Molecular phylogeny and biogeography of the arctic‐alpine genus Lagotis (Plantaginaceae)

Abstract

It has been suggested that many plants now found in the arctic originated from ancestors that occurred at high altitudes in the southern mountains of the Northern Hemisphere during the Tertiary. However, this hypothesis has rarely been tested using a molecular phylogenetic approach. Here, we present a fossil‐calibrated molecular phylogeny of Lagotis, an arctic‐alpine genus with the greatest diversity in the Qinghai‐Tibetan Plateau (QTP) and Central Asian mountains, based on five chloroplast (matK, psbA‐trnH, rps16, trnG‐S, trnL‐F) and nuclear ribosomal ITS DNA markers. Within this framework, we infer the ancestral area and biogeographic history of the genus. Four major clades (A–D) within Lagotis were recovered with strong support, which largely correspond to the previous classification of the genus. Within clade A, Lagotis species from QTP were distributed among several subclades, and L. integrifolia from Central Asia was sister to L. glauca and L. minor from the arctic and subarctic region. The Bayesian molecular dating and the ancestral area reconstruction analyses suggested that Lagotis could have originated in the QTP in the Miocene (Tertiary), and that the genus radiated from the Miocene to Pleistocene. The diversification of Lagotis probably took place predominantly in the QTP and it subsequently spread to the Central Asian highlands, followed by northward migration into the arctic. Our results support the hypothesis that the “Central Asiatic Highland Corridor” as an important route for the migration of the flora between the arctic and QTP.

Evolutionary history and underlying adaptation of alpine plants on the Qinghai–Tibet Plateau

“…Most QTP endemic genera originated in situ or in adjacent regions (e.g., Liu et al, ; Wang et al, ; Zhang et al, ; Zhou et al, ), although a few diverged from their sister genera or clades in other regions, far away from the QTP (e.g., Liu et al, ; Tu et al, ). Similarly, widespread genera occurring in both the QTP and other regions may have diverged from their sister clades in the QTP (e.g., Wang et al, ; Zhang et al, ; Jia et al, ; Li et al, ), adjacent regions (Wang et al, ; Zhang et al, ), or far away from the QTP (Milne et al, ). In most cases, it is difficult to determine the accurate origin location of some species‐rich genera due to frequent long‐distance dispersals, although they undoubtedly originated in Eurasia (Mao et al, ).…”

“…The relatively common occurrence of homoploid hybrid speciation in the QTP was ascribed to a special combination of frequent interspecific hybridization and newly created habitats by both geological and climatic changes (Sun et al, ). It should be noted that some genera or lineages diversified initially in the QTP and then migrated out of the QTP (Zhang et al, ; Jia et al, ; Sun et al, ; Nie et al, ; Li et al, ).…”

Serpentine mountain uplift in northern Japan triggered the divergence of a narrow endemic from a widespread (sub)arctic Asia-Alaska species complex ofLagotis(Plantaginaceae)

“…Wulfenia carinthiaca Jacq. was selected as an outgroup based on a previous phylogenetic analysis of Lagotis (Li et al 2014). All the other samples are listed in Table S2.…”

“…All the other samples are listed in Table S2. In monophyletic species, that was revealed in the previous study (Li et al 2014), sequence data were downloaded for one sample per species (in L. integrifolia (Wild.) Schischk., L. integra W.W.Sm., L. alutacea W.W.Sm.…”

“…Morphology-based taxonomy of these species is not settled yet. Molecular phylogenetic analyses of Lagotis are limited, and of the above-mentioned species only L. glauca (from Commander Islands) and L. minor (from Alaska) have been studied and formed a clade based on combined nrITS and cpDNA data (Li et al 2014).…”