PDF(Pubmed)
Abstract：
A principal goal in ecology is to identify the determinants of species abundances in nature. Body size has emerged as a fundamental and repeatable predictor of abundance, with smaller organisms occurring in greater numbers than larger ones. A biogeographic component, known as Bergmann\'s rule, describes the preponderance, across taxonomic groups, of larger-bodied organisms in colder areas. Although undeniably important, the extent to which body size is the key trait underlying these patterns is unclear. We explored these questions in diatoms, unicellular algae of global importance for their roles in carbon fixation and energy flow through marine food webs. Using a phylogenomic dataset from a single lineage with worldwide distribution, we found that body size (cell volume) was strongly correlated with genome size, which varied by 50-fold across species and was driven by differences in the amount of repetitive DNA. However, directional models identified temperature and genome size, not cell size, as having the greatest influence on maximum population growth rate. A global metabarcoding dataset further identified genome size as a strong predictor of species abundance in the ocean, but only in colder regions at high and low latitudes where diatoms with large genomes dominated, a pattern consistent with Bergmann\'s rule. Although species abundances are shaped by myriad interacting abiotic and biotic factors, genome size alone was a remarkably strong predictor of abundance. Taken together, these results highlight the cascading cellular and ecological consequences of macroevolutionary changes in an emergent trait, genome size, one of the most fundamental and irreducible properties of an organism.
摘要：
生态学的主要目标是确定自然界中物种丰度的决定因素。体型已经成为丰度的基本和可重复预测指标，较小的有机体比较大的有机体数量更多。生物地理组成部分，被称为伯格曼的规则，描述了优势，跨分类组，寒冷地区的大型生物。虽然不可否认的重要,体型在多大程度上是这些模式的关键特征尚不清楚.我们在硅藻中探索了这些问题，单细胞藻类因其在碳固定和通过海洋食物网的能量流动中的作用而具有全球重要性。使用来自全球分布的单一谱系的系统基因组数据集，我们发现身体大小（细胞体积）与基因组大小密切相关，不同物种之间的差异是50倍，并且是由重复DNA数量的差异驱动的。然而,定向模型识别温度和基因组大小，不是单元格大小，对最大人口增长率的影响最大。一个全球元编码数据集进一步确定了基因组大小是海洋物种丰度的强大预测指标，但只有在高纬度和低纬度的寒冷地区，大基因组的硅藻占主导地位，符合伯格曼规则的模式。尽管物种丰度是由无数相互作用的非生物和生物因素决定的，基因组大小是一个非常强的丰度预测指标。一起来看,这些结果突出了一个新兴性状的宏观进化变化的级联细胞和生态后果，基因组大小，有机体最基本和不可约的特性之一。
