Vicariance, speciation and diversity in Australopapuan rainforest frogs

Cunningham, Michael. (2001). Vicariance, speciation and diversity in Australopapuan rainforest frogs PhD Thesis, School of Biological Sciences, The University of Queensland.

       
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Author Cunningham, Michael.
Thesis Title Vicariance, speciation and diversity in Australopapuan rainforest frogs
School, Centre or Institute School of Biological Sciences
Institution The University of Queensland
Publication date 2001-04
Thesis type PhD Thesis
Supervisor Moritz, Craig
Total pages 368
Collection year 2002
Language eng
Subjects L
270599 Zoology not elsewhere classified
780105 Biological sciences
Formatted abstract This thesis is concerned with the reconstruction of rainforest history from mitochondrial DNA gene-trees, and the role of historical isolation in organismal evolution, particularly in the origin of new species. More directly, this thesis describes geographical patterns of diversity and the individual histories of four stream breeding frog species endemic to the Australian Wet Tropics region (Wet Tropics): the Green-eyed Treefrog, Litoria serrata (previously genimaculata); Australian Waterfall Frog, Litoria nannotis; Common Mist-frog, Litoria rheocola; and the Australian Lace-lid, Nyctimystes dayi. Recent declines and the disappearance of upland populations have affected these species to differing degrees. The central aim of this thesis is to provide an understanding of relationships among populations and the processes which have shaped diversity, in genes and appearance, as a background context to conservation.

Phylogenetic reconstructions using 16S mitochondrial DNA sequences demonstrate a long history for Green-eyed Treefrogs in the Australian Wet Tropics. Maximum Likelihood analyses reject monophyly of Litoria genimaculata with serrata, and suggest polyphyly of Australian Eucnemis complex populations (Cape York Litoria eucnemis and Wet Tropics serrata). Within the Wet Tropics serrata comprises deeply divergent lineages in the Northern and Southern Wet Tropics (7.0% divergence). By contrast, Australian and New Guinea populations of eucnemis are closely related (1.2% divergence), indicating late- Pleistocene or Holocene migration across Torres Strait. New Guinea genimaculata together with Litoria exophthalmia and Litoria sp. 'Ok Teditau' form a weU supported group, and these species can not be separated with mitochondrial DNA. The simple call which unites genimaculata with serrata is an ancestral state which has been retained in divergent lineages, some of which are more closely related to other species with other call types. This prompts the question, how do similarity of calls but genetic dissimilarity affect reproductive cohesion when historically isolated populations meet?

Mitochondrial gene-trees from COI sequences revealed two fundamental scales of genetic structure in frogs of the Wet Tropics. Each species comprises deeply divergent, geographically complementary lineages which are attributed to isolation of regional populations, perhaps as early as the late Miocene. Nested clade analyses revealed shallow but more detailed structure within lineages, resulting from a mosaic history of fragmentation, range expansion, and restricted dispersal over the late-Pleistocene and Holocene. Despite general similarity in form, species histories are incongruent in detail. Species differ in the number of deep lineages (two in serrata and N. dayi, three in nannotis Mitochondrial gene-trees from COI sequences revealed two fundamental scales of genetic structure in frogs of the Wet Tropics. Each species comprises deeply divergent, geographically complementary lineages which are attributed to isolation of regional populations, perhaps as early as the late Miocene. Nested clade analyses revealed shallow but more detailed structure within lineages, resulting from a mosaic history of fragmentation, range expansion, and restricted dispersal over the late-Pleistocene and Holocene. Despite general similarity in form, species histories are incongruent in detail. Species differ in the number of deep lineages (two in serrata and N. dayi, three in nannotis and rheocola), in the depth of divergence among lineages (net nucleotide divergence varies from 1.6% in rheocola to 13.5% in serrata), in the location of breaks between lineages, and in diversity within lineages (nucleotide diversity of 0.02-0.06% in N. dayi versus 0.24-0.64% in other species). Within lineages, consistent structure in the north indicates relative stability of refuges in the Fuinegan, Thornton and Carbine rainforest blocks. Incongruence and range expansions in the central and southern Wet Tropics suggest a more dynamic distribution of rainforest, with greater opportunity for ecological sorting.  .....................
Keyword Frogs -- Australia.
Frogs -- Papua.

 
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Created: Fri, 24 Aug 2007, 17:50:45 EST