Major global radiation of corvoid birds originated in the proto-Papuan archipelago

Abstract

A central paradigm in island biogeography has been the unidirectional "downstream" colonization of islands from continents (source to sink) based on the idea that less-diverse island communities are easier to invade than biologically more-diverse continental communities. Recently, several cases of "upstream" colonization (from islands to continents) have been documented, challenging the traditional view. However, all these cases have involved individual island species that have colonized mainland regions. Here, using molecular phylogenetic data, divergence time estimates, lineage diversity distributions, and ancestral area analyses, we reconstruct the spread of a species-rich (>700 species) passerine bird radiation (core Corvoidea) from its late Eocene/Oligocene origin in the emerging proto-Papuan archipelago north of Australia, including multiple colonizations from the archipelago to Southeast Asia. Thus, islands apparently provided the setting for the initiation of a major songbird radiation that subsequently invaded all other continents. Morphological and behavioral adaptations of the core Corvoidea as generalist feeders in open habitats, which facilitated dispersal and colonization, apparently evolved in the descendants of sedentary forest birds that invaded the proto-Papuan archipelago. The archipelago evidently provided islands of the right size, number, and proximity to continental areas to support the adaptation and diversification of vagile colonizers that went on to increase avian diversity on a global scale.Indo-Pacific | Passeriformes | community assembly | macroecology | range expansion

Out of the Neotropics: Late Cretaceous colonization of Australasia by American arthropods

“…New Guinea, New Caledonia, northern Australia). New Guinea is an especially diverse island with complex geological history, and the putative source region of many diverse metazoan radiations, some of which extend worldwide [5,49,50]. The recovery of all New Guinean species, which constitute the most morphologically diverse Zalmoxis, within a single derived clade (that may include a Palauan species) is therefore an unexpected result.…”

Relicts from Tertiary Australasia: undescribed families and subfamilies of songbirds (Passeriformes) and their zoogeographic signal

“…Of the eleven newly described taxa, moreover, seven are members of the corvoid assemblage. Although there is general agreement that other root lineages of songbirds arose on the Australian fragment of east Gondwana (Ericson et al 2002;Barker et al 2004;Jènsson et al 2011), the source of the corvoid assemblage has become subject to conflicting interpretations of phylogeographic history and the role of New Guinea.…”

Evidence of taxon cycles in an Indo-Pacific passerine bird radiation (Aves: Pachycephala )

“…Such adaptations may be reflected in morphological traits associated with diet, substrate use and movements [42,43]. We therefore expect to find morphological differentiation among sympatric island taxa, including relatively longer wings and shorter toes/tarsi in stages I and II taxa than in relictual lineages [26]. While we do find a tendency for relictual taxa to occupy inland primary montane habitats (five out of eight lineages, table 1), the ultimate comparison should be undertaken between sympatric island taxa.…”

“…Here, we focus on the passerine bird genus Pachycephala, which originated in Australo-Papua and later colonized the Indonesian and Philippine archipelagos to the west and the Pacific archipelagos to the east [25,26]. We focus on the parts of the island region with relatively simple geological history surrounding the area of origin, and thus exclude Borneo, Sumatra, Java, Sulawesi and the Philippines.…”