The influence of climatic changes occurring since the late Miocene on Australia's eastern mesic ecosystems has received significant attention over the past 20 years. In particular, the impact of the dramatic shift from widespread rainforest habitat to a much drier landscape in which closed forest refugia were dissected by open woodland/savannah ecosystems has long been a focal point in Australian ecology and biogeography. Several specific regions along the eastern coast have been identified previously as potentially representing major biogeographical disjunctions for closed forest taxa. Initially, evidence stemmed from recognition of common zones where avian species/subspecies distributions and/or floral communities were consistently separated, but the body of work has since grown significantly with the rise of molecular phylogeographic tools and there is now a significant literature base that discusses the drivers, processes and effects of these hypothesised major biogeographical junctions (termed barriers). Here, we review the literature concerning eight major barriers argued to have influenced closed forest taxa; namely, the Laura Basin, Black Mountain Corridor, Burdekin Gap, Saint Lawrence Gap, Brisbane Valley Barrier, Hunter Valley Barrier, Southern Transition Zone and East Gippsland Barrier. We synthesise reported phylogeographical patterns and the inferred timing of influence with current climatic, vegetation and geological characteristics for each barrier to provide insights into regional evolution and seek to elicit common trends. All eight putative biogeographical barriers are characterised currently by lowland zones of drier, warmer, more open woodland and savannah habitat, with adjacent closed forest habitats isolated to upland cool, wet refugia. Molecular divergence estimates suggest two pulses of divergence, one in the early Miocene (~20–15 Mya) and a later one from the Pliocene–Pleistocene (~6–0.04 Mya). We conclude with a prospectus for future research on the eastern Australian closed forests and highlight critical issues for ongoing studies of biogeographical barriers worldwide.
Fuller, S. J. (2011). Phylogenetic relationships and divergence date estimates among Australo-Papuan mosaic-tailed rats from the Uromys division (Rodentia: Muridae). -Zoologica Scripta, 40, 433-447. We inferred phylogenetic relationships and divergence date estimates among four genera of mosaic-tailed rats from the Uromys division in Australia, New Guinea and the Solomon Islands from both mitochondrial (16S rRNA) and nuclear (AP5 and DHFR introns) nucleotide sequence data. Phylogenetic analysis of our combined data shows that Melomys species from Australia and New Guinea are monophyletic to the exclusion of Paramelomys, which last shared a common ancestor with other members of the Uromys division approximately 3 MYA. However, Melomys was found to be paraphyletic with respect to the Solomon Islands endemic Solomys, suggesting the taxonomic distinction of the latter may need revision. The radiation of this group was estimated to have occurred between 2.1 MYA and 900 000 years ago. A currently undescribed taxon, species nova, which is apparently morphologically indistinguishable from sympatric M. cervinipes, was found to be a highly distinctive lineage and was not monophyletic with Melomys from Australia or New Guinea. Australian Uromys share a sister group relationship with sp. n. and the Melomys ⁄ Solomys clade. Australian Melomys were not monophyletic with respect to New Guinean Melomys. The New Guinean M. lutillus and Australian M. burtoni appear to be conspecific, supporting a previous suggestion that M. burtoni has an extralimital distribution encompassing New Guinea as M. lutillus. This also suggests sustained contact between these taxa, most likely enabled through historical landbridges that linked the two landmasses during periods of lower sea level. Melomys rubicola, found only on Bramble Cay, 50 km south of New Guinea, is more closely related to Australian Melomys, particularly M. capensis, than to any of the New Guinean species. Results suggest that M. rubicola and M. capensis last shared a common ancestor in the early Pleistocene, a time when land bridges existed connecting Bramble Cay to Cape York. Finally, polyphyly within M. cervinipes was also detected, corresponding to reciprocally monophyletic northern and southern clades. The northern M. cervinipes clade diverged from the M. capensis ⁄ rubicola clade approximately 1.2 MYA, with this split possibly resulting from isolation across the Normanby gap in far north Queensland.
Aim Our aim was to clarify the lineage‐level relationships for Melomys cervinipes and its close relatives and investigate whether the patterns of divergence observed for these wet‐forest‐restricted mammals may be associated with recognized biogeographical barriers. Location Mesic closed forest along the east coast of Australia, from north Queensland to mid‐eastern New South Wales. Methods To enable rigorous phylogenetic reconstruction, divergence‐date estimation and phylogeographical inference, we analysed DNA sequence and microsatellite data from 307 specimens across the complete distribution of M. cervinipes (45 localities). Results Three divergent genetic lineages were found within M. cervinipes, corresponding to geographically delineated northern, central and southern clades. Additionally, a fourth lineage, comprising M. rubicola and M. capensis, was identified and was most closely related to the northern M. cervinipes lineage. Secondary contact of the northern and central lineages was identified at one locality to the north of the Burdekin Gap. Main conclusions Contemporary processes of repeated habitat fragmentation and contraction, local extinction events and subsequent re‐expansion across both small and large areas, coupled with the historical influence of the Brisbane Valley Barrier, the St Lawrence Gap and the Burdekin Gap, have contributed to the present phylogeographical structure within M. cervinipes. Our study highlights the need to sample close to the periphery of putative biogeographical barriers or risk missing vital phylogeographical information that may significantly alter the interpretation of biogeographical hypotheses.
A dated molecular phylogeny is proposed for the Tanypodinae, a diverse subfamily of Chironomidae (Diptera). We used molecular data from fragments of one ribosomal gene (28S), one nuclear protein-coding gene (CAD), and one mitochondrial protein-coding gene (COI), analysed using mixed model Bayesian and maximum likelihood inference methods. All proposed tribes were sampled, namely, Anatopyniini, Clinotanypodini, Coelopyniini, Fittkauimyiini, Macropelopiini, Natarsiini, Pentaneurini, Procladiini and Tanypodini. A multilocus dataset of 1938 characters was compiled from 123 individuals including outgroups. Monophyly was supported for all tribes although some relationships were not robust. Relationships between tribes and some genus groups are highly congruent with a morphology-based estimate. Relationships within tribe Pentaneurini mostly find weak support, yet previously hypothesised groupings and monophyly or lack thereof in well-sampled genera are revealed. The tempo of diversification of the family was deduced by divergence time analysis (BEAST). Origination of a subfamily stem group in the late Jurassic to early Cretaceous was inferred, with all tribes and many genera of Pentaneurini originating and diversifying in the Cretaceous. Some nodes are biogeographically informative. Gene sections supported the backbone, but more extensive sampling is needed to estimate shallower phylogenies and to better understand the tempo and diversification of Tanypodinae.
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