The capacity for sustained adaptation in a rapidly changing environment

澳大利亚的珊瑚正在遭受痛苦，它们是由变暖的海洋带来的“珊瑚白化”的受害者。当这些五颜六色的水下动物驱逐它们的藻类伙伴，从而变成白色时，它们可能向我们传递了两个可能定义未来几年地球生物群的信息。其中之一是，地球现在变暖的速度比数百万年来都要快，联合国气候科学家的最新报告警告说，为了应对这种变暖，一些环境变化可能会自我维持，放大它们自己的影响。现在人们普遍认为，全球变暖是由二氧化碳等人为(人为)增加的温室气体造成的，但无论是什么原因，地球现在的温度比12.5万年来都要高。这种新的气候，以及它带来的许多环境变化，意味着植物和动物将不得不适应生存，并在可能数百年至数千年的时间尺度上这样做。在这种情况下，如果珊瑚继续漂白，珊瑚最终会死亡。来自珊瑚的另一个信息是，我们目前对物种适应速度的看法可能过于乐观了。对物种在野外或实验室实验中适应情况的研究往往表明，物种可能会迅速变化。他们可以，但这些研究通常是在几代人的时间内进行的，因此无法回答这样高的变化率可以持续多久的问题。任何给定物种的种群在身高或体重(或对珊瑚漂白的抵抗力)等特征上自然会有所不同，而正是这种变化受到自然选择的影响，通过偏爱一些变异而不是另一些变异来导致变化。但随着这一过程的进行，自然变异被耗尽，在这一点上，适应变得缓慢，甚至可能停止，物种可能会灭绝。根据联合国的《可持续发展报告》，自然已经在全球范围内以人类历史上前所未有的速度衰退，物种灭绝的速度正在加快。微小的珊瑚可能是这一效应的先驱之一。物种能以多长时间和多快的速度保持持续的适应？我们希望进行的研究将使用不是来自短期研究而是来自地球进化史的估计来解决这个问题。我们的方法将把新的统计建模技术应用于数千个物种，以估计它们在数百万年的进化过程中过去的变化率。从这个史无前例的数据库中，我们将能够绘制出在千禧年时间尺度上可以持续的变化量和上限的概况。然后，利用种群内自然变异的信息，我们将能够确定这些历史变化率是否处于进化的最大值，如果不是，则估计它们可以增加多少。我们的工作将把这些方法和想法应用于所有种类的脊椎动物(有脊椎的动物)，包括哺乳动物、鸟类、鱼类、爬行动物和两栖动物。我们将能够确定哪些种类的物种能够最大程度地适应变化，以及像飞行或水生生物这样的特征与变化的程度是大是小有关。我们的方法很容易应用于其他物种，并突出了预测地球生物群可能如何变化以应对快速变化的世界所需的信息。

Australia's corals are suffering, victims of 'coral bleaching' brought on by a warming ocean. When these colourful underwater animals expel their algal partners, thereby turning white, they may be sending us two messages that could define the Earth's biota in the coming years. One is that the Earth is now warming at rates faster than it has for millions of years, and the most recent report from the United Nation's climate scientists warns that some environmental changes in response to this warming could become self-sustaining, amplifying their own effects. There is now wide agreement that global warming has been brought on by anthropogenic (human-induced) increases in greenhouse gases such as carbon dioxide, but whatever the causes, the Earth is now warmer than it has been for 125,000 years. This new climate, and the many environmental changes it brings, mean that the plants and animals are going to have to adapt to survive, and do so over timescales of potentially many hundreds to thousands of years. In this context, if coral bleaching persists, the corals eventually die.The other message from the corals is that our current views on how rapidly species can adapt might be dangerously optimistic. Studies of species adapting in the wild, or in laboratory experiments, often reveal that species can change rapidly. They can, but these studies typically take place over a handful of generations and thereby fail to answer the question of for how long such high rates of change can be sustained. Populations of any given species naturally vary in features such as height or weight (or resistance to coral bleaching), and it is this variation that natural selection acts upon, causing change by favouring some variants over others. But as this process goes on, the natural variation gets used up, and at that point adaptation slows to a crawl, or can even stop, and species can go extinct. Already, according to the United Nations' Sustainable Development report "Nature is declining globally at rates unprecedented in human history - and the rate of species extinctions is accelerating". The tiny corals might be among the first harbingers of this effect.For how long and at what rates can species maintain sustained bouts of adaptation? The research we wish to conduct will address this question using estimates derived not from short-term studies but from the Earth's evolutionary history. Our approach will apply new statistical modelling techniques to thousands of species to estimate their past rates of change over millions of years of evolution. From this unprecedented database we will be able to develop profiles of the amounts and upper limits of change that can be sustained over millennial timescales. Then, using information on the natural variation within populations, we will be able to determine if these historical rates of change are at their evolutionary maximums, and if not, estimate how much they could be increased. Our work will apply these methods and ideas to species from all of the Classes of vertebrates (animals with a backbone), including mammals, birds, fish, reptiles and amphibians. We will be able to identify which kinds of species are capable of the greatest adaptive change, and whether traits like flying or an aquatic existence are associated with greater or lesser amounts of change. Our approach is easily applied to other species, and highlights the kind of information that will be needed to make predictions about how the Earth's biota might change in response to a rapidly changing world.