Résumé
Birds vary greatly in their life-history strategies, including their
breeding systems, which range from brood parasitism to a system with
multiple non-breeding helpers at the nest. By far the most common
arrangement, however, is where both parents participate in raising the
young. The traits associated with parental care have been suggested to
affect dispersal propensity and lineage diversification, but to date tests
of this potential relationship at broad temporal and spatial scales have
been limited. Here, using data from a globally distributed group of
corvoid birds in concordance with state-dependent speciation and
extinction models, we suggest that pair breeding is associated with
elevated speciation rates. Estimates of transition between breeding
systems imply that cooperative lineages frequently evolve biparental care,
whereas pair breeders rarely become cooperative. We further highlight that
these groups have differences in their spatial distributions, with pair
breeders over-represented on islands, and cooperative breeders mainly
found on continents. Finally, we find that speciation rates appear to be
significantly higher on islands compared to continents. These results
imply that the transition from cooperative breeding to pair breeding was
likely a significant contributing factor facilitating dispersal across
tropical archipelagos, and subsequent world-wide phylogenetic expansion
among the core Corvoidea.