Palaearctic steppes evolved under the Cenozoic cold arid climate and megaherbivore pressure. A large portion of the biome persisted into the Holocene but has recently been subjected to human land use alternation. Pseudophilotes bavius (Lepidoptera: Lycaenidae) is a steppe specialist sporadically distributed in Eastern Europe and Pontic-Caspian region (from Transylvania to Southern Urals), the Balkans, the South-Eastern Mediterranean and Irano-Anatolian regions. We used samples covering the distribution area to assess the phylogeography and population genetics of the species based on one mitochondrial and four nuclear genes. The basal lineages are situated in the Irano-Anatolian region, forming two Evolutionary Units. The species radiated to the Balkans and Pontic-Caspian steppes probably when the climatic conditions became suitable after the mid-Pleistocene transition and formation of vast steppe biome. In these parts of the range, the species survived both glacial and interglacial periods in situ, forming a third Evolutionary Unit. In the Balkans, the individual populations are distinct and have probably been isolated for a long time, owing to the diversity of Balkan habitats. In the Pontic-Caspian region, population connectivity probably existed until recently, since the life history of the species is unlikely to include long-distance dispersal. The distribution could have become fragmented with the conversion of steppes into cropland during the past centuries. Future conservation will require proper knowledge of the distribution and habitat needs of the species. Management of inhabited sites should respect historical disturbance-succession dynamics.

古生代草原在新生代寒冷干旱气候和巨型食草动物压力下演化。生物群落的很大一部分持续进入全新世，但最近遭到人类土地用途的交替。假单胞菌鳞翅目（鳞翅目：Lycaenidae）是散布在东欧和庞蒂克里海地区（从特兰西瓦尼亚到乌拉尔南部），巴尔干地区，东南地中海地区和伊朗-Anatolian地区的草原专家。我们使用覆盖分布区域的样本，根据一个线粒体和四个核基因评估该物种的系统地理学和种群遗传学。这些基础血统位于伊朗-安那托利亚地区，形成两个演化单位。在中更新世过渡和广泛的草原生物群落形成之后，当气候条件变得合适时，该物种辐射到巴尔干和蓬蒂里海-里海草原。在该范围的这些部分中，该物种在冰川期和冰川间期都原位存活，形成了第三个进化单位。在巴尔干半岛，由于巴尔干栖息地的多样性，各个种群是截然不同的，并且很可能已被隔离很长一段时间。在蓬蒂里海地区，人口连通性可能一直存在到最近，因为该物种的生活史不太可能包括远距离扩散。在过去的几个世纪中，随着草原转变为农田，分布可能变得零散。未来的保护将需要对物种的分布和栖息地需求有适当的了解。居住区的管理应尊重历史干扰演替动态。因为该物种的生活史不太可能包括远距离扩散。在过去的几个世纪中，随着草原转变为农田，分布可能变得零散。未来的保护将需要对物种的分布和栖息地需求有适当的了解。居住区的管理应尊重历史干扰演替动态。因为该物种的生活史不太可能包括远距离扩散。在过去的几个世纪中，随着草原转变为农田，分布可能变得零散。未来的保护将需要对物种的分布和栖息地需求有适当的了解。居住区的管理应尊重历史干扰演替动态。