报告题目：Drift, Mutation, Bioenergetics, and the Origin of Cell-biological Features              

        随机遗传漂变，突变，生物能量和细胞生物特性的起源

报告人：Michael Lynch  院士 
主持人：周  琦  教授
时   间：2023年11月29日（周三）下午4点
地   点：生科院245报告厅
报告人简介：

       Michael Lynch，美国国家科学院院士、美国艺术与科学院院士。Arizona State University生命科学学院教授、演化生物中心主任。曾担任美国遗传学会、分子生物学与演化学会、演化研究学会和美国遗传学会的主席。研究重点是基因、基因组、细胞和表型水平的演化机制，特别关注突变、随机遗传漂变和染色体重组的作用。Lynch教授提出了解释不同物种突变率差异的遗传漂变障碍假说(drift barrier hypothesis)，确认了生物的突变率下限主要取决于自然选择和遗传漂变的相互拮抗，进一步由物种的有效种群大小决定，同时创立了演化细胞生物学这一分支学科。在Nature、Science等重要刊物上发表了300多篇同行评议论文，出版专著3部。2021年获得分子生物学与演化学会颁发的终身研究成就奖(SMBE Lifetime Research Achievements Award)。

报告摘要：

For over a century, most biologists have been convinced that all aspects of biodiversity have been driven entirely by natural selection, with stochastic forces and mutation bias playing a minimal role. However, this is not the case at the molecular and cellular levels, where diverse traits scale with cell/organism size in ways that cannot be explained by optimization and/or speed vs. efficiency arguments. These include aspects of gene/genome architecture, intracellular error rates, the multimeric nature of proteins, swimming efficiencies, and maximum growth rates.

Although natural selection may be the most powerful force in the biological world, it is not all powerful, and the power of random genetic drift ultimately dictates what selection can and cannot accomplish. Many prokaryotes may reside in population-genetic environments where the limits to selection are indeed dictated only by the constraints of cell biology. However, in the eukaryotic domain, larger organism size is typically associated with a reduction in effective population size (Ne), enabling the accumulation of very mildly deleterious mutations, which in turn induces coevolutionary side effects leading to more complex and less efficient phenotypes.

This general conclusion is embodied in the drift-barrier hypothesis, which postulates that traits under persistent directional selection become stalled when further increments in improvement are thwarted by the power of random genetic drift. Integration of biology’s three engines of quantitative theory – population genetics, biophysics, and biochemistry, combined with observations from cellular bioenergetics, is providing a platform for the emergence of a formal field of evolutionary cell biology.