Evolution of social behaviour in the primitively eusocial waspRopalidia marginata: do we need to look beyond kin selection?

Abstract

One contribution of 18 to a theme issue 'The evolution of cooperation based on direct fitness benefits'. Ropalidia marginata is a primitively eusocial wasp widely distributed in peninsular India. Although solitary females found a small proportion of nests, the vast majority of new nests are founded by small groups of females. In such multiple foundress nests, a single dominant female functions as the queen and lays eggs, while the rest function as sterile workers and care for the queen's brood. Previous attempts to understand the evolution of social behaviour and altruism in this species have employed inclusive fitness theory (kin selection) as a guiding framework. Although inclusive fitness theory is quite successful in explaining the high propensity of the wasps to found nests in groups, several features of their social organization suggest that forces other than kin selection may also have played a significant role in the evolution of this species. These features include lowering of genetic relatedness owing to polyandry and serial polygyny, nest foundation by unrelated individuals, acceptance of young non-nest-mates, a combination of well-developed nest-mate recognition and lack of intra-colony kin recognition, a combination of meek and docile queens and a decentralized self-organized work force, long reproductive queues with cryptic heir designates and conflict-free queen succession, all resulting in extreme intra-colony cooperation and inter-colony conflict.

Correlated pay-offs are key to cooperation

“…However, also in these groups, reciprocal cooperation may be important, as we have outlined above. In addition, such groups often contain unrelated individuals [2,4,6,197,251,252], meaning that helping each other crucially depends on the give-and-take characterizing reciprocity. Close personal relationships between individuals in such groups will promote cooperation because the involved social partners will interact with each other more likely and more often.…”

Split sex ratios and genetic relatedness in a primitively eusocial sweat bee

“…In order for relatedness benefits alone to favour helping, we should expect to see high helper-brood relatedness across colonies (r > 0.5). However, data from primitively eusocial insects are limited and so far show mixed results, with some studies reporting high (Crozier et al, 1987;Kukuk, 1989;Matthews, 1989a, 1989b), and others lower estimates of nest mate relatedness (Packer and Owen, 1994;Brand and Chapuisat, 2016;Gadagkar, 2016;Sumner et al, 2007). If relatedness benefits are not sufficiently high, then additional ecological advantages of group living might also be required to explain the maintenance of helping behaviour.…”

Genetics and developmental biology of cooperation

“…Mutually beneficial behaviours can evolve even in the absence of relatedness between the interaction partners, because both partners gain direct net fitness benefits immediately or with some delay, and hence, no conflict of interest occurs (Lehmann & Keller, ). Many examples of cooperation in birds (Riehl, ), fish (Wong & Balshine, ), vampire bats (Wilkinson, Carter, Bohn, & Adams, ), humans (Jaeggi & Gurven, ) and insects (Field & Leadbeater, ; Gadagkar, ) demonstrate that interaction partners are indeed often unrelated. Therefore, kin selection may not be the primary evolutionary force driving cooperation in these systems (Taborsky et al., ), and alternative hypotheses focusing on the IGEs should be considered.…”

“…Early caste determination is a common phenomenon in most eusocial insects where nutrition and inhibitory pheromones play an important role (Schwander, Lo, Beekman, Oldroyd, & Keller, 2010). There are, however, a number of social insect species that are cooperative breeders without morphological specializations, which can switch between the role of subordinates and dominants within a lifetime (Field & Leadbeater, 2016;Gadagkar, 2016).…”