Mechanisms of adaptation in coral snake mimicry Public Deposited

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  • March 22, 2019
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  • Kikuchi, David William
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • In Batesian mimicry, an undefended prey species (the mimic) evolves to resemble a defended one (the model) because of the selective advantage of this resemblance in deterring predation. Although Batesian mimicry is one of the oldest known examples of natural selection's power to produce adaptation, many unanswered questions remain about its evolution, including how mimetic signals coevolve with the perceptual abilities of predators, how mimetic signals are produced, how important shared evolutionary history with a model species is for mimics, and if mimicry can evolve over rough adaptive landscapes. My thesis attempts to address these knowledge gaps by examining the venomous coral snake Micrurus fulvius and its nonvenomous mimic, the scarlet kingsnake Lampropeltis elapsoides. In addition to my empirical studies, I have produced two reviews: one is a general review of mimicry in the form of an annotated bibliography, and the other a review of the hypotheses for imperfect mimicry. In a field experiment, I asked whether or not predators were sensitive to differences between models and mimics in phenotype, that is to say, imperfect mimicry. My results revealed that imperfect mimicry was tolerated in some dimensions but not others, and that predators' cognitive biases play a role in perpetuating imperfect mimicry. Two analytical studies of snake pigmentation revealed that coral snakes, their mimics, and several nonmimetic snakes use the same structures and pigments to produce their coloration. The spectral properties of colors produced by those pigments produce similar perceptual experiences for likely agents of selection in coral snake mimicry. This suggests that sharing developmental systems may facilitate the evolution of mimicry. In another field experiment I tested the assumption that the adaptive landscape between mimicry and crypsis (from which mimicry is thought to evolve) is always rough, featuring an adaptive valley of selection against intermediate phenotypes. Under ecological conditions that produce strong selection for precise mimicry, intermediate phenotypes were selected against; however, this was not the case when selection for mimicry was less intense. Therefore, the assumption that the evolution of mimicry always involves a transition through maladaptive intermediate phenotypes may be unwarranted.
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  • In Copyright
Advisor
  • Pfennig, David William
Degree
  • Doctor of Philosophy
Graduation year
  • 2013
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