Population Biology of Cytoplasmic Incompatibility in Drosophila simulans

在拟态果蝇中，当受感染的雄性与未受感染的雌性交配时，垂直传播的细胞质不相容因素会导致卵孵化减少。这种不相容似乎与一种在加州迅速传播的细胞内寄生虫(沃尔巴克氏菌)有关。在建议的资助年度内，研究的目标是通过以下方式进一步了解这一系统的种群生物学：1)继续监测感染在加州的传播及其对线粒体DNA(MtDNA)变异分布的影响；2)确定沃尔巴克氏菌的存在是否可以通过后代测试来确定；3)获得对多态自然种群不亲和性水平和有害适合度影响的额外估计；以及4)使用田间和实验室数据来构建描述田间时间和空间频率动态的数学模型。新的数据和分析对于描述和了解感染的传播率以及评估当前模型的充分性至关重要。这一系统为研究自然种群的快速变化提供了一个不同寻常的机会。加州向北的快速传播提供了许多复制种群，在这些种群中，类似的频率变化正在发生。一个中心问题是，描述一个地区动态的选择和迁移参数值是否会准确地预测其他地区的动态。感染和线粒体DNA变异的联合动态为将细胞质遗传的变异引入自然种群提供了一个模式系统。这些变种在控制害虫方面可能很有用。鉴于建议只削减一年的拨款，私营机构督导会集中提供有关一九九二至九三年度秋季、春季和夏季感染频率的详细地图。一个主要的目标是建立一种标准化的分子检测方法，以确定现场捕获的单个苍蝇是否被感染，并确定感染剂的存在与后代测试所揭示的不相容之间的表型联系。在时间和资金允许的情况下，PI还计划继续监测随着感染而“搭便车”的(MtDNA)变异的频率，并在不同地点和不同季节获得更多关于感染造成的不相容水平和生殖力下降的现场估计。

In Drosophila simulans, a vertically transmitted, cytoplasmic incompatibility factor causes reduced egg hatch when infected males mate with uninfected females. The incompatibility seems to be associated with an intracellular parasite (Wolbachia) that is spreading rapidly in California. The goal of the research during the year of recommended funding is to understand further the population biology of this system by: 1) continuing to monitor the spread of the infection in California and its effect on the distribution of mitochondrial DNA (mtDNA) variants; 2) determining whether the presence of Wolbachia can be assertained by progeny tests; 3) obtaining additional estimates of incompatibility levels and deleterious fitness effects in polymorphic natural populations; and 4) using field and laboratory data to construct mathematical models describing temporal and spatial frequency dynamics in the field. The new data and analyses are essential for describing and understanding the rate of spread of the infection and assessing the adequacy of current models. This system offers an unusual opportunity to study rapid changes in natural populations. The rapid northward spread in California provides many replicate populations in which similar frequency changes are occurring. A central issue is whether the selection and migration parameter values that describe the dynamics in one area will accurately predict the dynamics elsewhere. The joint dynamics of the infections and mtDNA variants provide a model system for the introduction of cytoplasmically inherited variants into natural populations. Such variants may be useful in controlling insect pests. Given the reduced funding recommended for one year only, the PIs will concentrate on providing detailed maps of the infection frequency during the fall, spring and summer of 1992-93. A major goal will be to have a standardized molecular assay for determining whether individual field caught flies are infected, and to determine the phenotypic association between the presence of the infectious agent and incompatibility as revealed by progeny tests. To the extent that time and money permit, the PIs also plan to continue monitoring the frequency of (mtDNA) variants that are "hitch-hiking" along with the infection, and to obtain additional field estimates at different sites and in different seasons of the incompatibility levels and reductions of fecundity caused by the infection.