“Ant Collective Behavior Is Heritable and Shaped by Selection”, 2019-03-04 (; similar):
Collective behaviors are widespread in nature are usually assumed to be strongly shaped by natural selection. However, the degree to which variation in collective behaviors is heritable and has fitness consequences—the two prerequisites for evolution by natural selection—is largely unknown.
We used a new pharaoh ant (Monomorium pharaonis) mapping population to estimate the heritability, genetic correlations, and fitness consequences of 3 collective behaviors (foraging, aggression, and exploration) as well as body size, sex ratio, and caste ratio. Heritability estimates for the collective behaviors were moderate, ranging 0.22–0.40, but lower than our estimates for the heritability of caste ratio, sex ratio, and the body size of new workers, queens, and males. Moreover, the collective behaviors were phenotypically correlated and in some cases genetically correlated, suggesting that they form a suite of correlated traits.
Finally, we found evidence for directional, stabilizing, and disruptive selection that was similar in strength to estimates of selection in natural populations. Disruptive selection was very common and may act to maintain behavioral variation.
Altogether, our study begins to elucidate the genetic architecture of collective behavior and is one of the first studies to demonstrate that it is shaped by selection.