Abrams Melanie B, Brem Rachel B
UC Berkeley, Department of Plant and Microbial Biology, Berkeley, CA, USA.
Front Ecol Evol. 2022;10. doi: 10.3389/fevo.2022.859904. Epub 2022 Apr 27.
Many traits of industrial and basic biological interest arose long ago, and manifest now as fixed differences between a focal species and its reproductively isolated relatives. In these systems, extant individuals can hold clues to the mechanisms by which phenotypes evolved in their ancestors. We harnessed yeast thermotolerance as a test case for such molecular-genetic inferences. In viability experiments, we showed that extant cerevisiae survived at temperatures where cultures of its sister species died out. Then, focusing on loci that contribute to this difference, we found that the genetic mechanisms of high-temperature growth changed with temperature. We also uncovered an enrichment of low-frequency variants at thermotolerance loci in population sequences, suggestive of a history of non-neutral selective forces acting at these genes. We interpret these results in light of models of the evolutionary mechanisms by which the thermotolerance trait arose in the lineage. Together, our results and interpretation underscore the power of genetic approaches to explore how an ancient trait came to be.
许多具有工业和基础生物学意义的性状早在很久以前就出现了，现在表现为一个核心物种与其生殖隔离的亲属之间的固定差异。在这些系统中，现存个体可以为其祖先表型进化的机制提供线索。我们利用酵母耐热性作为此类分子遗传学推断的一个测试案例。在生存能力实验中，我们表明现存的酿酒酵母能在其姊妹物种培养物灭绝的温度下存活。然后，聚焦于导致这种差异的基因座，我们发现高温生长的遗传机制随温度而变化。我们还在群体序列中发现耐热性基因座处低频变异的富集，这表明这些基因存在非中性选择力作用的历史。我们根据耐热性性状在该谱系中出现的进化机制模型来解释这些结果。总之，我们的结果和解释强调了遗传方法在探索古老性状如何形成方面的力量。
