Rates of Evolution

One of the greatest wonders of the natural world is the immense phenotypic biodiversity we see, and evolutionary biologists continue to ask why there is this diversity. For years scientists have been aware that organisms evolve at different rates (tempo) and in different patterns (mode) across taxonomic groups. Of particular interest, rates of evolution and patterns of phenotypic traits can vary widely among clades and across lineages. There are many factors that contribute to morphological form such as niche availability, community interactions, reproduction and other life history characteristics. While these factors have been studied for over a century, it is the advent of new phylogenetic tools that has allowed an explosion of studies quantifying the tempo and mode of species diversification.

In this study, I use bill morphology of 269 species of hummingbirds from 6,794 specimens and use this as a trait to quantify sexual size dimorphism and sexual shape dimorphism. I determine which species exhibit sexual size and shape dimorphism in bill morphology and focus on the specific questions: 1) What are the rates of sexual size and sexual shape dimorphism in hummingbird bill morphology? 2) Is the rate of sexual size dimorphism different than that of sexual shape dimorphism and if so, in what direction? and 3) What factors influence the observed patterns of sexual dimorphism? In doing so, we ultimately address the question, what are the patterns and processes of the evolution of sexual dimorphism?

This study is currently in progress so check in soon!

Under Construction