Microsatellite markers unravel the population genetic structure of the Azorean Leontodon: implications in conservation

The genus Leontodon L. (Asteraceae) comprises approximately 50 species with a natural distribution area covering North America, Europe, northern Africa, and western Asia. Two of these species are endemic to the Azores Archipelago: Leontodon filii and Leontodon rigens. Although both species were targeted with several taxonomic revisions, so far no studies into their genetic diversity have been carried out. In this research, the population genetic structure and diversity of both taxa were assessed using five newly developed SSR markers. Four hundred and thirty-seven individuals collected throughout the archipelago were included in the study. A total of 98 alleles (25-12 per locus, average = 19.6) and an overall excess of homozygotes (multilocus F (is) = 0.37, range 0.16-0.53) were found for L. rigens populations. For L. filii, 52 alleles in total (8-13 per locus, average = 10.4) were found, overall near the HW equilibrium (multilocus F (is) = 0.07, range -0.25 to 0.57). The two species showed an equivalent proportion of rare alleles (L. rigens 80.6 %; L. filii 76.9 %). Both a Principal Coordinate Analysis and a Bayesian analysis proposed the existence of two well-defined groups, but pooled L. filii populations from Faial Island with L. rigens populations. The largest proportion of genetic variability was found within populations (L. rigens 72.6%; L. filii 78.9 %). The highest values of gene flow were obtained for L. filii within the central group of islands. Our results update the current distribution given for the Azorean Leontodon taxa, clearly indicating that conservation measures should be applied to several populations. The results also reveal that a revision of the Azorean Leontodon should be carried out to clarify species delimitation.