9317988 Emlen ABSTRACT This research is ultimately concerned with understanding behavioral differences between females and males, an extremely widespread biological phenomenon. Evolutionary theory and experimental evidence suggest that the amount of time and energy invested in the care-taking of offspring may strongly influence the options available to each sex. Such differences may have favored the expression of different behaviors in males and females. Among those animal species that show parental care, females usually provide the bulk of such care, leaving males free to increase their biological success through additional matings. Under such conditions, natural selection might be expected to have favored the development of different strategies in the two sexes. This has led to hypotheses about why the sexes often adopt different roles during interactions, why behavioral conflict between mates is so common, and what forms of behavioral resolution can be expected in such conflicts. These ideas can be subjected to particularly critical test by studying species in which care-taking responsibilities are reversed from the "norm". Dr. Emlen is studying an extreme example of such a species, in which males look after all offspring care and females increase their biological success by having multiple male mates. This research will carefully document the behavioral roles adopted by males and females and the contexts in which different roles are expressed. This will increase scientific understanding of why particular forms of behavior are favored by one sex over the other, and of the evolutionary role of the expression of such behaviors.
