Genetic micro-differentiation was studied in wild barley at the Neve Yaar microsite, Israel, an area of 3182 m2, which includes a mosaic of sun-rock, sun-soil, shade-rock, and shade-soil microniches. Fifty-six genotypes were tested for ecological-genetic microniche correlates. Analysis of 75 RAPD loci revealed a significantly higher polymorphism and gene diversity (P0.05 = 0.920; He = 0.411) on the more stressful sun-rock microniche, compared to the least stressful shade-soil microniche (P0.05 = 0.653; He = 0.188). Fifty-six (74.7%) out of the 75 loci varied significantly in allele frequencies. On the average, of the 75 loci, 75.7% of the total genetic diversity exists within the four microniches, while 24.3% exists between the microniches. The highest genetic distance was between shade-soil and sun-rock (D = 0.220), which confirmed their sharp microecological contrasts. Gametic phase disequilibria (LD) differed significantly between sunny and shady microniches. The levels of correct classification of individual genotypes into their respective microniche, based on the presence/absence of bands of the 2, 3, 4, 5, and 7 best differentiating loci, obtained by stepwise discriminant analysis, were 79, 84, 89, 95, and 100%, respectively. We conclude that ecological contrasts at the Neve Yaar microsite cause molecular diversifying selection (presumably at both coding and noncoding genomic regions of wild barley) overriding gene flow.
Bibliographical noteFunding Information:
Edward D. Owuor, supported by the Authority for Advanced Studies at the University of Haifa, the Israel Discount Bank Chair of Evolutionary Biology, and the Ancell-Teicher Research Foundation for Genetics and Molecular Evolution. The authors thank Avigdor Beiles and Eric Hallerman for critically reading the manuscript.
- Hordeum spontaneum
- Microscale selection
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Agronomy and Crop Science
- Plant Science