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How does variation in a mating trait evolve? Insights from studies of color signals and their perception in a highly polymorphic poison frog

Howell, Kimberly (2023) How does variation in a mating trait evolve? Insights from studies of color signals and their perception in a highly polymorphic poison frog. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Phenotypic polymorphism is commonly thought of as a step towards speciation in animals. Sexual selection can contribute to the development and maintenance of phenotypic polymorphism if mate preferences diverge along with the trait and reduces mating between the different variants. Color is a common sexually selected trait and divergence in color-based sexually selected traits has been found. The strawberry poison frog, Oophaga pumilio is highly variable in color across the Bocas del Toro Archipelago in Panama and color appears to be under natural and sexual selection, though the forces that drove divergence are unclear. My dissertation focused on understanding the divergence of color and color perception in this species. First, I tested for variation in expression and sequence differences in the light-absorbing protein opsin, to test whether differences might contribute to known color-based behavioral biases. Overall, I did not find convincing evidence that differences in color vision have evolved among distinctly colored populations, contrary to findings in aquatic systems. Next, I used a controlled breeding study to test for differences in the inheritance patterns and heritability of dorsal coloration between three color morphs to better understand how this trait has evolved and how it may further evolve. I found evidence for simple Mendelian dominance in one cross and additive genetic variance in two other crosses, suggesting the genetic architecture of color differs between morphs. I also found evidence heritability differs between morphs suggesting different populations might have different responses to selection. Finally, I compared patterns of trait variation among populations across an island with patterns of variation in neutral loci, testing for isolation by adaptation (IBA). I found a pattern of IBA for body size, suggesting this trait may under selection, but not for dorsal coloration or mating call. Overall, my research contributes new insights into the mechanisms by which coloration has diverged in this species, which is fast becoming a model species for the study of phenotypic divergence and speciation. More broadly, my work contributes to our understanding of animal evolution by providing an additional case study of how intraspecific variation in sexually selected traits can evolve.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Howell, Kimberlykih21@pitt.edukih21
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairRichards-Zawacki,
Committee MemberBoyle,
Committee MemberStephenson, Jessicajess.stephenson@pitt.eduu
Committee MemberLee,
Committee MemberO'Connell,
Date: 25 January 2023
Date Type: Publication
Defense Date: 1 December 2022
Approval Date: 25 January 2023
Submission Date: 9 December 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 159
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: poion frog, divergence, speciation
Date Deposited: 25 Jan 2023 19:31
Last Modified: 25 Jan 2023 19:31


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