Intra-individual polymorphism in diploid and apomictic polyploid hawkweeds (Hieracium, Lactuceae, Asteraceae): disentangling phylogenetic signal, reticulation, and noise
Abstract
The first molecular phylogeny of Hieracium s.str. based on diploids and polyploids of supposed non-hybrid origin (‘basic species’) is presented. The group is split into two major clades roughly corresponding to species with Eastern or Western European origin.
Contrary to expectation, abundant evidence for hybridization was found; most of it concerned parental combinations from both groups. Survival in different glacial refugia, and speciation and hybridization (accompanied by polyploidization and apomixis) as a result of secondary contact are probable.
The data also show evidence of extinct taxa that have left their molecular traces in contemporary hybrids and suggest the presence of a much larger range of ancestral diploids in former times. Prominent intra-individual variation in a multicopy nuclear region required detailed character state analysis in order to distinguish phylogenetic signal from hybrid origin and homoplasy.