LAUSR

Premise of research. Odontites is an herbaceous genus composed of 27 species, mostly distributed around the Mediterranean Basin. As a first step toward studying species diversification within this genus, our goals were to (i) test previous hypotheses about phylogenetic relationships among species; (ii) assess whether the closely related genera Bartsiella, Bornmuellerantha, Macrosyringion, and Odontitella should be included in Odontites; and (iii) detect potential events of reticulate evolution. Methodology. We estimated phylogenetic relationships based on nuclear (ITS and ETS) and chloroplast (psbA-trnH, trnC-ycf6, and trnL-trnF) DNA regions. Our sampling included 184 individuals representing 25 out of the 27 species of Odontites. We also counted chromosomes in five species and measured nuclear genome sizes in 139 individuals of 21 species. Pivotal results. We showed that Bartsiella and Bornmuellerantha should be returned to Odontites, while Odontitella was confirmed as distinct. Macrosyringion requires further investigations. Several phylogenetic incongruences were identified, suggesting two cases of hybrid speciation (in O. maroccanus and O. violaceus) and several introgression events. These events were very diverse in terms of number of individuals involved, species co-occurrence, direction of introgression, and incidence of genome doubling. We obtained new chromosome numbers for O. hispidulus (2n=4x=40) and O. powellii (2n=2x=20), and no relation between nuclear genome size and chromosome number was found. Conclusions. We inferred hybrid speciation and various introgression events, and polyploidy was also detected. Odontites appears as an interesting genus to study species diversification, providing a group of closely related species that display, e.g., morphological, ecological, or phenological character variation; cases of study at different temporal stages in the diversification process; and several contact zones between species.