Patterns of rapid diversification in heteroploid Knautia sect. Trichera (Caprifoliaceae, Dipsacoideae), one of the most intricate taxa of the European flora

BMC Evolutionary Biology

Research Article

Friedrich Ehrendorfer¹  Ivana Rešetnik²  Božo Frajman³  Peter Schönswetter³  Marjan Niketić⁴ 

[1] Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030, Vienna, Austria;Faculty of Science, University of Zagreb, Marulićev trg 20, HR-10000, Zagreb, Croatia;Institute of Botany, University of Innsbruck, Sternwartestraße 15, A-6020, Innsbruck, Austria;Natural History Museum, Njegoševa 51, 11000, Belgrade, Serbia;

关键词: Estimation of divergence times;    Genetic versus traditional species groups;    Haplotype sharing;    Hybridisation;    Knautia;    Polyploidy;    Random walk analysis;   

DOI  :  10.1186/s12862-016-0773-2

 received in 2016-03-16, accepted in 2016-09-28,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundPolyploidy is one of the most important evolutionary pathways in flowering plants and has significantly contributed to their diversification and radiation. Due to the prevalence of reticulate evolution spanning three ploidy levels, Knautia is considered one of the taxonomically most intricate groups in the European flora. On the basis of ITS and plastid DNA sequences as well as AFLP fingerprints obtained from 381 populations of almost all species of the genus we asked the following questions. (1) Where and when did the initial diversification in Knautia take place, and how did it proceed further? (2) Did Knautia undergo a similarly recent (Pliocene/Pleistocene) rapid radiation as other genera with similar ecology and overlapping distribution? (3) Did polyploids evolve within the previously recognised diploid groups or rather from hybridisation between groups?ResultsThe diversification of Knautia was centred in the Eastern Mediterranean. According to our genetic data, the genus originated in the Early Miocene and started to diversify in the Middle Miocene, whereas the onset of radiation of sect. Trichera was in central parts of the Balkan Peninsula, roughly 4 Ma. Extensive spread out of the Balkans started in the Pleistocene about 1.5 Ma. Diversification of sect. Trichera was strongly fostered by polyploidisation, which occurred independently many times. Tetraploids are observed in almost all evolutionary lineages whereas hexaploids are rarer and restricted to a few phylogenetic groups. Whether polyploids originated via autopolyploidy or allopolyploidy is unclear due to the weak genetic separation among species. In spite of the complexity of sect. Trichera, we present nine AFLP-characterised informal species groups, which coincide only partly with former traditional groups.ConclusionsKnautia sect. Trichera is a prime example for rapid diversification, mostly taking place during Pliocene and Pleistocene. Numerous cycles of habitat fragmentation and subsequent reconnections likely promoted hybridisation and polyploidisation. Extensive haplotype sharing and unresolved phylogenetic relationships suggest that these processes occurred rapidly and extensively. Thus, the dynamic polyploid evolution, the lack of crossing barriers within ploidy levels supported by conserved floral morphology, the highly variable leaf morphology and unstable indumentum composition prevent establishing a well-founded taxonomic framework.

【 授权许可】

CC BY   
© The Author(s). 2016