Date of Award:

8-2026

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

Karen Kapheim

Committee

Karen Kapheim

Committee

Justin Jones

Committee

Olav Rueppell

Committee

Noelle Beckman

Committee

Zachariah Gompert

Abstract

Individuals of some species mix their DNA frequently when producing sex cells, while others do so much less. Hymenopterans (ants bees and wasps) are especially useful for understanding this variation for several reasons. They show large differences in this frequency of shuffling, or rate of recombination, have well-studied genomes, and vary widely in how they live and reproduce. I capitalized on these features examines how recombination rates have evolved in this group at the trait, and gene level.

First, I revisited long-standing ideas about why recombination rates differ among these species, incorporating more than a decade of new research. This analysis suggests that one long-standing explanation, small breeding populations, is unlikely to drive recombination rate increases. I also found that the apparent positive association between the number of mates per female and higher recombination continues to appear plausible in light of more recombination rate estimates.

Next, I tested how different aspects of social behavior relate to recombination rates across 13 species, while accounting for their shared evolutionary history. Among the traits examined, the number of mates per female was one of the strongest predictors of recombination rate. I also identified several genes whose patterns of evolution coincide with recombination rate, including one involved both in sperm motility and linked to recombination in honey bees.

Finally, I expanded the dataset by estimating recombination rates in two additional bee species that evolved social behavior independently from other well-studied bees. This allowed me to test whether social complexity itself is related to recombination. Again, female mating behavior showed a strong relationship, and together with social complexity, it best explained differences in recombination rates across species. Additional analyses suggest that increased competition among males is consistent with the observed relationship between mating behavior and recombination rate.

Taken together, these findings reveal consistent links between recombination rate, mating behavior, and social traits. They provide clearer direction for understanding why this important genetic process varies so widely across ants, bees, and wasps.

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