Butterfly Mimicry: A "Huge" Problem for Evolutionary Biology
Can Darwinian evolution explain the complex coloration patterns found in insects that led to biomimicry? According to an article published late last year in BioScience, Darwinian evolution faces "problems" that are "huge" when trying to account for the origin of biomimicry in butterflies:
The balance of Dazzled and Deceived focuses on the genetics and development of mimetic patterns, as revealed mostly through work with butterflies. The problems here are huge for evolutionary biologists. How does natural selection build a complex organism with all its integrated parts through fixation of random mutations? Butterfly mimicry has been a classic arena in which to tackle this problem precisely because the gambit is so obvious: To be a good mimic of another species requires many pattern elements of bars, lines, colors, and even wing shapes to change at once. Moreover, how can this process produce females that are perfect mimics and males that look nothing of the sort within a single species? These genetic requirements are seemingly at odds with our understanding of gradual evolutionary change and genes of small effect.Perhaps it's appropriate that Brodie states that "dogma can be dangerous." Or maybe not, given that his explanation for the evolutionary origin of mimicry is nothing but vague:
(Edmund D. Brodie III, "Butterflies and Battleships," a review of Dazzled and Deceived: Mimicry and Camouflage by Peter Forbes (Yale University Press, 2009)," BioScience, Vol. 60(10):850-851 (November, 2010).)
Forbes takes us through the emergence of E. B. Ford's school of ecological genetics and the basement-made butterfly crosses that eventually began to illuminate the problem of linked-gene complexes ("supergenes"), sex-linked inheritance, and modifier genes. The answers to the mimicry paradox, preliminary as they are still, inform modern evolutionary-developmental studies in all species and have launched the current effort to map a number of butterfly genomes. These genomic excursions promise to uncover the genetic architecture of mimetic patterns in a variety of species and in doing so uncover the fundamental basis of adaptation and speciation.If our understanding of the genetic basis for these mimetic patterns is still "preliminary," then it would seem we're even further away from understanding how they evolved. Apparently these "problems" that are "huge for evolutionary biologists" are not going away anytime soon.