Department of Biological Sciences, Smith College, Northampton, Massachusetts 01063, USA.
Annu Rev Microbiol. 2012;66:411-27. doi: 10.1146/annurev-micro-090110-102808. Epub 2012 Jul 9.
The bulk of the diversity of eukaryotic life is microbial. Although the larger eukaryotes-namely plants, animals, and fungi-dominate our visual landscapes, microbial lineages compose the greater part of both genetic diversity and biomass, and contain many evolutionary innovations. Our understanding of the origin and diversification of eukaryotes has improved substantially with analyses of molecular data from diverse lineages. These data have provided insight into the nature of the genome of the last eukaryotic common ancestor (LECA). Yet, the origin of key eukaryotic features, namely the nucleus and cytoskeleton, remains poorly understood. In contrast, the past decades have seen considerable refinement in hypotheses on the major branching events in the evolution of eukaryotic diversity. New insights have also emerged, including evidence for the acquisition of mitochondria at the time of the origin of eukaryotes and data supporting the dynamic nature of genomes in LECA.
真核生物的多样性主要体现在微生物上。虽然较大的真核生物——即植物、动物和真菌——主宰着我们的视觉景观，但微生物谱系构成了遗传多样性和生物量的大部分，并且包含许多进化创新。通过对来自不同谱系的分子数据进行分析，我们对真核生物的起源和多样化有了更深入的了解。这些数据为最后一个真核生物共同祖先（LECA）的基因组性质提供了线索。然而，对于核和细胞骨架等关键真核特征的起源，我们仍然知之甚少。相比之下，过去几十年里，关于真核生物多样性进化过程中主要分支事件的假说有了很大的改进。新的见解也出现了，包括在真核生物起源时获得线粒体的证据，以及支持 LECA 基因组动态性质的数据。
