graduate students

Robert Comito

Doctoral Student


I was born and raised in Southern California. I received a Bachelor of Science in Molecular Environmental Biology from University of California, Berkeley. While there, I also developed a passion for plants, assisting in the Dodd lab researching population genetics of California oaks. I also have Master of Science in Biology from California State University, Long Beach. There, under the guidance of my advisor Dr. Amanda Fisher, I worked on a molecular systematics of the charismatic genus of shrubs Barleria in the tropical angiosperm family Acanthaceae. In the face of a globally catastrophic decline across a broad range of species, especially tropical flora, the characterization of biodiversity is increasingly important. These organisms perform essential ecosystem services and hold within themselves an invaluable record of our living planet. Documenting and conserving this diversity drives my interest in phylogenetics and population genetics at multiple scales.


A Multilevel Examination of Evolution, Phylogeography, and Diversification in Barlerieae (Acanthaceae)

The tribe Barlerieae (ca. 440 spp.) is one of the major lineages in the large pan-tropical plant family Acanthaceae (ca. 4,000 spp) that is most in need of further study.

Barlerieae contains 13 genera, the two largest and most widespread of which are Barleria (ca. 300 spp., primarily paleotropical), and the pantropical Lepidagathis (ca. 100 spp.). Sub-Saharan Crabbea contributes 14 species. The remaining ten genera contain ~25 species and are distributed across Latin America, South Asia, Africa, and Madagascar. Barlerieae present many taxonomic problems (e.g., Lepidagathis and Crabbea may not be monophyletic) and also intriguing biogeographic patterns. Notably, a few species have amphi-Atlantic distributions (e.g., Barleria oenotheroides and Lepidagathis alopecuroides).

Traditionally, Barlerieae have been united by quincuncial aestivation, a developmental character involving the arrangement petals in flower buds. However, only six genera have been sampled in phylogenetic studies, and the hypotheses that the remaining genera are part of Barlerieae have yet to be tested with molecular phylogenetic data. In a recent reclassification of Acanthaceae, three subtribes have been proposed based on corolla and calyx characters, pending further study: (1) Barleria; (2) Crabbea and allies, and (3) Lepidagathis and allies.

Using a next-generation sequencing (NGS) approach (ddRADseq), I will: (1) Estimate a well-sampled phylogeny of the tribe to test existing taxonomy as well as proposed classifications, (2) test genera and sub-generic groups for monophyly, (3) identify morphological characters that support monophyletic groups, (4) examine patterns of biogeography and diversification within the tribe.

Sampling will encompass the morphological and geographical diversity of Barlerieae, including each genus and major sub-generic groupings. Samples will initially be sourced from herbarium collections, then gaps in collections will guide future fieldwork.

I will prepare ddRADseq libraries from all samples using a modified protocol from Tripp et al., (2017), sequence, and then combine sequence data with data from Master’s thesis project. For that study, I used a similar approach to resolve relationships in Barleria. With the combined dataset, I will estimate phylogenetic relationships among Barlerieae applying: 1) a maximum likelihood analysis using IQ-TREE (Nguyen et al., 2014) with the concatenated RAD sequence data from all loci derived from the assembly and 2) a coalescent-based approach using quartet-based phylogenetic inference in tetrad (Eaton & Overcast, 2020). To examine phylogeography, I will implement BioGeoBEARS in R (Matzke, 2013).

This NGS-based project seeks to characterize diversity in an understudied, global plant lineage, using natural history collections in modern systematics research. It will contribute to taxonomic revisions and keys that will aid field identification and conservation efforts, as well as provide insight into the complex evolutionary processes that shape biodiversity in this remarkable lineage.

Additional Information

Twitter: @RPComito


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