Graduation Term
2024
Degree Name
Master of Science (MS)
Department
School of Biological Sciences
Committee Chair
Benjamin Sadd
Abstract
Although mating in sexually reproducing species is a necessity, male and female interests during and after mating may diverge, leading to a sexual conflict. In polyandrous systems, males benefit by monopolizing female reproduction, and have evolved manipulative traits to this end. This includes plastically increasing sperm allocation under a high risk of sperm competition, when females are likely to mate with additional males. However, less is known about plasticity in non-sperm components of the ejaculate. Nuptial gifts provisioned to females by males are a widespread sexual tactic in insects used by males to maximize sperm transfer. In decorated crickets, the gift comprises a portion of the spermatophore, the spermatophylax, that the male transfers at mating. Proteins in the spermatophylax may function to modify female behavior and physiology to increase male paternity. By experimentally varying the perceived risk of sperm competition of males derived from genetically distinct lines, I tested the hypothesis that sperm competition risk and male genotype influence the composition of food gifts. Specifically, I determined gene expression profiles of four accessory-gland proteins putatively involved in sexual conflict. I found differences among inbred lines in the expression of two abundant accessory gland proteins, indicative of heritable genetic variation. However, for the remaining two proteins, I found an interaction between genotype and the sperm competition risk treatment, indicating that males have evolved the ability to tailor investment into their gifts dependent upon the perceived risk of sperm competition. These molecular-level insights are helping to unravel our understanding of the evolution of nuptial gifts, strategic investment into them, and their utility in enhancing our understanding of sexual conflict and sexually antagonistic coevolution.
Access Type
Thesis-Open Access
Recommended Citation
Rengifo, Laura, "Variation in Sperm Competition Risk Reveals Genotype and Genotype-by-Environment Effects on Gene Expression of Nuptial Gift Proteins in Decorated Crickets" (2024). Theses and Dissertations. 2001.
https://ir.library.illinoisstate.edu/etd/2001
DOI
https://doi.org/10.30707/ETD2024.20240827063558172101.999962