Abstract
SAYA TAMURA, TOMOKO FUKUDA, ELENA A. PIMENOVA, EKATERINA A. PETRUNENKO, PAVEL V. KRESTOV, SVETLANA N. BONDARCHUK, OLGA A. CHERNYAGINA, YOSHIHISA SUYAMA, YOSHIHIRO TSUNAMOTO, AYUMU MATSUO, HAYATO TSUBOI, HIDEKI TAKAHASHI, KEN SATO, YOKO NISHIKAWA, TAKASHI SHIMAMURA, HIROKO FUJITA & KOH NAKAMURA An alpine plant Saxifraga yuparensis is endemic to a scree consisting of greenschist of Mt. Yubari in Hokkaido, Japan and it has been proposed as an immediate hybrid derived from two species of the same section Bronchiales based on morphological intermediacy: namely S. nishidae, a diploid species endemic to a nearby cliff composed of greenschist and tetraploid S. rebunshirensis comparatively broadly distributed in Japan and Russian Far East. Saxifraga yuparensis is red-listed and it is crucial for conservation planning to clarify whether this is an immediate hybrid and lacks a unique gene pool. The immediate-hybrid hypothesis was tested by molecular and cytological data. In nuclear ribosomal and chloroplast DNA trees based on maximum parsimony and Bayesian criteria, S. yuparensis and S. rebunshirensis formed a clade with several other congeners while S. nishidae formed another distinct clade. Genome-wide SNP data clearly separated these three species in principal coordinate space, placing S. yuparensis not in-between of S. rebunshirensis and S. nishidae. Chromosome observation indicated that S. yuparensis is tetraploid, not triploid directly derived from diploid-tetraploid crossing. Additionally, observation of herbarium specimens revealed that leaf apex shape of S. yuparensis fell within the variation of S. rebunshirensis. These results indicate that S. yuparensis is not an immediate hybrid of S. rebunshirensis and S. nishidae but a distinct lineage and an extremely narrow endemic species, that deserves for intensive conservation.
Highlights
The genus Saxifraga L. (1753: 398) (Saxifragaceae, e.g., Soltis et al 2001) encompasses more than 440 species and is composed of at least 13 sections and nine subsections (Tkach et al 2015)
In the MP analysis, 201 nucleotide substitutions were found in 57 variable sites and 114 sites were parsimony informative among them. 15,104 parsimonious trees of 314 steps were obtained with a consistency index (CI) = 0.78, a retention index (RI) = 0.91, and a resealed consistency index (RC) = 0.71
In the molecular phylogenetic analyses based on internal transcribed spacer (ITS) and cpDNA, S. yuparensis was not monophyletic and recovered in the same clade with S. rebunshirensis plus several other species (S. funstonii and S. caulescens in ITS; 11 species in trnL-F)
Summary
The genus Saxifraga L. (1753: 398) (Saxifragaceae, e.g., Soltis et al 2001) encompasses more than 440 species and is composed of at least 13 sections and nine subsections (Tkach et al 2015). (1753: 398) (Saxifragaceae, e.g., Soltis et al 2001) encompasses more than 440 species and is composed of at least 13 sections and nine subsections (Tkach et al 2015). This section has approximately 20 species (DeChaine et al 2013, DeChaine 2014) mostly in northern high latitudes, and among them, three species are distributed in Hokkaido, northern Japan: S. yuparensis Nosaka (1974: 149), S. rebunshirensis Sipliv. June 2016, Rebun Island), and S. nishidae (C, F, I & L, 26 July 2016, Gama-iwa at Mt. Yubari).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
