Spatio-temporal genetic variation in populations of wild emmer wheat, Triticum turgidum ssp. dicoccoides, as revealed by AFLP analysis

Abstract

Genetic structure of natural populations of wild crop relatives has been the subject of many studies. Yet, most of them focused on the assessment of spatial genetic diversity, while information on long-term variation, affected by yearly changes, has been considered only in few cases. The present study aimed therefore, to estimate the spatio-temporal genetic variation in populations of wild emmer wheat, the progenitor of domesticated wheat, and to assess the contribution of spatial versus temporal factors to the maintenance of genetic variation in a population. Single spikes were collected in the years 1988 and 2002 from plants that grew in the same sampling points, from six different habitats in the Ammiad conservation site, Eastern Galilee, Israel. Seeds were planted in a nursery and DNA was extracted from each plant and analyzed by the AFLP method. Fourteen primer combinations yielded 1,545 bands of which 50.0 and 48.8% were polymorphic in the years 1988 and 2002, respectively. Genetic diversity was much larger within populations than between populations and the temporal genetic diversity was considerably smaller than the spatial one. Nevertheless, population genetic structure may vary to some degree in different years, mainly due to fluctuations in population size because of yearly rainfall variations. This may lead to predominance of different genotypes in different years. Clustering the plants by their genetic distances grouped them according to their habitats, indicating the existence of genotype-environment affinities. The significance of the results in relation to factors affecting the maintenance of polymorphism in natural populations is discussed.

Resistance gene analog polymorphisms (RGAPs) in wild emmer wheat (Triticum dicoccoides) and their ecological associations

“…The T. dicoccoides populations showed a high level of variation, much of which was distributed within populations and regions (Table 6). This result was similar to the previous results AFLP markers in T. dicoccoides, which was 82.5% of total variation existed within populations (Ozbek et al 2007). While Nybom (2004) proposed that most of the genetic variation was between-rather than within-populations in annual, self-pollinating species, as also was shown for T. dicoccoides based on allozyme analysis (Nevo and Beiles 1989).…”

“…Many marker technologies, such as allozyme, RAPD, SSR, AFLP and SNP, had been used to evaluate the genetic variations of T. dicoccoides (Nevo and Beiles 1989;Fahima et al 1999Fahima et al , 2002Ozbek et al 2007;Wang et al 2008), while little information is known on the plant resistance gene analog polymorphisms (RGAPs) in T. dicoccoides. In this study, the genetic diversity and genetic structure of 15 populations of T. dicoccoides from Israel were estimated by using RGAP markers, and their ecological associations were also evaluated and discussed.…”

Geographic distribution and domestication of wild emmer wheat (Triticum dicoccoides)

“…According to Feldman and Kislev (2007), the hybridization could have occurred in the vicinity of Mt. Hermon and the catchment area of the Jordan River because of the larger morphological, phenological, biochemical and molecular variation of wild emmer from this region, compared to wild emmer from southeastern Turkey, northern Iraq, and southwestern Iran (Nevo and Beiles 1989;Ozbek et al 2007).…”

Genetic diversity of the killifish Aphanius fasciatus paralleling the environmental changes of Tarquinia salterns habitat

“…For example, past climatic oscillations signature is still present in the genetic structure of populations and has been widely studied (Hewitt 2000). Despite many naturally driven processes occurring too slowly to be appreciated in short to medium term surveys, there is an increasing interest for temporal studies analysing the effects of environmental changes on genetic variation (Barcia et al 2005;Ozbek et al 2007;Schwartz et al 2007). Coastal lagoons constitute a habitat of choice for this kind of studies because they are both shallow and are located at the interface between land and sea.…”