摘要
铁凌(Hopea reticulata Tardieu)隶属龙脑香科坡垒属,在我国仅天然分布于海南岛甘什岭一带。因刀耕火种和伐木,甘什岭原始低地雨林退化为次生林,在保护区建立后逐渐恢复为铁凌单优林。为评估保护成效及种群遗传动态,本研究采集了102份铁凌样品,按胸径划分为3个径级,与3个龄级(青幼年、成年和成年后)对应,采用简化基因组测序(ddRAD⁃seq)获得基因组水平的单核苷酸变异,评估不同龄级样品的核苷酸多样性与小尺度空间遗传结构。结果显示,铁凌总体的核苷酸多样性水平(π=0.25527)较高,超过广西青梅(π=0.21780)和海南风吹楠(π=0.17200)等濒危物种。遗传组分聚类、NJ树和PCoA分析显示龄级间无明显分化;小尺度空间遗传结构强度(Sp=0.0283~0.0240)随龄级增长递减,可能与种子扩散受限导致的基因型空间聚集和种群自疏作用相关。综上,甘什岭的铁凌种群维持了较高水平的遗传变异,这与该种现存的种群规模较大有关。铁凌果实无翅,成熟后掉落在母树周围,种子扩散距离局限,表现出较强的小尺度空间遗传结构。随龄级增长,自疏作用加剧,基因型的空间聚集程度下降,小尺度空间遗传结构减弱。基于上述研究结果,建议在种源采集和人工辅助授粉等工作中,确保花粉供受体间距大于260 m,以降低遗传同质性并维持子代遗传多样性。
Hopea reticulata Tardieu belongs to the genus Hopea from Dipterocarpaceae,which is only naturally dis⁃tributed in Ganza Ridge of Hainan Island in China.The slash⁃and⁃burn agriculture and logging have resulted in the degradation of the original lowland rainforest to secondary forest in Ganza Ridge.After the establishment of Ganza Ridge Provincial Nature Preserve,vegetation in lowland rainforest gradually recovered and developed into a tropical rainforest community with H.reticulata as the sole dominant species.To evaluate conservation efficacy and genetic dynamics,102 individuals of H.reticulata were divided into three age classes(youth,adult,and post⁃adult)based on diameter classes.Genome⁃wide single nucleotide polymorphisms(SNPs)were obtained via double⁃digest restric⁃tion site⁃associated DNA sequencing(ddRAD⁃seq)to assess nucleotide diversity and fine⁃scale spatial genetic structure.The results showed that H.reticulata maintained a high nucleotide diversity(π=0.25527),surpassing two endangered species,Vatica guangxiensis(π=0.21780)and Horsfieldia hainanensis(π=0.17200).The struc⁃ture analysis,NJ tree and PCoA analysis revealed no significant genetic differentiation among age classes.All the three age classes showed a significant fine⁃scale spatial genetic structure,the strength(Sp=0.0283-0.0240)of which was negatively correlated with ages,probably due to the limited seed dispersal and self⁃thinning within the population.In summary,H.reticulata population in Ganza Ridge maintained a relatively high level of genetic varia⁃tion due to the large population size.The nuts of H.reticulata are wingless and fall around its parent trees after ma⁃turity.The limited seed dispersal distance leads to a strong fine⁃scale spatial genetic structure.With increasing population ages,intraspecific competition intensifies,and the strength of fine⁃scale spatial genetic structure would decrease in elder age classes.Based on these findings,we suggest that the distance between individuals for seed collection and for cross⁃pollination should be at least more than 260 m to reduce genetic similarity,and preserve off⁃spring genetic diversity in the work of provenance collection and human⁃assisted pollination.
作者
段继煜
蔡颖
饶朝康
唐亮
DUAN Jiyu;CAI Ying;RAO Chaokang;TANG Liang(School of Ecology,Hai-nan University,Haikou 570100,China;International Joint Center for Terrestrial Biodiversity around South China Sea of Hainan Province,Hainan University,Haikou 570228,China)
出处
《生态学杂志》
北大核心
2025年第8期2582-2590,共9页
Chinese Journal of Ecology
基金
国家自然科学基金项目(32060236)资助。
关键词
铁凌
ddRAD⁃seq
遗传多样性
小尺度空间遗传结构
龄级
Hopea reticulata Tardieu
double⁃digest restriction site⁃associated sequencing(ddRAD⁃seq)
genetic diversity
fine⁃scale spatial genetic structure
age class
