Plant Diversity ›› 2023, Vol. 45 ›› Issue (04): 456-468.DOI: 10.1016/j.pld.2022.10.001

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Pre- and post-pollination barriers between two exotic and five native Sagittaria species: Implications for species conservation

Ting-Ting Zou, Sen-Tao Lyu, Qi-Lin Jiang, Shu-He Shang, Xiao-Fan Wang   

  1. Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
  • Received:2022-06-07 Revised:2022-10-04 Online:2023-07-25 Published:2023-08-21
  • Contact: Xiao-Fan Wang,
  • Supported by:
    We thank Xiaolei Yu for helping with the sequential analysis. We thank Xin Zan for the help in the field. We are grateful to Chun-hui Wang for her valuable advice. This study was supported by the National Science Foundation of China (31970250).

Abstract: Anthropogenic introduction of species has resulted in a breakdown of geographical barriers and hybridization in previously allopatric species. Thus, examining hybridization proneness of exotic species contributes to revealing its potential threat. Moreover, reproductive barriers may be strengthened or weakened due to long-term geographical isolation for these newly sympatric species. However, few studies have evaluated multiple barriers between alien and native species. In this study, we quantified the importance of four pre-pollination barriers (phenological, floral traits, pollen production, and floral constancy) and four post-pollination barriers (pollen-pistil incompatibility, seed set, seed viability, and seedling survival) between two introduced and five native Sagittaria species. Results showed that introduced S. platyphylla was cross-compatible with two native species, whereas introduced S. montevidensis was incapable of hybridizing with any native species. Different barriers were asymmetric within species pairs and multiple barriers acted in concert to maintain species boundaries. Post-pollination barriers contributed more to total reproductive isolation in native species, whereas pre-pollination barriers played a stronger role in total reproductive isolation for two introduced species. Seed set was the only barrier that was positively correlated with genetic distance. Our results provide a perspective to better understand reproductive barriers for secondary contact species. We highlight the importance of monitoring hybridization events before human introduction and the possible conservation strategies to remove invasive species with hybridization proneness.

Key words: Alismataceae, Introduced species, Conservation, Hybridization, Reproductive isolation, Sagittaria