Data for: Direct and indirect benefits of cooperation in collective defense against predation

The evolution and maintenance of public goods cooperation, despite
cheating, remains a key interest in social biology. Specifically,
identifying how ecological factors determine the direct and indirect
benefits that maintain cooperation has proven challenging, as these can
vary significantly across species and environments. Here, we study this
problem by using the social pine sawfly Neodiprion sertifer (Hymenoptera)
as a model system. During their larval stage, N. sertifer live in groups
and collectively secrete a defensive fluid against predators. This
behavior comprises a public good as it is costly to exhibit and beneficial
to others, and individuals vary in their contribution to group defense. We
experimentally manipulated individual contributions to defense to assess
how these influence individual survival. Our results indicate that defense
has a group-level benefit as individuals were more likely to survive in
cooperative groups that had a higher proportion of defending larvae.
Moreover, being able to deploy defensive fluid confers direct survival
benefits to individuals, regardless of group cooperativeness. Genetic and
phenotypic analysis of natural populations further shows that kin
selection promotes collective defense, as groups of larvae are often
composed of full siblings. We also find that contribution to defense is
female-biased and diminishes in male-biased and in larger groups,
indicating that individuals adjust their contributions based on the social
context. Overall, we find that cooperation in anti-predator defense
provides both direct and indirect benefits and that individuals regulate
their contributions mainly based on the social environment, resulting in
variation within and among natural populations.