Phylogeny and historical aspects of the ecology of eastern Australian scrubwrens Sericornis spp. — evidence from mitochondrial DNA

Authors


  • The research reported here is part of a broader study of patterns of genetic diversity in Australian rain-forest birds, reptiles, frogs and mammals, which aims to investigate theevolutionary ecology and history of the study species themselves and the historical biogeography of eastern Australian rain forests. Leo Joseph is currently completing a PhD focusing on birds in this work. Craig Moritz, in whose laboratory the project is conducted, has broad interests in conservation and evolutionary biology.

Abstract

A phylogeny of mainland eastern Australian scrubwrens (Sericornis citreogularis, S. frontalis, S. keri, S. tnagnirostris and S. beccarii) was constructed using presence or absence of phylogenetically informative restriction sites in 15 mitochondrial DNA (mtDNA) haplotypes. MtDNA sequence divergences between species were generally large (mostly between 10 and 18%) emphasizing the antiquity of this radiation. Phylogenetic analysis of the mtDNA resulted in a strongly supported phylogeny concordant with relationships suggested by a previous study of allozyme variation, but conflicting with concepts based on morphological similarity. The mtDNAs grouped the species into two lineages, one containing beccarii and tnagnirostris and the other comprising citreogularis, frontalis and keri. The mtDNAs of beccarii and tnagnirostris were paraphyletic with a northern variant of tnagnirostris being more similar to beccarii than other magnirostris. The mtDNA from keri was most closely related to that of frontalis and then citreogularis. The strongly corroborated molecular phylogeny confirms and extends the previous (Christidis et al. 1988; Auk 105 > 616) reinterpretation of morphological and ecological shifts in the group. This suggests considerable plasticity and parallelism in the plumage characters previously used to associate species. The low divergence and close relationship between the montane rain-forest specialist keri and the widely distributed generalist frontalis demonstrate the capacity for evolutionarily rapid and dramatic shifts in habitat use. This contrasts with the assumption of fixed habitat preference that underlies refuge-based models of diversification of rain-forest fauna.

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