Distribution of genetic and phenotypic diversity in the autogamous perennial Paspalum dilatatum subsp. flavescens Roseng., Arrill. & Izag. (Poaceae)

The current increase in climate variability requires new strategies and sources of germplasm to improve the resilience of sown pastures, among other agricultural systems. For an efficient use of wild germplasm in domestication and breeding it is necessary to achieve a thorough understanding of the structure of the germplasm of potentially useful wild species. Paspalum dilatatum subsp. flavescens Roseng., Arrill. & Izag. is a sexual, autogamous member of the species complex containing the highly valued apomictic forms of P. dilatatum (Dilatata group). In spite of its repeated use in genetic analyses, its genetic variability has never beensufficiently explored. In order to understand the geographical structure of variability and the forces shaping it, a representative group of populations was genotyped with molecular markers and phenotyped in a common garden experiment. A remarkable spatial pattern was observed in the distribution of expected heterozygosity, but genetic distance among populations was generally independent of geographic distance. Most genetic and morphological variability can be attributed to genetic drift and only three of the 12 measured traits showed signs of a possible process of selection. Our data suggest that the genetic diversity and its geographical distribution are probably due to recent geographical range changes. Less diverse peripheral populations contain morphologically differentiated genotypes which can be of great value for breeding.