The role of kinship and demography in shaping cooperation amongst male lions

Abstract

The influence of kinship on animal cooperation is often unclear. Cooperating Asiatic lion coalitions are linearly hierarchical; male partners appropriate resources disproportionately. To investigate how kinship affect coalitionary dynamics, we combined microsatellite based genetic inferences with long-term genealogical records to measure relatedness between coalition partners of free-ranging lions in Gir, India. Large coalitions had higher likelihood of having sibling partners, while pairs were primarily unrelated. Fitness computations incorporating genetic relatedness revealed that low-ranking males in large coalitions were typically related to the dominant males and had fitness indices higher than single males, contrary to the previous understanding of this system based on indices derived from behavioural metrics alone. This demonstrates the indirect benefits to (related) males in large coalitions. Dominant males were found to ‘lose less’ if they lost mating opportunities to related partners versus unrelated males. From observations on territorial conflicts we show that while unrelated males cooperate, kin-selected benefits are ultimately essential for the maintenance of large coalitions. Although large coalitions maximised fitness as a group, demographic parameters limited their prevalence by restricting kin availability. Such demographic and behavioural constraints condition two-male coalitions to be the most attainable compromise for Gir lions.

Benefits of living closer to kin vary by genealogical relationship in a territorial mammal

“…These findings demonstrate that cooperation with unrelated individuals can buffer individuals from the risks of temporarily or permanently losing access to a close relative. In other words, despite lacking the advantage of inclusive fitness benefits, group-living animals may choose to invest in mutualistic bonds with non-kin if it leads to a more predictable social environment [18,19]. So, while kin selection is typically considered the lower-threshold pathway to prosocial bonds [20], mammals living in less-structured social environments may instead prioritize mutualistic bonds with potentially unrelated individuals.…”

Parental breeding decisions and genetic quality predict social structure of independent offspring

“…On the other hand, associating with kin (e.g. Archie et al, 2006; Carter et al, 2013; Kurvers et al, 2013) can enhance social learning or cooperation (Kerth, 2008; Schwab et al, 2008) and improve growth, survival and indirect fitness (Chakrabarti et al, 2020; Feh, 1999; Gerlach et al, 2007; Thünken et al, 2016). Finally, social learning can also be enhanced by associating with familiar individuals, regardless of their genetic relatedness, as they are expected to be more reliable demonstrators (Camacho‐Alpízar & Guillette, 2023).…”

Intergenerational effects from spatial and genetic environment predict early-life social network structure

“…Early independence presents an opportunity for juveniles to associate with unrelated individuals for the first time, meaning that genetic relatedness underlying associations may become more variable at this point. In some species, siblings continue to form strong bonds despite the option to disassociate (Archie et al, 2006; Carter et al, 2013; Kurvers et al, 2013), which can enhance social learning or cooperation (Kerth, 2008; Schwab et al, 2008), and improve reproduction, survival, and growth (Chakrabarti et al, 2020; Feh, 1999; Gerlach et al, 2007; Thünken et al, 2016). However, the benefits of kin associations can be context-specific, particularly if social structure predicts later mating decisions (Firth and Sheldon, 2016) and developing associations between genetically dissimilar or unfamiliar non-kin prevents inbreeding (Godfrey et al, 2014; Hirsch et al, 2013; Kurvers et al, 2013; Mourier and Planes, 2021).…”