Minor Isolates and Minor Geographical Barriers in Avian Speciation in Continental Australia

Ford, Julian

doi:10.1071/mu9870090

Cited by 65 publications

(55 citation statements)

References 39 publications

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“…Both mtDNA and microsatellite molecular genetic datasets indicated that birds north of the Hunter River (figure 1) are a separate group relative to all others to the south and west (figures 2 and 3). While this result is of historical biogeographic interest (Ford 1987;Schodde & Mason 1997;Adams et al 2006), it directs our focus on where a ring speciation hypothesis can be examined in mainland southeastern Australian populations south and west of the Hunter River. .…”

Section: Discussionmentioning

confidence: 99%

Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

et al. 2008

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Speciation, despite ongoing gene flow can be studied directly in nature in ring species that comprise two reproductively isolated populations connected by a chain or ring of intergrading populations. We applied three tiers of spatio-temporal analysis (phylogeny/historical biogeography, phylogeography and landscape/population genetics) to the data from mitochondrial and nuclear genomes of eastern Australian parrots of the Crimson Rosella Platycercus elegans complex to understand the history and present genetic structure of the ring they have long been considered to form. A ring speciation hypothesis does not explain the patterns we have observed in our data (e.g. multiple genetic discontinuities, discordance in genotypic and phenotypic assignments where terminal differentiates meet). However, we cannot reject that a continuous circular distribution has been involved in the group's history or indeed that one was formed through secondary contact at the 'ring's' east and west; however, we reject a simple ring-species hypothesis as traditionally applied, with secondary contact only at its east. We discuss alternative models involving historical allopatry of populations. We suggest that population expansion shown by population genetics parameters in one of these isolates was accompanied by geographical range expansion, secondary contact and hybridization on the eastern and western sides of the ring. Pleistocene landscape and sea-level and habitat changes then established the birds' current distributions and range disjunctions. Populations now show idiosyncratic patterns of selection and drift. We suggest that selection and drift now drive evolution in different populations within what has been considered the ring.

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Section: Discussionmentioning

confidence: 99%

Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

et al. 2008

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“…There are no obvious current barriers to gene flow on mainland Australia (Ford 1987;Olsen 1995). However, Tasmania is separated from the mainland by the Bass Strait, approximately 200 km of open sea, which contains a few islands on which the species is known to have permanent breeding pairs.…”

Section: Introductionmentioning

confidence: 98%

Conservation status of the White-Bellied Sea-Eagle Haliaeetus leucogaster in Australia determined using mtDNA control region sequence data

et al. 2005

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Considered to have a declining world population, concern has been expressed in recent years over the conservation status of the White-bellied Sea-Eagle Haliaeetus leucogaster (Gmelin, 1788) within Australia. We used mitochondrial (mtDNA) control region sequence data to investigate the current distribution of genetic variation in this species at the continental level and within and between specified regional units. We were specifically interested in identifying breaks in genetic connectivity between the west and east of the continent and between Tasmania and the Australian mainland. We also investigated the likelihood of a bottleneck at the time of colonisation, and propose hypotheses regarding colonisation history. Sequence data were obtained from 128 individuals describing 15 haplotypes. Overall, diversity was low and AMOVA results failed to provide any significant level of genetic subdivision between regions. We suggest that the population expanded from a bottleneck approximately 160,000 years ago during the late Pleistocene, and spread throughout the continent through a contiguous range expansion. There is insufficient evidence to suggest division of the population into different units for conservation management purposes based on the theoretical definition of the 'evolutionary significant unit'. It is clear from the analysis that there are signatures of both historical and contemporary processes affecting the current distribution. Additional sampling and confirmation of the perceived pattern of population structure using a nuclear marker is recommended to validate conservation monitoring and management at a continental scale.

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“…Keast, 1961;Ford, 1987;Bowman et al, 2010). The broad region with a monsoonal climate provides near continuous savanna habitat broken only by stony plateaus and some dry corridors.…”

Section: Introductionmentioning

confidence: 99%

“…Keast, 1961;Ford, 1987) identified three major regions of endemicity that have since been recognized across multiple taxa in the AMT: the Kimberley Block and the escarpments of the Northern Territory and Cape York Peninsula (CYP; Fig. Early studies of regional endemism in birds (e.g.…”

Section: Introductionmentioning

confidence: 99%

Niche differentiation and spatial partitioning in the evolution of two Australian monsoon tropical tree species

Edwards

Crisp

Cook

2012

Journal of Biogeography

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Aim Geographical and climatic barriers to organismal dispersal and distribution play a major role in speciation. We use a sister‐pair of widespread savanna trees (Melaleuca argentea and M. fluviatilis) to test the influence of putative barriers on divergence within and between species across an otherwise continuous landscape. Location The Australian monsoon tropics (AMT). Methods Chloroplast and nuclear DNA sequences were used to estimate variation between and within species. Hypotheses invoking vicariance and ecological speciation as the mechanisms of divergence between species were explicitly tested using ecological niche modelling. Results We found little evidence for divergence across the Carpentaria Basin, although some chloroplast DNA haplotypes were restricted to regions to the east or west. Pilbara populations were distinct from those to the east across the Great Sandy Desert, including those from the Kimberley. There was a complex pattern of genetic divergence and niche differentiation among M. argentea and M. fluviatilis within a region of secondary range overlap coincident with currently recognized species boundaries across the Great Dividing Range. Main conclusions The two morphospecies are ecologically and genetically distinct, and maintain those differences in sympatry. Speciation might have occurred in allopatry in separate drainage basins that later came into contact. The Pilbara population appears to be distinct but requires further investigation.

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Minor Isolates and Minor Geographical Barriers in Avian Speciation in Continental Australia

Cited by 65 publications

References 39 publications

Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

Conservation status of the White-Bellied Sea-Eagle Haliaeetus leucogaster in Australia determined using mtDNA control region sequence data

Niche differentiation and spatial partitioning in the evolution of two Australian monsoon tropical tree species

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