Dissertation Research: Experimentally skewed ratio of males to females as a behavioral driver of genome evolution

为什么雄性和雌性在进化上会如此不同？随着进化时间的推移，雄性和雌性在行为和结构上可能会变得非常不同，但这种差异背后的过程却鲜为人知。这项研究的重点是社会互动如何塑造我们在自然界中看到的精心设计的差异。过多的男性或女性会通过改变一个人与潜在配偶或竞争对手互动的频率，从而改变这个人的特征在后代中保持的可能性，从而对许多特征产生强烈的影响。利用短命的蛔虫，这个项目测量了50代种群之间的遗传差异，这些种群大多是雌性的，大部分是雄性，或者是同等数量的雄性和雌性。分析这些种群中的遗传变化将揭示进化可以完全由于雄性和雌性的相互作用而改变种群特征的过程。此外，将多个种群的基因组与过多的雄性或雌性进行比较，将解决进化生物学中的一个核心问题：当种群面临相同的条件时，进化轨迹有多相似？该项目将利用现代基因组技术培训来自科学领域代表性不足背景的本科生，并制作在线资源来教育高中生和公众关于基因组方法和进化的知识。该计划的目标是测量选择对男性和女性差异的基因组影响，并量化驱动选择的行为互动所产生的基因变化。在线虫的实验进化中，有证据表明，由于选择的结果，可繁殖的雄性与雌性的比例始终偏向于男性或女性的种群在形态和行为上表现出了差异。这一建议扩展了行为相互作用推动进化变化的问题，方法是量化种群间基因组差异的程度，并识别整个基因组中离群点的选择特征。这项拟议中的研究将是第一批直接测量整个基因组进化的研究之一，此前已知的有选择性的男性和女性比例偏向制度，也是为数不多的使用行为制度来这样做的研究之一。由于实验治疗是在独立的种群中复制的，该项目还将解决长期存在的问题，即在核苷酸水平上的可重复性如何。揭示由行为产生的选择的基因组后果对于综合在表型和基因组水平上理解二型性的最近的和最终的方法是至关重要的。

Why have males and females evolved to be so different? Over evolutionary time, males and females can become very different from each other in behavior and structure, but the process behind this divergence is poorly understood. This research focuses on how social interactions shape the elaborate differences we see in nature. An excess of males or females can have a strong effect on many traits by changing how frequently an individual interacts with potential mates or rivals, and therefore how likely that individual's traits are to persist in later generations if they confer a mating or competitive advantage. Using the short-lived roundworm, this project measures the genetic differences between populations kept for 50 generations with mostly females, mostly males, or equal numbers of males and females. Analyzing genetic changes in these populations will reveal the processes by which evolution can alter traits in a population entirely due to male-female interactions. Moreover, comparing the genomes of multiple populations with an excess of males or females will address a core question in evolutionary biology: how similar are evolutionary trajectories when populations face identical conditions? This project will train undergraduate students from backgrounds underrepresented in science using modern genomic techniques, and produce online resources to educate high school students and the public about genomic methods and evolution.The goal of this proposal is to measure the genomic effect of selection on the differences between males and females and to quantify genetic changes resulting from the behavioral interactions that drive selection. Experimental evolution in the nematode Caenorhabditis remanei has yielded evidence that populations faced with a consistently male- or female-biased ratio of reproductively available males to females show differences in morphology and behavior as a consequence of selection. This proposal expands the question of behavioral interactions driving evolutionary change by quantifying the degree of genomic divergence across populations, and identifying signatures of selection at outlier loci across the entire genome. The proposed study will be among the first to directly measure evolution across the genome after a known selective regime of biased ratios of males to females, and one of the few to do so using a behavioral regime. Because experimental treatments were replicated across independent populations, the project will also address the long-standing question of how repeatable evolution is at the nucleotide level. Revealing the genomic consequences of selection generated by behavior is essential to synthesizing proximate and ultimate approaches to understanding dimorphism at the phenotypic and genomic level.