Proximate mechanisms of mate choice in zebrafish (Danio rerio)

Matthew Aaron Owen, Purdue University

Abstract

Studies of mating preferences contribute to our understanding of the evolution of male secondary sexual traits. How females respond to novel male characteristics may lend insight into these mating preferences and subsequent mate choice patterns. Studies on several species have shown that females prefer males with manipulated or novel phenotypes. However, few studies investigate the mechanisms that females use to determine these preferences. I used zebrafish (Danio rerio) to investigate female mate preference for normal and novel (i.e. red transgenic, GloFish™) males. I used an association test protocol in which female preference was assessed by the relative amount of time a female spent near each of two males (either normal or red). Females overwhelmingly preferred red males over normal males. To determine if the early social environment of females influenced this preference (sexual imprinting), I reared females in groups containing different frequencies of normal and red fish and tested their preference using the association test protocol as well as a single-male testing protocol which assessed preference in terms of latency to mate. Association tests revealed that early social environment did not influence preference patterns, as females from all rearing environments overwhelmingly preferred red males; however, single-male tests revealed no preference as female mating latency times did not differ between normal and red males. Mating latency tests may not accurately indicate preference in zebrafish because evidence suggests females commit to mate many hours prior to spawning. To determine if female perception of male color influenced preference, I calculated the chromatic contrast of each male phenotype against the white background of the test arena. However, because the red phenotype was expressed differently and the degree of red color expression of the red male used in each trial was not recorded, the influence of differences in chromatic contrast on preference patterns remains unknown. Additional work that includes the effects of food imprinting (demonstrated in zebrafish) and a red color sensory bias should further elucidate the proximate mechanisms underlying the observed female preference for red males in this species.

Degree

M.S.

Advisors

Howard, Purdue University.

Subject Area

Ecology|Zoology

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