Disentangling the distribution of Adenostyles in the Northern Iberian Peninsula: new insights from nuclear and plastid markers

Abstract

The genus Adenostyles (Asteraceae) comprises three species with high morphological variability that inhabit south Europe mountainous regions. The Iberian Peninsula harbours A. alpina subsp. pyrenaica and A. alliariae; the former (calcifugate) is restricted to western-central Pyrenees and the Cantabrian Mountains, while the latter (calcicole) is eastern Pyrenees and Sierra de Gredos. The number of taxa inhabiting the Cantabrian Mountains has remained controversial as the sole presence of A. alpina subsp. pyrenaica and the presence of both species and intermediate forms have been reported. Additionally, a recent study casted doubts on the A. alpina subsp. pyrenaica edaphic preference. We determined the number of taxa in the Cantabrian Mountains, their edaphic preference and the presence of hybrids, by conducting phylogenetic analyses based on plastid (trnL-rpL32 and trnH-psbA) and nuclear (ITS) markers. The ITS Maximum Likelihood and Bayesian Inference topologies revealed no edaphic preference for A. alpina subsp. pyrenaica. The plastid networks grouped individuals by geographical origin in the Centre of Distribution and the Peripheral groups. The plastid-nuclear and PhyloNetwork topologies suggested Incomplete Lineage Sorting (ILS) in the Peripheral group, supporting the hypothesis of Quaternary expansions and contractions. No hybrid was found in the Cantabrian Mountains, although evidence suggested gene flow between species.