Data from: The genetic relatedness in groups of joint-nesting Taiwan Yuhinas: low genetic relatedness with preferences for male kin

The relative importance of direct and indirect fitness and, thus, the role
of kinship in the evolution of social behavior is much debated. Studying
the genetic relatedness of interacting individuals is crucial to improving
our understanding of these issues. Here, we used a seven-year data set to
study the genetic structure of the Taiwan yuhina (Yuhina brunneciceps), a
joint-nesting passerine. Ten microsatellite loci were used to investigate
the pair-wised relatedness among yuhina breeding group members. We found
that the average genetic relatedness between same-sex group members was
very low (0.069 for male dyads and 0.016 for female dyads). There was also
a low ratio of closely-related kin (r>0.25) in the cooperative
breeding groups of yuhinas (21.59% and 9.68% for male and female dyads,
respectively). However, the relatedness of male dyads within breeding
groups was significantly higher than female dyads. Our results suggest
that yuhina cooperation is maintained primarily by direct fitness benefits
to individuals; however, kin selection might play a role in partner choice
for male yuhinas. Our study also highlights an important, but often
neglected, question: Why do animals form non-kin groups, if kin are
available? We use biological market theory to propose an explanation for
group formation of unrelated Taiwan yuhinas.