BRINGING HABITAT INFORMATION INTO STATISTICAL TESTS OF LOCAL ADAPTATION IN QUANTITATIVE TRAITS: A CASE STUDY OF NINE-SPINED STICKLEBACKS

• Published in: Evolution Vol. 68; no. 2; pp. 559 - 568
• Main Authors: Karhunen, M., Ovaskainen, O., Herczeg, G., Merilä, J.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.02.2014; Wiley Subscription Services, Inc; Oxford University Press
• Subjects: Adaptation; Adaptation, Physiological - genetics; Animals; Aquatic habitats; Ecological conditions; Ecosystem; Evolution; Evolutionary biology; Evolutionary genetics; Fish; FST; G matrix; Genetic Drift; Genetic Variation; Habitats; Models, Genetic; Natural selection; Personality traits; Phenotype; Phenotypic traits; Population characteristics; Population differentiation; Population genetics; Population mean; Pungitius pungitius; Quantitative Trait, Heritable; Quantitative traits; Risk taking; Smegmamorpha - genetics; Smegmamorpha - physiology; G matrix; Pungitius pungitius; population differentiation; FST; genetic drift; Adaptation
• ISSN: 0014-3820; 1558-5646; 1558-5646
• DOI: 10.1111/evo.12268

Detection of footprints of historical natural selection on quantitative traits in cross-sectional data sets is challenging, especially when the number of populations to be compared is small and the populations are subject to strong random genetic drift. We extend a recent Bayesian multivariate approach to differentiate between selective and neutral causes of population differentiation by the inclusion of habitat information. The extended framework allows one to test for signals of selection in two ways: by comparing the patterns of population differentiation in quantitative traits and in neutral loci, and by comparing the similarity of habitats and phenotypes. We illustrate the framework using data on variation of eight morphological and behavioral traits among four populations of nine-spined sticklebacks (Pungitius pungitius). In spite of the strong signal of genetic drift in the study system (average F ST = 0.35 in neutral markers), strong footprints of adaptive population differentiation were uncovered both in morphological and behavioral traits. The results give quantitative support for earlier qualitative assessments, which have attributed the observed differentiation to adaptive divergence in response to differing ecological conditions in pond and marine habitats.