Background: Plant phylogeographic studies of species in subtropical China have mainly focused on rare and
endangered species, whereas few studies have been conducted on taxa with relatively wide distribution, especially
polyploid species. We investigated the cytotype and haplotype distribution pattern of the Actinidia chinensis complex,a widespread geographically woody liana with variable ploidy in subtropical China comprising two varieties, withthree chloroplast fragments DNA (ndhF-rpl132, rps16-trnQ and trnE-trnT). Macroevolutionary, microevolutionary andniche modeling tools were also combined to disentangle the origin and the demographic history of the species or
cytotypes.
Results: The ploidy levels of 3338 individuals from 128 populations sampled throughout the species distribution
range were estimated with flow cytometry. The widespread cytotypes were diploids followed by tetraploids and
hexaploids, whereas triploids and octoploids occurred in a few populations. Thirty-one chloroplast haplotypes were
detected. The genetic diversity and genetic structure were found to be high between varieties (or ploidy races) chin-ensis and deliciosa. Our results revealed that these two varieties inhabit significantly different climatic niche spaces.Ecological niche models (ENMs) indicate that all varieties’ ranges contracted during the Last Inter Glacial (LIG), andexpanded eastward or northward during the Last Glacial Maximum (LGM).
Conclusions: Pliocene and Plio-Pleistocene climatic fluctuations and vicariance appear to have played key roles in
shaping current population structure and historical demography in the A. chinensis complex. The polyploidization
process also appears to have played an important role in the historical demography of the complex through improv-
ing their adaptability to environmental changes.
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