Stability of the genetic structure and association with microhabitat of a wild wheat population over 36 years
Authors: Tal Dahan-Meir 1; Thomas James Ellis 2; Fabrizio Mafessoni 1; Hanan Sela 3,4; Jacob Manisterski 4; Naomi Avivi-Ragolsky 1; Amir Raz 1,5; Moshe Feldman 1; Yehoshua Anikster 4; Magnus Nordborg 2; Avraham A. Levy 1
Affiliations: 1) Department of Plant and Environmental Sciences, Weizmann Institute of Science; Rehovot, Israel; 2) Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter; Vienna, Austria; 3) Institute of Evolution, University of Haifa; Haifa, Israel; 4) The Institute for Cereal Crops Improvement, Tel-Aviv University; Tel Aviv, Israel; 5) Migal, Galilee Technology Center; Kiryat Shmona, Israel
Keywords: Ecological & conservation genetics
Wild progenitors of major crops can provide the genetic resources needed for ensuring food security. Long-term studies of progenitor species in their natural ecological niches are especially important for understanding the likely impacts of climate change, and inform strategies for conservation of such resources in-situ as well as in gene banks. We examined the genetic structure of Ammiad wild emmer wheat population which was sampled over 36 years while both temperature and atmospheric CO2 concentration increased significantly. At each sampling, seeds were collected from plants at 100 marked locations along four linear transects traversing seven ecologically distinct microhabitats. The genotypes of 832 individuals revealed high genetic diversity over scales of tens of meters and spatial clustering of the population. We found a striking concordance between genotype’ groups and ecological microhabitats, which were previously defined based on topographic and floristic data. This pattern was remarkably stable over time. Analyses and simulations indicate that neutral processes alone are unlikely to fully explain the spatial and temporal stability of the population. This suggests that natural selection, in addition to limited dispersal, contributed to shaping population structure. Our work shows that conservation of wild populations should take into account ecological niches, even in a small area, in order to best sample their diversity.