A temperate radiation in a tropical plant family – factors underpinning evolution of the Eurasian Vincetoxicum (Apocynaceae) complex

主要是热带木本被子植物的温带草本分支在最近经历了物种多样化和/或不同--辐射--的加速事件，经常与新生境的殖民有关。然而，除了山脉或岛屿等一些研究得很好的生物地理热点外，人们对驱动这种辐射的因素知之甚少。在夹竹桃科形成花粉的热带Asclepiadoideae亚科中，只有3个谱系在温带经历了实质性的辐射，其中Vincetoxium(s.l.)是最年轻的一个。长春花属(Vincetoxicum)是一个由几个热带藤本分支和两个草本温带辐射组成的属。其中之一是“Vincetoxicum s.str.”克雷德，已经从远东通过亚洲山脉扩展到亚洲草原，并进入欧洲，从那里它进入了新人的新大陆。为了了解最近这场温带辐射的进化史，我们将研究三条证据：形态测量、分子和化学。特别是，我们测试了这个分支进化成功的最有可能的因素之一，它的不寻常的化学特征是菲咯吲哚-生物碱(PIA)。综合分析将阐明该分支的表型变异、遗传基础和推测的化学防御策略，以检验最成功的谱系是拥有最佳化学防御系统的谱系的假设。我们将(1)开发一个全面的形态数据集，以区分“形态种”；(2)提供一个密集采样的Vincetoxicum s.str的系统发育。通过对低拷贝核基因进行有针对性的测序，从而能够对基于联合的物种进行定界；(3)检查形态种和基于联合的物种的一致性，并根据不同的证据线索，推导出欧亚Vincetoxicum的稳定的物种概念；(4)根据气候变化和养护，为今后对Vincetoxicum的监测提供迫切需要的工具；(4)检验最成功的物种是那些拥有最佳化学防御系统的物种的假设，并利用PIA的数量和多样性作为防御强度的指标。

Temperate herbaceous clades in mainly tropical, woody Angiosperm families often have undergone accelerated episodes of species diversifications and / or disparification – radiations – in the recent past, frequently associated with the colonization of new habitats. However, little is known about the factors driving such radiations outside some well-studied biogeographic hotspots like, e.g., mountains or islands. In the pollinia-forming, tropical subfamily Asclepiadoideae of Apocynaceae, only three lineages have undergone a substantial radiation in the temperate zones, of which Vincetoxium (s.l.) is the youngest one. Vincetoxicum is a genus comprising several tropical lianescent clades and two herbaceous temperate radiations. One of these, the "Vincetoxicum s.str." clade, has expanded from the Far East via the Asian mountain chains into the Asian steppes and into Europe, from where it has entered the New World with neophytes. To understand the evolutionary history of this recent temperate radiation, we will study three lines of evidence: morphometric, molecular, and chemical. Especially, we test one of the most likely factors contributing to the evolutionary success of this clade, its unusual chemistry featuring phenanthroindolizidine-alkaloids (PIAs). Synthetic analysis will elucidate the phenotypic variation, the genetic basis, and the supposed chemical defence strategy in this clade to test the hypothesis that the most successful lineages are the ones with the best chemical defence system. We will (1) develop a comprehensive morphological dataset allowing the delimitation of "morphospecies"; (2) provide a densely sampled phylogeny of the Vincetoxicum s.str. clade using targeted sequencing of low-copy nuclear genes, allowing the delimitation of coalescent-based species; (3) check the congruence of morphospecies and coalescent-based species and derive a stable species concept for Eurasian Vincetoxicum based on different lines of evidence; a tool urgently needed for future monitoring of Vincetoxicum in the light of climate change and conservation; (4) test the hypothesis that the most successful species are the ones with the best chemical defence system, using quantity and diversity of PIAs as a proxy for the strength of the defence.