Christina Richards -

PhD student
Department of Botany
The University of Georgia

Evolutionary ecology and ecophysiology of clonal salt marsh plants

The broad objective of my dissertation studies was to quantify the direction and magnitude of phenotypic selection in contrasting environments of a dominant marsh species Borrichia frutescens (Asteraceae) by asking three questions:

1. Is there adaptive differentiation of ecotypes in response to contrasting environments in the salt marsh?

2. Does selection on morphological and physiological traits vary under contrasting salt marsh environments?

3. Are there genetic correlations among traits that constrain adaptive evolution?

My studies synthesize the ecology, physiology and genetics of this species to deepen our understanding of microscale evolution in natural plant populations. The results will lead to a new level of understanding of the mechanisms underlying salt marsh plant ecology and evolution.

In developing these questions I received funding from several agencies to work on these projects:

1. Community-wide patterns of phenotypic variation in salt marsh plants on Sapelo island. Published in Plant Ecology 2005.

2. Clonal structure in 2 salt marsh plants: Borrichia frutescens and Spartina alterniflora using allozyme markers in Dr. Jim Hamrick's lab. Published in Ecology Letters 2004.

3. Greenhouse study in collaboration with Susan White, Mary Anne McGuire and Steve Franks to identify whether growth response of Borrichia frutescens to salinity is explained by plasticity or differentiation.

4. Study of genetic variation in sea oats (Uniola paniculata) throughout its range in the United States in collaboration with Steve Franks, Eva Gonzales and Dr. Jim Hamrick. The fact that this plant occurs along an extremely long and narrow band of habitat fragments consisting of barrier islands and stretches of mainland coast make it an especially interesting organism for testing theories of phylogeography and gene flow. We are also interested in using the genetic information gained in this study to aid in the protection and restoration of this important coastal species. Published in American Journal of Botany 2004.

5. Field study of natural selection on morphological and physiological traits of Borrichia frutescens.

1. Community-wide patterns of phenotypic variation in salt marsh plants on Sapelo island. Published in Plant Ecology 2005.

2. Clonal structure in 2 salt marsh plants: Borrichia frutescens and Spartina alterniflora using allozyme markers in Dr. Jim Hamrick's lab. Published in Ecology Letters 2004.

3. Greenhouse study in collaboration with Susan White, Mary Anne McGuire and Steve Franks to identify whether growth response of Borrichia frutescens to salinity is explained by plasticity or differentiation.
4. Study of genetic variation in sea oats (Uniola paniculata) throughout its range in the United States in collaboration with Steve Franks, Eva Gonzales and Dr. Jim Hamrick. The fact that this plant occurs along an extremely long and narrow band of habitat fragments consisting of barrier islands and stretches of mainland coast make it an especially interesting organism for testing theories of phylogeography and gene flow. We are also interested in using the genetic information gained in this study to aid in the protection and restoration of this important coastal species. Published in American Journal of Botany 2004.

5. Field study of natural selection on morphological and physiological traits of Borrichia frutescens.