UCLA

A.J. Bateman (1948) hypothesized that a metric of sexual selection is in sex differences of intrasexual variance in number of mates (V _NM). AJB predicted that (a) males have greater variance in reproductive success (V _RS) than females; (b) males have greater V _NM than females; and (c) a positive relationship between V _NM and V _RS is stronger among males. AJB used phenotypically observable mutations in offspring to identify parents and to count subjects' NM and RS. AJB's conclusions matched his predictions, later called "Bateman's Principles." Empirical challenges to his conclusions guided analyses herein. (a) AJB's analysis pseudo-replicated sample sizes, violating a sexual selection assumption: That is, individuals must be in the same population to choose and compete. (b) AJB's methods overestimated subjects with no mates while underestimating subjects with one or more. (c) A replication (Gowaty et al., 2012) showed that offspring inheriting nametags from both parents often died before expressing adult phenotypes, proving some of AJB's methods produced biased data. Science historian Thierry Hoquet located AJB's archived, handwritten laboratory notes, photocopied, and transcribed them. We tested each of the 65 unique populations for expected combinations in offspring of parental mutations: 41.5% failed Punnett's tests: Offspring carrying nametags simultaneously from both parents were missing showing estimates of parents' NM and V _NM were undercounted. 58.5% of populations met Punnett's expectations providing an unparalleled opportunity to re-evaluate AJB's predictions. 34 unbiased populations had no sex differences in V _RS; 37 had no sex differences in V _NM. No sex differences in slopes of RS and NM occurred in any unbiased population. Regressions showed weak, positive, significant associations between V _NM and V _RS for females and males, contrary to AJB's prediction that the relationship would be positive in males but not in females. AJB's laboratory data are inconsistent with "Bateman's Principles."