Shining a light on species delimitation in the tree genus Engelhardia Leschenault ex Blume (Juglandaceae)

Zhang, Can-Yu; Low, Shook Ling; Song, Yi-Gang; Nurainas; Kozlowski, Gregor; Do, Truong Van; Li, Lang; Zhou, Shi-Shun; Tan, Yun-Hong; Cao, Guan-Long; Zhou, Zhuo; Meng, Hong-Hu; Li, Jie

doi:10.1016/j.ympev.2020.106918

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Shining a light on species delimitation in the tree genus Engelhardia Leschenault ex Blume (Juglandaceae)

Zhang, Can-Yu Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650023, China - University of Chinese Academy of Sciences, Beijing 100049, China
Low, Shook Ling CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China
Song, Yi-Gang Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai 201602, China - Department of Biology and Botanic Garden, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
Nurainas Department of Biology, Faculty of Math. & Nat. Sci. Andalas University, Padang 25163, West Sumatra, Indonesia
Kozlowski, Gregor Department of Biology and Botanic Garden, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
Do, Truong Van Vietnam National Museum of Nature, Vietnam Academy of Science & Technology, 18 Hoang Quoc Viet, Hanoi, Viet Nam
Li, Lang Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650023, China - Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Nay Pyi Taw 05282, Myanmar - Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, China
Zhou, Shi-Shun Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Nay Pyi Taw 05282, Myanmar
Tan, Yun-Hong Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Nay Pyi Taw 05282, Myanmar - Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, China
Cao, Guan-Long Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650023, China - University of Chinese Academy of Sciences, Beijing 100049, China
Zhou, Zhuo CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
Meng, Hong-Hu Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650023, China - Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Nay Pyi Taw 05282, Myanmar
Li, Jie Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650023, China - Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Nay Pyi Taw 05282, Myanmar - Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, China

01.11.2020

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Molecular Phylogenetics and Evolution. - 2020, vol. 152, p. 106918

English Enhanced efficacy in species delimitation is critically important in biology given the pending biodiversity crisis under global warming and anthropogenic activity. In particular, delineation of traditional classifications in view of the complexity of species requires an integrative approach to effectively define species boundaries, and this is a major focus of systematic biology. Here, we explored species delimitation of Engelhardia in tropical and subtropical Asia. In total, 716 individuals in 71 populations were genotyped using five chloroplast regions, one nuclear DNA region (nrITS), and 11 nuclear simple sequence repeats (nSSR). Phylogenetic trees were constructed and relationships among species were assessed. Molecular analyses were then combined with 14 morphological characteristics of 720 specimens to further explore the species boundaries of Engelhardia. Integrating phylogenetic and morphological clusters provided well-resolved relationships to delineate seven species. The results suggested that: first, that E. fenzelii, E. roxburghiana, E. hainanensis, E. apoensis, and E. serrata are distinct species; second, E. spicata var. spicata, E. spicata var. aceriflora, E. spicata var. colebrookeana, and E. rigida should be combined under E. spicata and treated as a species complex; third, E. serrata var. cambodica should be raised to species level and named E. villosa. We illuminated that bias thresholds determining the cluster number for delimiting species boundaries were substantially reduced when morphological data were incorporated. Our results urge caution when using the concepts of subspecies and varieties in order to prevent confusion, particularly with respect to species delimitation for tropical and subtropical species. In some cases, re-ranking or combining subspecies and/or varieties may enable more accurate species delimitation.

Faculty

Faculté des sciences et de médecine

Department

Département de Biologie

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