Osikowski Artur, Georgiev Dilian, Hofman Sebastian, Falniowski Andrzej
Department of Comparative Anatomy, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387, Kraków, Poland.
Department of Ecology and Environmental Conservation, University of Plovdiv, Tzar Assen Str. 24, BG-4000 Plovdiv, Bulgaria.
Zookeys. 2015 Aug 25(518):67-86. doi: 10.3897/zookeys.518.10035. eCollection 2015.
Bythinella is a minute dioecious caenogastropod that inhabits springs in central and southern Europe. In the Balkans, previous studies have addressed its morphological and genetic differentiation within Greece and Romania while the Bulgarian species have remained poorly known. The aim of the present paper has been to expand the knowledge on the subject in Bulgaria. Shell morphology and anatomy of the reproductive organs were examined, and a fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene and the nuclear ribosomal Internal Transcribed Spacer 1 (ITS-1) were sequenced from 15 populations. Additional sequences from eight previously studied populations were included in our analyses. Phylogenetic analyses revealed five main mitochondrial DNA clades, which were partly confirmed by analyses of the ITS-1 sequences. The genetic differentiation between the clades was found to be in the range p=2.4-11.8%. Most of the populations belonged to clade I, representing Bythinella hansboetersi, and were distributed in SW Bulgaria. Clades II and III inhabit areas adjacent to clade I and were most closely related with the latter clade. Much more distinct were clade V, found at one locality in NW Bulgaria, and clade IV, found at one locality in SE Bulgaria, close to the sea. Four populations were found in caves, but only one of these represented a distinct clade. Considering the observed pattern of interpopulation differentiation of Bythinella in Bulgaria, we can suppose that isolation between clades I, II and III may have been caused by glaciations during the Pleistocene. The time of isolation between the above three clades and clade IV coincides with the Messinian Salinity Crisis, and the time of isolation between the clade V and the other four most probably reflects the isolation of the Rhodopes from western Balkan Mts by the seawater of the Dacic Basin.
薄壳螺是一种微小的雌雄异体的新腹足类动物，栖息于欧洲中部和南部的泉水之中。在巴尔干地区，此前的研究探讨了其在希腊和罗马尼亚境内的形态和遗传分化情况，而保加利亚的该物种仍鲜为人知。本文的目的是扩充保加利亚这方面的知识。对贝壳形态和生殖器官解剖结构进行了检查，并对来自15个种群的线粒体细胞色素氧化酶亚基I（COI）基因片段和核糖体内部转录间隔区1（ITS-1）进行了测序。我们的分析还纳入了来自8个此前已研究种群的额外序列。系统发育分析揭示了5个主要的线粒体DNA分支，ITS-1序列分析部分证实了这些分支。各分支之间的遗传分化在p = 2.4 - 11.8%范围内。大多数种群属于代表汉斯博特斯薄壳螺的分支I，分布在保加利亚西南部。分支II和III栖息于与分支I相邻的区域，且与后一分支关系最为密切。位于保加利亚西北部一个地点的分支V和位于靠近大海的保加利亚东南部一个地点的分支IV则明显不同。在洞穴中发现了4个种群，但其中只有一个代表一个独特的分支。考虑到在保加利亚观察到的薄壳螺种群间分化模式，我们可以推测，分支I、II和III之间的隔离可能是由更新世的冰川作用造成的。上述三个分支与分支IV之间的隔离时间与墨西拿盐度危机相符，分支V与其他四个分支之间的隔离时间很可能反映了罗多彼山脉被达契亚盆地海水与巴尔干山脉西部隔离的情况。
