Spatial and temporal genetic structure of wild emmer wheat in Jordan. I. Phenotypic traits

Natural populations of wild emmer wheat in Jordan represent a unique and si zable part of the species' distribution in the Fertile Crescent. However, i nformation on their genetic structure and diversity is limited. An understa nding of the way genetic variation is partitioned among these populations i s of primary importance for the ex situ sampling and in situ conservation o f their genetic diversity. Fourteen categorical traits were used to charact erize different phenotypes found in 12 wild emmer wheat populations in Jord an. They were scored in plants growing in 207 marked sampling sites and rep resenting a wide range of observable variation. A strong effect of the hete rogeneous habitats, encountered across collecting sites, was reflected in t he magnitude and spatial distribution of phenotypic diversity. Several, and probably unique, first- and second-order associations among phenotypic tra its reflect functional adaptation of the species to and and semiarid Medite rranean environments. Phenotypic distances among populations were highly in fluenced by latitude and rainfall quotient (Q2) of collection sites. Spatia l factors accounted for large portions (60.5-93.1%) of total variation in p henotypic diversity indices, suggesting strong provenance specificity. Temp oral variation was less pronounced than spatial variation, and there were n o drastic changes between years in frequencies of genotypes. Both spatial a nd temporal variation varied among populations.