Does Sexual Selection Drive the Evolution of the Female Sperm Storage Organ in Drosophila?

In polyandrous species, the sperm of multiple males may coexist within the female reproductive tract, generating postcopulatory sexual selection (PCSS) that can lead to rapid diversification of male and female traits. In Drosophila, PCSS drives the evolution of extremely long sperm, which are also coevolving with the female sperm storage organ, the seminal receptacle (SR). This male-female coevolutionary dynamic may be mediated by Fisherian sexual selection, fueled by a genetic correlation between SR length and sperm length. SR length is also genetically correlated with remating rate within D. melanogaster, suggesting that the intensity of PCSS may be driving the evolution of SR length in this species. Here, I ask if this microevolutionary process can explain the macroevolutionary pattern of male-female coevolution across the Drosophila lineage. I investigate the association between PCSS and SR length across 17 Drosophila species and find that they are not significantly associated. I additionally test alternative hypotheses that SR evolution is mediated by natural selection on fecundity and again fail to find support for this hypothesis. Although it is assumed that Fisherian sexual selection drives the evolution of extraordinarily long sperm through postcopulatory female choice mediated by SR length, it is still unclear what is driving SR evolution.

Author

• Smith, Tiffini

Language

• en

Keyword

• Coevolution
• Drosophila
• Sperm Storage Organs
• Seminal Receptacle
• Post Copulatory Sexual Selection

Date created

• 2018

Type of Work

• Master's Thesis

License

• All rights reserved

Rights statement

• In Copyright

GW Unit

• Biological Sciences

Degree

• M.S.

Advisor

• Manier, Mollie

Committee Member(s)

• Martin, Arnaud
• Hernandez, Patricia

Persistent URL

•  https://scholarspace.library.gwu.edu/etd/cn69m450p