HORMONAL MECHANISMS OF MATE CHOICE

Mate choice is a critically important determinant of reproductive succ ess, Because of its significance in the evolutionary process, it has r eceived a great deal of attention from animal behaviorists interested in ultimate causes of behavior. Much less effort has been directed at uncovering the physiological mechanisms of mate choice, including thos e operating during ontogeny that lead to adult mate preferences. As a result of natural and sexual selection, many aspects of mate choice ar e sexually dimorphic. How do adult males and females of the same speci es come to show different mating partner preferences? One possibility is that sex steroid hormones play important roles, acting either durin g early development to permanently establish sex differences or during adulthood to facilitate their expression, roles similar to the organi zational and activational effects of sex steroids ore sexually dimorph ic copulatory and courtship behavior patterns. This review (1) summari zes what is known about hormones and mate choice, highlighting those r esults most relevant to understanding proximate causation from an evol utionary perspective; (2) describes recent work from the author's lab testing an organizational hormone hypothesis of mate choice, focusing on a particularly widespread and robust aspect. of mate choice-prefere nce for opposite sex partners-in a pair bonding species-the zebra finc h; and (3) suggests some future directions for research that might int egrate ultimate and proximate causation.