Patterns of hybridization in a multispecies hybrid zone in the Ranunculus cantoniensis complex (Ranunculaceae)

Simultaneous hybridizations among three or more parental taxa occur in nature, but these have rarely been analysed. The present study investigates the natural hybridization of diploid members of the Ranunculus cantoniensis complex over a microgeographical area in south-western China. Sequence information from maternally inherited plastid DNA (trnQ-rps16 and rpL32-trnL) and biparentally inherited nuclear ribosomal DNA was used to identify hybrids, and these were further confirmed by a dramatic reduction in pollen viability. The populations from the contact zone contained individuals that had more than two nuclear ribosomal internal transcribed spacer (nrITS) types; in addition, a network analysis revealed the presence of hard conflicts between the nuclear and plastid DNA data. These results prove that R.trigonus and R.silerifolius var. dolicanthus have relatively little reproductive isolation from each other, leading to a high gene flow rate in contact populations. The four investigated species can hybridize with each other in this contact zone, forming seven hybrid types.(c) 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 227-239.