Natural selection of allozyme polymorphisms: A micro-geographical spatial and temporal ecological differentiations in wild emmer wheat

Allozymic variation in proteins encoded by 43 loci was analysed electrophoretically from 1983-4 to 1986-7, during four consecutive growing seasons, in 812 individual plants of wild emmer wheat, Triticum turgidum var. dicoccoides, from micro-sites at Ammiad, north of the Sea of Galilee, Israel. Significant genetic differentiation according to vegetationally and topographically defined habitats and subhabitats was found primarily in space over very short distances, and secondarily over time. The highest gene diversity occurred in the Karst formation where soil moisture was most variable, i.e. in the habitat displaying the broadest niche. Our results suggest that allozyme polymorphisms in wild emmer wheat are partially adaptive. Genetic differentiation appears to be primarily affected by environmental factors related to topography and temporal climatic changes, probably through drought, i.e. aridity stress.