Date of Award

Fall 12-2018

Degree Type

Honors College Thesis


Biological Sciences

First Advisor

Jake Schaefer

Advisor Department

Biological Sciences


This study was conducted in order to investigate the effects that reinforcement selection has on non-hybridized and hybridized populations of two separate species of Gambusia (G. affinis and G. holbrooki). In order to examine if organisms from a population that had been previously exposed to hybridization would choose mates so as to not produce species hybrid offspring, 29 trials consisting of 9 different mate preference combinations and 87 individuals were recorded and analyzed. Once mate preference was determined for each female used in each trial, the effect that reproductive isolation had on reinforcement in hybrid zones was analyzed. The results yielded evidence that contradicted and supported published literature discussed in this study. Major conclusions included the understanding that many more trials need to be conducted in order to accurately understand the effects of reinforcement selection on Gambusia spp. populations.