DOI: 10.5061/dryad.2sh53
title: Data from: Extremophile Poeciliidae: multivariate insights into the complexity of speciation along replicated ecological gradients

description: Background: Replicate population pairs that diverge in response to similar
 selective regimes allow for an investigation of (a) whether phenotypic
 traits diverge in a similar and predictable fashion, (b) whether there is
 gradual variation in phenotypic divergence reflecting variation in the
 strength of natural selection among populations, (c) whether the extent of
 this divergence is correlated between multiple character suites (i.e.,
 concerted evolution), and (d) whether gradual variation in phenotypic
 divergence predicts the degree of reproductive isolation, pointing towards
 a role for adaptation as a driver of (ecological) speciation. Here, we use
 poeciliid fishes of the genera Gambusia and Poecilia that have repeatedly
 evolved extremophile lineages able to tolerate high and sustained levels
 of toxic hydrogen sulfide (H2S) to answer these questions. Results: We
 investigated evolutionary divergence in response to H2S in Gambusia spp.
 (and to a lesser extent Poecilia spp.) using a multivariate approach
 considering the interplay of life history, body shape, and population
 genetics (nuclear miscrosatellites to infer population genetic
 differentiation as a proxy for reproductive isolation). We uncovered both
 shared and unique patterns of evolution: most extremophile Gambusia
 predictably evolved larger heads and offspring size, matching a priori
 predictions for adaptation to sulfidic waters, while variation in adult
 life histories was idiosyncratic. When investigating patterns for both
 genera (Gambusia and Poecilia), we found that divergence in
 offspring-related life histories and body shape were positively correlated
 across populations, but evidence for individual-level associations between
 the two character suites was limited, suggesting that genetic linkage,
 developmental interdependencies, or pleiotropic effects do not explain
 patterns of concerted evolution. We further found that phenotypic
 divergence was positively correlated with both environmental
 H2S-concentration and neutral genetic differentiation (a proxy for gene
 flow). Conclusions: Our results suggest that higher toxicity exerts
 stronger selection, and that divergent selection appears to constrain gene
 flow, supporting a scenario of ecological speciation. Nonetheless,
 progress toward ecological speciation was variable, partially reflecting
 variation in the strength of divergent selection, highlighting the
 complexity of selective regimes even in natural systems that are seemingly
 governed by a single, strong selective agent.
description: Microsatellite data for
 Gambusia spp.Microsatellite data for
 Gambusia spp. "N/A" refers to missing data.Microsatellites for
 Dryad_Riesch et al BMC Evol
 Biol.xlsxDryad_Gambusia and
 Poecilia LHsLlife-history data used
 for the analyses in the publication. Data codes are explained on the last
 spreadsheet.Dryad_Gambusia and
 Poecilia LandmarksLandmark data used for
 geometric morphometric analyses in the publication. Data codes are
 explained on the last spreadsheet.