Data from: Inbred and furious: negative association between aggression and genetic diversity in highly inbred fish

Aggressive behaviour plays an important role in securing resources,
defending against predators and shaping social interactions. Although
aggression can have positive effects on growth and reproductive success,
it is also energetically costly and may increase injury and compromise
survival. Individual genetic diversity has been positively associated with
aggression, but the cause for such an association is not clear, and it
might be related to the ability to recognize kin. To disentangle the
relationships between genetic diversity, kinship and aggression, we
quantified aggressive behaviour in a wild, self-fertilizing fish
(Kryptolebias marmoratus) with naturally variable degrees of genetic
diversity, relatedness and familiarity. We found that in contrast to
captive fish, levels of aggression among wild K. marmoratus are positively
associated with individual homozygosity, but not with relatedness or
familiarity. We suggest that the higher aggression shown by homozygous
fish could be related to better kin discrimination and may be facilitated
by hermaphrodite competition for scarce males, given the fitness
advantages provided by outcrossing in terms of parasite resistance. It
seems likely that the relationship between aggression and genetic
diversity is largely influenced by both the environment and population
history.