The Interaction between Learning and Speciation Public Deposited

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  • March 20, 2019
Creator
  • Yeh, Douhan
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • Assortative mating displays, preferences, or both can be affected by learning across a wide range of animal taxa, but the specifics of how this learning affects speciation with gene flow are not well understood. I use population genetic models with trait learning to investigate how the identity of the tutor affects the divergence of a self-referent phenotype-matching trait. I find that oblique learning (learning from unrelated individual of the previous generation) and maternal learning mask sexual selection and therefore do not allow the maintenance of divergence. In contrast, by enhancing positive frequency-dependent sexual selection, paternal learning can maintain more divergence than genetic inheritance, but leads to the loss of polymorphism more easily. Furthermore, paternal learning inhibits the invasion of a novel self-referent phenotype-matching trait, especially in a large population. Reinforcement is the process through which assortative mating evolves by natural selection to reduce costly hybridization. Sexual imprinting could facilitate reinforcement by decreasing hybridization, or it could impede the process if heterotypic pairs imprint on each other. Either result could then subsequently affect speciation. Here, I use deterministic population genetic simulations to explore conditions under which sexual imprinting can evolve through reinforcement. I demonstrate that sexual imprinting can evolve as a one-allele assortative mating mechanism by reducing the risk of hybridization. The evolution of imprinting has the unexpected side effect of homogenizing an existing innate preference, because the imprinted preference overrides the effect of innate preference, effectively making it neutral. I also find that the weight of the imprinting component in the female preference may evolve to a lower value when migration and divergent selection are strong and the cost of hybridization is low, conditions which make it beneficial for maladaptive immigrant females to acquire locally adaptive genes by hybridizing with the local males. Together, these results suggest that sexual imprinting has the capacity to promote or retard divergence through complex interactions, and can itself evolve as part of the speciation process. The effect of learned culture (e.g., birdsong dialects and human languages) on genetic divergence is unclear. Previous theoretical research suggests that because oblique learning allows phenotype transmission from individuals with no offspring to an unrelated individual in the next generation, the effect of sexual selection on the learned trait is masked. However, I propose that migration and spatially constrained learning can form a statistical association between cultural and genetic traits, which may allow selection on the cultural traits to indirectly affect the genetic traits. Here, I build a population genetic model that allows such a statistical association to form, and found that sexual selection and divergent selection on the cultural trait can indeed help maintain genetic divergence through such a statistical association. Furthermore I found that the genetic divergence maintained by this effect persists even when the cultural trait changes over time due to drift and mutation. These results suggest the role of obliquely transmitted traits in evolution may be underrated, and the lack of one-to-one associations between cultural and genetic traits may not be sufficient to disprove the role of culture in divergence.
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Advisor
  • Pfennig, David William
  • Servedio, Maria
  • Feldman, Marcus
  • Pfennig, Karin
  • Kingsolver, Joel
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2018
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