Research
Overview
Because all organisms are related via evolution, it follows that disparities in biodiversity across both space (e.g., tropical versus temperate regions) and taxa (e.g., flowering plants versus conifers) result from differences in evolutionary time and/or rates. In other words, species richness, genetic diversity, and phenotypic diversity are inextricably linked to the balance of speciation and extinction rates, rates of molecular evolution, and rates of trait evolution, respectively. Thus, accurate estimation of evolutionary rates is absolutely essential to understanding and explaining the Earth’s uneven distribution of biodiversity.
In my research, I aim to develop new statistical tools for determining how evolutionary processes vary (especially in terms of rates) and the underlying factors that drive this variation. Unfortunately, between to the regularity of extinction and incompleteness of the fossil record (not to mention our short lifespans), estimating the rates of evolutionary processes is not straightforward. In my work, I use the phylogenetic comparative approach–essentially, using reconstructed phylogenies (i.e., evolutionary trees) and data from the relatively few living and/or fossilized organisms we can observe to make inferences about past evolutionary processes. Hopefully, these methods will ultimately help researchers understand the forces the shape the tree of life and structure the distribution of biodiversity across the globe.
Modeling variation in rates of continuous trait evolution
Rates of trait evolution vary markedly across the tree of life, from adaptive radiations to lineages of “living fossils”, but our tools for characterizing and analyzing this rate heterogeneity are still lacking in some cases. My dissertation work largely focused on developing novel models, approaches, and algorithms to address some of these gaps in the case of modeling continuous trait evolution. Some of this work has already been published, though I’m still wrapping a lot of it up, as these things tend to go!
Life history trait evolution in eucalypts
Eucalypts are a fabulously diverse and iconic radiation consisting of hundreds of tree and shrub (“mallee”) species largely native to Australia. Conventionally at least, eucalypts are split among the genera Angphora, Corymbia, and Eucalyptus (plus maybe the recently-named genus Blakella–depending on who you ask). Of these genera, Eucalyptus is by far the most diverse and well-known, though there are many economically/horticulturally important Corymbia/Blakella species as well. My current position is funded by a National Science Foundation Postdoctoral Research Fellowship in Biology (NSF PRFB) to try and characterize the genetic basis of life history trait evolution in this group, with two main subgoals: 1) model trait evolution while more explicitly accounting for “phylogenomic discordance” (i.e., variation in the evolutionary history of different segments of the genome due to rampant hybridization, etc.) and 2) identify genetic variation linked to life history trait evolution, with the ultimate goal of identifying genetic loci which might be of interest to eucalypt breeders/growers. The gist here is that there is only so much variation within any given eucalypt species, and we might have better luck characterizing the genetic basis of trait variation by leveraging the genetic/phenotypic diversity across different species of eucalypts.
While eucalypts are traditionally considered challenging to investigate in a phylogenetic framework due to rampant hybridization and–by extension–generally “fuzzy” species boundaries, they also represent a fantastic model clade in some respects. In terms of trait evolution, they offer this somewhat ideal balance between uniformity and diversity–their general anatomical structures are rather conserved yet vary widely in shape and size, and they mostly occur on a single continent yet are found across a wide variety of habitats. Further, there’s a lot of economic and conservation interest in eucalypts due to their desirable wood properties, chemical diversity, aesthetic qualities, and ecological dominance within Australia (not to mention issues with invasive eucalypts in places like western North America, South America, and Africa). Indeed, my work here is building off a wide collaborative network of ongoing efforts to sequence/analyze the genomes of as many eucalypt species as possible.
I admittedly only started this work in earnest during October 2024 and don’t have too much to show for it yet! Though I did take an opportunity to “revamp” a manuscript based on some my dissertation work (continuous stochastic character mapping) with some of the preliminary phylogenetic/phenotypic data I’ve been working on here. There’s still A LOT of data to gather and analyze here, so stay tuned!