DECIPHERING THE EVOLUTIONARY HISTORY OF THE MONTANE NEW GUINEA AVIFAUNA: COMPARATIVE PHYLOGEOGRAPHY AND INSIGHTS FROM PALEODISTRIBUTIONAL MODELING IN A DYNAMIC LANDSCAPE
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Issue Date
2011-12-31Author
Benz, Brett W.
Publisher
University of Kansas
Format
201 pages
Type
Dissertation
Degree Level
Ph.D.
Discipline
Ecology & Evolutionary Biology
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This item is protected by copyright and unless otherwise specified the copyright of this thesis/dissertation is held by the author.
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Integrating comparative phylogeographic methods with taxon-specific paleodistributional modeling provides a powerful approach for assessing historical environmental factors that have contributed to patterns of population genetic structure and species formation. Herein, I reconcile spatial analyses of genetic diversity with contemporary and paleoecological niche reconstructions in four co-distributed montane passerines to examine how Pleistocene climate change and topographic relief have influenced avian diversification across the New Guinea highlands. Phylogeographic analyses revealed substantial disparity in the distribution of genetic diversity among focal taxa, with Peneothello cyanus and Crateroscelis robusta exhibiting deep divergences along the Strickland River Valley, whereas Rhipidura atra and Amblyornis macgregoriae displayed evidence of gene flow and shallow genetic structure across this biogeographic boundary. Patterns of population genetic structure in P. cyanus and C. robusta were largely congruent with the distribution of contemporary sky-islands and historical population connectivity inferred from Last Glacial Maximum ecological niche reconstructions; however, Mantel tests indicate an isolation-by-distance effect has also impacted the distribution of genetic diversity in each of these taxa. By contrast, R. atra and A. macgregoriae exhibited weak geographic structure and indications of admixture or ancestral polymorphism among most sky-island populations, yet have maintained highly divergent lineages in the Vogelkop and Huon Peninsula, respectively. Signatures of demographic expansion were observed across each species complex, corroborating elevational shifts and range expansion predicted by Last Glacial Maximum ecological niche models. Although differences in dispersal capacity may have contributed to the discordant evolutionary histories among these taxa, limitations of the mtDNA data set preclude assessing the impact of stochastic or selective processes with confidence. This investigation yields novel insight into the evolutionary dynamics that have shaped patterns of avian diversification and historical demography across the New Guinea highlands. Moreover, the phylogenetic relationships recovered within these geographically structured lineages have important implications for understanding the evolution of phenotypic traits, redefining species limits, and clarifying areas of endemism--knowledge critical to guiding future biodiversity investigation and developing informed conservation policies across the region.
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