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

为什么男性和女性会进化得如此不同？在进化过程中，男性和女性在行为和结构上会变得非常不同，但这种差异背后的过程却知之甚少。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复杂差异。过多的雄性或雌性可以通过改变个体与潜在配偶或竞争对手互动的频率对许多特征产生强烈影响，因此如果它们赋予交配或竞争优势，那么个体的特征在后代中持续存在的可能性有多大。该项目使用寿命短的蛔虫，测量了保持50代的种群之间的遗传差异，其中大多数是雌性，大多数是雄性，或者雄性和雌性数量相等。分析这些种群的遗传变化将揭示进化完全由于男女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量的男性或女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对科学背景不足的本科生进行培训，并制作在线资源，对高中生和公众进行基因组方法和进化的教育。该项目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相互作用导致的遗传变化。实验进化的线虫线虫Caelophabditis remanei已经产生的证据表明，人口面临着一个一贯的男性或女性的偏见比例的生殖可用的男性女性表现出不同的形态和行为的选择的结果。该提议通过量化种群间基因组差异的程度，并在整个基因组中识别离群位点的选择特征，扩展了行为相互作用驱动进化变化的问题。这项拟议的研究将是第一个直接测量整个基因组进化的研究，在已知的男性与女性的偏倚比例的选择性制度之后，也是少数几个使用行为制度这样做的研究之一。由于实验处理在独立的群体中重复，该项目还将解决长期存在的问题，即在核苷酸水平上如何重复进化。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近似和最终方法是必不可少的。

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.