Professor Thomas J. Givnish

Terra Theim - Ph.D. candidate, Department of Botany B. A. (2000) University of Wisconsin-Madison • 301 Birge Hall • 608-265-5473 • ttheim@wisc.edu Spatial scales of gene flow and incipient mating barriers in Psychotria (Rubiaceae)
Broadly speaking, I am interested in patterns of gene flow and their ecological correlates. For my dissertation research, I am investigating the spatial genetic structure of four Neotropical shrub species of Psychotria (Rubiaceae). While several studies have looked at genetic structuring in tropical trees, few have dealt with the short-statured trees and shrubs that make up much of the woody diversity in tropical forests. My research will help fill this gap by obtaining data on gene flow and spatial genetic structure in four closely related species with similar pollinator syndromes and avian seed dispersal, but occurring in gaps vs. densely shaded understories. For a variety of reasons, I expect that seed dispersal should be more limited in understory species, so that these should undergo genetic differentations at finer spatial scales than gap species. To test this prediction, I am relating patterns of genetic structure to light environment and plant fecundity; I'm also conducting pollination experiments to investigate the effect of genetic distance on seed set. Together, these data will allow me to assess putative differences in spatial genetic structure between light-dependent gap species and shade-tolerant understory species, as well as to determine the importance of fecundity upon gene flow. This study is also a pioneering endeavor in correlating parental genetic data with reproductive data in the field. My field work is conducted in Barro Colorado Nature Monument and nearby Soberanía National Park, Panamá. Courses \| Research Group \| Ecology Section \| Botany Department © 2000 University of Wisconsin Department of Botany Last updated: 19 November 2000

Terra Theim - Ph.D. candidate, Department of Botany

B. A. (2000) University of Wisconsin-Madison • 301 Birge Hall • 608-265-5473 • ttheim@wisc.edu

Spatial scales of gene flow and incipient mating barriers in Psychotria (Rubiaceae)

Broadly speaking, I am interested in patterns of gene flow and their ecological correlates. For my dissertation research, I am investigating the spatial genetic structure of four Neotropical shrub species of Psychotria (Rubiaceae). While several studies have looked at genetic structuring in tropical trees, few have dealt with the short-statured trees and shrubs that make up much of the woody diversity in tropical forests. My research will help fill this gap by obtaining data on gene flow and spatial genetic structure in four closely related species with similar pollinator syndromes and avian seed dispersal, but occurring in gaps vs. densely shaded understories. For a variety of reasons, I expect that seed dispersal should be more limited in understory species, so that these should undergo genetic differentations at finer spatial scales than gap species. To test this prediction, I am relating patterns of genetic structure to light environment and plant fecundity; I'm also conducting pollination experiments to investigate the effect of genetic distance on seed set. Together, these data will allow me to assess putative differences in spatial genetic structure between light-dependent gap species and shade-tolerant understory species, as well as to determine the importance of fecundity upon gene flow. This study is also a pioneering endeavor in correlating parental genetic data with reproductive data in the field. My field work is conducted in Barro Colorado Nature Monument and nearby Soberanía National Park, Panamá.

Courses | Research Group | Ecology Section | Botany Department