Ecological Implications of Body Size in Deep-Sea Gastropods

雷克斯9301687 该项目的主要目标是在体型最佳模型的背景下，严格评估深海腹足类的体型趋势。个体大小的进化是一个基本的问题，对群落结构和生物多样性的保护有重要的影响。深海底栖生物最明显和最普遍的特点是大多数物种体型小。为记录和解释深海的大小模式所作的无数尝试都集中在物种或整个动物群组成部分之间的差异上，并导致了相互矛盾的结果，总的来说，人们没有认识到，研究大小作为对深海环境的适应必须包括对物种内部进行分析，使用对共同生长阶段进行标准化的大小测量。 此外，大多数研究没有采用适当的统计方法来证明或比较大小趋势。Sebens的海洋无脊椎动物体型最优模型为探索深海物种体型进化提供了一个有用的概念框架。它预测，最佳的身体尺寸应减少与深度的情况下，减少营养输入降低食物摄入率和觅食成本增加，但它也允许进化的大小高于最佳时，较大的尺寸赋予竞争优势。对8种深海腹足类动物的初步分析显示，幼体和成体的大小有明显的随深度增加的趋势。根据这一初步分析和Sebens的最优模型，本项目将检验以下假设：大小-深度趋势存在物种内和物种间成分。使用一个单一的分类学一致的家庭生态相似的物种（Turridae）和协方差分析，该项目将测试四个具体的预测：1。物种的大小随深度增加而增加，但大小-深度关系的斜率随深度减小。当物种之间沿着沿着深度梯度相互替换时，其尺寸将减小，3.在大小上会有纬度梯度，较大的物种会在较高的纬度发现，以及4。高产量地区的粒度深度回归将比低产量地区具有更高的海拔。该项目将首次准确分析深海物种大小的地理差异，并将大大有助于我们对大小是对深海环境的一种适应性反应的基本理解。 ***

9301687 REX The primary objective of this project is to critically evaluate size trends in deep-sea gastropods in the context of an optimality model of body size. The evolution of body size is a problem of fundamental interest, and one that has an important bearing on community structure and conservation of biodiversity. The most obvious and pervasive characteristic of the deep-sea benthos is the small size of most species. The numerous attempts to document and explain size patterns in the deep sea have focused on variation among species or whole faunal components, and have led to conflicting and contradictory results, In general, there has been a failure to recognize that studying size as an adaptation to the deep-sea environment must include analyses within species using measures of size that are standardized to common growth stages. Also, most studies have not applied appropriate statistical methods for either demonstrating or comparing size trends. Sebens' optimality model of body size in marine invertebrates provides a useful conceptual framework for exploring the evolution of size in deep-sea species. It predicts that optimal body size should decrease with depth under circumstances where decreased nutrient input lowers food intake rates and increases costs of foraging; but it also allows for the evolution of size above the optimum when larger size confers a competitive advantage. A preliminary analysis within eight species of deep-sea gastropods reveals a clear trend for size to increase with depth in both larvae and adults. Based on this preliminary analysis and Sebens' optimality model, this project will test the hypothesis that there are within- and among- species components to size-depth trends. Using a single taxonomically coherent family of ecologically similar species (the Turridae) and the analysis of covariance, this project will test four specific predictions: 1. that size will increase with depth within species, but that the slopes of size-depth relations will decrease with depth, 2. that size will decrease among species as they replace one another along a depth gradient, 3. that there will be a latitudinal gradient in size, with larger species found at higher latitudes, and 4. that size-depth regressions in regions of higher production will have higher elevations than those in regions of low productions. This project will provide the first accurate analysis of geographic variation in size within deep-sea species, and will contribute significantly to our basic understanding of size as an adaptive response to the deep-sea environment. ***