Linking Population and Physiological Diversity in a Toxin-producing DinoflagellateEPA Grant Number: R830413
Title: Linking Population and Physiological Diversity in a Toxin-producing Dinoflagellate
Investigators: Campbell, Lisa , Gold, John R.
Institution: Texas A & M University
EPA Project Officer: Hiscock, Michael
Project Period: September 1, 2002 through August 31, 2005 (Extended to February 28, 2007)
Project Amount: $464,880
RFA: Ecology and Oceanography of Harmful Algal Blooms (2002) RFA Text | Recipients Lists
Research Category: Water Quality , Ecosystems , Water , Aquatic Ecosystems
- Optimizing a suite of hypervariable, nuclear-encoded DNA markers (microsatellites) that have been developed to characterize genetic diversity among isolates of K. brevis;
- Establishing clonal cultures of K. brevis during the onset, bloom, and decline of a red tide event in order to assess genetic and physiological variability within a bloom; and
- Testing the following null hypotheses: (a) spatial/temporal samples from a single bloom are genetically homogeneous; and (b) geographic isolates of K. brevis from the northern Gulf are genetically homogeneous.
A suite of microsatellite markers will be employed as tools to link diversity and structure of isolates of K. brevis with the physiological and ecological bases of bloom formation. This is the first broad-scale application of microsatellites in studies of toxic dinoflagellates. For each clonal isolate established during the course of a bloom event, allele distributions at approximately 10 - 15 microsatellite loci will form the basis for tests of temporal (genetic) homogeneity. Physiological characterization of unique clones will consist of determining growth rates and cellular brevetoxin levels at three light irradiances and five salinities in a factorial design. Data analysis primarily will include tests of spatial and temporal homogeneity (including molecular analysis of variance or AMOVA) of allele (haplotype) distributions (frequencies). Estimates of haplotype (nucleon) diversity and intrapopulational nucleotide diversity will also be generated. Neighbor-joining of genetic distance matrices will be used as a means to assess genetic and evolutionary relationships among spatial and temporal samples.
A database for dinoflagellate microsatellite alleles will be initiated for the Gulf. Initial results will assess population-genetic structure and elucidate levels of genetic variation and diversity within blooms as they develop. Ultimately, results will provide profiles of genetic and ecological diversity on appropriate spatial and temporal scales to test rigorously hypotheses regarding various environmental variables and how they affect and influence bloom formation and population structure of species of Karenia. The work will be critical to interpretation of dynamics of field populations and in models used to predict occurrences of harmful algal blooms.