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Examples of cooperative breeding vary in important ways. In particular, there is much variation in the influence of potential helpers on reproductive success by breeders, in the relatedness of helpers to breeders, and in the distribution of reproduction among group members. Nevertheless, four important generalities emerge.
First, nonbreeding individuals usually remain with their close relatives. Although the contributions of helpers to the success of breeders are too lw, in most cases, for kin selection to provide a sufficient explanation for helping, kin selection does successfully predict whom an individual helps. If nonbreeders help at all, they overwhelmingly help relatives.
Second, most long-term studies of cooperative breeders have revealed that individuals stand to gain by joining groups as nonbreeders and queuing for subsequent opportunities to breed. In this way. cooperative breeding is often a long-term strategy for maximizing reproductive success combined with some short-term advantages from kin selection. For the breeders, retention of offspring in their territory is a long-term form of parental care.
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Third, the association of relatives in cooperative breeders does not preclude competition among them. Although it is often clear that individuals help relatives rather than unrelated individuals, they do not necessarily help relatives rather than promote their own interests -- for example, competition for breeding opportunities within groups of bee-eaters or acorn woodpeckers.
Finally, individuals do not necessarily have to discriminate degrees of relatedness in order to associate with relatives. In many cooperatively breeding species, individuals associate with relatives simply as a consequence of remaining in their natal groups of with individuals that raised them.
Much about cooperative breeding remains to be clarified. Little is known about the behavioral mechanisms that produce the comlex social interactions in cooperatively breeding species, especially individuals' capabilities for discriminating degrees of relatedness or recognizing other group members.
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