USING A POPULATION GENETICS APPROACH FOR A PRELIMINARY INVESTIGATION CONCERNING SPECIES BOUNDARIES IN HERBERTIA (IRIDACEAE)

摘要

Premise of research. The population genetics approach is an important tool for determining boundaries in closely related plant species. Here, we adopt this approach to investigate the relationship between three species of Herbertia endemic to the Pampa biome, a complex grassland environment in southern South America. Methodology. A multianalytic approach based on population genetics was used to analyze 102 intersimple sequence repeat loci sampled in 11 populations (333 individuals) unequivocally attributed to Herbertia, aiming to test the boundaries between species. Controlled pollination experiments were performed to estimate the index of self-incompatibility (ISI), and the viability of pollen grains was estimated using the Alexander dye method, aiming to determine the breeding system in studied populations. Pivotal results. Bayesian analysis revealed three unambiguous genetic pools that corresponded to the spe cies Herbertia darwinii (94 individuals), Herbertia pulchella (111 individuals), and Herbertia quareimana (128 individuals). Analysis of molecular variance highlighted that the genetic groups are statistically divergent (P=0.001) and that 58% of the total genetic variance was within populations. The 11 populations sampled in this study are genetically differentiated (F~(ST)=0.41, P=0.001). The ISI suggests that both pools are self incompatible. Differences in pollen viability are not significant between the genetic groups studied (F=0.043, P—0.958), and pollen viability was over 90% within groups. Conclusions. The population genetic approach allowed the recognition of H. darwinii, H. pulchella, and H. quareimana as three genetically differentiated clusters despite the close genetic relationship between them. The results presented in this article also contribute useful information about genetic diversity within populations, breeding systems, and pollen viabilities for herbaceous and perennial species endemic to the Brazilian Pampa.