Broodcare helpers in the cichlid fish Lamprologus brichardi: Their costs and benefits

Kinship reduces alloparental care in cooperative cichlids where helpers pay-to-stay

“…To distinguish reciprocity from other forms of cooperation it is important to critically evaluate if social interactions involve temporary fitness costs, resemble the exchange of services or resources, generate immediate shared benefits, and happen regularly between unrelated individuals 17 . These conditions have been experimentally demonstrated in our study species, where temporary fitness costs of helping are caused by the increased energy expenditure of different helping behaviours 36,37 , which can affect growth 19 . Access to resources in a safe territory is traded against help in defence against competitors 44 and immediate shared benefits to the group members can be generated by cooperative territory defence and digging out shelters, but not by alloparental brood care, which only benefits the breeding group members.…”

“…Therefore, the cooperative behaviour experimentally elicited in this study is of crucial importance for a test of the pay-to-stay hypothesis, as alloparental egg-care does not provide immediate fitness benefits to unrelated helpers, whereas it involves clear costs 36,37 . As this helping effort is hence altruistic, it can be selected for only if helpers receive other fitness benefits in return, which result from the tolerance in a safe territory that provides them with access to vital resources such as shelter and protection 19,29,48 , and opportunities to share in reproduction 49,50 .…”

“…Together, this suggests the existence of direct fitness benefits to helpers 17,18 . Such benefits were experimentally demonstrated in cooperatively breeding vertebrates 19 and can explain cooperative brood care also in some primitively eusocial insects 20 .…”

“…In addition, subordinates may benefit from group membership without group augmentation, for instance because this provides them with access to limited resources or enhances protection from predators 19 . If dominant group members incur costs from the presence of subordinates, for example through competition for resources or for reproduction, they may enforce help from subordinates (for example, to raise the dominants' offspring) in order to compensate for these costs.…”

Fish cognition: a primate's eye view

“…This is because social strategies could have a major influence on reproductive success, as subordinates will try to combine mating success with avoidance of eviction from the group as a consequence of their mating attempts. Such a situation exists in the cichlid fish species with helpers and in the extended family groups of N. multifasciatus, and the functional aspects of these conflicts are well studied (Taborsky 1984(Taborsky , 1985Dierkes et al 1999). Subordinates' frequent submissive behaviours towards high-ranking group members (Kohler 1997) could be seen as a behavioural adaptation to manipulate the decisions of group members.…”