Department of Evolution and Ecology, University of California, Davis, California 95616, USA.
Evolution. 2010 Jan;64(1):232-41. doi: 10.1111/j.1558-5646.2009.00822.x. Epub 2009 Aug 17.
Many insects and other arthropods harbor maternally inherited bacteria inducing "cytoplasmic incompatibility" (CI), reduced egg hatch when infected males mate with uninfected females. CI-causing infections produce a frequency-dependent reproductive advantage for infected females. However, many such infections impose fitness costs that lead to unstable equilibrium frequencies below which the infections tend to be eliminated. To understand the unstable equilibria produced by reduced lifespan or lengthened development, overlapping-generation analyses are needed. An idealized model of overlapping generations with age-independent parameters produces a simple expression showing how the unstable point depends on the population growth rate, the intensity of CI, and the infection's effects on development time, longevity, and fecundity. The interpretation of this equilibrium is complicated by age structure. Nevertheless, the unstable equilibrium provides insight into the CI-causing infections found in nature, and it can guide potential manipulations of natural populations, including those that transmit diseases, through the introduction of infections that alter life-table parameters.
许多昆虫和其他节肢动物携带由母体遗传的细菌，诱导“细胞质不相容性”（CI），当感染雄性与未感染雌性交配时，减少卵的孵化。导致 CI 的感染为感染雌性带来了频率依赖性的生殖优势。然而，许多此类感染会带来适应度成本，导致不稳定的平衡频率降低，感染倾向于被消除。为了理解由寿命缩短或发育延长引起的不稳定平衡，需要进行重叠世代分析。具有与年龄无关参数的理想化重叠世代模型产生了一个简单的表达式，展示了不稳定点如何取决于种群增长率、CI 的强度以及感染对发育时间、寿命和繁殖力的影响。该平衡的解释因年龄结构而变得复杂。尽管如此，不稳定平衡为自然界中发现的导致 CI 的感染提供了深入了解，并可以指导对自然种群的潜在操纵，包括通过引入改变生命表参数的感染来传播疾病。
