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Allozyme variation in the endangered insular endemic Castilleja grisea
Kaius Helenurm1, Rachel West, Steven J Burckhalter
1Department of Biology, University of South Dakota, Vermillion, SD 57069, USA. helenurm@usd.edu
Annals of Botany
|April 12, 2005
Summary
Genetic diversity in Castilleja grisea, an endangered plant, is moderately high, suggesting it is not endangered by genetic factors. This finding is unusual for an island endemic species.
Area of Science:
- Botany
- Conservation Genetics
- Island Ecology
Background:
- Castilleja grisea is an endangered, perennial herb endemic to San Clemente Island, California.
- Following goat eradication in 1992, C. grisea populations have recovered and increased in size.
Purpose of the Study:
- To investigate the genetic diversity of Castilleja grisea populations.
- To assess the impact of historical pressures and recovery on the genetic health of this endemic species.
Main Methods:
- Surveyed 19 populations of C. grisea.
- Analyzed genotypes at 19 allozyme loci.
Main Results:
- High genetic variation at the taxon level (57.9% polymorphic loci).
- Most genetic variation resides within populations, with significant differentiation among them.
- Gene flow is substantial (Nm = 1.70-2.50), and the species primarily outcrosses (t = 1.01).
Conclusions:
- Genetic variation in C. grisea is moderately high, which is unusual for an island endemic.
- The species likely retained significant genetic variation despite 150 years of overgrazing.
- Genetic factors are unlikely to pose a threat to the endangered status of C. grisea.
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