Mate Choice and Personality in the Swordtail Fish Xiphophorus birchmanni
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Mate choice behavior underlies many significant phenomena in biology including sexual conflict, selection, hybridization and speciation. Members of the genus Xiphophorus provide an excellent model for studying these processes because swordtail fish have robust and reproducible mate choice behaviors. Previous studies regarding female preference for male traits in the species X. birchmanni indicate that females prefer the male traits large body size, small dorsal fin, and the absence of a sword. Because males raise their dorsal fin in aggressive displays during intrasexual competition, it is possible that females avoid males with large dorsal fins because this trait may be an indicator of aggression and thus potential physical harm. Poeciliid fish have been shown to possess shy and bold personality traits. A bold individual is more likely to explore a novel environment while shy individuals are more conservative. Mate choice trials will be combined with measures of personality in order to investigate the relationship between personality and mate preference in female X. birchmanni. The personality traits of shy and bold can easily be tested through latency to emerge from a shelter. In the mate choice trials, the females are presented with two computer animated stimuli and preference is calculated using association times. We hypothesize that bold females will prefer exaggerated male traits (large body, large dorsal fin, and sword) while shy females will have the opposite preferences. Mate choice and personality may be related because selection may favor females that avoid traits that represent potential physical damage. We found that overall females showed no significant preferences for any of the male traits tested. We found no correlation between the body size and swordtail trait and latency to emerge but females with shorter latencies to emerge (bolder) preferred the larger finned male while females with longer latencies (shyer) to emerge preferred the smaller fin. This result supports our hypothesis that a large dorsal fin is suggesting aggression and possible harm to the females and that shyer females are less likely to mate with a large-finned male but bold females are more likely to take this risk.
Spahn, Alexandra 1990- (2012). Mate Choice and Personality in the Swordtail Fish Xiphophorus birchmanni. Honors and Undergraduate Research. Available electronically from