Associations between isozyme phenotypes and environment in the slender wild oat (Avena barbata) in Israel

Abstract

Collections from 31 populations of A. barbata from diverse habitats in Israel were assayed electrophoretically for seven enzyme systems. Phenotype frequencies were scored in nine enzyme zones, probably representing 27 loci, to determine isozyme variability within and among populations. Many different isozyme phenotypes were found in all of the populations; also the array of isozyme phenotypes found in each population differed distinctly from that found in each other population. Overlays of phenotypic frequencies on map locations showed that isozyme variability is distributed in mosaic patterns not related to geographical distance. Principal-component and multiple-regression analyses revealed that temperature and moisture-related variables are significantly correlated with particular isozyme phenotypes. Further, the mosaic patterns of isozyme variation were found to correspond closely to mosaic patterns of the habitat. This structuring of the genetic variability into multilocus combinations was attributed to the combined effects of directional and diversifying selection. Comparisons of patterns and extent of genetic variation in Israel and California led to the conclusion that the evolution of 'ecotypes,' each adapted to a specific habitat and marked by a particular set of enzyme alleles, has proceeded further in Israel, where A. barbata is endemic, than in California, where it is a recent introduction.

Phenotypic Variation and Plasticity in the Colonizing Species Xanthium Strumarium L. (Noogoora Burr)

“…In particular, Marshall and Allard (1970) reported a significant correlation between patterns of variation for allozyme and morphological markers in the species. However, more recently Allard et al (1978) and Kahler et al (1980) reported significant genetic variability for measurement characters, both within and between populations of A. barbata, monomorphic for both morphological and allozyme marker loci. Kahler et al (1980) concluded as a result: 'It is therefore apparent that no single class· of loci such as those governing enzyme variants, or those governing morphological polymorphisms, or those governing measurement.…”

Isozyme polymorphism in natural populations of Avena canariensis from the Canary Islands

“…Perhaps the most convenient method of assessing such variation is by conducting an electrophoretic separation of proteins Nevo and his co-workers have recently made detailed electrophoretic surveys of the wild relatives of wheat (Nevo eta!., 1982) and barley (Nevo et a!., 1979(Nevo et a!., , 1983(Nevo et a!., , 1986, and Kahler et a!. (1980) carried out a similar survey involving the wild oat A. barbata.…”

The role of polyploidy in the adaptive significance of polymorphism at the GOT 1 locus in the Dactylis glomerata complex

“…One of the reasons for this lack of understanding may be the absence of data correlating genetic diversity with selective factors. Although patterns of genetic diversity including enzymatic polymorphism have often been shown to be non-random (Hamrick and Allard, 1972; Levy and Levin, 1975;Nevo and Bar, 1976;Levin, 1977;Bergmann, 1978;153 154 R. LUMARET Valizadeh and Valdeyron, 1979;Nevo et a!., 1979;Kahler et aL, 1980;Anderson, 1981;Nevo and Yang, 1982), there have been very few cases where selective factors have been identified. When they have been, there are only a few situations where selection could be reasonably considered to act directly upon the alleles segregating at a specific locus.…”