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Oke, K. B.

Publications and source records attributed to Oke, K. B..

2 recordsLinked to original sources

The pace of modern life, revisited

Wild populations must continuously adapt to environmental changes or they risk extinction. Such adaptations can be measured as phenotypic rates of change and can allow us to predict patterns of contemporary evolutionary change. About two decades ago, a dataset of phenotypic rates of change in wild populations was compiled. Since then, researchers have used (and expanded) this dataset to look at microevolutionary processes in relation to specific types of human disturbances. Here, we have updated the dataset adding 5675 estimates of phenotypic changes and used it to revisit established patterns of contemporary evolutionary change. Using this newer version, containing 7338 estimates of phenotypic changes, we revisit the conclusions of four published articles. We then synthesize the expanded dataset to compare rates of change across different types of human disturbance. Analyses of this expanded dataset suggests that: I. a small absolute difference in rates of change exists between human disturbed and natural populations, II. harvesting by humans results in larger rates of change than other types of disturbances, III. introduced populations have increased rates of change, and IV. body size does not increase through time. Overall, findings from earlier analyses have largely held-up in analyses of our new dataset that encompass a much larger breadth of species, traits, and human disturbances. Lastly, we found that types of human disturbances affect rates of phenotypic change, and we call for this database to serve as a steppingstone for further analyses to understand patterns of contemporary evolution.

evolutionary biology

Clinal genomic analysis reveals strong reproductive isolation across a steep habitat transition in stickleback fish

How ecological divergence causes strong reproductive isolation between populations in close geographic contact remains poorly understood at the genomic level. We here study this question in a stickleback population pair adapted to contiguous, ecologically different lake and stream habitats. Dense clinal whole-genome sequence data reveal numerous regions fixed for alternative alleles over a distance of just a few hundred meters. This strong polygenic adaptive divergence must constitute a genome-wide barrier to gene flow because a steep cline in allele frequencies is observed across the entire genome, and because the cline center co-localizes with the habitat transition. Simulations confirm that such strong reproductive isolation can be maintained by polygenic selection despite high dispersal and small per-locus selection coefficients. Finally, comparing samples from the cline center before and after an unusual ecological perturbation demonstrates the fragility of the balance between gene flow and selection. Overall, our study highlights the efficacy of divergent selection in maintaining reproductive isolation without physical isolation, and the analytical power of studying speciation at a fine eco-geographic and genomic scale.

evolutionary biology