11Collective behaviors are widespread in nature and usually assumed to be strongly shaped 12 by natural selection. However, the degree to which variation in collective behavior is heritable 13 and has fitness consequences --the two prerequisites for evolution by natural selection --is 14 largely unknown. We used a new pharaoh ant (Monomorium pharaonis) mapping population to 15 estimate the heritability, genetic correlations, and fitness consequences of three collective 16 behaviors (foraging, aggression, and exploration) as well as body size, sex ratio, and caste ratio.
17Heritability estimates for the collective behaviors were moderate, ranging from 0.17 to 0.32, but 18 lower than our estimates for the heritability of caste ratio, sex ratio, and the body size of new 19 workers, queens, and males. Moreover, variation among colonies in collective behaviors was 20 phenotypically correlated, suggesting that selection may shape multiple colony collective 21 behaviors simultaneously. Finally, we found evidence for directional selection that was similar in 22 strength to estimates of selection in natural populations. Altogether, our study begins to elucidate 23 the genetic architecture of collective behavior and is one of the first studies to demonstrate that it 24 is shaped by selection. 25