为了进一步探讨大麝鼩(Crocidura lasiura)的亚种分化问题,在中国东北地区采集大麝鼩标本13号,结合已报道的大麝鼩形态学数据和Cyt b基因序列一并进行分析。形态学结果显示:在绝大多数个体中,分布于中国东北—俄罗斯远东的大麝鼩体型大于分布于韩国的个体(体长:> 82 mm vs.<82 mm,尾长:> 39 mm vs.<39 mm,颅基长:> 20 mm vs.<20 mm);中国东北—俄罗斯远东种群体背毛色更黑,韩国种群体背毛色更灰;中国东部种群尾较长,绝大多数超过体长之半;而分布于中国东北—俄罗斯远东、韩国的大麝鼩种群尾长绝大多数不及体长之半。基于Cyt b基因的遗传距离、系统发育关系和中介网络分析,都显示大麝鼩样本可分为3个地理谱系:中国东北—俄罗斯远东谱系、韩国谱系、中国东部谱系。研究结果支持大麝鼩分为3个亚种:东北亚种(C. l. lasiura)分布于中国东北和俄罗斯远东,韩国亚种(C. l. thomasi)分布于韩国,华东亚种(C. l. campus-lincolnensis)分布于中国东部。
Extant giant pandas are divided into Sichuan and Qinling subspecies.The giant panda has many speciesspecific characteristics,including comparatively small organs for body size,small genitalia of male individuals,and low reproduction.Here,we report the most contiguous,high-quality chromosomelevel genomes of two extant giant panda subspecies to date,with the first genome assembly of the Qinling subspecies.Compared with the previously assembled giant panda genomes based on short reads,our two assembled genomes increased contiguity over 200-fold at the contig level.Additional sequencing of 25 individuals dated the divergence of the Sichuan and Qinling subspecies into two distinct clusters from 10,000 to 12,000 years ago.Comparative genomic analyses identified the loss of regulatory elements in the dachshund family transcription factor 2(DACH2)gene and specific changes in the synaptotagmin 6(SYT6)gene,which may be responsible for the reduced fertility of the giant panda.Positive selection analysis between the two subspecies indicated that the reproduction-associated IQ motif containing D(IQCD)gene may at least partly explain the different reproduction rates of the two subspecies.Furthermore,several genes in the Hippo pathway exhibited signs of rapid evolution with giant panda-specific variants and divergent regulatory elements,which may contribute to the reduced inner organ sizes of the giant panda.
