Shota Sakaguchi1, Takuma Kimura2, Ryuta Kyan2, Masayuki Maki2, Takako Nishino3, Naoko Ishikawa4, Atsushi J Nagano5,6,7, Mie N Honjo6, Masaki Yasugi8, Hiroshi Kudoh6, Pan Li9, Hyeok Jae Choi10, Olga A Chernyagina11, Motomi Ito4. 1. Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto, Japan. 2. Botanical Gardens, Tohoku University, Kawauchi, Sendai, Japan. 3. Graduate School of Science, Osaka Prefecture University, Osaka, Japan. 4. Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan. 5. Faculty of Agriculture, Ryukoku University, Otsu, Shiga, Japan. 6. Center for Ecological Research, Kyoto University, Otsu, Shiga, Japan. 7. JST CREST, Honcho, Kawaguchi, Saitama, Japan. 8. National Institute for Basic Biology, Higashiyama, Myodaiji, Okazaki, Aichi, Japan. 9. College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China. 10. Department of Biology & Chemistry, Changwon National University, Changwon, Gyeongnam, Korea. 11. Kamchatka Branch of Pacific Geographical Institute, Petropavlovsk-Kamchatskyi, Russia.
Abstract
Background and Aims: The processes and mechanisms underlying lineage diversification are major topics in evolutionary biology. Eurasian goldenrod species of the Solidago virgaurea complex show remarkable morphological and ecological diversity in the Japanese Archipelago, with ecotypic taxa well adapted to specific environments (climate, edaphic conditions and disturbance regimes). The species complex is a suitable model to investigate the evolutionary processes of actively speciating plant groups, due to its ability to evolve in relation to environmental adaptation and its historical population dynamics. Methods: Two chloroplast markers, 18 nuclear microsatellite markers and ddRAD-sequencing were used to infer population genetic demography of S. virgaurea complex with its related species/genera. Key Results: Our analysis showed that populations in Japan form an evolutionary unit, which was genetically diverged from adjacent continental populations. The phylogenetic structure within the archipelago strongly corresponds to the geography, but interestingly there is no concordance between genetic structure and ecotypic boundaries; neighbouring populations of distinct ecotypes share a genetic background. Conclusions: We propose that the traits specific to the ecotypic entities are maintained by natural selection or are very recently generated and have little effect on the genomes, making genome-wide genetic markers unsuitable for detecting ecotypic differentiation. Furthermore, some sporadically distributed taxa (found as rheophytes and alpine plants) were repeatedly generated from a more widespread taxon in geographically distant areas by means of selection. Overall, this study showed that the goldenrod complex has a high ability to evolve, enabling rapid ecological diversification over a recent timeframe.
Background and Aims: The processes and mechanisms underlying lineage diversification are major topics in evolutionary biology. Eurasian goldenrod species of the Solidago virgaurea complex show remarkable morphological and ecological diversity in the Japanese Archipelago, with ecotypic taxa well adapted to specific environments (climate, edaphic conditions and disturbance regimes). The species complex is a suitable model to investigate the evolutionary processes of actively speciating plant groups, due to its ability to evolve in relation to environmental adaptation and its historical population dynamics. Methods: Two chloroplast markers, 18 nuclear microsatellite markers and ddRAD-sequencing were used to infer population genetic demography of S. virgaurea complex with its related species/genera. Key Results: Our analysis showed that populations in Japan form an evolutionary unit, which was genetically diverged from adjacent continental populations. The phylogenetic structure within the archipelago strongly corresponds to the geography, but interestingly there is no concordance between genetic structure and ecotypic boundaries; neighbouring populations of distinct ecotypes share a genetic background. Conclusions: We propose that the traits specific to the ecotypic entities are maintained by natural selection or are very recently generated and have little effect on the genomes, making genome-wide genetic markers unsuitable for detecting ecotypic differentiation. Furthermore, some sporadically distributed taxa (found as rheophytes and alpine plants) were repeatedly generated from a more widespread taxon in geographically distant areas by means of selection. Overall, this study showed that the goldenrod complex has a high ability to evolve, enabling rapid ecological diversification over a recent timeframe.