Genetic and population structure of the least shrews Sorex minutissimus in Eurasia

2005年，从保留标本和自己捕获的标本中获得的标本如下：芬兰15个，挪威1个，堪察加1个，马加丹地区（俄罗斯）4个，滨海地区5个，哈巴罗夫斯克地区1个，库页岛2个，国尻岛1个，北海道Satobetsu 11个，Nemuro 5个，滨中町2个，Kenbokki岛5个。2006年，我在北海道白中町捕获鼩鼱12只，在sarufutsuura捕获鼩鼱1只，在蒙古北部捕获鼩鼱1只。通过采样，获得了对小绥螨生境的新认识。在其他鼩鼱很少使用的沙丘和多岩石的地方捕获了小鼩鼱。因此，我们认为s.m untissimus可能是被其他竞争优势物种推向了不利的生活习性。根据线粒体细胞色素b和控制区的序列进行系统发育研究。欧亚大陆东部和西部的人口在遗传上有很大的差别。此外，在欧亚东部人群中，观察到与地理位置相对应的遗传多样化。北海道人群遗传变异较小，而芬兰人群遗传变异较大，但取样面积基本相同。北海道种群遗传变异低可能是近期种群瓶颈事件的结果。芬兰的高度变化可能与末次冰期大陆冰盖的发展有关。在最后一个冰期，北欧被冰原覆盖。因此，芬兰的S. minutissimus可能撤退到几个避难所，并在变暖后从几个地区返回芬兰，导致各种单倍型的遗传混合。

In 2005, samples obtained from reserved specimens and those captured by myself is as follows : 15 specimens from Finland, 1 from Norway, 1 from Kamchatka, 4 from Magadan region (Russia), 5 from Primorski, 1 from Khabarovsk region, 2 from Sakhalin, 1 from Kunashiri Island, 11 from Satobetsu (Hokkaido), 5 from Nemuro, 2 from Hamanaka-cho, and 5 from Kenbokki Island. In 2006, 12 shrews from Shiranuka-cho (Hokkaido), 1 from Sarufutsu-mura, and 1 from northern Mongolia were captured by myself. According to the sampling, new knowledge about habitat of Sorex minutissimus was obtained. Sorex minutissimus was captured in sand dune and rocky place, which are rarely used by other shrew species. Thus, it is suggested that S. minutissimus might be pushed to unpreferable habits by other competitively dominant species.Phylogenetic investigation was conducted based on sequences of the mitochondrial cytochrome b and the control region. Populations genetically rather differentiated between the eastern and western parts of Eurasia. In addition, within the eastern Eurasian population, genetic diversification was observed, corresponding to geographic position. There was little genetic variation within Hokkaido population whereas there was much genetic variation within Finnish population although sampling area were almost the same between the two. The low genetic variation in Hokkaido population may be the result of a recent bottleneck event of population. The high variation in Finland may have been related to continental ice sheet development in the last glacial age. In the last glacial age, northern Europe was covered with ice sheet. Thus, Finnish S. minutissimus might have retreated to several refugia and returned to the Finland from several regions after warming, causing a genetic mixture of various haplotypes.