Bridging the Alps and the Middle East: Evolution, phylogeny and systematics of the genus Wulfenia (Plantaginaceae)

Abstract

The genus Wulfenia (Plantaginaceae) demonstrates a striking disjunction between the southeastern Alps (Carnic Alps), the southeastern Dinaric Alps (Prokletije Mountains, Balkan Peninsula) and the Amanos mountains of southern Turkey. This puzzling biogeographic pattern has interested botanists for more than 100 years and Wulfenia has been widely regarded as a Tertiary relict of at least Miocene age in southeastern Europe. Specifically, the identity of populations in the Prokletije Mountains either referred to as disjunct populations of W. carinthiaca or a separate species, “W. blecicii”, has been much debated. Here we analyze AFLP, plastid and nuclear ribosomal sequence data in conjunction with a morphometrical analysis to clarify the taxonomy of the genus and the relationships of the populations to one another. Furthermore, we employ a molecular dating strategy to put these results in a time frame to assess the Miocene relict–hypothesis. Our results provide evidence for a new classification of the genus with four species, W. orientalis, W. glanduligera comb. & stat. nov., W. baldaccii and W. carinthiaca. The split of the last species into populations disjunctly distributed in the southeastern Alps (W. carinthiaca s.str.) and southeastern Dinaric Alps (“W. blecicii”), is not supported either by molecular or morphological data, while we find enough evidence in DNA sequence data, growth site specifics and morphology for W. orientalis var. glanduligera to be treated at the species rank. Our dating analysis suggests that the extant genus is rather young with a crown node age of only about 1.24 Ma and 0.61 Ma for the European populations despite a stem node age of about 10.69 Ma. Thus, Wulfenia as a genus is likely a Miocene relict but its uninterrupted presence on the Balkan Peninsula cannot be demonstrated.

How many taxa? Spatiotemporal evolution and taxonomy of Amphoricarpos (Asteraceae, Carduoideae) on the Balkan Peninsula

“…Similarly as in Edraianthus graminifolius (Surina et al 2014) populations in the south of the distribution area of Balkan Amphoricarpos are highly disjunct . The genetic divergence of the southernmost populations 28 and 29 of Amphoricarpos from Albania and northern Greece is likely caused by both, geographic isolation preventing contemporary gene flow, and long-term in situ persistence (Surina et al 2014).…”

“…We are aware that the inclusion of the Anatolian A. praedictus and the Caucasian A. elegans might change our age estimates and thus suggest viewing them with appropriate caution. Tertiary origin of Balkan Amphoricarpos contrasts with diversification within Balkan Atocion compactum and Wulfenia, whose divergence from Anatolian relatives was dated to the Pleistocene (Frajman et al 2009b;Surina et al 2014). Acknowledging the contribution of the Asian flora to the species richness of the Balkan Peninsula (Turrill 1929;Stevanović 1996;Nieto Feliner 2014), additional studies are needed to explore temporal diversification patterns in other plants with similar distribution.…”

“…The genetic divergence of the southernmost populations 28 and 29 of Amphoricarpos from Albania and northern Greece is likely caused by both, geographic isolation preventing contemporary gene flow, and long-term in situ persistence (Surina et al 2014).…”

“…; the split between the species was dated to the early Pliocene, ca. 5 Ma (Barres et al 2013), which is significantly older than the diversification of the similarly distributed Atocion compactum (Frajman et al 2009b) and Wulfenia (Surina et al 2014), which likely took place in the Pleistocene.…”

“…A few phylogenetic studies accompanied with dating analyses have shown that many Balkan endemics originated in the Tertiary (e.g. Campanula comosiformis; Frajman and Schneeweiss 2009;Heliosperma macranthum, Frajman et al 2009a; Viscaria asterias and likely Atocion lerchenfeldianum; Frajman et al 2009b); exceptions are, for instance, species from the Heliosperma pusillum group (Frajman et al 2009a) and Wulfenia (Surina et al 2014) that likely diversified in the Pleistocene.…”