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Can phenotypic plasticity and DNA methylation promote adaptive radiation?

表型可塑性和 DNA 甲基化能否促进适应性辐射？

基本信息

批准号：
NE/S002081/1
负责人：
George Turner
金额：
$ 6.78万
依托单位：
Bangor University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FS002081%2F1
关键词：
phenotypic plasticity DNA methylation promote

项目摘要

How do living things adapt to a new environment? In the long-run this will need genetic (or occasionally cultural) changes, but biologists are beginning to take seriously the idea that the genome has evolved to allow an organism's development to be responsive to the environment. This process may operate at a fundamental level, with chemical changes to the structure of the DNA itself in the form of 'epigenetic' marks which can enhance or inhibit the expression of individual genes. Mostly, these are short-term changes that vary among tissues and life-stages in an individual organism as part of the normal process of development, but it is now known that sometimes they can be induced by the environment and occasionally even persist across generations. Can this type of epigenetic change help organisms cope with new environmental challenges or even lead to them evolving into new species through later genetic changes, a process called 'genetic assimilation'? These are important questions for understanding the origins of biodiversity and its maintenance in a changing world. We aim to investigate these questions focussing on a small fish- the Eastern Happy- which belongs to one of the most spectacular examples of explosive evolutionary diversification, the African Great Lakes cichlid fishes, which have evolved into thousands of species in a few million years. Cichlid fishes have a second set of (pharyngeal) jaws in their throats that they use for processing their food, while the external (oral) jaws are specialised for capturing prey. Many closely-related cichlid species have subtly different jaw structures allowing them to feed on different things. This helps populations adapt to different environments, and allows different species to live together, exploiting different resources. We plan to look at three closely-related pairs of populations of the Eastern Happy: in each pair one population feeds mostly on soft food- plankton or plant material, but the other includes hard-shelled prey such snails in its diet, and this is reflected in their more powerful jaws. We aim to see how much of these difference in jaw structures can be explained by environmentally-induced flexibility and how much is genetic. We will test live fish in aquaria to see whether the anatomical differences among populations really do improve how they capture and process different kinds of prey. We will see whether genetic differences cause anatomical variation in the same direction as the environmentally-induced changes. We will investigate the structure of the genomes to see whether epigenetic changes are associated with divergent diets and structures, and try to determine if different population pairs are diverging in similar ways. We aim to test if the activities of key genes in the jaws are associated with epigenetic changes. These experiments will be based around investigations of fish reared in research aquaria, fed on different diets to mimic the hard and soft-diets they experience in the wild. This allows us to feed fish from soft-diet populations on hard diets and vice versa. Particularly good insights will come from splitting a single brood of fish after 6th months and rearing one half on hard diet and the other half on a soft diet, thus controlling for the effects of genetics. By rearing several generations in this way, we will be able to see whether epigenetic changes to the genome can persist over several generations. This study has the potential to reveal exciting new insights at the most fundamental level into how organisms adapt rapidly to their environments. The findings and techniques will have applications across a range of species and situations and perhaps cast light on how species will respond to the challenges of the environmental changes being caused by humans, through climate change, pollution and the introduction of alien species.

生物如何适应新环境？从长远来看，这将需要遗传（或偶尔文化）的变化，但生物学家开始认真对待基因组已经进化到允许有机体的发展对环境做出反应的想法。这一过程可能在基础水平上进行，DNA本身结构的化学变化以“表观遗传”标记的形式存在，可以增强或抑制单个基因的表达。大多数情况下，这些都是短期的变化，作为正常发育过程的一部分，在个体生物体的组织和生命阶段中各不相同，但现在知道，有时它们可以由环境引起，偶尔甚至会持续几代人。这种类型的表观遗传变化是否可以帮助生物体科普新的环境挑战，甚至通过后来的遗传变化（称为“遗传同化”的过程）导致它们进化成新的物种？这些问题对于理解生物多样性的起源及其在不断变化的世界中的维持至关重要。我们的目标是调查这些问题集中在一个小的鱼-东部快乐-这属于爆炸性的进化多样化，非洲五大湖慈鲷鱼，已演变成数千种在几百万年的最壮观的例子之一。慈鲷科鱼类在其喉咙中有第二套（咽）颚，用于处理食物，而外部（口腔）颚专门用于捕获猎物。许多密切相关的慈鲷物种有微妙不同的下巴结构，使他们以不同的东西为食。这有助于种群适应不同的环境，并允许不同的物种生活在一起，利用不同的资源。我们计划研究三对密切相关的东方快乐种群：在每一对中，一个种群主要以软性食物-浮游生物或植物材料为食，但另一个种群的饮食中包括硬壳猎物，如蜗牛，这反映在它们更强大的下巴上。我们的目标是看看这些颌骨结构的差异有多少可以通过环境引起的灵活性来解释，有多少是遗传的。我们将在水族馆中测试活鱼，看看种群之间的解剖学差异是否真的能改善它们捕获和处理不同种类猎物的方式。我们将看到遗传差异是否会导致与环境引起的变化相同方向的解剖变异。我们将研究基因组的结构，看看表观遗传变化是否与不同的饮食和结构有关，并试图确定不同的人口对是否以类似的方式分化。我们的目标是测试颌骨中关键基因的活动是否与表观遗传变化有关。这些实验将基于对研究水族馆中饲养的鱼类的调查，这些鱼类以不同的饮食喂养，以模仿它们在野外经历的硬饮食和软饮食。这使我们能够用硬饲料喂养软饲料种群的鱼，反之亦然。特别好的见解将来自分裂一个单一的育雏鱼后6个月和饲养一半的硬饮食和另一半的软饮食，从而控制遗传学的影响。通过以这种方式培育几代人，我们将能够看到基因组的表观遗传变化是否可以持续几代人。这项研究有可能在最基本的层面上揭示令人兴奋的新见解，即生物体如何快速适应环境。这些发现和技术将适用于一系列物种和情况，并可能揭示物种将如何应对人类通过气候变化、污染和引进外来物种造成的环境变化的挑战。