基于元素组的生物地球化学生态位及其在不同生态系统中的应用

The biogeochemical niche based on elementome and its applications in different ecosystems

生态位作为解决群落如何构建、物种如何共存的探索,从其最初定性描述物种在生境中的空间分割,到反映物种在群落中功能上的分异,再到从多维空间和资源利用等方面进行的定量分析,生态位理论逐渐发展。然而,在非随机过程影响下物种生态位的大小,尤其是在不同环境条件下生态位的位移、收缩或扩张等变化过程的量化,需要进一步研究。元素是组成生物有机体的基本物质,生物体内元素含量及其比例(元素组,elementome)具有物种特异性,同时也反映了物种对其生存环境的适应性。随着生态化学计量学的发展,生物元素组在生态学各个研究尺度中的应用愈加广泛。在群落生态学研究中,生物元素组及其在环境梯度上的变异为量化群落中物种生态位分化、预测环境变化条件下生态位的变化提供了极佳指标。生物地球化学生态位使用生物元素组及生态位多维超体积的概念,对物种生态位进行了量化。基于文献检索结果,本文阐述了生物地球化学生态位假说的理论框架,对其在不同生物分类群(植物、动物和微生物)中的研究进展进行了综述,最后对其在不同生态系统中的研究进行了展望,以期对该假说的适用性进行检验并推动生态位理论研究的发展。

Background&Aims:All biological organisms are constructed with a specific range and ratio of bioelements—namely the elementome.Organisms integrate multiple elements in optimal ratios to adapt to environmental heterogeneity.Biological elementome is assumed to be species-specific,which is determined by evolutionary history(phylogenetic distances)and controlled by inter-species competition and homeostasis.In community ecology,bioelemental composition and the variations in elementome provide an ideal indicator for quantifying the niche segregation of certain species in a community and predicting the possible responses of niche(displacement,expansion or concentration)to changes in environmental conditions.Biogeochemical niche(BN)quantifies species niches using the concept of elementome and n-dimensional hypervolume.On the basis of a brief summary of niche theory and ecological stoichiometry,we introduced the theoretical framework and the confirmatory studies of biogeochemical niche hypothesis(BNH)in this review.The prospects of its applications in different ecosystems were also discussed.Review results:According to the BNH,the biogeochemical niche of certain species is defined as a function of phylogenetic distances(taxonomy),species sympatry(inter-species competitive pressure)and homeostasis/plasticity(the ability to maintain a stable elemental composition).This theory applies not only to plants,but also to animals and microbes.Using“biogeochemical niche(s)”,“metabolomic niche(s)”,“stoichiometric niche(s)”as key words,we conducted literature searches utilizing Web of Science(WoS)and CNKI,and manually picked out 84 relevant studies in November 2023.The studies mainly focused on C,N and P,and the most common keywords were“ecological stoichiometry”and“elemental composition”.In terms of taxa,the main taxa concerned in the studies were plants(54 articles),followed by animals(14 articles)and microorganisms(14 articles).We review the recent progress of BNH by taxa in this article.Prospects&Suggestions:We suggest that the study of BNH be extended from C,N and P to more bioelements,to identify the species niche more accurately in higher dimensions.In different ecosystems,especially in stressful habitats,organisms should change their elementome to adapt to varied environments.More studies focusing on additional taxa(aquatic plants,plankton,fish,etc.)or certain habitats(freshwater or saline lake,river,high mountain,desert,etc.)are likely to help validate the universality of BNH.Furthermore,we propose to study the variations in biogeochemical niche at different life history stages of living beings,and bridge BN and population dynamics,to provide evidence for mechanism of species coexistence.