Doctor of Philosophy (PhD)
In 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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Claramunt Tammaro, Santiago Javier, "Testing models of biological diversification: morphological evolution and cladogenesis in the neotropical furnariidae (Aves: Passeriformes)" (2010). LSU Doctoral Dissertations. 3852.
Remsen Jr., James V.