A GTT microsatellite repeat motif and differentiation between morphological forms of Littorina saxatilis: speciation in progress?

Wilding, Craig S.; Grahame, J.; Mill, P. J.

doi:10.3354/meps227195

Cited by 11 publications

(7 citation statements)

References 28 publications

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“…A total of 259 snails (20–22 individuals per sample) were genotyped for four L. saxatilis microsatellite loci: Lsax6CAA, Lx‐12 and Lx‐18 (Sokolov et al . 2002) and LsaxRAPDRPT1 (Wilding et al . 2002).…”

Section: Methodsmentioning

confidence: 99%

Comparing geographical genetic differentiation between candidate and noncandidate loci for adaptation strengthens support for parallel ecological divergence in the marine snail Littorina saxatilis

Galindo¹,

Morán²,

Rolán‐Alvarez³

2009

Molecular Ecology

143

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The Galician sympatric ecotypes of Littorina saxatilis have been proposed as a model system for studying parallel ecological speciation. Such a model system makes a clear prediction: candidate loci (for divergent adaptation) should present a higher level of geographical differentiation than noncandidate (neutral) loci. We used 2356 amplified fragment length polymorphisms (AFLPs) and four microsatellite loci to identify candidate loci for ecological adaptation using the F(ST) outlier method. Three per cent of the studied AFLP loci were identified as candidate loci associated with adaptation, after multitest adjustments, thus contributing to ecotype differentiation (candidate loci were not detected within ecotypes). Candidate and noncandidate loci were analysed separately at four different F(ST) partitions: differences between ecotypes (overall and local), differences between localities and micro-geographical differences within ecotypes. The magnitude of F(ST) differed between candidate and noncandidate loci for all partitions except in the case of micro-geographical differentiation within ecotypes, and the microsatellites (putatively neutral) showed an identical pattern to noncandidate loci. Thus, variation in candidate loci is determined partially independent by divergent natural selection (in addition to stochastic forces) at each locality, while noncandidate loci are exclusively driven by stochastic forces. These results support the evolutionary history described for these particular populations, considered to be a clear example of incomplete sympatric ecological speciation.

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Section: Methodsmentioning

confidence: 99%

Comparing geographical genetic differentiation between candidate and noncandidate loci for adaptation strengthens support for parallel ecological divergence in the marine snail Littorina saxatilis

Galindo¹,

Morán²,

Rolán‐Alvarez³

2009

Molecular Ecology

143

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“…There are additional examples of extreme and replicated tidal height variation at one marker relative to others in Littorina (Wilding et al 2002). A clear advantage of this genomic scan approach is that any marker linked to a potential target of selection could, in principle, be identified if the density of marker loci is sufficient.…”

Section: Genomic Scans For Intertidal Differentiationmentioning

confidence: 99%

Ecological Genetics in the North Atlantic: Environmental Gradients and Adaptation at Specific Loci

Schmidt

Serrão

Pearson

et al. 2008

Ecology

136

145

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Abstract. The North Atlantic intertidal community provides a rich set of organismal and environmental material for the study of ecological genetics. Clearly defined environmental gradients exist at multiple spatial scales: there are broad latitudinal trends in temperature, meso-scale changes in salinity along estuaries, and smaller scale gradients in desiccation and temperature spanning the intertidal range. The geology and geography of the American and European coasts provide natural replication of these gradients, allowing for population genetic analyses of parallel adaptation to environmental stress and heterogeneity. Statistical methods have been developed that provide genomic neutrality tests of population differentiation and aid in the process of candidate gene identification. In this paper, we review studies of marine organisms that illustrate associations between an environmental gradient and specific genetic markers. Such highly differentiated markers become candidate genes for adaptation to the environmental factors in question, but the functional significance of genetic variants must be comprehensively evaluated. We present a set of predictions about locus-specific selection across latitudinal, estuarine, and intertidal gradients that are likely to exist in the North Atlantic. We further present new data and analyses that support and contradict these simple selection models. Some taxa show pronounced clinal variation at certain loci against a background of mild clinal variation at many loci. These cases illustrate the procedures necessary for distinguishing selection driven by internal genomic vs. external environmental factors. We suggest that the North Atlantic intertidal community provides a model system for identifying genes that matter in ecology due to the clarity of the environmental stresses and an extensive experimental literature on ecological function. While these organisms are typically poor genetic and genomic models, advances in comparative genomics have provided access to molecular tools that can now be applied to taxa with well-defined ecologies. As many of the organisms we discuss have tight physiological limits driven by climatic factors, this synthesis of molecular population genetics with marine ecology could provide a sensitive means of assessing evolutionary responses to climate change.

