Abstract
Unlike eusocial systems, which are characterized by reproductive division of labour, cooperative breeders were predicted not to exhibit any reproductive specialization early in life. Nevertheless, also cooperative breeders face a major life-history decision between dispersal and independent breeding vs staying as helper on the natal territory, which might affect their reproductive strategies. In the cooperatively-breeding cichlid Neolamprologus pulcher early-life social and predator experiences induce two behavioural types differing in later-life social and dispersal behaviour. We performed a long-term breeding experiment to test whether the two early-life behavioural types differ in their reproductive investment. We found that the early-dispersing type laid fewer and smaller eggs, and thus invested overall less in reproduction, compared to the philopatric type. Thus N. pulcher had specialised already shortly after birth for a dispersal and reproductive strategy, which is in sharp contrast to the proposition that reproductively totipotent cooperative breeders should avoid reproductive specialization before adulthood.
Highlights
Unlike eusocial systems, which are characterized by reproductive division of labour, cooperative breeders were predicted not to exhibit any reproductive specialization early in life
In a two-by-two factorial developmental experiment the early social and early predator experiences of N. pulcher had been manipulated in the laboratory, which revealed that these two environmental factors interactively shape the behavioural phenotype of individuals as well as their decision whether to stay as subordinate in a social group or to disperse early for own breeding[17]
The interaction between social and predator experiences resulted in a specialization into two behavioural types: Individuals raised during their first 2 months of life with older group members and with predator experience (+F/+P) and those raised without older group members and without predator experience (−F/−P) engaged more in helping behaviour later in life and dispersed from their group as soon as given the opportunity to do so
Summary
Unlike eusocial systems, which are characterized by reproductive division of labour, cooperative breeders were predicted not to exhibit any reproductive specialization early in life. Many cooperative breeders face a major life history decision early in life, namely whether to delay dispersal into later adulthood and stay as subordinate brood care helper or to disperse soon after attaining sexual maturity and to breed independently[7,8,9]. We predicted that fish reared under environmental conditions that induced early dispersal (−F/−P and +F/+P)[17] had prepared for the immediate onset of reproduction after dispersal They should (i) be able to reproduce more readily and at a faster rate, and (ii) possibly invest more energy in reproduction relative to their body size, compared to philopatric individuals remaining as subordinate group members for an extended period of time (i.e., fish reared in +F/−P and –F/ + P conditions[17])
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