Data from: Large fitness benefits of social nesting in a small carpenter bee

Facultatively social insects are an optimal model group for the study of
the emergence of cooperation between individuals. Factors influencing the
fitness benefits of social nesting are still debated. Non-reproductive
subordinates can benefit from indirect fitness benefits due to increasing
reproductive success of related individuals or direct fitness benefits due
to direct future reproduction. Here, we studied the costs and benefits of
social nesting in the small carpenter bee Ceratina albosticta. From
demographic data and within-nest relatedness we obtained key parameters
for assessing the fitness of solitary females, social primaries, and
social secondaries. C. albosticta were found to usually mate with one male
and multiple mating is not common although exists at low frequencies.
Social nests usually contain two females, which were found to be related
(full sisters), but also some females were unrelated to each other.
Patterns of parentage from microsatellite loci revealed that only one
female reproduces in social nests. Our results show that relatedness, per
capita brood productivity, and offspring survival strongly increase the
fitness benefits of social nesting strategies. Social secondaries, when
related to the social primaries, have higher inclusive fitness than
solitary females, but unrelated social nesting females had no indirect
fitness and much reduced inclusive fitness compared to solitary females.
Interestingly, average fitness benefits of the social secondary were
higher than solitary females. This study provides important empirical data
on the costs and benefits of sociality in a facultatively social bee and
sets the stage for future comparative studies.