CAREER: A Size-Based Test of Species-Energy Theory in Stream Ecosystems - Linking Individuals, Communities, and Underrepresented Minorities

地球上的生物多样性有一个既定的模式，在热带地区发现的生物多样性最高，随着纬度向两极的增加，生物多样性减少。 生态学家认为，这种模式的原因是在热带地区发现了更高水平的生命食物资源。 该项目将对这一假设进行直接检验，方法是测量横跨广泛纬度梯度的溪流中的生物多样性和食物资源水平。在八个研究区域的每一个区域，将对鱼类和无脊椎动物进行密集采样。研究人员将利用这些数据建立一个社区内个体平均大小与个体丰度之间关系的数学模型，作为检验生物多样性和资源概念的一种手段。该项目还将侧重于让代表性不足的少数群体参与淡水研究。在四年的每一年，一组三个少数民族本科生将接受培训，进行流调查，分析原始数据，并在淡水科学学会年会上介绍结果，在整个项目中，共有12名本科生得到指导。一个博士被认定为代表性不足少数民族学生也将接受培训，以竞争环境研究或管理方面的领导职位。2在溪流生态系统中进行物种-能量理论的实证检验将分三个步骤进行。在第1步，大小谱（平均个体体重和人口丰度之间的比例关系）将在八个研究区域中的每一个进行量化，并用于模拟初级，二级和三级消费者之间的丰度分布。氮稳定同位素样本和已发表的摄食行为也将用于评估营养位置是否与体型一致。系统的大小谱模型的比较，然后将测试是否与个人的身体质量和营养位置的丰度的缩放是恒定的热带和温带流。在第2步中，将为每个研究溪流汇编物种-丰度分布，然后在溪流之间进行比较，以评估热带溪流中物种丰富度是否相对于恒定数量的个体增加得更快。在步骤3中，将使用来自国家生态观测站网络溪流的补充鱼类和无脊椎动物数据来检验大小谱和物种丰度分布模型的季节或年际差异。

There is a well-established pattern of biodiversity on Earth, with highest biodiversity found in the tropics and a decrease in biodiversity with increasing latitude towards the poles. Ecologists have suggested that the reason for this pattern is that higher levels of food resources for life are found in the tropics. This project will perform a direct test of that hypothesis by making measurements of biodiversity and food resource levels in streams across a broad latitudinal gradient. In each of eight study regions, fishes and invertebrates will be intensively sampled. The data will be used by the researcher to develop mathematical models of the relationships between the average size of individuals and the abundance of those individuals within a community as a means of testing the idea about biodiversity and resources. This project will also focus on engaging underrepresented minorities in freshwater research. In each of four years, a group of three minority undergraduates will be trained to conduct stream surveys, to analyze original data, and to present results at the annual meeting of the Society for Freshwater Science, for a total of 12 undergraduates mentored throughout the project. One Ph.D. student identified as an underrepresented minority student also will be trained to compete for leadership-level positions in environmental research or management.An empirical test of species-energy theory within stream ecosystems will be conducted in three steps. In Step-1, size-spectra (scaling relationships between average individual body mass and population abundance) will be quantified in each of the eight study regions and used to model the distribution of abundance among primary, secondary, and tertiary consumers. Nitrogen stable isotope samples and published feeding behaviors will also be used to assess whether trophic position is a consistent function of body size. Systematic, among-site comparisons of size-spectra models will then test whether the scaling of abundance with individual body mass and trophic position is constant among tropical and temperate streams. In Step-2, species-abundance distributions will be compiled for each study stream then compared among streams to assess whether species richness increases more rapidly, relative to a constant number of individuals, in tropical streams. In Step-3, supplementary fish and invertebrate data from National Ecological Observatory Network streams will be used to test for seasonal or inter-annual differences in the size-spectra and species-abundance distribution models.