Self-sacrifice in 'desperado' contests between relatives

Table 2 Examples of contests between relatives in a potential 'desperado' context in social insects.

	Species	Contestants	Reason for contest	Relatedness to competitors	Overt reciprocal fighting?	References
	Aphaenogaster senilis	Queens	Colony inheritance during requeening	High (0.75)	N	[20, 21]
	Cataglyphis cursor	Queens	Colony inheritance during requeening or fission	Low (polyandry) to high (parthenogenesis)	Y	[43], Chéron unpublished data
Ants	Cardiocondyla wroughtonii	Males	Mating opportunities	Low (polygyny)	Y	[6, 7]
	Hypoponera bondroiti	Males	Mating opportunities	Low (polygyny)	Y	[44]
	Apis mellifera	Queens	Colony inheritance during requeening or fission	Low (polyandry)	Y	[13, 14]
Bees	Melipona beecheii	Queens	Normal colony cycle	Moderate (mother - daughter) to High (full-sisters)	N (workers kill new queens quickly)	[42, 45]
	Pleibia remota	Queens	Colony inheritance during colony cycle	Moderate?	Y (mother and daughter)	[46]

In most instances relatedness is lower than in A. senilis, which may explain the prevalence of fighting reported in other species. The transitory presence of multiple related queens arises in monogynous social insects during preparation for colony fission, queen replacement, and as part of the normal colony cycle in stingless bees (continuous rearing). Male-male contests arise when mating occurs in the natal nest.

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