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（或偶尔的文化）变化，但是生物学家开始认真对待基因组已经进化以使生物体的发育能够对环境做出反应。该过程可能在基本层面上运行，将DNA本身结构的化学变化以“表观遗传”标记的形式变化，该标记可以增强或抑制单个基因的表达。通常，这些短期变化在单个生物体中的组织和生命阶段之间有所不同，这是正常发展过程的一部分，但是现在众所周知，有时它们可能会被环境诱导，偶尔有时甚至在几代人之间持续存在。这种表观遗传学变化是否可以帮助生物体应对新的环境挑战，甚至可以通过以后的遗传变化（称为“遗传同化”的过程）发展成为新物种？这些是了解生物多样性及其在不断变化的世界中维护的起源的重要问题。我们的目的是调查这些问题的重点是一条小鱼 - 东部快乐 - 属于爆炸性进化多样化的最壮观的例子之一，非洲伟大的大湖丽鱼科学湖水（Cichlid Fishes）在数百万年内已进化为数千种物种。酸辣酱鱼在喉咙中有第二组（咽）下颌，它们用于处理食物，而外部（口服）下颌专门用于捕获猎物。许多密切相关的丽鱼科具有微妙的下颌结构，使它们可以以不同的方式为食。这有助于人口适应不同的环境，并允许不同的物种共同生活，利用不同的资源。我们计划查看东部快乐的三对密切相关的人群：在每对中，一个人群主要以软浮游生物或植物材料为食，但另一种人的饮食中包括硬壳的猎物，这反映在其更强大的下颌中。我们的目的是通过环境引起的柔韧性以及遗传量有多少来解释颌结构中的这些差异。我们将在水族馆测试活鱼，以查看人群之间的解剖学差异是否确实改善了它们捕获和处理不同种类的猎物的方式。我们将看到遗传差异是否在与环境引起的变化相同的方向上引起解剖变异。我们将研究基因组的结构，以查看表观遗传变化是否与饮食和结构发散有关，并尝试确定不同的种群对是否以相似的方式分歧。我们旨在测试颌骨中关键基因的活性是否与表观遗传变化有关。这些实验将基于对研究水族箱中饲养的鱼类的研究，并以不同的饮食为食，以模仿他们在野外经历的硬和软饮食。这使我们能够从软饮食中的软饮食中喂食鱼类，反之亦然。特别好的见解将来自六个月后分裂一条鱼，而在硬饮食中饲养一半，而另一半则以软饮食为基础，从而控制了遗传学的影响。通过以这种方式饲养几代人，我们将能够看到对基因组的表观遗传变化是否可以持续数代。这项研究有可能在最基本的水平上揭示出令人兴奋的新见解，以使生物如何迅速适应其环境。这些发现和技术将在各种物种和情况下都有应用，也许会阐明物种将如何应对人类，气候变化，污染和引入外星物种引起的环境变化的挑战。