The brood parasite's guide to inclusive fitness theory

Abstract

One contribution of 18 to a theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.Hamilton's theory of inclusive fitness provides a framework for understanding the evolution of social behaviour between kin, including parental and alloparental care. Brood parasitism is a reproductive tactic in which parasites exploit the care of other individuals of the same species (conspecific parasitism) or different species (interspecific parasitism) to rear their brood. Here, drawing from examples in birds and social insects, we identify two insights into brood parasitism that stem from inclusive fitness theory. First, the kin structure within nests, or between neighbouring nests, can create a niche space favouring the evolution of conspecific parasitism. For example, low average relatedness within social insect nests can increase selection for reproductive cheats. Likewise, high average relatedness between adjacent nests of some birds can increase a female's tolerance of parasitism by her neighbour. Second, intrabrood conflict will be high in parasitized broods, from the perspective of both parasite and host young, relative to unparasitized broods. We also discuss offspring recognition by hosts as an example of discrimination in a kin-selected social behaviour. We conclude that the inclusive fitness framework is instructive for understanding aspects of brood parasite and host evolution. In turn, brood parasites present some unique opportunities to test the predictions of inclusive fitness theory.This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

The coevolutionary biology of brood parasitism: a call for integration

“…Riehl & Feeney [14] Cohen et al [18] Cini et al [22] Gloag & Beekman [30] Cotter et al [24] Suhonen et al [64] McClelland et al [76] Medina & Langmore [77] How readily can parasites switch hosts? Are the outcomes of coevolutionary arms' races predictable?…”

“…Can brood parasitism provide insight into the evolution of other life-history strategies? In this special issue, Cini et al [22] consider this for sociality, Gloag & Beekman [30] for inclusive fitness and Riehl & Feeney [14] for cooperative breeding. These studies focus on the brood parasites of social insects and/or birds, but brood-parasitic cuckoo catfish may provide new avenues for similar work if we can experimentally modify the amount of care, or paternity certainty, of cichlid host males (a point argued by Polacik et al [17] in this issue).…”

“…B 374: 20180190 these questions are naturally addressed in the context of social living and indirect fitness (e.g. [22,23,30] in this issue); questions that are rarely considered in avian systems ( [31] and [30] in this issue).…”

“…Brood parasitism in any taxonomic group is a derived behaviour of parental care. Therefore, understanding how cheating by brood parasites evolves requires knowledge of the costs and benefits of providing parental care (see [24], this issue), and who pays these costs (see [30], this issue). Any social behaviour is vulnerable to a cheater phenotype, and answering the question of what keeps costly social behaviours, especially social cooperation, evolutionarily stable is of broad relevance in biology.…”

Defences against brood parasites from a social immunity perspective

“…Theory predicts that the presence and strength of social immune defences produced on behalf of kin will vary because of the balance of costs (c) versus benefits (b), modified by the relatedness (r) of the donor to the recipient (Hamilton's rule: r  b . c [126]) (also see [127] for a similar approach from the brood parasite's perspective). As discussed above, any mechanisms that could reduce the costs The potential for conflict between donors and recipients is estimated across the stages of parasite encounter for defences against classic parasites (yellow), brood parasites (red) or both (orange).…”