Type of Document Dissertation Author Claramunt Tammaro, Santiago Javier Author's Email Address email@example.com URN etd-04152010-114242 Title Testing Models of Biological Diversification: Morphological Evolution and Cladogenesis in the Neotropical Furnariidae (Aves: Passeriformes) Degree Doctor of Philosophy (Ph.D.) Department Biological Sciences Advisory Committee
Advisor Name Title Remsen Jr., James V. Committee Chair Brumfield, Robb T. Committee Co-Chair Hellberg, Michael E. Committee Member Sheldon, Frederick H. Committee Member King, Sammy Dean's Representative Keywords
- comparative methods
- South America
Date of Defense 2010-03-24 Availability unrestricted AbstractIn this dissertation I explored the processes that generated high species diversity in a continental adaptive radiation of passerine birds: the family Furnariidae. Although there is a vast amount of information on the microevolutionary mechanisms that generate speciation and adaptation, much less is known about the processes underlying large-scale patterns of diversity. I used new techniques that exploit information contained in phylogenetic trees to investigate the diversification process in Furnariidae at a macroevolutionary scale.
First, I conducted the first quantitative study that demonstrated that the Furnariidae constitute a case of rapid diversification in both species numbers and morphology as compared to six closely related families. To evaluate phenotypic diversity, I developed a new multivariate extension of the variance, which I called 'proper variance', and a new simulation procedure to test for differences in phenotypic diversity when complete phylogenies are not available. I found that the Furnariidae, although not particularly diverse in body size, is unusually diverse in shape. These results support the idea that the Furnariidae constitute a continental adaptive radiation.
To explore processes responsible for high species diversity in the Furnariidae, I first investigated the effect of dispersal ability on species proliferation. Assuming that dispersal in birds is highly influenced by flying ability, I used an index of wing shape as a surrogate for flying ability. Using a nearly complete species-level phylogeny of the Furnariidae and a recently developed method, I found a negative correlation between flying ability and speciation rates, suggesting that low dispersal has stimulated species proliferation in Furnariidae.
Finally, I investigated the effect of three key innovations on furnariid diversification: adaptations for trunk climbing, spiny-tail morphologies, and skull kinesis. I found that increases in diversification rates are not associated with major morphological changes. In addition, I found that climbing specialization had a negative effect on speciation rates, but that the spiny-tail morphology was positively correlated with speciation rates. These results provide mixed support for a role of key innovations promoting speciation.
My results suggest a stronger role of geographic isolation (low dispersal) than ecological opportunities in species diversification in the continental radiation of the Furnariidae.
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