Kin-selected conflict and the evolution of lifespan and ageing

亲属选择冲突以及寿命和衰老的演变

• 批准号: NE/G005370/1
• 负责人: Joel Parker
• 金额: $ 19.33万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG005370%2F1
• 关键词: Kin; selected; conflict; evolution; lifespan; Kin; selected; conflict; evolution; lifespan

Why organisms age, i.e. grow feebler, as they grow old is a central topic in evolutionary ecology. Since bodies self-repair, why cannot every organism constantly renew itself and remain at peak condition despite its chronological age? The evolutionary theory of ageing answers this question with natural selection. Accidents inevitably ensure that there are fewer old individuals than young ones. This means that old individuals make a smaller genetic contribution to future generations. In turn, this means that natural selection values them less highly, or, put another way, that genes with harmful effects are less strongly selected against in older individuals. The result is selection for ageing. However, this conventional view of the evolution of ageing is incomplete, because it omits social effects. Normally an individual's death benefits only the unrelated conspecifics who gain access to the resources it leaves behind. But in a population made up of groups of relatives, death of one individual benefits its related group-mates. This affects the evolution of lifespan and ageing through kin selection, i.e. because relatives share genes in common. An example is the case, common in nature, of a parent whose death releases a resource, such as a nest or territory, required by an offspring to breed (resource inheritance). Eventually this benefits the offspring, creating an incentive for the parent to die prematurely, but there is a twist; parent and offspring do not 'agree' on the exact timing of parental death and resource handover. When the parent dies, it effectively 'trades' its own offspring (relatedness, r, = 0,5) for the less-related offspring of its young, namely its grandoffspring (r = 0.25). But the offspring trades its siblings (r = 0.5) for its own, equally-related offspring (r = 0.5). It follows that, if the parent is declining in fecundity, the offspring favours inheriting the resource before the parent favours yielding it. So, in social systems meeting these conditions, offspring should harass and even kill a parent whose fecundity is declining. If parental fecundity declines sufficiently, the parent gains more fitness by dying and allowing the offspring to reproduce than by remaining alive. Such a parent should rapidly age and die. In this proposal, we aim to test the hypothesis that kin-selected conflict over resource inheritance affects lifespan and ageing using the bumble bee Bombus terrestris as our experimental system. This species is highly suitable for the work because workers inherit the nest from their mother, the queen, and produce their own offspring within it. In addition, B. terrestris workers do sometimes kill their own mother before reproducing (worker matricide). We will test the two central predictions of the hypothesis. The first is that workers harass the queen and commit matricide when they assess that they will gain greater fitness from offspring production than from keeping the queen alive and rearing siblings. The second is that, at or approaching the threshold when the queen is selected to cede control of the nest to workers, queen ageing should be accelerated. To test the first prediction, we will carry out experiments such as comparing the lifespans of queens with and without aggressive, potentially reproductive workers. To test the second, we will confirm that genes known to be indicators of ageing in other social insects act likewise in B. terrestris. We will then test whether, in queens being harassed by workers, these genes show changes in expression level indicating accelerated ageing. The proposed research is novel because the focal hypothesis has not previously been tested, and nor has a combined behavioural and genetic approach to investigating such issues been implemented. It is fundamental because of the theoretical and practical importance of understanding how sociality affects ageing. The work should therefore yield results of value and relevance to several disciplines.

为什么有机体年龄，即随着年龄的增长而变老是进化生态学中的一个核心话题。由于身体自我修复，为什么每个有机体都不能不断地恢复自己，尽管年龄年龄的年龄，但仍能保持峰值状态？衰老的进化理论通过自然选择回答了这个问题。事故不可避免地确保老年人的年龄少于年轻人。这意味着老年人对子孙后代做出了较小的遗传贡献。反过来，这意味着自然选择对它们的重视程度不高，或者换句话说，在老年人中，具有有害作用的基因不太强烈。结果是选择衰老。但是，这种对衰老演变的传统观点是不完整的，因为它忽略了社会影响。通常，一个人的死亡只有无关的同种人就可以访问其留下的资源。但是，在由亲戚组成的人群中，一个人的死亡使其相关群体受益。这会影响寿命和衰老通过亲戚的进化，也就是说，因为亲戚共享共同的基因。一个例子就是一个例子，在本质上是父母，其死亡释放了后代繁殖（资源继承）所要求的资源，例如巢或领土。最终，这使后代受益，从而激励父母过早死亡，但有一个转折。父母和后代不同意父母死亡和资源移交的确切时机。当父母死亡时，它有效地“交易”了自己的后代（相关性，r，= 0,5），因为其年轻人的少年后代，即其Grandoffspring（r = 0.25）。但是后代将其兄弟姐妹（r = 0.5）以其自身相关的后代（r = 0.5）而交易。因此，如果父母的繁殖力下降，则后代有利于在父母偏爱产生它之前继承资源。因此，在满足这些条件的社会系统中，后代应该骚扰，甚至杀死一个繁殖力下降的父母。如果父母的繁殖力越来越大，父母通过死亡和允许后代繁殖而获得更多的健身，而不是保持活着。这样的父母应该迅速变老并死亡。在此提案中，我们旨在检验以下假设：种族选择的资源继承冲突会影响使用大黄蜂炸弹式地面作为我们的实验系统的寿命和衰老。该物种非常适合工作，因为工人从母亲，女王那里继承了巢穴，并在其中产生了自己的后代。此外，B. terrestris工人有时会在繁殖之前杀死自己的母亲（工人矩阵）。我们将测试假设的两个核心预测。首先是工人在评估后代生产中获得更大的健身性时，骚扰女王并犯下了矩阵，而不是让女王活着和抚养兄弟姐妹。第二是，当选择女王将巢穴控制给工人时，在接近或接近阈值时，应加速女王的老化。为了测试第一个预测，我们将进行实验，例如比较有或没有侵略性，潜在生殖工人的皇后的寿命。为了测试第二次，我们将确认在其他社会昆虫中已知已知是衰老的指标的基因在B. terrestris中也起作用。然后，我们将测试在皇后受到工人骚扰的皇后中，这些基因在表达水平的变化表明，表明加速衰老。拟议的研究之所以新颖，是因为焦点假设以前尚未进行过测试，并且也没有采用合并的行为和遗传方法来研究此类问题。这是基本的，因为理论和实践的重要性是了解社会性如何影响衰老。因此，这项工作应产生价值和相关性的结果。