Repeated expansions and fragmentations linked to Pleistocene climate changes shaped the genetic structure of a woody climber,Actinidia arguta(Actinidiaceae)

Abstract

The genetic structure of temperate plants was extremely affected by climate changes during the Pleistocene. In East Asia, however, there are a limited number of phylogeography studies of widely distributed species. Actinidia arguta (Sieb. & Zucc.) Planch. ex Miq. (Actinidiaceae), a widely distributed woody climber, was chosen for this study. Twelve haplotypes were obtained using five chloroplast fragments. No haplotypes were shared on two sides of the Qinling–Dabie mountain ranges, indicating a phylogeographic break. The break was further revealed by analysis of molecular variance, spatial analysis of molecular variance, and ecological niche modelling. The most recent common ancestor of all haplotypes showed that global cooling and aridity of the Asian interior at the Pliocene–Pleistocene boundary may triggered this divergence. Two monophyletic lineages (north and south lineage) were revealed by Bayesian phylogeny and the maximum parsimony network. In the north lineage, mismatch analysis indicated an ancient spatial expansion. Distant distribution of closely related haplotypes indicated subsequent allopatric fragmentation. The widespread haplotype H2 implied another significant range expansion. In the south lineage, a considerable rise in sea level of the East China Sea may have triggered population fragmentation. The nested clade analysis also indicated that expansion and allopatric fragmentation were the main processes shaping the haplotype distributions. So, repeated range expansions and fragmentations have shaped the present genetic structure of A. arguta.