Phylogenetics and Biogeography of Pieris (Lyonieae, Ericaceae) Inferred from Sequences of Nuclear and Chloroplast Genomes

Pieris is an eastern Asian (EA)-eastern North American (NA) disjunct genus with P cubensis in the West Indies (WI). In this study, we inferred interspecific relationships using nucleotide sequences of the internal and external transcribed spacer regions of nuclear ribosomal DNA and chloroplast genome (matK, trnL-F, and psbA-trnH). Pieris nana was sister to the rest of Pieris, i.e. Pieris subg. Pieris. The species Of subg. Pieris diverged consecutively in the order of Pieris cubensis, P. swinhoei, P. floribunda, P. phillyreifolia, and P. formosa Plus P japonica. Neither section Phillyreoides nor section Pieris was monophyletic, and P. phillyreifolia of NA was more closely related to two of the EA species (P. formosa and P. japonica) than to the other NA species (P. floribunda). Morphological characters, such as inflorescence position, testa cell shape, and placenta attachment, used to define the sections were hoinoplasious. Dispersal and vicariance analyses suggested that ancestral populations of Pieris were widespread in the composite area of EA, NA, and WI, and two dispersal events may have occurred from the New World to the Old World. Pieris cubensis may have originated as the result of a dispersal event from the composite area of NA and EA during the early diversification of Pieris in the late Eocene.