Phylogenetics, Conservation, and Historical Biogeography of the West Indian Genus Leucocroton (Euphorbiaceae)

EPA Grant Number: MA916302
Title: Phylogenetics, Conservation, and Historical Biogeography of the West Indian Genus Leucocroton (Euphorbiaceae)
Investigators: Jestrow, Brett
Institution: Florida International University
EPA Project Officer: Zambrana, Jose
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $103,786
RFA: GRO Fellowships for Graduate Environmental Study (2004) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Natural and Life Sciences , Biology/Life Sciences


Leucocroton has 28 species, 27 endemic to Cuba and 1 endemic to Hispanola. This makes the genus one of the largest, by species, of genera endemic to the Caribbean islands. All species are indicators of soil type. Twenty-six species on Cuba are known to grow only on serpentine soils, a soil type that is toxic to most plants, whereas the remaining two species are found only on limestone soils. Of those on serpentine soils, 11 have been found to hyperaccumulate nickel at a level of a thousand times that of typical plants. The objective of this research is to explore the evolutionary history of Leucocroton.


This research project consists of three parts. The first part is based on phylogenetics and will determine if Leucocroton is monophyletic, the genus’ position in the tribe, and a molecular phylogenetic tree. I will use ndhF from the chloroplast DNA and internal transcribed spacers from the nuclear DNA to obtain data. I then will use both parsimony and maximum likelihood methods for analysis. Next the conservation status of the species of the genus will be determined. I will use the IUCN conservation categories of 2001, which have not yet been used for any plants in Cuba. Once the status of each species has been determined, I will investigate the genetic diversity of the three rarest species using inter-simple sequence repeats. Finally, I will investigate the historical biogeography by comparing the aforementioned phylogenetic tree with the soils on which the plants are growing. The ancestral soil states will be determined by using methods described by Bremer and Ronquist. I am especially interested in the nickel content of the soils and the leaf tissue of Leucocroton to determine the ability of each species to hyperaccumulate this metal. Understanding the evolutionary history of the genus is the first step in investigating the genetic basis for nickel hyperaccumulation, ultimately leading to developing new methods of phytoremediation.

Supplemental Keywords:

fellowship, Leucocroton, phylogenetics, Cuba, Caribbean, Euphorbiaceae, ndhF, parsimony, maximum likelihood, IUCN, biogeography, serpentine, nickel, hyperaccumulation, phytoremediation, Scientific Discipline, Waste, Remediation, Environmental Chemistry, Environmental Monitoring, fate and transport, Leucocroton, sediment transport, chemical contaminants, phylogenetics, phytoremediation, extraction of metals, soil sampling, chemistry and transport

Progress and Final Reports:

  • 2004
  • 2005
  • Final