Abstract

The Irano-Turanian (IT) floristic region in Asia contains three biodiversity hotspots and has been a source of xerophytic taxa for neighboring regions. Despite its species richness and large territory, the evolutionary history and biogeography of this floristic region is poorly understood. Acanthophyllum, encompassing ca. 70 subshrubby mostly thorny-cushion species, is one of the important components of the steppe and mountain vegetation of this region. In this study, we investigate the tempo and mode of diversification as well as the biogeographic patterns of this genus. The ancestral area analysis suggests that Acanthophyllum originated east of the Zagros Mountains in the Miocene, from where it expanded westwards. A shift in the speciation rate in the late Pliocene (ca. 3.24 Ma) was detected, based on a nrDNA ITS tree, affecting the lineage of the largest section in the genus, Acanthophyllym sect. Oligosperma. Parallelisms with another IT species-rich genera in aspects such as largely coincident ranges and habitats, presence of a thorny-cushion life-form, similar areas reconstructed for their MRCA, and the inference of a shift in speciation in the region suggest common underlying abiotic and biotic factors or even drivers for diversification and speciation in the high elevation dry continental landscape of IT region.

摘要

亚洲的伊朗-土耳其语（IT）植物区系包含三个生物多样性热点，并且一直是邻近地区的旱生植物分类群的来源。尽管其物种丰富且地域广阔，但对该植物区系的进化历史和生物地理学知之甚少。棘皮动物，包括ca。70个半灌木林大多是棘手的垫层物种，是该地区草原和山区植被的重要组成部分之一。在这项研究中，我们调查了多样化的速度和模式以及该属的生物地理模式。祖先面积分析表明，刺五加起源于中新世的扎格罗斯山脉以东，向西扩展。根据nrDNA ITS树，发现了上新世晚期（约3.24 Ma）的物种形成率发生了变化，影响了Acanthophyllym属中最大部分的谱系。少精子。与其他IT物种丰富的属之间的平行性在诸如范围和栖息地重合，棘手垫形生物存在，针对其MRCA重建的相似区域以及该地区物种形成变化的推断等方面暗示了常见的潜在非生物和生物因素，甚至是IT地区高海拔干旱大陆景观中多样化和物种形成的驱动力。