Stickleback fish show scientists how evolution is done

Tuesday, April 24th, 2012

There’s a controversy over evolution—and it’s not the one you’re probably thinking of.

Scientists have been debating whether physiological/structural/behavioral adaptation to new environments—i.e., evolution—is the result of many genes, each of relatively small effect, or just a few genes of large effect. Associate professor Andrew Hendry, from McGill’s Redpath Museum and Department of Biology, and a team of evolutionary geneticists from Switzerland went to British Columbia, Canada, in the hope to discover which of the two theories is right. The journal Molecular Ecology published their findings.

Stickleback populations can evolve, independent of other sticklebacks, in lakes or streams. Using high-resolution genetic methods, the team found more than a dozen of positions (“loci”) scattered across the stickleback genome—too many for the few-genes-big-effect theory to be realistic. They also examined four different population pairs and discovered that increasing divergence between the populations involved larger genetic differences, present at more and more loci.

In other words, adaptation is a complex process.

Prof. Hendry expects further studies to support this view that adaptation involves many genes spread across diverse places in the genome. It might be that previous studies led to different conclusions due to the lower-resolution genomic methods they used. With top-notch genetic methods, evolution theories can evolve.

Read more about this study here.

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