This project provides a methodology to understand large and complex groups of organisms, using the spurge genus Euphorbia, with about 2000 species worldwide, as the model. Following field work in biodiversity hotspots and examination of museum collections and literature, the research team will produce updated lists and descriptions of all species, tools for amateurs and scientists to identify species, DNA sequencing analyses to determine evolutionary relationships, analyses of the distributions and rarity of endangered species, and evaluation of control methods for several noxious weedy species. There will be a core team of Euphorbia taxonomists worldwide, and the resulting information will be organized and conveyed by a separate team of bioinformatic specialists. This comprehensive study of a complex plant genus of over 2000 species in a 5-year time frame using mainly Internet-based tools will demonstrate the feasibility of obtaining and disseminating information quickly for other large and diverse groups of organisms. The project provides extensive training of students from K-12 to the postdoctoral levels, an educational outreach module using Euphorbia as an example, and a global approach to conducting scientific collaboration. It examines both the control of noxious weeds like the leafy spurge complex and the conservation of the 900-odd species of Euphorbia considered endangered by CITES.
This project was an outcome of the NSF Planetary Biodiversity Inventory program, which sought teams of investigators to advance the discovery and study of the world’s biodiversity by conducting worldwide, species-level inventories and taxonomic revisions of major groups of organisms. Our selected group was Euphorbia, which is one of the three largest genera of plants on earth, with around 2000 species that show great morphological diversity and the most varied photosynthetic systems of any other group. We assembled a team of over 50 professionals and students and proceeded to conduct field studies in all continents except Antarctica, gathering thousands of new herbarium collections as well as a collection of over 2000 tissue samples we used to reconstruct the first well-represented molecular phylogeny of the genus. The previous classification of Euphorbia was confusing and did not accurately reflect the relationships of the species because the genus has evolved many similar-looking adaptations in unrelated lineages, most notably the multiple convergences on succulent life forms. By combining detailed molecular analyses with traditional field and herbarium studies, our team has produced a new genus-wide phylogeny and classification system for Euphorbia. It places nearly all of the ca. 2000 recognized species in the genus into one of four subgenera, and within those into one of 64 sections. The relationships of these subgenera and sections are well resolved, providing a predictive system for future studies. All described taxa (7500 names including synonyms) have been documented and included in a web-based database (Tolkin), which is accessible through the Data Portal of the project website at www.euphorbiaceae.org. Many of the accepted names include type collections, plant images, distribution data, and maps. Over 50 publications have been produced so far as part of the project, and some of these include species-level treatments, identification keys, or data on the conservation status of the species. Two collaborative papers by Horn et al. delve into questions concerning the age of the genus and component groups, accelerated diversification rates in diverse lineages, particularly among groups with alternative photosynthetic systems that optimize CO2 fixation (CAM and C4), and the evolution of different habit types and succulence. It is estimated that over 20 separate origins of succulence have occurred in the genus within the past 50 million years. Six postdoctoral researchers were trained as part of the grant, as well as eight Ph.D. students, eight Masters students, and six undergraduates (three of them under the Research Experiences for Undergraduates program). A network of active Euphorbia researchers across all six populated continents has yielded novel collaborations and facilitated the broad-base molecular survey of over half the species in the genus. Our results have been widely disseminated at scientific meetings and symposia, in addition to our web pages and publications.
