A new biological species in the Mercurialis annua polyploid complex: functional divergence in inflorescence morphology and hybrid sterility. (17th May 2019)

• Record Type: Journal Article
• Authors: Ma, Wen-Juan; Santos del Blanco, Luis; Pannell, John R
• Is Part Of: Annals of botany. Volume 124:Number 1(2019)
• Page Start: 165
• Page End: 178
• Publication Date: 2019-05-17
• Subjects: Male-like inflorescence -- polyploidy -- functional divergence -- female sterility -- reproductive isolation -- phylogeny -- evolutionary origin; Botany -- Periodicals; 580
• DOI: 10.1093/aob/mcz058
• Languages: English
• ISSNs: 0305-7364

Abstract

Abstract: Background and Aims: Polyploidy has played a major role in the origin of new plant species, probably because of the expansion of polyploid populations in the species' ecological niche, and because reproductive isolation can be established between a new polyploid population and its diploid progenitor species. It is well established that most polyploid species are polyphyletic, with multiple independent origins, and that polyploid genomes may undergo rapid change after their duplication and hybridization associated with their origin. We considered whether multiple independent origins and rapid genomic change might lead to reproductive isolation between polyploid populations of the same ploidy but with potentially different evolutionary histories. Methods: We tested our hypothesis by assessing differences in DNA content and morphology, the evolution of reproductive isolation, and the phylogenetic placement of two broadly sympatric hexaploid lineages of the wind-pollinated annual plant Mercurialis annua hitherto regarded as populations of the same species. Key Results: The two hexaploid lineages of M. annua have slightly divergent DNA content, and distinct inflorescence morphology. They also fall into largely different clades of a chloroplast phylogeny and are reproductively isolated from one another. Conclusions: The distinct evolutionary histories of the two hexaploid lineages of M. annua have contributed to the remarkable reproductive diversity of the species complex. It seems likely that reproductive interference between them will eventually lead to the displacement of one lineage by the other via pollen swamping. Thus, whereas polyploidization can contribute to speciation, diversification might also be compromised by reproductive interference.