Genetic diversity in wild wheats and goat grass

The genetic structure of 35 populations of wild relatives of cultivated whe ats, all collected in Syria and Lebanon, was assessed using ten isozymes. T he populations consisted of diploid goat grass, Aegilops speltoides, diploi d wild wheats, Triticum monococcum spp. aegilopoides and T. urartu, and tet raploid wild wheat, T. turgidum ssp. dicoccoides. The majority of the popul ations were polymorphic (P=0-70%) having low within-population mean genetic diversity (H-ep=0.05-0.10) and relatively high within-species genetic dive rsity (H-es=0.14-0.31). The linkage between loci did not seem to be one of the causes for the observed polymorphism. All four species showed significa nt inbreeding at both the population (0.31-0.64) and species (0.77-0.96) le vels, and the extent of inbreeding did not correlate with mating systems. D espite their apparent common ecological and evolutionary history, between-p opulation or between-species level genetic identity was low (I=0.43-0.86), Among the diploid species, populations of Ae. speltoides clustered distinct ly from those overlapping clusters of T. monococcum ssp. aegilopoides and T . urartu. The tetraploid species T. turginum ssp. dicoccoides had relativel y less genetic diversity (H-es=0.14) and was highly homozygous (F=0.96), Th e results suggest that these wild progenitors of cultivated wheats have und ergone extensive local differentiation and inbreeding. We discuss the impli cations of our results on the management of wild wheat and goat grass popul ations.