Eusociality and Cooperation

Abstract

Ants, termites and many species of bees and wasps form tightly integrated social groups in which permanently nonreproducing workers help rear the offspring of a few fertile individuals, the queens and males. Such societies with marked reproductive division of labour are called eusocial. The evolution of eusociality puzzled Darwin: How could workers pass on their characteristics to the next generation if they did not reproduce? Kin selection, the indirect transmission of genes through relatives, is the key process explaining the evolution and maintenance of permanently nonreproducing workers. Overall, eusociality evolved in life‐long associations of monogamous parents and offspring, which jointly exploit and defend common resources. Robust and efficient division of labour contributes to the great ecological success of eusocial species. Yet, despite high levels of integration, conflicts among individuals are still common in eusocial groups, and several sophisticated mechanisms have evolved to maintain social cohesion. Key Concepts Eusociality is characterised by reproductive division of labour, cooperative brood care and overlap of generations. The hallmark of eusociality is the presence of a caste that is permanently committed to a nonreproductive helper role. Eusociality confers great ecological success, but has a scattered taxonomic distribution. Kin selection is the key process explaining the evolution of permanently nonreproducing helpers. Eusociality evolved in groups of highly related individuals, typically comprising the offspring of a monogamous pair. Eusociality is linked with division of labour, which is sometimes associated with morphological castes. The allocation of workers to tasks is a self‐organising process that occurs without central control and emerges from local interactions. In social insects, division of labour is remarkably robust and flexible to cope with unpredictable changes in the environment. Individuals in animal societies are not clones; they have partially divergent genetic interests, which can lead to various forms of conflicts. Some types of conflicts are controlled by social means such as bribing, coercion or punishment.

Peer Review #2 of "The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species (v0.1)"

“…PDF | (2017:03:17118:2:0:NEW 29 Sep 2017) Manuscript to be reviewed Studies providing a quantitative measure of the link between maternal investment and group size in eusocial species are rare. Moreover, we did not specifically search for these as our focus was on instances where maternal investment could vary both pre-and post-natally: in eusocial species, mothers tend not to provide any offspring care beyond egg production when helpers are present and almost all post-natal care is performed exclusively by helpers (Keller and Chapuisat, 2010). We also did not include species where offspring care is shared only among reproductively active females (e.g., Grinsted, Breuker & Bilder, 2014), as it is difficult to determine how individual mothers differ in their investment.…”

The impact of social complexity on the efficacy of natural selection in termites

“…Eusociality represents the pinnacle of social organization within the animal kingdom, characterized by a clear division of reproductive labor among different castes, cooperative care for young and the presence of overlapping generations within a colony (Keller and Chapuisat, 2001). Various forms of social organizations have independently emerged in several taxa such as Coleoptera, Thysanoptera (Choe and Crespi, 1997), crustaceans (Duffy, 1996) or mammals (Jarvis et al, 1994), but the most complex forms of eusociality appeared only within Hymenoptera (e.g., bees, wasps, ants) and Isoptera (termites; Howard and Thorne, 2011).…”

Shadow competition: its definition, prevalence, causes and measurement

“…4–5). Some groups are highly cooperative and share much more than simply space, and an extreme example is the case of the complex collective behaviour and dominant importance of inclusive fitness in eusocial animals (Keller and Chapuisat 2001). Individuals in most groups, however, are more loosely linked to each other and aggregate for reasons such as the dilution of predation risk, collective foraging or seeking mating opportunities (Hamilton 1971, Svensson and Petersson 1992, Hamilton and Dill 2003).…”