A common hypothesis for the high biodiversity of mountains is the diversification driven by orogeny creating conditions for rapid in situ speciation of resident lineages. The Caucasus is a young mountain system considered as a biodiversity hotspot; however, the origin and evolution of its diversity remain poorly understood. This study focuses on mayflies of the subgenus Caucasiron, one of the most diversified stenotopic mayflies inhabiting various types of streams throughout the Caucasus. Using the time-calibrated phylogeny based on two mitochondrial (COI, 16S) and three nuclear (EF-1α, wg, 28S) gene fragments, we tested the role of Caucasian orogeny in biogeography, diversification patterns, and altitudinal diversification of Caucasiron mayflies. We found that orogeny promoted the lineage diversification of Caucasiron in the Miocene. The highest diversification rate corresponding with the uplift of mountains was followed by a significant slowdown towards the present suggesting minor influence of Pleistocene climatic oscillations on the speciation. The Caucasiron lineages cluster into three principal clades originating in the Upper Miocene. We found a strong support that the one of the three clades diversified via allopatric speciation in the Greater Caucasus isolated in the Parathetys Sea. The other two clades originating most likely outside the Greater Caucasus diversified towards high and low altitude, respectively, indicating possible role of climatic factors and/or passive uplift on their differentiation. Current high Caucasiron diversity in the Greater Caucasus is a result of in situ speciation and later immigration from adjacent mountain ranges after the Parathetys Sea retreat. Our phylogeny supported the monophyly of Rhithrogeninae, Epeorus s.l., Caucasiron, and Iron. Epeorus subgenus Ironopsis was found paraphyletic, with its European representatives more closely related to Epeorus s.str. than to Iron. Therefore, we re-arranged taxa treated within Ironopsis to comply with the phylogeny recovered herein.

中文翻译：

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中新世造山运动对高加索尺eo（高加索人）may的多样性的影响（E翅目：七子科）。

山区生物多样性高的一个常见假设是造山运动推动的多样化，这为居民沿袭物种的原位物种形成创造了条件。高加索地区是一个年轻的山区系统，被认为是生物多样性的热点。然而，人们对其多样性的起源和演变仍知之甚少。这项研究的重点是高加索亚种的may，这是最多样化的狭窄地topic之一，栖息于整个高加索地区的各种溪流中。使用基于两个线粒体（COI，16S）和三个核（EF-1α，wg，28S）基因片段的时间校准的系统发育系统，我们测试了高加索造山运动在高加索s可能的生物地理学，多样化模式和高度多样化中的作用。我们发现，造山运动促进了中新世高加索人的世系多样化。最高的多样化速率与山脉的隆升相对应，随后是目前的显着放缓，表明更新世气候振荡对物种形成的影响较小。高加索族谱系分为三个主要进化枝，起源于中新世上层。我们找到了强有力的支持，即在帕拉蒂海（Parathetys Sea）隔离的大高加索地区，通过异源物种形成使三个进化枝之一多样化。起源于大高加索地区以外的其他两个进化枝分别向高海拔和低海拔方向发展，表明气候因素和/或被动抬升对它们的分化可能具有作用。大高加索地区目前高加索山脉的高度多样性是原住民物种形成和随后在帕拉提海（Parathetys Sea）撤退后从相邻山脉迁移的结果。我们的系统发育支持根瘤菌科，Epoeorus sl，Caucasiron和Iron。Ironopsis亚属中的Epeorus亚属被发现是共生的，其欧洲代表与Epeorus s.str。密切相关。比铁。因此，我们重新安排了在Ironopsis中处理的分类单元，以符合此处回收的系统发育。