July 25, 2005 | David F. Coppedge

Do Butterflies Evolve Via Team Stripes?

A BBC News story is claiming that butterflies split into competing teams when differences in their wing patterns emerge.  Based on a paper in Nature,1 this is supposed to be an example of a rarely-observed mechanism for speciation, called reinforcement: in this case, “These wing colours apparently evolved as a sort of ‘team strip’, allowing butterflies to easily identify the species of a potential mate.”  Why is this newsworthy?  Julianna Kettlewell explains, “Given our planet’s rich biodiversity, ‘speciation’ clearly happens regularly, but scientists cannot quite pinpoint the driving forces behind it” (emphasis added in all quotes).
    The authors of the paper are careful to describe their hypothesis of reinforcement as merely a suggestion: “Therefore, although we cannot distinguish at what level (intraspecific or interspecific) reinforcement has operated, our comparative study demonstrates that natural selection against maladaptive matings is likely to have caused widespread divergence in pre-zygotic isolating characters between sympatric species of Agrodiaetus, and could have led to speciation.”


1Lukhtanov et al., “Reinforcement of pre-zygotic isolation and karyotype evolution in Agrodiaetus butterflies,” Nature 436, 385-389 (21 July 2005) | doi: 10.1038/nature03704.

Ironic that Julianna Kettlewell has the same surname as the infamous researcher of peppered moths (see 06/25/2004 entry).  This article doesn’t improve much on evolutionary storytelling.  Who is asking how or why the little flying bugs developed team spirit?  Can they even see their own wing patterns, let alone care whether that attractive, sweet-smelling female over there has identical strips?  Seems to be another case of imputing human aesthetic values on bugs.  As long as we’re speculating about butterfly fashion fads, why wouldn’t they just as easily be saying, vive la difference?
    The authors of the paper note that “empirical evidence has been sufficiently scarce to raise doubts about the importance of reinforcement in nature.”  Their own case is full of speculation and doubt.  So is this the best that evolutionists can do, 146 years after The Origin of Species supposedly settled the issue?  Look how excited they all get over a few wing styles, and how eagerly they want to invoke the magic phrase natural selection to help Charlie get a little credit.  They should be worried (see next entry).

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