The levels of genetic diversity were compared by means of 35 allozyme, 60 RAPD, and 25 microsatellite (SSR) markers for 75-175 individuals of tetraploid wild emmer wheat (Triticum dicoccoides) collected in 1993 from a microgeographic microsite, Ammiad, north of the Sea of Galilee, Israel. This microsite included four major habitats, which showed highly significant differentiation in ecological factors, in particular with respect to rock cover, proximity and height, and surface soil moisture in the early growing season of T. dicoccoides. Higher within-subpopulation genetic diversity was found in the primarily non-coding DNA regions (RAPD and SSR) rather than in the protein-coding (allozymes) regions. However, much larger gene differentiation (GST) among the subpopulations was observed in the protein-coding allozymes than in the RAPDs and SSRs. Larger genetic distance was found at SSR loci, followed by allozyme and RAPD loci. The subpopulations in drier habitats tend to have higher allozyme, RAPD and SSR diversities (He), the relatively wet Karst subpopulation showed only about half He of the other relatively drier habitats. The subpopulations with larger difference of soil moisture between habitats tend to show larger genetic distances at allozyme, RAPD and SSR loci. These results suggest that climatic selection through aridity stress may be an important factor acting on both structural protein-coding and presumably partly regulatory non-coding DNA regions, resulting in microscale adaptive patterns, although hitchhiking and random drift may also intervene. These results have profound implications for genetic conservation both in situ and ex situ.
Bibliographical noteFunding Information:
We thank Prof. Y. Anikster for kindly supplying us with seeds of wild emmer from the Ammiad microsite. We also thank Dr. V. Korzun and Ms. K. Wendehake for their excellent help in SSR analysis. This research is a part of the PhD research project of the first author. This work was partly supported by the Israel Discount Bank Chair of Evolutionary Biology, the Ancell-Teicher Research Foundation for Genetics and Molecular Evolution, the German-Israeli Cooperation Project (DIP project No. DIP–B4.3 funded by the BMBF and supported by BMBF’s International Bureau at the DLR), and The Israel Science Foundation (No. 9048/99).
- Microgeographic divergence
- Natural selection
- Triticum dicoccoides
- Wild emmer wheat
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics