Female preference for complex male displays in hybridizing swordtails
MetadataShow full item record
Swordtail fishes of the genus Xiphophorus have been studied as a model of sexual selection for many years. Many single-trait manipulation studies have been performed, determining female preferences for individual male traits. I characterized how five traits (standard body length, body depth, dorsal fin width, sword length and vertical bar number) correlate to one another within natural variation of populations of X. birchmanni, X. malinche and three hybrid populations and created synthetic 3- dimensional animations exhibiting these traits within ranges of natural variation. I then performed choice tests on females of the above populations using a computer system that automatically played these stimulus videos and simultaneously tracked a female’s position within a test tank to determine female preference for different male phenotypes. Only X. birchmanni females showed significant preferences. Their preferences were in line with past research of univariate trait manipulation experiments. They showed significant preference for larger bodies and dorsal fins and smaller or no swords. They also showed a non-significant preference for vertical bar numbers. My results also confirmed univariate studies in which X. malinche females showed reduced preference for conspecific males and being rather indifferent to the presence of swords. Hybrid females were also shown to have reduced preferences for any specific trait, suggesting that they express recombinant preferences, which can also be explained by reduced color vision at low levels of light.
Cress, Zachary Pierce (2008). Female preference for complex male displays in hybridizing swordtails. Master's thesis, Texas A&M University. Available electronically from