Mitochondrial-Dna Phylogeography of Birds in Eastern Australian Rain-Forests - First Fragments

Abstract

We studied the historical biogeography of eastern Australian rainforests, in particular whether Plio-Pleistocene rainforest refugia existed, through phylogeography of mitochondrial DNA (mtDNA) in seven bird species. Restriction fragment length polymorphisms in four species endemic to northeastern Queensland rainforests showed that within-species differentiation was concordantly structured in two of these (grey-headed robin, Poecilodryas albispecularis, and chowchilla, Orthonyx spaldingii) but not in the others (Australian fernwern, Oreoscopus gutturalis, and Atherton scrubwren, Sericornis keri). Between two more geographically widespread species not confined to rainforests (yellow-throated scrubwren, S. citreogularis, and large-billed scrubwren, S. magnirostris), phylogeographic patterns in north-eastern Queensland were not structured; in the same two species, however, mtDNA diversity was clearly apportioned between south-eastern and north-eastern Queensland, so showing phylogeographic congruence at that geographic scale. A seventh species (white-browed scrubwren, S. frontalis), a wide-ranging habitat-generalist, showed no phylogeographic structure at any geographical scale. The refuge hypothesis is supported in that the location of the genetic break in the grey-headed robin and the chowchilla is identical to that previously reported for mammals and skinks. However, the lack of complete congruence across all endemic species suggests that species with broadly similar current ecologies were not affected in the same way. Evolutionary histories that are more complex and idiosyncratic than previously thought are implicated rather than outright rejection of the refuge hypothesis.