In many cooperative breeders, the contributions of helpers to cooperative activities change with age, resulting in age-related polyethisms. In contrast, some studies of social mole rats (including naked mole rats, Heterocephalus glaber, and Damaraland mole rats, Fukomys damarensis) suggest that individual differences in cooperative behavior are the result of divergent developmental pathways, leading to discrete and permanent functional categories of helpers that resemble the caste systems found in eusocial insects. Here we show that, in Damaraland mole rats, individual contributions to cooperative behavior increase with age and are higher in fast-growing individuals. Individual contributions to different cooperative tasks are intercorrelated and repeatability of cooperative behavior is similar to that found in other cooperatively breeding vertebrates. Our data provide no evidence that nonreproductive individuals show divergent developmental pathways or specialize in particular tasks. Instead of representing a caste system, variation in the behavior of nonreproductive individuals in Damaraland mole rats closely resembles that found in other cooperatively breeding mammals and appears to be a consequence of age-related polyethism.division of labor | eusociality | caste | cooperative breeding | social mole rats I n cooperatively breeding vertebrates and primitively eusocial insects, subordinate group members frequently vary widely in their investment in cooperative tasks. These differences are often consequences of state-dependent changes in fitness costs and benefits, which vary with age, growth, and sex (1-6), and result in age-and sex-related polyethisms where behavior varies in relation to opportunities to breed. In cooperatively breeding meerkats (Suricata suricatta) for example, fast growing helpers contribute more to overall cooperative behavior; supplementary feeding increases help; and subordinates do not specialize in certain tasks (3, 4, 7). Similar patterns are widespread among other cooperative breeders from diverse taxa [birds (8), mammals (9), fish (10, 11), and primitively eusocial insects (5, 6)].It has been suggested that naked mole rats (Heterocephalus glaber) and Damaraland mole rats (Fukomys damarensis) are an exception to this pattern (12)(13)(14). In these species, the main cooperative task performed by nonbreeding helpers (building a large network of foraging tunnels) is primarily carried out by small individuals of both sexes (12,(14)(15)(16)(17) and it has been argued previously that this may be the result of a caste system, similar to those found in some eusocial insect species. Some studies suggested that in mole rats, specialized, smaller workers conduct most of the energetically demanding burrowing and remain in this state for their entire life, whereas larger workers contribute little to cooperative burrowing but specialize in other cooperative tasks, including nest building, alloparental care, or colony defense (12,14). Others have argued that it is premature to assume that naked mole...

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Social information allows the rapid dissemination of novel information among individuals. However, an individual’s ability to use information is likely to be dependent on phenotypic constraints operating at three successive steps: acquisition, application, and exploitation. We tested this novel framework by quantifying the sequential process of social information use with experimental food patches in wild baboons (Papio ursinus). We identified phenotypic constraints at each step of the information use sequence: peripheral individuals in the proximity network were less likely to acquire and apply social information, while subordinate females were less likely to exploit it successfully. Social bonds and personality also played a limiting role along the sequence. As a result of these constraints, the average individual only acquired and exploited social information on <25% and <5% of occasions. Our study highlights the sequential nature of information use and the fundamental importance of phenotypic constraints on this sequence.DOI: http://dx.doi.org/10.7554/eLife.13125.001

Dispersal behaviour in cooperatively breeding mammals often differs between the sexes, which can affect how individuals of both sexes compete for breeding opportunities. However, it is largely unknown how the males and females in social mole‐rats differ in frequency, timing and social context of dispersal. Here we show, in Damaraland mole‐rats (Fukomys damarensis), that rainfall increases dispersal probabilities in both sexes. Dispersal is male biased with males dispersing earlier and more frequently in dispersal coalitions than females. Most non‐reproductive individuals disperse from the natal groups before reproducing. Territory inheritance is rare, but when it occurs, female non‐breeders inherit the breeding position from the precious breeding female. After dispersing from the natal group, males are more likely than females to join other established groups and to replace the resident breeder. Our study suggests that differences in dispersal strategy may generate contrasts in intra‐sexual competition, where male breeders are more often challenged by competitors from outside the group and female breeders may face higher competition from individuals within the group.