Phylogeographic analysis suggests two origins for the riparian azalea Rhododendron indicum (L.) Sweet. (December 2018)

• Record Type: Journal Article
• Authors: Yoichi, Watanabe; Kawamata, Izumi; Matsuki, Yu; Suyama, Yoshihisa; Uehara, Koichi; Ito, Motomi
• Is Part Of: Heredity. Volume 121:Number 6(2018)
• Page Start: 594
• Page End: 604
• Publication Date: 2018-12
• Subjects: Genetics -- Periodicals; Heredity -- Periodicals; Evolution -- Periodicals
• DOI: 10.1038/s41437-018-0064-3
• Languages: English
• ISSNs: 0018-067X

Abstract

Abstract Ecological speciation is an important factor in the diversification of plants. The distribution of the woody speciesRhododendron indicum, which grows along rivers and is able to withstand water flow when rivers flood (i.e. it is a rheophyte), is disjunct, in contrast to the widespread distribution of its relative, Rhododendron kaempferi . This study aimed to elucidate the phylogenetic relationships betweenR. indicum andR. kaempferi and the evolutionary processes that gave rise to them. The sequences of three non-coding chloroplast DNA regions (total length 1977 bp) were obtained from 21 populations covering the ranges of the two species. In addition, genome-wide SNPs were genotyped from 20 populations using a genotyping by sequencing method. Leaf morphologies were measured for eight representative populations. Two chloroplast DNA haplotypes, which were detected inR. indicum, were shared between the two species. Genome-wide SNPs identified two lineages inR. indicum and these lineages did not constitute a monophyletic group. Each of these two lineages was related to geographically close populations ofR. kaempferi . Leaf morphology, which is a characteristic feature in rheophytes, was not differentiated between the two lineages inR. indicum . The morphological similarity between the two heterogeneous lineages may be a result of parallel evolution fromR. kaempferi or of introgressive hybridization between the species due to strong selective pressure imposed by flooding.