CAREER: Maintenance of Variation in a Developmental Pathway as a Result of Environmental Heterogeneity

一只动物是否发育成雄性或雌性取决于环境线索或雄性和雌性之间的遗传差异。启动这种雄性/雌性决定的环境线索或基因在不同物种之间是不同的，它们甚至可能在一个物种内是不同的。目前尚不清楚生态因素如何有助于维持物种内雄性/雌性的遗传变异。为了解决这一缺点，这项研究使用了家蝇作为模型系统，因为这种物种在如何做出雄性/雌性的决定方面有很大的差异。值得注意的是，有两种常见的方式可以启动男性发育，而且它们的地理分布不同。一种决定男性的变异在北纬地区占主导地位，另一种在南方更为常见。研究人员正在调查这两种不同的变种是否都保持了下来，因为它们在不同的温度下是有益的。此外，雌性发育可以独立于家蝇中决定雄性的变体而启动。研究人员还在调查启动男性发育的变异是否会对女性产生有害影响。这些拮抗效应可以进一步解释为什么家蝇种群中雄性/雌性决定的差异保持不变。本科生培养成为高中教师将对这项研究做出贡献。这些学生将与研究人员合作，为现有教师提供继续教育培训。他们还将带领初中和高中教室进行练习，使用家蝇来说明遗传学和进化论的核心概念。这些活动将影响来自科学中代表性不足的服务不足社区的学生。为了确定自然选择如何保持男性/女性决定的多样性，研究人员结合了实验室实验、自然种群调查和基因组技术。具体地说，这项研究测试了一种假设，即雄性/雌性特定的基因型与环境的交互作用会影响作用于Y染色体的选择压力，以维持家蝇雄性/雌性决定的变异。将使用实验室实验和高通量基因表达谱来评估非常年轻的Y染色体的环境相关表型效应。对实验室种群和野外季节的等位基因频率的预测将进行测试，并对健康效应进行建模。将利用重组图谱、基因组测序和群体遗传学数据来检验X-Y分化，以评估被抑制的重组维持男性决定基因和其他具有男性/女性拮抗或环境特定效应的遗传变异之间的联系的假设。这项研究将生态上相关的选择压力和男女冲突与一条基本发展路径的演变联系起来，在一个单一的框架内加入人口遗传学和发展的进化。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Whether an animal develops into a male or female depends on either environmental cues or genetic differences between males and females. The environmental cues or genes that initiate this male/female-determination differ across species, and they can even be variable within a species. It is not well understood how ecological factors contribute to the maintenance of genetic variation in male/female-determination within species. To address this shortcoming, this research uses the house fly as a model system because this species has substantial variation in how the male/female decision is made. Notably, there are two common ways that male development can be initiated, and they differ in their geographical distributions. One male-determining variant predominates at northern latitudes, and the other is more common in the south. The researchers are investigating if the two different variants are both maintained because they are beneficial at different temperatures. In addition, female development can be initiated independently from the male-determining variants in house fly. The researchers are also investigating if the variants that initiate male development have deleterious effects in females. These antagonistic effects could further explain why variation in male/female-determination is maintained in house fly populations. Undergraduate students training to be high school teachers will contribute to this research. Those students will work with the researchers to provide continuing education training to current teachers. They will also lead middle and high school classrooms in exercises that use house flies to illustrate core concepts in genetics and evolution. These activities will impact students from under-served communities that are under-represented in the sciences.To determine how natural selection can maintain variation in male/female-determination, the researchers are combining laboratory experiments, surveys of natural populations, and genomic techniques. Specifically, the research tests the hypothesis that male/female-specific genotype-by-environment interactions affect selection pressures acting on Y chromosomes to maintain variation in male/female-determination in house fly. The environment-dependent phenotypic effects of very young Y chromosomes will be assessed using laboratory experiments and high throughput gene expression profiling. Predictions about allele frequencies in laboratory populations and over seasons in the wild will be tested, and fitness effects will be modeled. The hypothesis that suppressed recombination maintains linkage between male-determining genes and other genetic variation with male/female-antagonistic or environment-specific effects will be evaluated using recombination mapping, genome sequencing, and population genetic data to test for X-Y differentiation. This research connects ecologically relevant selection pressures and male-female conflict with the evolution of an essential developmental pathway, joining population genetics and the evolution of development in a single framework.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.