VARIATION IN MATE PREFERENCES AND SIGNALS OF THE SPADEFOOT TOAD (SPEA MULTIPLICATA) ACROSS POPULATIONS AND TIME: INFLUENCE OF REINFORCEMENT, SEXUAL SELECTION AND CLIMATE
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Calabrese, Gina
- Affiliation: College of Arts and Sciences, Department of Biology
- Abstract
- Mating traits, including preferences and sexual signals, determine the genetic makeup of individuals and populations. Mating traits facilitate population divergence and speciation in some circumstances and collapse species boundaries in others: understanding their evolution is thus essential to explaining the origins of biodiversity. Here I explore how female mate preferences and male sexual signals have evolved in spadefoot toads, Spea multiplicata, across time and populations. S. multiplicata risk deleterious hybridization in populations sympatric with Spea bombifrons, which exerts divergent selection on female preferences from those in allopatric populations. Spadefoot populations also vary in environmental attributes and have been subject to recent climate change, which might affect sexual trait expression and the fitness of sexual phenotypes. I found that female S. multiplicata in sympatric populations facultatively express mate preferences that reduce hybridization risk when S. bombifrons cues are present, and switch to expressing preferences that favor conspecific mate quality when such cues are absent. I also found substantial variation in female mate preferences across populations—however, this variation was not related to hybridization risk. Further, male sexual signals did not correlate with female preferences for these signals across populations, which indicates that male signals are not diverging in response to female preference, and that reproductive isolation due to preference-signal mismatch is unlikely between these populations. Finally, I describe changes in temperature and rainfall patterns in these populations over 22 years, and show that expression of male mating calls has changed in concert with breeding pond temperature, while males have also evolved faster calls for a given temperature over this period. Together this work shows that mating traits are context- and environment-dependent, subject to a variety of ecological and evolutionary forces, and that patterns of trait diversity in this system do not always follow predictions of reinforcement or preference-signal coevolutionary theory.
- Date of publication
- 2022
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright - Educational Use Permitted
- Advisor
- Pfennig, Karin
- Servedio, Maria
- Buford-Reiskind, Martha
- Pfennig, David
- Langerhans, Brian
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill Graduate School
- Graduation year
- 2022
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