Extensive local-scale gene flow and long-term population stability in the intertidal mollusc Katharina tunicata (Mollusca: Polyplacophora)

Abstract

The dispersal capabilities of intertidal organisms may represent a key factor to their survival in the face of global warming, as species that cannot adapt to the various effects of climate change will have to migrate to track suitable habitat. Although species with pelagic larval phases might be expected to have a greater capacity for dispersal than those with benthic larvae, interspecies comparisons have shown that this is not always the case. Consequently, population genetic approaches are being increasingly used to gain insights into dispersal through studying patterns of gene flow. In the present study, we used nuclear single‐nucleotide polymorphisms (SNPs) and mitochondrial DNA (mtDNA) sequencing to elucidate fine‐scale patterns of genetic variation between populations of the Black Katy Chiton, Katharina tunicata, separated by 15–150 km in south‐west Vancouver Island. Both the nuclear and mitochondrial data sets revealed no genetic differentiation between the populations studied, and an isolation‐with‐migration analysis indicated extensive local‐scale gene flow, suggesting an absence of barriers to dispersal. Population demographic analysis also revealed long‐term population stability through previous periods of climate change associated with the Pleistocene glaciations. Together, the findings of the present study suggest that this high potential for dispersal may allow K. tunicata to respond to current global warming by tracking suitable habitat, consistent with its long‐term demographic stability through previous changes in the Earth's climate. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 589–597.

Levels and patterns of population genetic diversity in the red seaweedChondrus crispus(Florideophyceae): a direct comparison of single nucleotide polymorphisms and microsatellites

“…Data from both the six SNPs and the seven microsatellites were sufficient to identify F ST values of as low as 0.02, based on the results of the simulation studies. This level of resolution for the SNP data set was similar to that obtained using six SNP loci in five populations of the mollusc Katharina tunicata (Doonan et al ., ). By contrast to levels of within‐population genetic diversity, patterns of variation between populations were largely congruent between the SNP and microsatellite data sets.…”

“…Furthermore, the increased functional constraint on expressed regions of the genome compared to noncoding regions means that, in the absence of EST data for the target species, there is a good chance that primers designed from EST data in a related species will amplify orthologous loci. If EST data are not available for the target species or related taxa, there are alternative ways of generating libraries of random fragments that will yield anonymous sequence data, such as inter‐simple sequence repeat cloning (Beatty, Philipp & Provan, ; Doonan et al ., ) or the cloning of amplified fragment length polymorphism products (Bensch, Akesson & Irwin, ).…”

Life history, patchy distribution, and patchy taxonomy in a shallow-water invertebrate (Mollusca: Polyplacophora: Lepidopleurida)

“…Other coastal invertebrate species, including chitons, from the northeast Pacific are known to be panmictic across very large ranges (e.g. Doonan et al 2012;Marko et al 2010). The new insight into potential brooding behaviour in L. cascadiensis sp.…”

Historical Refugia and Isolation by Distance of the Mud Snail, Bullacta exarata (Philippi, 1849) in the Northwestern Pacific Ocean

“…Phylogenetic relationships and frequencies of the COI gene haplotypes were determined by constructing a median-joining network using Network v4.6 ( Bandelt et al, 1999 ). The time to most recent common ancestor ( t MRCA ) was estimated using BEAST v1.8.2 ( Doonan et al, 2012 ). The prior settings were the General Time Reversible (GTR) model for nucleotide substitution with four gamma categories, the uncorrelated lognormal relaxed molecular clock model with the mean of the branch rates constrained to 2.4% per million years (Myr −1 ) as estimated for the COI gene of two marine teguline snails separated by the Isthmus of Panama ( Hellberg and Vacquier, 1999 ), and the Yule process of speciation with a random starting tree.…”