The colonisation of hydrothermal vents by complex life: a natural experiment in macroevolution

我们的计划联合了来自矿物学、古生物学、深海生物学和遗传学的多学科研究团队，以提供地球上一些最引人注目的环境何时以及如何被高度专门化的动物殖民的综合图景，并为现代深海保护挑战提供信息。20世纪70年代末深海热液喷口的发现彻底改变了我们对地球上生命极限的理解。这些探索发现了由化学合成支持的令人难以置信的郁郁葱葱的生态系统，这是一种以前被认为微不足道的碳固定过程，以及具有许多新的适应在这个黑暗的栖息地生存的动物群，其特点是从海底喷出极热的有毒液体。尽管它们的环境看似敌对，但我们现在知道，动物在喷口周围茁壮成长至少有4.4亿年，在地球历史的进程中，不同的分类谱系不断适应这种环境。令人惊讶的是，喷口的进化似乎已经发生了无数次，而不是作为古代遗迹动物群在大规模环境变化中孤立生存的进化避难所。这表明喷口作为进化新颖性的孵化器具有耐人寻味的作用，它们在进化中的重要性也被生命本身起源于这一背景的理论所突显。自从它们的初步探索以来，在调查这些生态系统以及理解现代喷口动物与支持它们的微生物的密切相互作用方面已经取得了重要的里程碑。然而，对于动物最初何时转变到占据这种环境的基本问题，推动新喷口动物适应的过程，以及喷口殖民的生物学基础，仍然缺乏答案。掌握这些原则对于了解动物如何适应不稳定的温度制度，以及大规模环境变化如何影响深海--世界上最大的生态系统--至关重要。这在今天尤其重要，因为深海越来越多地受到人类活动的影响，但它如何应对气候变化和采矿作业等影响尚不清楚。为了获得对现代海洋和整个地球历史上热液喷口殖民的重要进化见解，我们提出了一个以四个假设为指导的综合研究计划：1)寒武纪生命爆发后不久，动物在热液喷口环境中定居；2)随着时间的推移，新的喷口栖息地的形成反复推动喷口动物的进化；H3)古代喷口动物与微生物类似，与现代喷口动物在恶劣的喷口环境中生存；我们将从挪威、加拿大和塔斯马尼亚的关键地质地点以及乌拉尔山脉南部保存了1亿年的古代喷口化石历史的实地研究中收集初步数据。挪威、加拿大和塔斯马尼亚可能包含已知最古老的骨骼喷口动物。总而言之，这些地区拥有一些世界上保存最完好的古代热液喷口矿床。收集的化石样本将接受新的详细古生物调查和高分辨率硫同位素分析。为了研究现代热液喷口最近和正在进行的适应，我们将利用先进的DNA技术，对传统的非喷口动物样本进行研究，我们可以观察到这些动物在新的热液系统中定居。

Our proposal unites a multidisciplinary team of researchers from mineralogy, palaeontology, deep-sea biology and genetics to provide an integrated picture of when and how some of the most remarkable environments on our planet were colonised by highly-specialised animals, and inform modern deep-sea conservation challenges.The discovery of hydrothermal vents in the deep sea during the late 1970s revolutionised our understanding of the limits of life on our planet. These explorations uncovered incredibly lush ecosystems supported by chemosynthesis, a carbon-fixation process previously deemed insignificant, and faunas with many novel adaptations to surviving in this dark habitat characterised by the ejection of extremely hot, toxic fluids from the seafloor. Despite their seemingly-hostile conditions, we now know that animals have thrived around vents for at least 440 million years, and that diverse taxonomic lineages have continually adapted to this environment over the course of Earth's history. Surprisingly, rather than functioning as evolutionary refuges in which ancient relict faunas have survived in isolation from large-scale environmental changes, evolution at vents appears to have occurred numerous times. This suggests that vents have an intriguing role as incubators of evolutionary novelty, their importance in evolution also highlighted by theories that life itself originated within this setting.Since their initial exploration, significant milestones have been achieved in surveying these ecosystems and in understanding the intimate interactions that modern vent faunas have with the microorganisms that support them. However, answers to fundamental questions of when animals first transitioned to occupy this environment, the processes driving the adaptation of new vent animals and the biological basis for vent colonisation are still lacking. A grasp of these principles is vitally important to understanding how animals adapt to unstable temperature regimes, and of how large-scale environmental changes affect the deep sea, the world's largest ecosystem. This is particularly pertinent today as the deep sea is increasingly affected by human activities, but how it responds to impacts such as climate change and mining operations is unknown.To gain vital evolutionary insights into the colonisation of hydrothermal vents, both in the modern ocean and throughout Earth history, we propose a comprehensive research programme guided by four hypotheses: H1) animals colonised hydrothermal vent environments soon after the Cambrian Explosion of life; H2) new vent habitat formation has repeatedly driven vent animal evolution over time; H3) ancient vent animals exhibited similar associations with microorganisms to modern vent animals to survive within harsh vent environments; and H4) adaptation to vent environmental regimes is evolutionarily rapid.We will assemble primary data for this project from field studies of key geological localities in Norway, Canada and Tasmania, which likely contain the oldest known bone-fide vent animals, and the southern Ural Mountains where a remarkable 100 million year fossil history of ancient vents is preserved. Together, these regions contain some of the best-preserved ancient hydrothermal vent deposits in the world. Collected fossil samples will be subjected to new detailed palaeontological investigations, and high resolution sulphur isotopic analyses. To investigate recent and ongoing adaptation at modern hydrothermal vents we will work on samples of traditional non-vent fauna that we can observe colonising new hydrothermal systems, using advanced DNA techniques.