DOIs
    Publication statusPublished - 2015

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