Data from: Ecological niche features override biological traits and taxonomic relatedness as predictors of occupancy and abundance in lake littoral macroinvertebrates

The degree to which species ecological and biological traits determine their distribution and abundance has intrigued ecologists for a long time, and it has seen a revival in recent years. This topic is important because it provides information about the determinants of species rarity and their conservation implications. We examined the effects of niche breadth, niche position, biological traits and taxonomic relatedness on the interspecific occupancy-abundance relationship, as well as on occupancy and abundance, in lake littoral macroinvertebrates. We sampled 48 lakes in a boreal lake district, found altogether 155 species, and calculated regional occupancy (as the proportion of sites occupied) and local abundance (as mean abundance at occupied site) for each species. We determined niche position and niche breadth for each species using the outlying mean index analysis. Also, we calculated trait vectors and taxonomic vectors describing species trait similarity and taxonomic relatedness, respectively, using principal coordinates analysis. We found a strong positive occupancy-abundance relationship that was mostly explained by among-species variation in niche position, followed by niche breadth. Instead, trait vectors and taxonomic vectors tended to be less important in affecting occupancy and abundance than the niche features. Our results strongly suggest that niche position, a measure of habitat availability for littoral macroinvertebrates, is the chief determinant of their occupancy and abundance. This finding has important implications for ecology and conservation of species, as species with marginal niche position, a reflection of low habitat availability, are both regionally rare and locally uncommon. Such species may face double jeopardy if environmental conditions change and affect their preferred marginal habitat types.长期以来，物种的生态与生物学性状对其分布格局及种群丰度的调控程度，一直是生态学界关注的核心议题，且近年来再度掀起研究热潮。该议题意义重大，因其可揭示物种稀有种群的成因，并为物种保护提供理论依据。本研究以寒带湖区湖滨大型底栖无脊椎动物（lake littoral macroinvertebrates）为研究对象，探讨了生态位宽度（niche breadth）、生态位位置（niche position）、生物学性状以及分类学亲缘关系对种间占有-丰度关系，以及物种占有度与种群丰度的影响。研究团队于寒带湖区共采样48个湖泊，总计发现155个物种，并计算了每个物种的区域占有度（以其占据的样点比例计）与局域丰度（以占据样点内的平均种群密度计）。本研究采用偏平均指数（Outlying Mean Index, OMI）分析方法，确定了每个物种的生态位位置与生态位宽度；此外，通过主坐标分析（Principal Coordinates Analysis, PCoA）分别构建了表征物种性状相似性的性状向量，以及表征分类学亲缘关系的分类学向量。研究结果显示，种间占有-丰度间存在显著正相关关系，其中物种间生态位位置的差异是该关系的主要解释因子，其次为生态位宽度。相较而言，性状向量与分类学向量对物种占有度及种群丰度的影响则远弱于生态位特征。本研究结果明确表明，生态位位置——作为湖滨大型底栖无脊椎动物栖息地可获得性的衡量指标——是决定其分布占有度与种群丰度的核心因子。该发现对物种生态学研究与保护工作均具有重要意义：生态位位置偏边缘化的物种（反映出其可获得栖息地较少），往往同时呈现区域分布狭窄与局域种群稀少的特征。若环境条件发生变化并破坏其偏好的边缘生境类型，这类物种将面临双重生存危机。