Mr. Abbas Salehi, In case of ecotypes that are self pollinated, natural selfing were occured during a long term and traits differentiated and land race lines provided and a mix of same and different individuals were made, this differences due to variance between individuals.
and in case of open pollinated plants, natural open pollination due to genetically recombination and achieve to Hardy-weinberg equilibrium if selection and genetic drift were not occured. in this situation the population included homozygous and heterozygous individuals that cause to variance between them.