Mutation, adaptation, and speciation in experimental populations of fungi

真菌实验种群的突变、适应和物种形成

• 批准号: 7792-2011
• 负责人: Anderson, James
• 金额: $ 2.33万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=474281
• 关键词: Mutation; adaptation; speciation; experimental; populations

The overall goal of this proposal is to observe and measure mutation, adaptation, and incipient speciation in experimental populations, each with a known ancestor and history. Mutation is the ultimate source of all genetic variation and yet inferences on mutations and their rates in natural populations have remained indirect. Objective 1 is to sample long-lived individuals of Armillaria gallica, an important opportunistic fungal pathogen of tree roots. Each individual of A. gallica arises in a single mating event and then grows to occupy a discrete spatial territory including many adjacent tree root systems. In effect, this leaves a spatial record of growth over time and allows estimation of the rate of selectively neutral and advantageous mutations in a direct manner not previously possible under natural conditions. To identify the mutations, the entire genomes of samples of individuals will be sequenced. Objective 2 is observe the mutations and measure their effects on fitness and on reproductive isolation in 12 diploid populations of the yeast Saccharomyces cerevisiae, that were propagated in two different environments, high salt and low glucose for 500 generations. Most studies of speciation, the process by which one species splits into two, are based on extant, fully fledged species. This can be problematic because the earliest events of speciation may be obscured by changes accumulated during the long evolutionary history since the split. The evolution experiments proposed here will bring focus to the earliest stages of the speciation process, with all underlying mutations identified at the DNA level and characterized for fitness effects. This will establish which modes of adaptation and reproductive isolation occur most generally. Objective 3 is to propagate all 12 yeast populations for a further 10,000 generations in their respective environments with daily transfers over the next four years, extending the time frame for observation of adaptation and speciation by more than an order of magnitude, again with full characterization of the underlying molecular determinants. This will establish which mechanisms of adaptation and isolation are modified over time and will identify any new mechanisms that emerge with confidence.

这项提案的总体目标是观察和测量实验种群中的突变、适应和初期物种形成，每个种群都有一个已知的祖先和历史。 突变是所有遗传变异的最终来源，然而关于突变及其在自然群体中的发生率的推断仍然是间接的。 目的1是采集树木根部重要条件致病菌--高卢蜜环菌的长寿个体。 A. Gallica在单一交配事件中出现，然后生长占据包括许多相邻树根系统的离散空间领域。实际上，这留下了随时间增长的空间记录，并允许以直接方式估计选择性中性和有利突变的速率，这在自然条件下是不可能的。为了鉴定突变，将对个体样本的整个基因组进行测序。 目的二是观察在高盐和低糖两种不同环境中繁殖500代的12个酿酒酵母二倍体群体的突变情况，并测定其对适合度和生殖隔离的影响。 大多数物种形成的研究，一个物种分裂成两个的过程，是基于现存的，完全成熟的物种。 这可能是有问题的，因为最早的物种形成事件可能会被自分裂以来漫长的进化历史中积累的变化所掩盖。 这里提出的进化实验将把重点放在物种形成过程的最早阶段，在DNA水平上识别所有潜在的突变，并以适应性效应为特征。这将确定哪些模式的适应和生殖隔离发生最普遍。 目标3是在未来四年内每天转移，在各自的环境中将所有12个酵母种群再繁殖10，000代，将观察适应和物种形成的时间范围延长一个数量级以上，再次充分表征潜在的分子决定因素。 这将确定哪些适应和隔离机制会随着时间的推移而改变，并将确定任何有信心出现的新机制。