ADAPTIVE DIVERGENCE IN MOOR FROG (RANA ARVALIS) POPULATIONS ALONG AN ACIDIFICATION GRADIENT: INFERENCES FROM QST-FST CORRELATIONS

Microevolutionary responses to spatial variation in the environment seem ubiquitous, but the relative role of selection and neutral processes in driving phenotypic diversification remain often unknown. The moor frog (Rana arvalis) shows strong phenotypic divergence along an acidification gradient in...

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Bibliographic Details
Published in:Evolution 2012-03, Vol.66 (3), p.867-881
Main Authors: Hangartner, Sandra, Laurila, Anssi, Räsänen, Katja
Format: Article
Language:English
Subjects:
Acid stress
Acidification
Acids
adaptive divergence
Amphibians
Breeding
Correlation
Divergence
Embryos
environmental gradient
environmental stress
Genetic markers
Growth rate
Latitude
Life history
Microsatellites
Natural populations
Natural selection
pH effects
Ponds
Populations
QST-FST comparisons
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Summary:Microevolutionary responses to spatial variation in the environment seem ubiquitous, but the relative role of selection and neutral processes in driving phenotypic diversification remain often unknown. The moor frog (Rana arvalis) shows strong phenotypic divergence along an acidification gradient in Sweden. We here used correlations among population pairwise estimates of quantitative trait (PST or QST from common garden estimates of embryonic acid tolerance and larval life‐history traits) and neutral genetic divergence (FST from neutral microsatellite markers), as well as environmental differences (pond pH, predator density, and latitude), to test whether this phenotypic divergence is more likely due to divergent selection or neutral processes. We found that trait divergence was more strongly correlated with environmental differences than the neutral marker divergence, suggesting that divergent natural selection has driven phenotypic divergence along the acidification gradient. Moreover, pairwise PSTs of embryonic acid tolerance and QSTs of metamorphic size were strongly correlated with breeding pond pH, whereas pairwise QSTs of larval period and growth rate were more strongly correlated with geographic distance/latitude and predator density, respectively. We suggest that incorporating measurements of environmental variation into QST–FST studies can improve our inferential power about the agents of natural selection in natural populations.
ISSN:0014-3820
1558-5646
DOI:10.1111/j.1558-5646.2011.01472.x