Document: ANA-3-39-8

Establishing the relationship between compact sand and dune populations of desert lily (Pancratium sikenbergeri) in Makhtesh Ramon using genetic analysis.

LEVY, A.*, D.SALTS, S.MENDLINGER and D.WARD

Ben-Gurion University of the Negev, Beer Sheva 84990 Israel ¹

Abstract:
In Israel, the desert sand lily (Pancratium sickenbergeri) population grows in sand islands throughout the Negev desert and Arava. The research focuses on four such populations in two different valleys in Makhtesh Ramon separated by a 5-km mountain range. In each valley the lilies grow in two different habitats. One is a dune, formed near the valleys' eastern wall, in which a dense and heavily grazed population grows and the second is a compact sand plane in which a scarce lightly grazed population grows. Dorcas gazelles (Gazella dorcas) eat nearly all the flowers of the dune population each year, so that the population is unable to reproduce and maintain itself, though they are the larger population and grow in the more favorable habitat. Using a starch-gel electrophoresis technique testing for differences between alozymes in different populations, we compared between the genetic composition of each dune/compact sand populations in each of the two valleys. We found that within each valley the dune population significantly resembled the compact sand population, representing only a genetic subset of that population. Between valleys comparison, showed that the compact sand populations significantly resembled each other while no such significance was found for the dune populations. This suggests that each dune population relies entirely on immigration from the nearby compact sand population creating a sink source relationship between these populations, in which the smaller population is the source and the larger population is the sink. A small number of seeds (subset) from the source population are carried by wind to recolonize the dune every year thus maintaining a viable population there. The genetic composition of the sink/source populations was compared with ten other small isolated (but not sink) populations throughout the Negev and Arava. Significant differences were found between the other populations and the source populations, suggesting that isolation causes genetic drift and that the resemblance between dune and compact sand population in each valley is indeed a sink/source one.

Keywords: Desert sand lily; Pancratium sickenbergeri; Gazella dorcas; sink-source; genetic composition; genetic variability

This abstract is being presented at: 10:30 AM in session:
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