Abstract Detail

Population Genetics/Genomics

Magota, Kana [1], Sakaguchi, Shota [1], Lee, Jung-Sim [2], Yamamoto, Masaya [3], Takahashi, Daiki [4], Nagano, J. Atsushi [5], Setoguchi, Hiroaki [1].

Phylogeographic analysis of Saxifraga fortunei complex (Saxifragaceae) reveals multiple origins of morphological and ecological variations in the Japanese Archipelago.

Phenotypic polymorphism within a species is a notable phenomenon in evolutionary biology to understand the process of adaptive speciation and other historical events. The Saxifraga fortunei complex is a widespread herb found in East Asia, specifically in mainland China, the Korean Peninsula, Japanese Archipelago, and Russian Far East, including Sakhalin. It includes several ecotypic taxa corresponding to its geographical arrangement, highly diversified morphology, and ecological traits corresponding to the habitat environment. This species grows commonly in moist and shaded understory with subcordate leaf blade. In contrast to the stable morphology and habitat in the Eurasian continent, the plants growing in the Japanese Archipelago show diversified characters. There are more than six lower taxa; the most common forest floor taxon (S. f. var. incisolobata), an alpine taxon with a smaller body size (S. f. var. alpina), a riparian taxon with a deeply dissected leaf blade base (S. f. var. obtusocuneata), another rheophytic taxon with a cuneate leaf blade shape (S. f. var. suwoensis), an insular taxon with a thick and deeply haired leaf blade (S. f. var. jotanii), and a dwarf taxon endemic to Yakushima Island (S. f. var. obtusocuneata f. minima). The distribution of the various ecotypes in a limited area of the Japanese Archipelago makes the species a suitable model to investigate the impact of population demographic history and natural selection on lineage diversification. Here, Sanger-based sequencing was used to estimate the divergence timeframe between populations of the Eurasian continent and Japan. Genome-wide SNPs obtained by ddRAD sequencing were used to investigate the phylogeographic origins of ecotypic taxa. We found a sharp genetic break between populations in the Korean Peninsula and Japanese Archipelago, suggesting that both populations have been isolated by geographic barriers after divergence in late Miocene. Two distinct regional clades of North and South Japan were identified; phenotypic diversification was evident only in the southern clade. The South Japan clades displayed a historical distribution expansion from north to south. The phenotypic variations appeared to have been generated during the Quaternary expansion, especially in the leading-edge populations. The incongruence between the ecotypic boundaries and the genetic grouping implied various phenotypes would have arisen in parallel. We propose that morphological and ecological specialization in Japanese populations was repeatedly generated by local natural selection.

1 - Kyoto University, Yoshida Nihonmatsu-cho, Sakyo-ku, Kyoto, Kyoto, 606-8501, Japan
2 - Korean National Arboretum, 415 Gwangneung Sumokwon-ro, Soheul-eup, Pocheon, Gyeonggi, 11186, Republic of Korea
3 - Hyogo university of Teacher Education, 942-1 Shimokume, Kato, Hyogo, 673-1494, Japan
4 - Tohoku University, 232-3, Yomogida, Narukoonsen, Osaki, Miyagi, 989-6711, Japan
5 - Ryukoku University, Faculty of Agriculture, 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga, 520-2194, Japan

Keywords:
ddRAD-seq
East Asia
infraspecific polymorphisms
parallel evolution
Saxifraga.

Presentation Type: Oral Paper
Session: PGG1, Population Genetics and Genomics I
Location: /
Date: Tuesday, July 20th, 2021
Time: 4:45 PM(EDT)
Number: PGG1008
Abstract ID:340
Candidate for Awards:Margaret Menzel Award