两极分布 meaning in English

bipolar distribution

The cladogram shows that the opatrini of 14genera in china is not a monophyly , mesomorphus is a monophyly , and another monophyly is composed of others 13 genera . and according to the faunal analysis , we can conclude that opatrini in china is mainly distributed in palaearetic region , hi which the number of genera makes up 59 . 1 % ( 13 genera ) of the total , including 50 % ( 11 genera ) in middle asian subreahn , which combined with distribution of this tribe in the world , so it is proposed that the middle asian subrealm can be viewed as the core of distribution . most of genera distributed in limited area , only gonocephalum distributed in extensive area
根据已知种类，对世界和中国范围内土甲种类的区系组成和地理分布特征进行了首次分析，结论为：世界土甲族以西半球最丰富，古北区最多，其次为非洲区；我国土甲的主体成分是古北区种类，共有12属( 54 . 5 ) ，其中11属( 50 )分布于中亚地区，据此认为我国土甲在区系组成上以中亚成分为主；我国除土甲属gonocephalum广泛分布外，绝大多数属均为狭域分布；蒙新区和华南区的特有属较多，说明中国土甲族具有中亚起源和热带起源两种可能；物种数量分布以蒙新区最多，华南区其次，呈现两极分布格局。