Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
Proc Natl Acad Sci U S A. 2010 Jul 20;107(29):12941-5. doi: 10.1073/pnas.1007783107. Epub 2010 Jun 29.
The diversification of life involved enormous increases in size and complexity. The evolutionary transitions from prokaryotes to unicellular eukaryotes to metazoans were accompanied by major innovations in metabolic design. Here we show that the scalings of metabolic rate, population growth rate, and production efficiency with body size have changed across the evolutionary transitions. Metabolic rate scales with body mass superlinearly in prokaryotes, linearly in protists, and sublinearly in metazoans, so Kleiber's 3/4 power scaling law does not apply universally across organisms. The scaling of maximum population growth rate shifts from positive in prokaryotes to negative in protists and metazoans, and the efficiency of production declines across these groups. Major changes in metabolic processes during the early evolution of life overcame existing constraints, exploited new opportunities, and imposed new constraints.
生命的多样化涉及到体型和复杂性的巨大增加。从原核生物到单细胞真核生物再到后生动物的进化转变伴随着代谢设计的重大创新。在这里，我们表明，代谢率、种群增长率和生产效率与体型的比例在进化转变中发生了变化。在原核生物中，代谢率与体重呈超线性比例，在原生生物中呈线性比例，在后生动物中呈亚线性比例，因此克莱伯的 3/4 幂律不适用于生物体的普遍情况。最大种群增长率的比例从原核生物中的正增长转变为原生生物和后生动物中的负增长，并且生产效率在这些群体中下降。在生命的早期进化过程中，代谢过程的重大变化克服了现有限制，利用了新机会，并施加了新限制。
