Environmental and Neurogenetic Framework of Mate-Choice Relevant Behaviors in Xiphophorus Fishes
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Mate-choice related behaviors are highly variable and sensitive to a wide array of environmental and social factors. Therefore, the stability of a given behavior can largely depend on the level of environmental variability within a population. My research aims to understand the mechanisms whereby behaviors are influenced by social conditions and other environmental factors. I first describe the level of preference variation within a population of swordtail fish across time and small-scale space. Over three years, I found marked, but highly variable differences in female mating preferences between sampling sites. These results highlight the importance of accounting for small-scale heterogeneity when modelling and measuring the evolution of mating preferences and display traits, and may help explain why empirical measures of sexual selection via mate choice are often very weak. Next, I take advantage of the socially-sensitive olfactory mating preferences of female Xiphophorus birchmanni to elucidate the neurogenetic mechanisms by which these preferences are learned. I compare whole brain and olfactory epithelial gene expression profiles of females that were socially isolated from adults, or exposed to either adult conspecifics or members of the closely related X. malinche. I found that conspecific-exposed females experienced an upregulation of genes with functional roles in immune response and the detection of visual and olfactory cues. Meanwhile, heterospecific-exposed females showed upregulation of genes involved in neurogenesis and synaptic transmission, suggesting a prioritization of processing sensory cues. Lastly, I used this same system to determine the role of cultural transmission -- the intergenerational transfer of information -- in shaping male and female personalities. I found that both males and females learn to develop boldness behaviors similar to those of their exposure models. These culturally-sensitive personalities are likely to have important mate choice and evolutionary implications. Together, these studies describe the complex direct and indirect relationships between the environment and female mate choice.
Delclos, Pablo Jose (2017). Environmental and Neurogenetic Framework of Mate-Choice Relevant Behaviors in Xiphophorus Fishes. Doctoral dissertation, Texas A & M University. Available electronically from