Evidence that niche specialization explains species-energy relationships in lake fish communities

1. Interspecific niche differences have long been identified as a major explanation for the occurrence of species-rich communities. However, much fieldwork studying variation in local species richness has focused upon physical habitat attributes or regional factors, such as the size of the regional species pool. 2. We applied indices of functional diversity and niche overlap to data on the species niche to examine the importance of interspecific niche differentiation for species richness in French lake fish communities. We combined this information with environmental data to test generalizations of the physiological tolerance and niche specialization hypotheses for species-energy relationships. 3. We found evidence for a largely non-saturating relationship (relative to random expectation) between species richness and functional evenness (evenness of spacing between species in niche space), while functional richness (volume of niche space occupied) peaked at moderate levels of species richness and niche overlap showed an initial decrease followed by saturation. This suggests that increased niche specialization may have allowed species to coexist in the most species-rich communities. 4. We tested for evidence that increased temperature, local habitat area, local habitat diversity and immigration affected species richness via increased niche specialization. Temperature explained by far the largest amount of variation in species richness, functional diversity and niche overlap. These results, combined with the largely non-saturating species richness-functional evenness relationship, suggest that increased temperature may have permitted increased species richness by allowing increased niche specialization. 5. These results emphasize the importance of niche differences for species coexistence in species-rich communities, and indicate that the conservation of functional diversity may be vital for the maintenance of species diversity in biological communities. Our approach may be applied readily to many types of community, and at any scale, thus providing a flexible means of testing niche-based hypotheses for species richness gradients.     

植物群落构建的生态过滤机制研究进展

生物多样性的形成和维持机制,即群落构建机制,一直以来都是群落生态学研究的核心问题。植物群落构建的确定性过程主要是生态过滤机制(包括环境过滤和生物过滤,其中生物过滤包括种间竞争和种内功能性状变异)作用的结果。学者们构建了大量的理论、方法、模型来解释和验证生态过滤机制对群落构建的影响,并取得了显著的成果。然而,关于生态过滤机制在不同尺度的作用、生态过滤机制的各要素分解和量化等方面的研究仍有诸多疑问。重点综述了环境过滤、种间竞争和种内功能性状变异的最新研究进展,并指出了现有研究的不足之处。在未来的研究中,应注重生态过滤机制的各要素分解和量化,加强研究手段的综合运用,关注时空动态变化对植物群落构建的影响,重视对不同植物群落构建机制的共性和个性特征的认识,同时强调与其他生态过程、群落构建机制的整合。通过这些尝试,有助于人们更好的理解植物群落构建过程中的生态过滤机制的作用。     

植物群落构建机制研究进展

群落构建研究对于解释物种共存和物种多样性的维持是至关重要的,因此一直是生态学研究的中心论题。尽管近年来关于生态位和中性理论的验证研究已经取得了显著的成果,但对于局域群落构建机制的认识仍存在很大争议。随着统计和理论上的进步使得用功能性状和群落谱系结构解释群落构建机制变为可能,主要是通过验证共存物种的性状和谱系距离分布模式来实现。然而,谱系和功能性状不能相互替代,多种生物和非生物因子同时控制着群落构建,基于中性理论的扩散限制、基于生态位的环境过滤和竞争排斥等多个过程可能同时影响着群落的构建。所以,综合考虑多种方法和影响因素探讨植物群落的构建机制,对于预测和解释植被对干扰的响应,理解生物多样性维持机制有重要意义。试图在简要回顾群落构建理论及研究方法发展的基础上,梳理其最新研究进展,并探讨整合功能性状及群落谱系结构的研究方法,解释群落构建和物种多样性维持机制的可能途径。在结合功能性状和谱系结构研究群落构建时,除了考虑空间尺度、环境因子、植被类型外,还应该关注时间尺度、选择性状的种类和数量、性状的种内变异、以及人为干扰等因素对群落构建的影响。