This is the main reason to conduct a meta-analysis and cannot be ignored. In addition to male vs. Although our hypothesis of a sex-by-environment interaction predicts that phenotypic differences among treatments should be sex-specific at the level of the individual, it also predicts that increases in the proportion of males within a brood should adversely affect their mass and survival as they face increased competition from other males. This savings rate, in turn, drives the Chinese demand for U. In both experiments, we predicted that the body mass of sons should be more strongly affected than that of daughters by the range of rearing conditions we created. In , for instance, the sex ratio west of the Mississippi was to Furthermore, a meta-analysis of published data on sex ratio variations in primates shows that although no overall effect was detectable, the relation between birth sex ratio and dominance rank was affected by level of resource availability and degree of sexual dimorphism. Sex allocation theory is among the most debated topics of evolutionary ecology. Prostitution booms, too—and not the sex-positive kind that Western feminists are so fond of. The TWM rests upon several important assumptions that must be true for selection to favour sex-ratio adjustment: We also predicted that increases in the proportion of males within a brood should adversely affect their development and survival as they faced increased competition from other males. Figure 2 shows that the relation between population growth rate and effect size is heavily influenced by one possible outlier the Amboseli baboon population studied by Altmann et al. Some nestlings, typically small, underdeveloped runts, occasionally remain in the nest and die of starvation Johnson She also notes that the dearth of women along the frontier in the American West probably had a lot to do with its being wild. Our analyses of nestling body mass focus on asymptotic mass at 11 days of age, and we included tarsus length at this age as a covariate. The odds of courtship are solidly in your favor. As sex-specific effects of early rearing conditions may manifest themselves though differences in post-fledging survival or reproductive success later in life, we monitored the survival and recruitment of these offspring to the breeding population by attempting to catch all breeding adults in subsequent years.