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“…It was considered that the reproductive barrier was likely to be only partial. Subsequent work has shown that shells conforming to the H and M morphotypes occur at sites widespread in the British Isles (Wilding et al 2002). Distinct pairs of morphs have also been described on shores in Sweden (Janson 1983) and Spain (Johannesson et al JOHN W. GRAHAME ET AL.…”

Section: Adaptation Environment and Gene Flowmentioning

confidence: 99%

Adaptation to a Steep Environmental Gradient and an Associated Barrier to Gene Exchange in Littorina Saxatilis

Grahame¹,

Wilding²,

Butlin³

2006

Evol

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Adaptation to a steep environmental gradient and an associated barrier to gene exchange in Littorina saxatilis http://researchonline.ljmu.ac.uk/2895/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription.For more information please contact researchonline@ljmu.ac.uk http://researchonline.ljmu.ac.uk/ Citation (please note it is advisable to refer to the publisher's version if you intend to cite from this work) Abstract.-Steep environmental gradients offer important opportunities to study the interaction between natural selection and gene flow. Allele frequency clines are expected to form at loci under selection but unlinked neutral alleles may pass easily across these clines unless a generalized barrier evolves. Here we consider the distribution of forms of the intertidal gastropod Littorina saxatilis, analyzing shell shape and AFLP loci on two rocky shores in Britain. On the basis of previous work, the AFLP loci were divided into differentiated and undifferentiated groups. On both shores, we have shown a sharp cline in allele frequencies between the two morphs for differentiated AFLP loci. This is coincident with a habitat transition on the shore where the two habitats (cliff and boulder field) are immediately contiguous. The allele frequency clines coincide with a cline in shell morphology. In the middle of the cline, linkage disequilibrium for the differentiated loci rises in accordance with expectation.The clines are extremely narrow relative to dispersal, probably as a result of both strong selection and habitat choice. An increase in F ST for undifferentiated AFLPs between morphs, relative to within-morph comparisons, is consistent with there being a general barrier to gene flow across the contact zone. These features are consistent either with an episode of allopatric divergence followed by secondary contact or with primary, non-allopatric, divergence. Further data will be needed to distinguish between these alternatives.Key words -adaptation, AFLP, clines, ecotone, gene flow JOHN W. GRAHAME ET AL. ADAPTATION, ENVIRONMENT AND GENE FLOW 3There has recently been renewed interest in adaptation to environmental gradients and the possibility, or perhaps the likelihood, that such adaptation may lead to speciation in the face of gene flow (Via 2002). One factor in this is the development of new models in which competition (Di...

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A GTT microsatellite repeat motif and differentiation between morphological forms of Littorina saxatilis: speciation in progress?

Cited by 11 publications

References 28 publications

Comparing geographical genetic differentiation between candidate and noncandidate loci for adaptation strengthens support for parallel ecological divergence in the marine snail Littorina saxatilis

Comparing geographical genetic differentiation between candidate and noncandidate loci for adaptation strengthens support for parallel ecological divergence in the marine snail Littorina saxatilis

Ecological Genetics in the North Atlantic: Environmental Gradients and Adaptation at Specific Loci

Adaptation to a Steep Environmental Gradient and an Associated Barrier to Gene Exchange in Littorina Saxatilis

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