Common but overlooked: Study uncovers hidden genetic vulnerability of the widespread mangrove fern Acrostichum aureum in Hainan
image: Acrostichum aureum across nine coastal sites in Hainan Island was examined using morphological, cytometric, and genomic approaches. Three priority conservation areas are proposed to preserve extant genetic diversity and maintain habitat connectivity.
Credit: Bingyan Guo, Rui Guo, Hongjuan Zhu, Changwang Ma, Dan He, Xialan Cheng, Yougen Wu, Ya Liu, Jing Yu, and Dongmei Yang
Date: June 5, 2026
Sanya, China: Mangroves are vital coastal ecosystems that protect shorelines and support biodiversity, yet over half of global mangrove cover has been lost to human activities. In China, Hainan Island—home to 32 true mangrove species—has seen its mangrove area decline by more than 50% since the 1950s. While dominant mangrove trees have been extensively studied, the ecologically important edge species A. aureum has long been overlooked, with most previous research focusing on its medicinal properties rather than its genetic health.
To address this gap, researchers from Hainan University and the Chinese Academy of Sciences collected 122 A. aureum samples from 12 populations across 9 coastal sites in Hainan. They integrated morphological analysis, flow cytometry, and genotyping-by-sequencing (GBS) to comprehensively assess the species' diversity and population structure.
The study yielded three key findings. First, morphological cluster analysis identified five ecologically distinct clades strongly correlated with pinna morphology and habitat types (ranging from riverside to shrimp pond edges), though spore number showed no association with either trait. Second, cytological evidence confirmed sexual reproduction across all samples, challenging the conventional fern paradigm that links low spore counts to apomixis. Notably, ploidy level was independent of spore number, highlighting the need for direct ploidy assessment in coastal fern studies. Third, genetic analyses revealed cohesive population structure with minimal differentiation (Fst < 0.05) among populations, moderate nucleotide diversity (π = 0.0647–0.0780), and high heterozygosity indicating dominant outcrossing. However, 12 samples showed minor introgression from the closely related Acrostichum speciosum, and one confirmed hybrid was identified.
Based on genetic diversity metrics, the researchers designated three priority conservation areas: two high-diversity hotspots in Haikou and Lingshui, and one genetically vulnerable site in Haikou. The findings emphasize that widespread distribution does not guarantee genetic resilience, underscoring the importance of protecting marginal mangrove species to maintain ecosystem stability.
This study, published in Biological Diversity, provides a scientific framework for mangrove conservation and offers methodological insights for studying overlooked species in threatened coastal habitats.
Original Source
Guo, Bingyan, Rui Guo, Hongjuan Zhu, et al. 2025. “Common but Least Noticed: Diversity of the Mangrove Fern Acrostichum aureum in Hainan Island, China,” Biological Diversity 2(4): 143–153.
https://onlinelibrary.wiley.com/doi/10.1002/bod2.70011
Keywords
Acrostichum aureum, genetic diversity, Hainan Island, mangroves, protection
About the Author
Bingyan Guo (First author), Master's Candidate in Horticulture at Hainan University. Her research focuses on the conservation and utilization of plant resources, with a particular dedication to systematic conservation biology of rare ferns in Hainan Island. During her postgraduate studies, she has served as the principal investigator (PI) of one Hainan Provincial Postgraduate Innovation Research Project.
Dongmei Yang (Corresponding author), received her Ph.D. in Botany from South China Botanical Garden, Chinese Academy of Sciences. She is currently an Associate Professor and Master's Supervisor at Hainan University, and a Council Member of the Fern Branch of China Flower Association. Her research focuses on plant taxonomy and conservation biology. She has led and completed 1 project funded by the National Natural Science Foundation of China (NSFC) and 3 provincial-level research projects, and has published nearly 50 peer-reviewed academic papers.
About the Journal
Biological Diversity (ISSN: 2994-4139) is a peer-reviewed, international, open-access journal sponsored by the South China Botanical Garden, Chinese Academy of Sciences, and published in partnership with Wiley. Launched in 2024 and issued quarterly, it is dedicated to advancing biodiversity conservation, safeguarding ecosystem functions and services, and promoting the sustainable utilization of biological resources under global environmental change. The journal welcomes original research, reviews, commentaries, and short communications across a broad spectrum of disciplines, including botany, zoology, microbiology, taxonomy, phylogenetics, genomics, cytology, ecology, climatology, economics, sociology, and real-time policy theory. It publishes innovative research addressing pressing global challenges of biodiversity loss and ecosystem degradation.