What drives evolutionary diversification in a biodiversity hotspot? A `next generation´ phylogenetic approach comparing three clades of the Cape Floristic Region´s mega-genus Erica

是什么推动了生物多样性热点地区的进化多样化？

• 批准号: 251415172
• 负责人: Dr. Nicolai M. Nürk, since 12/2018
• 金额: --
• 依托单位: Lehrstuhl für Pflanzensystematik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/251415172?language=en
• 关键词: What; drives; evolutionary; diversification; biodiversity

The Cape Floristic Region (CFR) of South Africa is a botanical hotspot and represents an ideal system with which to investigate biological diversity. The total area of the CFR is small but the number of plant species found there is disproportionally high, and an astonishing 70% of them are found nowhere else in the world. The largest Cape clade, the genus Erica (Ericaceae), alone accounts for 7% of the flora, making it a key taxon for understanding the causes of evolutionary diversification. In a renewal of my current DFG-funded project, I propose to test a number of the most likely factors proposed as potential causes of the high plant diversity of the CFR, principally those relating to shifts in geographic range and pollinators. Extending from the original aims, we would compare three groups of closely related Erica species: the imbricata/coccinea-clade (data collected in current project), the abietina/viscaria-clade, and E. plukenetii. The clades comprise a total of c. 34 species, with often highly localised geographic distributions. They are each characterised by variation in floral macro-morphological characters that are generally related to pollination by different vectors. The recent divergence of the species and populations in these clades means that phylogenetic evidence for evolutionary events, such as dispersals, may remain unmasked by subsequent events. However, reticulate processes, such as hybridisation, and coalescent stochasticity can result in considerable differences between gene trees when comparing closely related individuals and clades, as is apparent in our imbricata/coccinea-clade dataset. Accurate phylogenetic inference is only possible under these circumstances if we sample numerous, meaningfully resolved independent gene trees and model the processes underlying their differences appropriately. To this end, I propose to use our Erica-optimised hybridisation capture and high-throughput sequencing pipeline to obtain 132, up to c. 7 Kb long DNA sequence markers for each of 72 representative specimens of the two additional clades. For improved sampling of populations, we will use a multiplex PCR approach to obtain a subset of the markers for up to 192 further samples. By analysing the data with coalescence-based methods we can infer meaningful, potentially reticulate, species trees. The species trees of all three clades can then be used with further phylogeny-based inference methods as independent tests of competing hypotheses of geographic range and character evolution. Plausible hypotheses to be tested with this data include allopatric speciation models and the Grant-Stebbins model for pollinator driven speciation. In so doing we can yield profound insight into the processes driving the divergence of species, both in the Cape, and in general.

南非的开普植物区系区（CFR）是一个植物学热点地区，是研究生物多样性的理想系统。CFR的总面积很小，但在那里发现的植物物种数量却非常多，其中70%是世界上其他地方没有的。最大的海角分支，属埃里卡（杜鹃花科），仅占7%的植物群，使其成为一个关键的分类单元，了解进化多样化的原因。在更新我目前DFG资助的项目，我建议测试一些最有可能的因素提出的高植物多样性的CFR的潜在原因，主要是那些有关的地理范围和传粉者的转变。从最初的目的出发，我们将比较三组密切相关的埃里卡属物种：imbricata/coccinea-分支（本项目收集的数据），冷杉属/viscaria-clade，和E。普卢凯氏菌这些进化枝总共包括C。34种，具有高度本地化的地理分布。它们各自的特点是花的宏观形态特征的变化，通常与不同的载体授粉。最近的分歧的物种和人口在这些分支意味着进化事件，如扩散的系统发育证据，可能会继续揭露随后的事件。然而，网状的过程，如杂交，和合并的随机性可以导致基因树之间的相当大的差异时，比较密切相关的个人和分支，这是显而易见的，在我们的覆瓦/coccinea-分支数据集。在这种情况下，只有我们对大量有意义的独立基因树进行采样，并对它们的差异进行适当的建模，才有可能进行准确的系统发育推断。为此，我建议使用我们的Erica优化的杂交捕获和高通量测序管道来获得132，高达c。另外两个分支的72个代表性样本中的每一个的7 Kb长DNA序列标记。为了改进人群的采样，我们将使用多重PCR方法来获得多达192个进一步样本的标记子集。通过使用基于合并的方法分析数据，我们可以推断出有意义的、潜在的网状物种树。所有三个分支的物种树，然后可以使用进一步的基于遗传的推理方法作为独立的测试竞争的假设的地理范围和字符的进化。用这些数据进行检验的合理假设包括异域物种形成模型和传粉者驱动物种形成的格兰特-斯特宾斯模型。这样做，我们可以产生深刻的洞察力的过程中，推动物种的分歧，无论是在好望角，并在一般。