SCT: Peppered Hares Fail as an Example of Evolution

Snowshoe hares are not evolving.
Learn how to ask the right questions
when responding to Darwinian claims.

This article was first published in Science & Culture Today.

Peppered Hares — An Emerging Evolutionary Icon
by David Coppedge
Science & Culture Today, July 3, 2018

Here is an emerging icon of evolution: the snowshoe hare. This animal is similar to the jackrabbit, except that it turns white in winter, giving it camouflage against the snow. In milder climates, though, turning white would be a disadvantage, so its relatives remain brown in winter. One notices a similarity to the story of peppered moths, but the authors of a recent study compare it to Darwin’s finches. Maybe we’ll get two icons hybridizing into one!

No Support for Directional Evolution

The report by Jones et al. in Science, “Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares,” makes this comparison to Darwin’s finches:

Recurrent introgression of coat color variants could facilitate evolutionary responses to environmental change within populations as well as the long-term maintenance of adaptive variation among species, similar to adaptive polymorphisms of beak morphology across the radiation of Darwin’s finches. [Emphasis added.]

They refer to a couple of earlier papers by Peter and Rosemary Grant (2016, 2017, both open access). Neither paper, however, supports directional evolution, since the finch species can interbreed. The species can exchange genetic traits by “introgressive hybridization,” and so can adapt to the food supply by using pre-existing genetic information that regulates beak size. The best they can say is that their data is “consistent” with Darwinian evolution, and that eventually interbreeding might cease. In the 2017 paper in Genome Research, the Grants use metaphor and promissory notes to envision Darwinian speciation occurring someday.

Our data are consistent with an evolutionary scenario where genomic islands of divergence have evolved throughout the radiation of the Darwin’s finches, most often in regions with low recombination and often due to genetic adaptation, as exemplified by the beak loci. Introgression may occur through inter-island movements and interbreeding. As divergence proceeds further, introgression gradually diminishes as the islands are now “protected” by selective exclusion of foreign gene regions corresponding to the islands, and d_XY rises above background level. Later still, interbreeding ceases, or all but ceases, and the number of islands decreases as divergence of the background increases and the islands no longer stand out: metaphorically, the sea rises and the islands disappear.

In other words, the Grants have not demonstrated reproductive isolation or speciation, but only imagined that it might occur in the future.

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For more on snowshoe hares, see our 28 Feb 2018 article.
What about peppered snakes? See 16 Aug 2017. And peppered mice, too? (28 Aug 2009).

For relief from Darwinian storytelling, watch Illustra Media’s video that includes snowshoe hares, “Let it Snow.”