Contrasting effects of environment and genetics generate a continuum of parallel evolution

Stuart, YE; Veen, T; Weber, JN; Hanson, D; Ravinet, M; Lohman, BK; Thompson, CJ; Tasneem, T; Doggett, A; Izen, R; Ahmed, N; Barrett, RDH; Hendry, AP; Peichel, Catherine; Bolnick, DI (2017). Contrasting effects of environment and genetics generate a continuum of parallel evolution. Nature ecology & evolution, 1(6), 0158. Nature Publishing Group 10.1038/s41559-017-0158

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Parallel evolution of similar traits by independent populations in similar environments is considered strong evidence for adaptation by natural selection. Often, however, replicate populations in similar environments do not all evolve in the same way, thus deviating from any single, predominant outcome of evolution. This variation might arise from non-adaptive, population-specific effects of genetic drift, gene flow or limited genetic variation. Alternatively, these deviations from parallel evolution might also reflect predictable adaptation to cryptic environmental heterogeneity within discrete habitat categories. Here, we show that deviations from parallel evolution are the consequence of environmental variation within habitats combined with variation in gene flow. Threespine stickleback (Gasterosteus aculeatus) in adjoining lake and stream habitats (a lake–stream ‘pair’) diverge phenotypically, yet the direction and magnitude of this divergence is not always fully parallel among 16 replicate pairs. We found that the multivariate direction of lake–stream morphological divergence was less parallel between pairs whose environmental differences were less parallel. Thus, environmental heterogeneity among lake–stream pairs contributes to deviations from parallel evolution. Additionally, likely genomic targets of selection were more parallel between environmentally more similar pairs. In contrast, variation in the magnitude of lake–stream divergence (independent of direction) was better explained by differences in lake–stream gene flow; pairs with greater lake–stream gene flow were less morphologically diverged. Thus, both adaptive and non-adaptive processes work concurrently to generate a continuum of parallel evolution across lake–stream stickleback population pairs.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Ecology and Evolution (IEE) > Evolutionary Ecology

UniBE Contributor:

Peichel, Catherine

Subjects:

500 Science > 570 Life sciences; biology

ISSN:

2397-334X

Publisher:

Nature Publishing Group

Funders:

[UNSPECIFIED] US National Science Foundation 1144556

Language:

English

Submitter:

Catherine Peichel

Date Deposited:

13 Sep 2017 15:46

Last Modified:

06 Nov 2017 10:37

Publisher DOI:

10.1038/s41559-017-0158

BORIS DOI:

10.7892/boris.101003

URI:

https://boris.unibe.ch/id/eprint/101003

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