Female-female aggression in a sexual/unisexual species complex over resources

Abstract

Kin selection theory predicts that closely related individuals should be more altruistic and less antagonistic towards one another. In addition, it would predict that the higher the relatedness value (R) between individuals, such as in clonal organisms, the more likely kin selection is to evolve. One benefit of kin selection is a reduction in aggression towards kininvarious social contexts, such as foraging. In the gynogenetic Amazon molly, Poecilia formosa, females have been shown to differentiate between clone types, preferring to associate with clonal sisters to non-sisters, and regulate their aggressive behaviors accordingly. We ask ifAmazon mollies in resource-limited environments: 1) still maintain the ability to regulate aggressive behaviors according to relatedness (heterospecific females, clonal sisters or non-sisters), and 2) how their aggressivebehaviors change relative to a females social partner? Using a repeated-measures design, we found that focal females regulated their aggressive behaviors depending on partner type (i.e., a heterospecific female, clonal sister, or non-sister). Heterospecific females and the non-sister clones spent more time behaving aggressively towards the focal females, and these females also received significantly more bites from heterospecific females. Interestingly, the clonal sisters, when compared to the other two female types, performed significantly more tail beats towards focal females.We are able to confirm that females do show more aggression towards heterospecific females and non-sister clones in a food-limited environment, andthat their aggression scales with relatedness (R).\n\nLay SummaryKin recognition allows individuals to adjust costly behaviors, such as aggression, according to the degree of genetic relatedness. We show that in a food-limited environment, a clonal species of fish, the Amazon molly, females regulate aggressive behaviors depending on how closely related they are to the recipient female, behaving more aggressively to both heterospecific females and non-sister clones. The ability to regulate costly behaviors under variable socialconditions is advantageous, especially when resources are limited.