Maintenance of species boundaries in three sympatric Ligularia (Senecioneae, Asteraceae) species

• Published in: Journal of integrative plant biology Vol. 60; no. 10; pp. 986 - 999
• Main Authors: Zhang, Ningning, Ma, Yongpeng, Folk, Ryan A., Yu, Jiaojun, Pan, Yuezhi, Gong, Xun
• Format: Journal Article
• Language: English
• Published: China (Republic : 1949- ) Wiley Subscription Services, Inc 01.10.2018; University of the Chinese Academy of Sciences, Beijing 100049, China%Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, the Chinese Academy of Sciences, Kunming 650201, China%Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, USA; Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, the Chinese Academy of Sciences, Kunming 650201, China
• Subjects: Asteraceae - genetics; Biodiversity; Boundaries; Datasets; Deoxyribonucleic acid; DNA; DNA sequencing; DNA, Plant - genetics; Hybridization; Maintenance; Plant Proteins - genetics; Polymorphism, Single Nucleotide - genetics; Reproductive isolation; Single-nucleotide polymorphism; Speciation; Species diversity; Sympatric populations
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.12674

The key process in speciation concerns the formation and maintenance of reproductive isolating barriers between diverging lineages. Although species boundaries are frequently investigated between two species across many taxa, reproductive isolating barriers among multiple species (>2) that would represent the most common phenomenon in nature, remain to be clarified. Here, we use double digest restriction‐site associated DNA (ddRAD) sequencing to examine patterns of hybridization at a sympatric site where three Ligularia species grow together and verify whether those patterns contribute to the maintenance of boundaries among species. The results based on the RAD SNP datasets indicated hybridization Ligularia cyathiceps × L. duciformis and L. duciformis × L. yunnanensis were both restricted to F1s plus a few first‐generation backcrosses and no gene introgression were identified, giving rise to strong reproductive isolation among hybridizing species. Moreover, hybrid swarm simulation, using HYBRIDLAB, indicated the RAD SNP datasets had sufficient discriminatory power for accurate hybrid detection. We conclude that parental species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligularia in the eastern Qinghai‐Tibetan Plateau and adjacent areas. Moreover, this study highlights the effectiveness of RAD sequencing in hybridization studies. Although natural hybridization occurred in three sympatric Ligularia species, these species show strong reproductive isolation and they still maintain species boundaries, which may be the key mechanism to maintain species diversity of Ligularia in the eastern Qinghai‐Tibetan Plateau and adjacent areas.