Contrasting phylogeographic signatures in two Australo-Papuan bowerbird species complexes (Aves: Ailuroedus)

The Australo-Papuan catbird genus Ailuroedus has a complex distribution and a contested taxonomy. Here, we integrate phylogenetic analysis of DNA data and morphology to study the group's biogeography and to re-examine its taxonomy. We couple phylogeographic and abiotic data to examine differences between the major groups defined in our phylogenetic analysis. Our results are consistent with Ailuroedus catbirds being divided into two species complexes, one distributed in humid forests in the lowlands on New Guinea and another in comparably drier and colder forests mainly in mid-mountains on New Guinea and Australia. Vicariant events during the Pliocene are surmised to have been the major force in shaping the contemporary phylogeographical signature of this genus. Several previously suggested vicariant events, such as fragmentation of xeric forests in Australia and the uplift of the central mountain range on New Guinea, are reinforced as important Pliocene barriers for tropical forest taxa in this region. Interaction between Pleistocene climatic fluctuations and differences in habitat requirements may explain a higher and more recent population structures in the mid-mountain catbird complex and the lack of representatives from the lowland clade in the comparably drier Australia. Phylogeographical patterns in both catbird complexes, respectively, both comply and deviate from other lowland and mid-mountain taxa in the region. This highlights that taxon-specific properties, such as their historical spatial and ecological distributions, capacity to disperse and tolerance to habitat changes, affect the phylogeographical histories of organisms. Within both species complexes, the genetic differentiation between several geographically isolated populations was found to exceed those commonly observed for avian sister species. As these genetically distinct taxa also were found to be morphological diagnosable, we suggest a revised classification of the genus Ailuroedus, where we recognize three species within the lowland complex and seven species within the mid-mountain complex.