How do parental effects introduce variation into individual phenotypes, fitness and population dynamics?

随着时间的推移，种群规模的变化是由于个体的变化(例如，通过生存或繁殖)。同样，通过自然选择进行的进化需要个体之间的差异，并以可遗传的差异为基础。因此，个体在生活史表型(生长、成熟、繁殖和死亡的方式)上的差异是种群变化和进化变化的关键。传统上，个体差异被认为是由于遗传和环境差异而产生的。我们越来越多地认识到还有第三个原因：过去的环境条件通过父亲的影响代代相传。最常见的例子是母体对后代状况的影响。如果我母亲怀孕时吃了很多食物，我更有可能在子宫里长大，生下一个健康的大个子。因此，我很可能会活得很长。有些类型的母性效应不是通过营养来调节的，而是通过开启或关闭基因来实现的。这种基因沉默或激活(一种“表观遗传效应”)可以持续几代人。通过研究个体及其生活史(生长、成熟、健康、存活、寿命的模式)--无论是人类、其他哺乳动物、鸟类、鱼类、蜥蜴还是无脊椎动物--我们越来越意识到，父母的影响在决定个人生活的许多方面都很重要。亲本效应可以通过营养或表观遗传产生，也可以通过雄性或雌性品系产生。许多研究都是观察性的(注意到模式并试图解释它们)，所以很少进行系统的实验。关于亲本效应在生态学中的整体重要性，仍有许多悬而未决的问题。父母的影响会产生多大的差异？在什么时间尺度上：它们可以被超越或逆转吗？母亲和父亲的影响是如何相互作用的？表观遗传效应的作用与营养效应不同吗？它们在多大程度上通过在个体之间创造差异来影响种群动态？在这项资助中，我们首先探索导致父母影响的条件--通过改变男性和女性的年龄和条件，然后从头到尾审视后代的生活史。其次，我们调查了这些影响是否源于遗传(后代与父母的基因组合不同)、营养(通过观察蛋黄的数量及其化学成分)和表观遗传学(哪些基因被打开或关闭)。第三，我们建立了一个模型来问为什么观察到的父母效应会演变。最后，我们创建了数百个个体的实验种群，以了解父母的影响如何在个体之间造成差异，以及这在多大程度上造成了种群规模和结构的差异。这些实验是用一种实验性的“模型”动物进行的：一种土壤螨类。这具有快速的世代时间和较小的规模，允许在个体和种群上进行实验。

Changes over time in population size arise due to changes in individuals (e.g. via survival or reproduction). Similarly, evolution via natural selection requires differences between individuals, under-pinned by heritable differences. The variation between individuals in their life-history phenotype (the way they grow, mature, reproduce and die) is thus key both to population changes and evolutionary changes. Traditionally, individual variation has been thought to arise because of genetic and environmental differences. Increasingly, we are recognising there is a third cause: past environmental conditions being passed across generations via paternal effects. The most common example of which are maternal influences on offspring condition. If my mother had a lot of food when she was pregnant, I am more likely to have grown in the womb and be born a large and healthy baby. As a result, I am likely to live a long time. Some types of maternal effect are not mediated by nutrition, but by switching on or off genes. Such gene silencing or activation (an 'epigenetic effect') can last several generations. By studying individuals and their life-histories (patterns of growth, maturity, health, survival, longevity) - whether in humans, other mammals, birds, fish, lizards or invertebrates - we are increasingly realising that parental effects are important in determining manay aspects of an individual's life. Parental effects can arise through nutrition or epigenetics, and arise through the male or female line. Many studies have been observational (noting patterns and trying to explain them) and so little systematic experimentation has been undertaken. There remain many unanswered questions about the overall importance for parental effects in ecology. How much variation do parental effects create? Over what timescale: can they be outgrown or reversed? How do maternal and paternal effects interact? Do epigenetic effects act differently from nutritional effects? How much do they influence population dynamics by creating variation between individuals? In this grant we first explore the conditions leading to parental effects - by varying male and female age and condition and then looking across the offspring life history from start to finish. Second, we investigate whether the effects arise due to genetics (offspring have different combinations of genes to their parents), nutrition (by looking at the amount of yolk and its chemical composition) and epigenetics (which genes are switched on or off). Third, we build a model to ask the question why did the observed parental effects evolve. Finally, we create experimental populations of hundreds of individuals to see how parental effects created variability between individuals and how much this creates variation in population size and structure. The experiments are conducted using an experimental 'model' animal: a soil mite. This has a fast generation time and a small size, allowing experiments on both individuals and populations.