Microsatellite diversity in natural populations of ascomycetous fungus, Emericella nidulans, from different climatic-edaphic conditions in Israel

The genetic divergence of Israeli populations of the soil ascomycetous fungus Emericella nidulans was studied on regional and local scales using fifteen microsatellite (SSR) markers. The study was performed in the framework of the "Evolution Canyon" research program at the Institute of Evolution, University of Haifa, in three "Evolution Canyons" (ECs): EC I (Mt. Carmel), EC II (western Upper Galilee), and EC III (the southern Negev desert). The first two canyons (EC I and EC II) are located in the northern part of Israel at a distance of 38 km apart; EC III is located southward at a distance of nearly 350 km from the northern ECs. In each canyon, E. nidulans strains were isolated from opposite slopes and, in EC III, from the valley bottom. All three EC populations of E. nidulans were found to be genetically distinct. The estimated genetic divergences correspond to geographical distances and ecological differences between the three studied canyons. On a regional scale, simple sequence repeat (SSR) polymorphism tends to increase with severity of ecological conditions. In general, both environmental parameters (soil moisture and temperature) and genetic factors (predicted number of repeats in SSR markers, distance from marker to centromere, codon evolutionary chronologies, and hydrophobic vs. hydrophilic character of encoded amino acid) influenced genetic diversity of E. nidulans populations.