Evolutionary diversification in an endangered biodiversity hotspot: the Southeast Asian peat swamp forest fish fauna

进化生物学的一个中心主题是理解有助于生物多样性起源和维持的过程。最近物种的多样性在分类学群体和全球范围内的分布并不均匀--少数支系占世界多样性的很大一部分，一些相对较小、特有程度较高的地区居住着异常大量的物种。这些生物多样性热点构成了研究进化多样化过程的重要系统；这是记录、解释和保护我们今天观察到的生物多样性的先决条件。东南亚泥炭沼泽林(PSF)位于Sundaland生物多样性热点地区，是生长在一层枯死植物材料上的受涝森林。尽管PSF是最受威胁的生态系统之一，但对其特有动植物进化多样化的模式和过程几乎一无所知。PSF的特点是一个独特的、极其狭窄的淡水鱼群落，适应高度酸性(pH低至3)的黑色水域，由许多微型分类群和范围狭窄的特有种组成，其中许多是近年来才发现的。我们将使用多基因、分子系统的方法来研究选定的狭窄性PSF鱼类分支的生物地理、系统地理和人口学历史。我们的项目将首次为全球PSF保护工作提供一个进化的视角。其具体目标是：(1)重建泥炭沼泽森林鱼类多样化的时间框架，并测试长期存在争议的替代生物地理假说--中新世--上新世--更新世预期的结果将对我们对PSF进化的理解产生巨大影响，并将提供对PSF群落的一个关键组成部分--狭义嗜酸淡水鱼动物群的了解。将PSF鱼类动物群置于历史背景下，将对侧重于东南亚古气候和古生态系统重建的研究工作作出积极贡献。我们项目中产生的分子系统发育数据将使这种独特的动物群更好地作为东南亚泥炭沼泽森林多样化和保护的模型组。我们的发现有望对有关进化模式和过程的几个更广泛的问题产生重大影响，即：(1)过去地质事件和气候诱导的变化对多样性模式的影响(2)更新世保护区在热带生物多样性热点中的作用(3)热点物种多样性和系统发育多样性之间的关系(4)预测性生态建模和群落聚集。

A central theme in evolutionary biology is the understanding of the processes that contribute to the origin and maintenance of biodiversity. The diversity of recent species is not equally distributed among taxonomic groups and across the globe - a small number of clades accounts for a large part of the world's diversity and a number of relatively small areas with high levels of endemism are populated by unusually large numbers of species. These biodiversity hotspots comprise important systems for investigating the processes of evolutionary diversification; a prerequisite to document, explain, and conserve the diversity of life we observe today. The Southeast Asian peat swamp forests (PSF), found in the Sundaland biodiversity hotspot, are waterlogged forests that grow on a layer of dead plant material. Although PSF are one of the most threatened ecosystem, virtually nothing is known about the patterns and processes of evolutionary diversification of its endemic fauna and flora. PSF are characterized by a unique, vastly stenotopic freshwater fish community, which is adapted to highly acidic (pH as low as 3) black waters and comprises many miniature taxa and narrow range endemics many of which have only been discovered in recent years. We will use a multigene, molecular systematic approach to investigate the biogeography, phylogeography and demographic history of selected stenotopic PSF fish clades. Our project will for the first time provide an evolutionary perspective to global PSF conservation efforts. The specific aims are to, (1) reconstruct the time frame for the peat swamp forest fish diversification and test alternative biogeographic hypotheses that have long been contentious - Miocene-Pliocene vicariance vs Pleistocene dispersal among the landmasses of Sundaland, (2) identify past demographic expansions and their taxonomic, geographic and temporal correlates and thus infer the areas that might have been refugia or centres of diversification as opposed to recently colonized areas, and (3) identify regions of elevated taxonomic and genetic diversity that contribute most to the evolutionary legacy of this unique ecosystem. Anticipated results will have an immense impact on our understanding of PSF evolution and will provide an understanding of a key PSF community component, the stenotopic acidophilic freshwater fish fauna. Placing the PSF fish fauna in a historic context will positively contribute to research efforts focussing on palaeoclimate and palaeoecosystem reconstruction of Southeast Asia. The molecular phylogenetic data generated in our project will allow this unique fauna to be better used as model group for Southeast Asian peat swamp forest diversification and conservation. Our findings promise to have a major bearing on several wider issues concerning evolutionary patterns and processes, namely: (1) the effect of past geological event and climate induced changes on diversification patterns (2) the role of Pleistocene refuges in tropical biodiversity hotspots (3) the relationship between species diversity and phylogenetic diversity in hotspots (4) predictive ecological modelling and community assembly.