Suboscine trait evolution

Macroevolution of the suboscine passerines

Much of our current research involves questions about macroevolution in the suboscine passerines. This is one of dominant groups of passerine birds in South America, where they have diversified into a wide variety of habitats, from deserts to rainforests, and from sea level to the highest mountains. They comprise about 1,300 species, and occupy a broad diversity of niches that are occupied by the oscine passerines elsewhere in the world. We are interested in how this diversity came about, both the diversity of species and the diversity of traits. In collaboration with researchers from many instituions, we compiled a species-level database of phylogenetic, distributional, song, plumage, morphometric, and ecological data from all species of suboscine passerine birds. This is an active area of research, and if this research interests you, either as a student or a collaborator, please reach out. Below, we have outlined two current research projects using these data, but there are many additional avenues of research that would be fruitful.

This work is in collaboration with the following researchers, and we encourage anyone interested in this topic to look into their research as well. Joseph Tobias at Imperial College London, Gustavo Bravo at the Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Santiago Claramunt at the University of New Orleans, Elizabeth Derryberry at the University of Tennessee Knoxville, Robb Brumfield at the Louisiana State University Museum of Natural Science, Rafael Marcondes at Barnard College, and Michael Harvey at the University of Texas El Paso. All of the work outlined on this page is done in collaboration with this resarch group.

Tradeoffs in sexually selected traits

As far back as Charles Darwin, researchers have noted that species of birds that sing complex or loud songs often have “dull” plumage, and vice versa. This idea is often termed the Transfer or the Trade-off Hypothesis, with the idea being that a species only needs to “invest” in a single trait (either plumage OR song) to attract a mate and defend its territory. Although this has been tested in a many groups of birds, most studies have focused on smaller groups of species, and with conflicting results. The suboscines are a great group in which to test this idea, and we have been applying phylogenetic comparative methods to our song and plumage datasets to ask these questions.

Temporal dynamics of the transition to sympatry

The transition from allopatry to secondary sympatry following speciation is a central aspect to the buildup of species diversity. Speciation in birds is largely allopatric, in other words it takes place between geographically isolated populations. The ability of two species to co-exist (sympatry) after speciation is predicated on the two new species having diverged sufficiently in some aspect of their biology that allows them to either recognize one another as different species (divergence in signaling traits) or acquire resources differently (divergence in niche), or both. Both the time that it takes for species to come back into sympatry following speciation, and the amount of morphological divergence that is necessary to allow for that transition to sympatry are poorly known. My research aims to answer these questions in the suboscine passerine birds, a diverse group of species with the greatest diversity in the Neotropics. Along with a stellar group of collaborators, I have compiled data on geographic distributions, genetic data, song, plumage, and morphometrics for all suboscine birds. This project can be broadly divided into 1) the timing of the transition to sympatry and 2) the traits that mediate the transition to sympatry.

Some results on the timing of the transition to sympatry can be seen in my talk at the 2021 American Ornithological Society conference, below: Note: includes captions in Spanish.