Microbial Experimental Ecology and Evolution Reading Group

On Thursday, February 27th we’re in for a treat since the EEB seminar speaker, Sergey Kryazhimskiy, will be joining the reading group. He suggested we read this paper, which is a nice contrast to the last paper we read (last time, we read about deep sequencing to track with high resolution the initial steps of adaptation — this paper uses deep sequencing to study the long-time dynamics of evolution). 

The dynamics of molecular evolution over 60,000 generations [https://www.nature.com/articles/nature24287/]

Abstract:

The outcomes of evolution are determined by a stochastic dynamical process that governs how mutations arise and spread through a population. However, it is difficult to observe these dynamics directly over long periods and across entire genomes. Here we analyse the dynamics of molecular evolution in twelve experimental populations of Escherichia coli, using whole-genome metagenomic sequencing at five hundred-generation intervals through sixty thousand generations. Although the rate of fitness gain declines over time, molecular evolution is characterized by signatures of rapid adaptation throughout the duration of the experiment, with multiple beneficial variants simultaneously competing for dominance in each population. Interactions between ecological and evolutionary processes play an important role, as long-term quasi-stable coexistence arises spontaneously in most populations, and evolution continues within each clade. We also present evidence that the targets of natural selection change over time, as epistasis and historical contingency alter the strength of selection on different genes. Together, these results show that long-term adaptation to a constant environment can be a more complex and dynamic process than is often assumed.

Microbial Experimental Ecology and Evolution Reading Group - Group list for folks interested in monthly readings focusing on experimental ecology and evolution with microbes! Contact Luis Zaman for additional information. Join on MCommunity at MicroEcoEvo@umich.edu