Local adaptation and reproductive isolation in the copepod Tigriopus californicus Public Deposited

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  • March 22, 2019
Creator
  • Lima, Thiago
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • The evolution of reproductive barriers between species, in many cases is a consequence of genetic divergence that evolves between populations that have become geographically isolated. In this case, processes such as local adaptation and genetic drift will contribute to this divergence, to the point where if the populations come into contact again, some form of reproductive isolation between them will have evolved. Understanding local adaptation, and how it affects a population’s ability to deal with environmental changes has also become of interest to biologists, as way to assess how organisms will deal with predict climate changes. In chapter 2 of this dissertation I address how the evolution of reproductive isolation due to intrinsic postzygotic barriers (hybrid sterility and inviability) is affect by the presence/absence of sex chromosomes, which have been deemed important for the evolution of these reproductive barriers. I show that taxa that have heteromorphic sex chromosomes reach higher levels of intrinsic postzygotic isolation at lower levels of genetic divergence. On the other hand, taxa without sex chromosomes remain compatible until much higher levels of genetic divergence. In chapter 3, I look at genome-wide patterns of hybrid inviability in crosses of different levels of genetic divergence between populations of the copepod Tigriopus californicus. Theory and data in other species suggest that the more divergent cross should show higher levels of intrinsic reproductive isolation, caused by a larger number of genomic regions that are incompatible between the hybridizing populations. Results however show that the least divergent cross suffers the largest effects due to hybrid inviability, suggesting that either this cross has a larger number of incompatibilities than the other two crosses, or that the architecture of these incompatibilities leads to a larger inviability effect. In chapter 4 I focus on the effects that differences in local adaptation play on a population’s ability to deal with changes in thermal variability in their environment. The results show the populations studied have very different profiles of gene expression across the different temperature treatments, and changes in thermal variability elicited large differences in transcriptome wide expression changes, especially in the least thermal tolerant populations.
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  • In Copyright
Advisor
  • Servedio, Maria
  • Jones, Corbin
  • Vision, Todd
  • Willett, Christopher
  • Noor, Mohamed
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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