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

一个动物是发育成雄性还是雌性取决于环境因素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，甚至在一个物种内也是可变的。目前还不清楚生态因素如何有助于维持物种内雄性/雌性决定的遗传变异。为了解决这个缺点，这项研究使用家蝇作为模型系统，因为这个物种在如何做出雄性/雌性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展，它们在地理分布上有所不同。一种雄性决定变异在北方纬度地区占主导地位，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体是否都能保持，因为它们在不同的温度下都是有益的。此外，在家蝇中，雌性发育可以独立于雄性决定变体启动。研究人员还在调查启动雄性发育的变异是否对雌性产生有害影响。这些拮抗作用可以进一步解释为什么家蝇种群中维持雄性/雌性决定的差异。本科生培养成为高中教师将有助于本研究。这些学生将与研究人员合作，为现任教师提供继续教育培训。他们还将带领初中和高中课堂练习，使用家蝇来说明遗传学和进化的核心概念。这些活动将影响来自服务不足社区的学生，这些社区在科学领域的代表性不足。为了确定自然选择如何保持男性/女性决定的变化，研究人员将实验室实验，自然种群调查和基因组技术相结合。具体而言，该研究测试的假设，即男性/女性特定的基因型与环境的相互作用影响选择压力作用于Y染色体，以保持变化的男性/女性确定家蝇。将使用实验室实验和高通量基因表达谱评估非常年轻的Y染色体的环境依赖性表型效应。将测试实验室种群和野生季节中等位基因频率的预测，并建立适应性效应模型。将使用重组作图、基因组测序和群体遗传数据来测试X-Y分化，以评估抑制重组维持雄性决定基因与具有雄性/雌性拮抗或环境特异性效应的其他遗传变异之间的联系的假设。该研究将生态相关的选择压力和男女冲突与基本发展途径的进化联系起来，将人口遗传学和发展的进化加入到一个单一的框架中。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.