Disentangling phylogeography, polyploid evolution and taxonomy of a woodland herb (Veronica chamaedrys group, Plantaginaceae s.l.) in southeastern Europe

Abstract

Southeastern Europe is a centre of European biodiversity, but very little is known about factors causing the observed richness. Here, we contribute to fill this gap by reconstructing the spatio-temporal diversification of the cytologically variable and taxonomically intricate complex of Veronica chamaedrys (Plantaginaceae s.l.), growing in open forests, forest edges and grasslands, with flow cytometry, molecular markers (AFLPs, plastid DNA sequences) and morphometry. Our results show that both diploid and tetraploid cytotypes are widespread, but diploids predominate on the southern Balkan Peninsula. Plastid sequences suggest a first split into three main lineages in the mid-Pleistocene and a continuous diversification during the last 0.4 my. Two of the identified plastid lineages coincide with geographically distinct AFLP clusters. Altogether, the genetic data suggest forest refugia on the southern-most Balkan Peninsula (Greece), in Bulgaria, Istria (Croatia and Slovenia) and maybe the southeastern Carpathians (Romania). Morphometric and genetic data show little congruence with current taxonomy.

Disentangling the Origins of Cultivated Sweet Potato (Ipomoea batatas (L.) Lam.)

“…It is now appreciated that multiple origin of autopolyploidy is common [7], [45], [46]. Autopolyploid complexes may evolve by multiple independent genome duplication events [45], or alternatively result from the hybridization and genome doubling of differentiated con-specific populations brought into contact, for example, by climate-induced range shifts [46]. Such “intermediary” cases are sometimes referred to as segmental allopolyploids, where the genomes involved are sufficiently similar to form multivalents in meiosis [47], but progenitors still considered as distinct species.…”

Dealing with Discordant Genetic Signal Caused by Hybridisation, Incomplete Lineage Sorting and Paucity of Primary Nucleotide Homologies: A Case Study of Closely Related Members of the Genus Picris Subsection Hieracioides (Compositae)

“…The latter possibility has been favoured in case of several other complex plant species groups [30], [32], [80], [81]. Picris hieracioides has been here evidenced to be highly heterogeneous across both markers.…”

“…This, however, was at the expense of sample size at the population level [30], [31], [32]. We also co-analyzed a limited number of samples of the closely related Asian taxa P. japonica (2 populations) and P. nuristanica (1 population).…”

Is genome downsizing associated with diversification in polyploid lineages ofVeronica?

“…Polyploidy is in fact rampant across the genus in both hemispheres, with 76% of all species of known ploidy being polyploid (http://onlinelibrary.wiley.com/doi/10.1111/boj.12276/suppinfo; 56% considering Northern Hemisphere species only), and estimates of 20–25% of all speciation events being associated with polyploidy (Albach et al ., ). Numerous studies have investigated some of these polyploid complexes and have highlighted the importance of detailed analyses for the distribution of particular ploidies (Martínez‐Ortega et al ., ; Albach, ; Bardy et al ., , ; Sonibare et al ., ). Although polyploidy occurs in almost all subgenera of Veronica , polyploid lineages have had mixed diversification success (http://onlinelibrary.wiley.com/doi/10.1111/boj.12276/suppinfo; see also table 3 from Albach et al ., ).…”