First Faculty Advisor
Jerald B Johnson
First Faculty Reader
Byron J Adams
Steven L Peck
poeciliidae, variation, morphology, lateralization
How genetic variation is maintained in the face of strong natural selection is an important problem in evolutionary biology. Selection should erode genetic diversity, leading to more and more homogeneous populations. Yet in nature, we commonly see high degrees of genetic variation, even for traits that are important to fitness. Negative frequency-dependent selection, a balancing selective force that favors traits when they are rare but not when they are common, is a mechanism proposed to maintain polymorphisms in a population. However, there is little empirical data to demonstrate how negative frequency-dependent selection sustains variation. Xenophallus umbratilis is a bilaterally symmetrical species of livebearing fish that exhibits asymmetry in the male gonopodium, the male intromittent organ which terminates with a sinistral or dextral twist. I test the hypothesis that in species such as Xenophallus umbratilis, where such asymmetrical morphologies exist, negative frequency-dependent selection maintains variation in the gonopodium within populations.
BYU ScholarsArchive Citation
Johnson, Mary-Elise, "Does Negative Frequency-Dependent Selection Maintain Gonopodial Asymmetry in a Livebearing Fish?" (2020). Undergraduate Honors Theses. 125.