Phylogeny of Woodsia (Woodsiaceae): recent speciation through polyploidization is common in old diploid stock.
(English)Manuscript (preprint) (Other academic)
Woodsia is a genus of small tufted ferns growing in rocky habitats. It is widely distributed in temperate and montane regions of the world. Through previous cytological studies and allozyme work it is known to have a complex evolutionary history and includes numerous polyploid taxa and hybrids. We present here for the first time detailed phylogenetic analyses of a wide range of taxa within Woodsia, including samples from many chromosome-counted specimens. Five plastid (atpA, atpB, matK, rbcL and trnG-R) and two nuclear (pgiC and RPA2) regions have been used from an ingroup of 188 samples representing 36 taxa and six hybrids. In a complementary expanded analysis the polyploid speciation frequency is estimated within the 10 families most closely related to Woodsiaceae (the Eupolypods II). Woodsia is monophyletic if the often segregated genera Protowoodsia, Cheilanthopsis and Hymenocystis are included. The genus comprises two major well-supported clades, one including the circumboreal and most of the Asian species, and the other including all American and the remaining Asian species. The split between these clades is estimated to 45 Ma. Woodsia × abbae is a remarkable triploid hybrid between members of these two clades. Most taxa in Woodsia are polyploid and polyploidization is the most common mode of speciation in the genus with an estimated polyploid speciation rate of 54%. The polyploids are mostly young. Some of the polyploid taxa, such as W. alpina and W. obtusa, seem to have been formed multiple times. The Eupolypod II study agrees with the Woodsia study in showing a high proportion of polyploids with a polyploid speciation rate of 46%. Old polyploid lineages are rare. The circumboreal species do not form a monophyletic group and are nested among various Asian species, whereas the "American clade" is monophyletic and nested among Asian species. Within the American clade W. montevidensis has its main distribution in South America, but also has made a recent leap to Southern Africa and Madagascar.
biogeography, chromosome numbers, Eupolypods II, hybrids, nuclear and plastid DNA, polyploid speciation
Research subject Biology with specialization in Systematics
IdentifiersURN: urn:nbn:se:uu:diva-232232OAI: oai:DiVA.org:uu-232232DiVA: diva2:747143
FunderFormas, 2006-429 and 2010-585