The mammals of northern Melanesia: biogeography, systematics and ecology

Lavery, Tyrone (2014). The mammals of northern Melanesia: biogeography, systematics and ecology PhD Thesis, School of Agriculture and Food Sciences, The University of Queensland. doi:10.14264/uql.2014.113

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Author Lavery, Tyrone
Thesis Title The mammals of northern Melanesia: biogeography, systematics and ecology
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
DOI 10.14264/uql.2014.113
Publication date 2014-01-01
Thesis type PhD Thesis
Total pages 199
Language eng
Subjects 0602 Ecology
0603 Evolutionary Biology
Formatted abstract
Northern Melanesia is an ideal location for biogeographical studies. Such studies of the region’s avifauna have led to fundamental advances in biogeographic and evolutionary theory. However, the mammals of northern Melanesia are poorly known, with incomplete inventories and taxonomic descriptions hampering research and conservation efforts. Biogeographic studies in this region may lead to novel insights given the dominance of marsupials within source pools. Northern Melanesia is experiencing a period of rapid development. Primary forests are rapidly shrinking due to logging and volcanic islands holding mineral resources are increasingly being exploited.

This thesis has provided empirical analyses of northern Melanesia’s and New Guinea’s mammalian zoogeography. Chapter 2 tested the hypothesis that marsupials also have low rates of long-term persistence on continental fragments and shelf islands. Modelling data from Australo-Papuan continental shelf islands, I found a significant difference in this rate between the four orders of non-volant mammals. The order Dasyuromorphia had the lowest rate of persistence overall. Within northern Melanesia, the rate of persistence did not differ between dasyuromorphs, peramelemorphs and rodents, but diprotodontids did exhibit a lower rate than rodents.

Previous studies have also noted differences in rates of speciation among volant lineages of the region. The family Pteropodidae has undergone in situ diversification with numerous endemics whilst insectivorous families show limited diversification and few endemics. Chapter 3 further substantiated this by testing for cryptic diversity in the Family Hipposideridae. Mitochondrial and nuclear genetic sequencing confirmed limited divergence of Solomon Island samples from New Guinean, Australian and Southeast Asian samples. The results indicated an extended presence of Hipposideridae (the most recent common ancestor of Hipposideros and Anthops ornatus was estimated at 22.3 MYA, CI ± 5.6).

Chapter 4 focussed on a finer geographic and temporal scale. Genetic sequencing was combined with microsatellite genotyping and morphological and ecological data to critically determine the evolutionary relationships of leaf-nosed bats (Hipposideros) in the Solomon Islands. The results uncovered a novel example of speciation by demonstrating ‘genetically cryptic morpho-species’. These sympatric species clearly separate by morphology and echolocation call, and are likely reproductively isolated from each other. Yet they showed less that 2% genetic divergence in the mitochondrial gene Cytochrome-b, and even less among the nuclear genes sequenced, and did not separate into individual clades. Larger forms appear to have arisen rapidly, most likely via morphological plasticity and disruptive natural selection in a newly colonised environment. The data suggested that this has in fact happened twice in the Solomon Islands.

In Chapter 5, the hypothesis that marsupials are extremely poor over-water dispersers was supported by the result that distance from New Guinea better explains their distribution than does island size. For all mammals, the model containing island size and percentage of land within a 50 km buffer explained approximately 69% of the between-island variation in species richness.

The results from this thesis have added to biogeographic theory at both regional and local scales. They have linked ecological and evolutionary processes and provided an important empirical baseline to biogeographic patterns in the mammals of northern Melanesia previously only assessed qualitatively. 
Keyword Biogeography

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Created: Wed, 04 Jun 2014, 20:28:30 EST by Mr Tyrone Lavery on behalf of Scholarly Communication and Digitisation Service