Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China

ABSTRACT Over long‐term evolutionary processes, sympatric affinities may develop reproductive isolation mechanisms, such as temporal isolation and ecological divergence, to maintain species independence. However, due to lacking strict geographic isolation barriers, sympatrically distributed closely...

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Main Authors: Fanggui Zheng, Yiqing Wang, Huihui Xi, Siyue Xiao, Xiuyan Feng, Xun Gong, Jian Liu
Format: Article
Language:English
Published: Wiley 2025-07-01
Series:Ecology and Evolution
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Online Access:https://doi.org/10.1002/ece3.71769
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author Fanggui Zheng
Yiqing Wang
Huihui Xi
Siyue Xiao
Xiuyan Feng
Xun Gong
Jian Liu
author_facet Fanggui Zheng
Yiqing Wang
Huihui Xi
Siyue Xiao
Xiuyan Feng
Xun Gong
Jian Liu
author_sort Fanggui Zheng
collection DOAJ
description ABSTRACT Over long‐term evolutionary processes, sympatric affinities may develop reproductive isolation mechanisms, such as temporal isolation and ecological divergence, to maintain species independence. However, due to lacking strict geographic isolation barriers, sympatrically distributed closely related species may experience interspecific gene flow and genetic introgression, which can blur species boundaries. Here we focus on two sympatrically distributed Cycas species along the Lancang (Mekong) River in three populations from Southwest China, Cycas pectinata and C. simplicipinna, to investigate the extent of genetic introgression between them and how they maintain species boundaries. Using 16 microsatellite markers, we first genotyped and assessed the introgression patterns between the two species and their seedlings in each population. We further compared their geographical and ecological divergence, including the fine‐scale spatial distribution, habitats, reproductive phenology, and pollinators, based on a systematic field survey across its entire range in China. We found that sympatric populations of C. pectinata and C. simplicipinna, along with their seedlings, showed no genetic admixture. Further evidence supports that the two species exhibited significant variations in habitat indicators such as slope position and soil pH. Additionally, significant differences were observed in pollinator communities and coning behavior. These findings indicate that there is no hybridization between C. pectinata and C. simplicipinna under natural conditions. Instead, they maintain species boundaries primarily through reproductive isolation driven by divergent coning times and pollinator specificity, coupled with niche differentiation. This study not only provides a representative case for understanding mechanisms of plant species boundary maintenance but also offers critical theoretical support for the reintroduction and conservation of cycads.
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spelling doaj-art-9c6f8de5ee0c4c9aa14da439377971af2025-08-20T03:08:40ZengWileyEcology and Evolution2045-77582025-07-01157n/an/a10.1002/ece3.71769Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest ChinaFanggui Zheng0Yiqing Wang1Huihui Xi2Siyue Xiao3Xiuyan Feng4Xun Gong5Jian Liu6Southwest Forestry University Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaKey Laboratory for Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany, Chinese Academy of Sciences Kunming ChinaABSTRACT Over long‐term evolutionary processes, sympatric affinities may develop reproductive isolation mechanisms, such as temporal isolation and ecological divergence, to maintain species independence. However, due to lacking strict geographic isolation barriers, sympatrically distributed closely related species may experience interspecific gene flow and genetic introgression, which can blur species boundaries. Here we focus on two sympatrically distributed Cycas species along the Lancang (Mekong) River in three populations from Southwest China, Cycas pectinata and C. simplicipinna, to investigate the extent of genetic introgression between them and how they maintain species boundaries. Using 16 microsatellite markers, we first genotyped and assessed the introgression patterns between the two species and their seedlings in each population. We further compared their geographical and ecological divergence, including the fine‐scale spatial distribution, habitats, reproductive phenology, and pollinators, based on a systematic field survey across its entire range in China. We found that sympatric populations of C. pectinata and C. simplicipinna, along with their seedlings, showed no genetic admixture. Further evidence supports that the two species exhibited significant variations in habitat indicators such as slope position and soil pH. Additionally, significant differences were observed in pollinator communities and coning behavior. These findings indicate that there is no hybridization between C. pectinata and C. simplicipinna under natural conditions. Instead, they maintain species boundaries primarily through reproductive isolation driven by divergent coning times and pollinator specificity, coupled with niche differentiation. This study not only provides a representative case for understanding mechanisms of plant species boundary maintenance but also offers critical theoretical support for the reintroduction and conservation of cycads.https://doi.org/10.1002/ece3.71769conservationCycasreproductive isolationspecies boundariessympatric distribution
spellingShingle Fanggui Zheng
Yiqing Wang
Huihui Xi
Siyue Xiao
Xiuyan Feng
Xun Gong
Jian Liu
Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
Ecology and Evolution
conservation
Cycas
reproductive isolation
species boundaries
sympatric distribution
title Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
title_full Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
title_fullStr Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
title_full_unstemmed Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
title_short Ecological Isolation Maintains the Species Boundaries Between Two Sympatric Cycas From Southwest China
title_sort ecological isolation maintains the species boundaries between two sympatric cycas from southwest china
topic conservation
Cycas
reproductive isolation
species boundaries
sympatric distribution
url https://doi.org/10.1002/ece3.71769
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