School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
Integrated Science Lab, Umeå University, Umeå, Sweden.
Nat Commun. 2021 May 14;12(1):2838. doi: 10.1038/s41467-021-23104-0.
Atmospheric oxygen is thought to have played a vital role in the evolution of large, complex multicellular organisms. Challenging the prevailing theory, we show that the transition from an anaerobic to an aerobic world can strongly suppress the evolution of macroscopic multicellularity. Here we select for increased size in multicellular 'snowflake' yeast across a range of metabolically-available O levels. While yeast under anaerobic and high-O conditions evolved to be considerably larger, intermediate O constrained the evolution of large size. Through sequencing and synthetic strain construction, we confirm that this is due to O-mediated divergent selection acting on organism size. We show via mathematical modeling that our results stem from nearly universal evolutionary and biophysical trade-offs, and thus should apply broadly. These results highlight the fact that oxygen is a double-edged sword: while it provides significant metabolic advantages, selection for efficient use of this resource may paradoxically suppress the evolution of macroscopic multicellular organisms.
大气氧被认为在大型复杂多细胞生物的进化中发挥了至关重要的作用。与流行理论相悖，我们的研究表明，从无氧到有氧世界的转变会强烈抑制宏观多细胞生物的进化。在这里，我们在一系列可利用的氧水平下选择增加多细胞“雪花”酵母的大小。虽然在厌氧和高氧条件下酵母进化得更大，但中间氧限制了大尺寸的进化。通过测序和合成菌株构建，我们证实这是由于氧介导的对生物体大小的分歧选择。我们通过数学建模表明，我们的结果源于几乎普遍的进化和生物物理权衡，因此应该广泛适用。这些结果强调了一个事实，即氧气是一把双刃剑：虽然它提供了显著的代谢优势，但对这种资源的有效利用的选择可能会反过来抑制宏观多细胞生物的进化。
