Blair, Andrew W. , Williamson, Paula S. .
Pollen dispersal in star cactus (Astrophytum asterias).
Understanding gene flow has become a priority in the conservation of endangered species. We examined pollen dispersal in Astrophytum asterias, an endangered cactus occurring in southern Texas and northern Mexico. The species is self-incompatible and bee pollinated. Fruits disintegrate while attached to the plant resulting in most seed being deposited directly on or around the mother plant. In cases where seed dispersal is limited, pollen dispersal can have a substantial impact on the genetic makeup of plant populations. The study site was a ~1.9 hectare parcel of private land in Starr County, Texas with approximately 1,146 A. asterias individuals and an average density of individuals of approximately 445/ha. Since A. asterias is an endangered plant, we selected a non-invasive method to examine pollen dispersal. Fluorescent dye was used in this study as a pollen analogue to track the distribution of pollen dispersal within a 1.9 hectare patch of star cactus. Approximately 80% of all recipient plants were located within 30m of the source plant. The longest dispersal event recorded was 142.2m. Dispersal distances between source and recipient plants were used to calculate estimates of genetic neighborhood size and area using Wright's neighborhood model. These neighborhood estimates (neighborhood size = 41.8 individuals, neighborhood area = 0.094 hectares) indicate the potential for population subdivision within the larger patch due to restricted pollen dispersal.
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1 - Texas State University-San Marcos, Department of Biology, 601 University Dr., San Marcos, TX, 78666, USA
2 - Texas State University-San Marcos, Graduate College, 601 University Dr., San Marcos, TX, 78666, USA
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM