Understanding apparently maladaptive floral morphology as genetic diversity maintained through balancing selection

2019 Fiscal Year Final Research Report

• Project/Area Number: 15K14592
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Biodiversity/Systematics
• Research Institution: Kyoto University
• Principal Investigator: Nakagawa Sayaka (中川さやか) 京都大学, 農学研究科, 研究員 (00750621)
• Project Period (FY): 2015-04-01 – 2020-03-31
• Keywords: 集団内変異 / 集団間変異 / 四倍体 / 二年生草本 / 生活史 / ロゼット

Outline of Final Research Achievements

Aster hispidus species complex and A. kantoensis have been considered biennial and semelparous. However, I had found aerial rosettes at the base of the flowering stems (hereafter referred to as post-flowering rosettes) in some of those taxa. which suggested the potential for iteroparity. I hypothesized that the post-flowering rosettes are adaptive in disturbed environments where most of the study species are distributed. Individual tracking and between-population comparison, I revealed that the post-flowering rosettes indeed contributed to reproduction in the next generation, and that the post-flowering rosettes were more frequently observed in disturbed habitats (e.g., floodplain and serpentine area).
Moreover, we performed population genetic analyses using SNPs obtained by ddRAD-seq method to reveal genetic relationships among A. hispidus species complex and related species. The results showed that traditional morphological classification is not consistent with genetic relatedness.

Free Research Field

多様性生物学

Academic Significance and Societal Importance of the Research Achievements

ヤマジノギク種群・カワラノギクは繁殖回数進化のよいモデルとなる可能性を示すとともに開花株ロゼットが保全上も重要な生活史上のステージであることを示した。
また、ヤマジノギク種群・近縁種は、日本固有分類群を含み、河原や蛇紋岩地、岩場や海岸といった多様な環境に適応している。本研究では、ツツザキヤマジノギクの近縁分類群との遺伝的関係が明らかになっただけでなく、ヤマジノギク種群・近縁種の生態的種分化研究や保全生態学研究の材料としての基盤を築くことができた。