Intraspecific structure and reproductive relationships between Elymus mutabilis and E-transbaicalensis (Poaceae) in southern Siberia from the viewpoint of taxonomical genetics

The relationships between StH-genomic species Elymus mutabilis ( Drob.) Tzvel. and E. transbaicalensis (Nevski) Tzvel. were examined using biosystematic and biochemical (SDS electrophoresis of endosperm proteins) methods. The results showed the following. ( 1) There is interspecific morphological discreteness that permits assigning most individuals from the wild to a definite species. However, self-fertile intermediate individuals of introgressive origin were found. ( 2) Both taxa exhibited marked specificity of electrophoretic characteristics of endosperm proteins. ( 3) The species form two separate recombination gene pools (RGPs). Thus, E. mutabilis and E. transbaicalensis should be regarded as two distinct species. Nevertheless, there is some genetic exchange and unidirectional gene flow between the RGPs, especially in secondary ( successive) habitats where mixed populations are observed. Two RGPs form the single introgressive gene pool (IGP), which includes other StH-genomic species of Northern Eurasia.