Systematics Research Lab

Plant Systematics Research

In The Huntington's molecular systematics lab, the botanical staff investigates fundamental processes of plant evolution using cutting edge methods combined with traditional field work. Systematics research is the understanding and documentaton of biological diversity and the processes that produce it. The lab's current focus is on speciation, phylogeography, phylogenetics, and biogeography in the cycad genus Dioon.

Dioon is one of ten living genera of cycads, with 15 species mostly endemic to Mexico, but with one species in Honduras. While they may look a bit like palm trees, they are actually gymnosperms – they make seeds but not flowers – and are relatives of gingkos and pines. Cycads in general are mostly found in tropical and subtropical habitats. The species of Dioon can be found across all of the major mountain systems of Mexico with the center of diversity for this genus in southern Mexico, south of the Trans-Mexican Volcanic Belt. Populations range from several hundred to only a few dozen individuals and most species are considered vulnerable or endangered, which is why they are protected. Species are distinguished by relatively subtle characters, many quite similar to each other. This suggests some interesting possibilities for their evolutionary history – including recent divergence from a common ancestor and/or hybridization between species.

Reconstructing Dioon Evolutionary History

The purpose and goal of the research is to reconstruct the evolutionary history and genetic diversity of these species to better understand the processes that have led to their diversity and distribution, and to inform conservation efforts both in Mexico and at institutions such as The Huntington. Questions we hope the research will answer:

  • What are the evolutionary relationships among species?
  • What has driven speciation in this group?
  • What are the true species boundaries in Dioon?
  • What is the genetic diversity of populations and how isolated are they from each other?
  • What is the timing of divergence and any hybridization events among species?

DNA Sequence Data

Gardens are an invaluable resource for botanical research providing specimens and material of species from around the world. To test hypotheses that may answer our questions we use DNA sequence data produced in the lab and morphological data collected in the field. Because informative regions of the Dioon genome have been elusive, we have developed our own set of "genetic markers" from the DNA from plants in The Huntington collection using transcriptomics and next-generation sequencing technology. In doing so we, along with collaborators at UC Berkeley, have compiled the first genomic data sets for Dioon and are using them to look back in time at the evolutionary history of these species. By reconstructing the timing of diversification in Dioon we can test whether processes such as climate change may have been involved in the speciation events that ultimately produced the living species of today.

Intern, Volunteer, and Student Research Participation

A research and educational institution by definition, The Huntington's systematics lab includes interns, volunteers, and students in its research. Students from Pasadena City College work in a range of capacities in the lab, from performing basic molecular techniques, such as DNA extraction, to curating collections, to leading research projects into molecular markers of sex in cycads.