The effect of alternative mating on sperm competition in coercive livebearing fish

• In Event: Poster Presentation and Judging for: Anthropology; Botany; Conservation Ecology; Environmental Science; Freshwater Science; Geosciences; Mathematics & Computer Science; Neuroscience; Physics & Eng; Science Education; Terrestrial Ecology & Management.
  In Poster Session: Freshwater Science Poster Session

Abstract

The objective of the experiment was to determine if exposure to males of different sizes would lead to alternative reproductive strategies associated with sperm plasticity in the coercive western mosquitofish, Gambusia afffinis. This study provided a unique opportunity to investigate the evolution of ejaculation as a result of sperm competition because males vary substantially in body size and, as a result, exhibit alternative mating strategies. In a previous study on Xipophorus nigrensis, commonly known as swordtails, it was confirmed that alternative mating tactics result in sperm plasticity. However, it was unknown if alternative reproductive strategies affect sperm plasticity in Gambusia afffinis that mate coercively regardless of body size. In order to measure sperm plasticity, three treatment groups were exposed to males of varying sizes, and after several days sperm was collected from each focal male. The data collected from the study is in the process of analysis and will be reported. We predict that small parasitic males will increase the number of sperm produced when placed around a larger male. Future studies will aim at determining if the properties of the sperm are dependent on competition, and the physiological mechanisms by which sperm plasticity can be achieved.

Authors

• Briana Martinez, St. Edward's University

• Raelynn Deaton Haynes, St. Edward's University