Evolution of sociability by artificial selection ^*

Abstract

There has been extensive research on the ecology and evolution of social life in animals that live in groups. Less attention, however, has been devoted to apparently solitary species, even though recent research indicates that they also possess complex social behaviors. To address this knowledge gap, we artificially selected on sociability, defined as the tendency to engage in nonaggressive activities with others, in fruit flies. Our goal was to quantify the factors that determine the level of sociability and the traits correlated with this feature. After 25 generations of selection, the high-sociability lineages showed sociability scores about 50% higher than did the low-sociability lineages. Experiments using the evolved lineages indicated that there were no differences in mating success between flies from the low and high lineages. Both males and females from the low lineages, however, were more aggressive than males and females from the high lineages. Finally, the evolved lineages maintained their sociability scores after 10 generations of relaxed selection, suggesting no costs to maintaining low and high sociability, at least under our settings. Sociability is a complex trait, which we currently assess through genomic work on the evolved lineages.

Host and pathogen drivers of infection-induced changes in social aggregation behavior

“…This results confirms previous findings [25,27,44], where sociality exhibits moderate broad sense heritability (H 2 = 0.21-0.24) [27], and readily responds to directional selection [45].…”

“…We also found that genetic background strongly influences social aggregation in fruit flies. This results confirms previous findings [25,27,44], where sociality exhibits moderate broad sense heritability ( H 2 = 0.21-0.24)[27], and readily responds to directional selection [45]. This large variation is to be expected for a polygenic trait such as sociality [27], and is not just characteristic of insects, as genetic background has been also found to influence social behaviours in humans and other mammalian species [9,46].…”

Digest: The evolution of social behavior and its effect on aggressiveness and reproduction

“…Recently, Scott et al. ( 2021 ) used artificial selection on the behavior of fruit flies ( Drosophila melanogaster ) to explore the evolution of sociability and its effect on reproductive traits. Using an experimental approach, they artificially selected individuals (females and males, separately) that showed low and high social behavior based on the size of the groups they formed during feeding (Fig.…”

“… Artificial selection on sociability in fruit flies (Scott et al. 2021 ). (A) Experimental design for the production of low and high sociability lineages via artificial selection and crossing over 25 generations.…”

“…First, these experiments on D. melanogaster showed that sociability is, at least partially, genetically determined (Scott et al. 2021 ). After several generations under selection, low‐ and high‐sociability lineages evolved diverging sociability scores, with males showing a stronger response to selection than females.…”