Molecular evidence for the subspecific differentiation of blue sheep (Pseudois nayaur) and polyphyletic origin of dwarf blue sheep (Pseudois schaeferi)

Blue sheep (Pseudois nayaur), a Central Asian ungulate with restricted geographic distribution, exhibits unclear variation in morphology and phylogeographic structure. The composition of species and subspecies in the genus Pseudois is controversial, particularly with respect to the taxonomic designation of geographically restricted populations. Here, 26 specimens including 5 dwarf blue sheep (Pseudois schaeferi), which were collected from a broad geographic region in China, were analyzed for 2 mitochondrial DNA fragments (cytochrome b and control region sequences). In a pattern consistent with geographically defined subspecies, we found three deeply divergent mitochondrial lineages restricted to different geographic regions. The currently designated two subspecies of blue sheep, Pseudois nayaur nayaur and Pseudois nayaur szechuanensis, were recognized in the phylogenetic trees. In addition, the Helan Mountain population showed distinct genetic characteristics from other geographic populations, and thus should be classified as a new subspecies. In contrast, dwarf blue sheep clustered closely with some blue sheep from Sichuan Province in the phylogenetic trees. Therefore, dwarf blue sheep appear to be a subset of Pseudois nayaur szechuanensis. After considering both population genetic information and molecular clock analysis, we obtained some relevant molecular phylogeographic information concerning the historical biogeography of blue sheep. These results also indicate that western Sichuan was a potential refugium for blue sheep during the Quaternary period.     

从细胞色素b基因全序列差异分析岩羊和矮岩羊的系统进化关系

矮岩羊的分类地位从它被发现后就一直存在着争议。本文测定了分别来自四川和青海的岩羊(Pseudois nayaur)和矮岩羊(Pseudois schaeferi)共7个个体的Cyt b基因全序列(1140bp)，结合山羊(Capra hircus)、北山羊(Capra ibex)、绵羊(Ovis aries)和盘羊(Ovis ammon)同源DNA序列进行比较，分析了碱基组成和变异情况以及核苷酸序列差异。用简约法和距离距阵法构建了分子系统树，得到了相同的拓扑结构。结果显示：岩羊和矮岩羊互为单系群，有着较山羊、北山羊、绵羊和盘羊间更近的亲缘关系，它们之间的序列差异(Cyt b＝3．2％)低于牛科不同种间的序列差异水平(8．3％-12．1％)，明显高于种内个体的序列差异，而处于牛科亚种的序列差异范围内。因此，推测矮岩羊与岩羊之间的差异可能已经达到了亚种的水平。它们的分歧时间为l-3百万年[动物学报49(2)：198—204，2003]。     

Genetic distinctiveness of endangered dwarf blue sheep (Pseudois nayaur schaeferi): evidence from mitochondrial control region and Y-linked ZFY intron sequences

To elucidate the controversial systematic relationship of blue sheep (Pseudois nayaur) and endangered dwarf blue sheep, we sequenced part of the mtDNA control region and Y-linked ZFY intron, and carried out phylogenetic analyses. Mitochondrial results revealed that the dwarf blue sheep is a strongly supported monophyletic group, with an average of 12.21% sequence divergence from the blue sheep. This is the first genetic evidence for the distinctness of the dwarf blue sheep. ZFY intron results showed an average of 0.51% sequence divergence, and one shared haplotype between the dwarf blue sheep and blue sheep. By analyzing an expanded data set that incorporated ZFY intron sequences of two additional Ovis (sheep) species-O. nivicola and O. ammon--we demonstrated that ZFY intron provides good resolution at the species and genus levels. The ZFY intron sequence divergence between dwarf blue sheep and blue sheep was comparable to that within the two Ovis species. Moreover, we found intraspecific sequence variation in ZFY intron for all three species examined. We propose that dwarf blue sheep be designated as a subspecies of blue sheep, P. n. schaeferi.     

Mitogenomic analysis of the genus Pseudois: Evidence of adaptive evolution of morphological variation in the ATP synthase genes

The genus Pseudois includes two variable taxa, blue sheep (Pseudois nayaur) and dwarf blue sheep (Pseudois schaeferi), that exhibit notable geographic variation in morphology and ecological niche, suggesting the potential for significant adaptive differentiation between these two goats. Blue sheep are broadly distributed in the Tibetan Plateau and peripheral mountains through Central Asia, while dwarf blue sheep are only found in the gorges of the upper Yangtze River (Jinsha River) near Batang county, Sichuan province and adjacent mountains. Although they are all adapted to high altitude environments, endangered dwarf blue sheep show unique morphological variation and niche shifts compared to blue sheep. Mitochondria play important roles in oxygen usage and energy metabolism. The energetically demanding lifestyles of these high altitude species may have altered the selective regimes on mitochondrial genes encoding proteins related to cellular respiration. Here, we compared the sequences of 13 protein-coding genes in the mitochondrial genome of dwarf blue sheep with those of blue sheep to understand the genetic basis of morphological variation. Using neighbor-joining, maximum-likelihood and Bayesian approaches, we estimated rates of synonymous (d(S)) and nonsynonymous (d(N)) substitutions. Independent analyses showed that no ω ratio was larger than 1, suggesting that all mitochondrial 13 genes were under the purifying selection. Surprisingly, we found that the ω ratio (d(N)/d(S)) of the ATP synthase complex (ATP6 and ATP8) in blue sheep is sixteen times that of dwarf blue sheep (0.340 compared to 0.021). This result was confirmed by a separate analysis of ATP synthase genes from two additional P. schaeferi individuals and two P. nayaur individuals. We hypothesize that the large body size and diverse feeding styles are factors influencing the nonsynonymous substitutions in the ATP synthase complex of blue sheep.     

从线粒体细胞色素b基因探讨矮岩羊物种地位的有效性

用采自四川省的岩羊和矮岩羊共18个头骨或皮张标本，分析了线粒体Cyt6基因1140bp的全序列(其中一个样品只测到802bp的基因片段)。用NJ、MP、ML等系统发育分析法分别重建的系统发育树的拓扑结构完全一致，均不支持矮岩羊是单系群。结果提示：所研究的全部样品都属于同一个物种，即岩羊P．nayaur，不支持矮岩羊的物种地位。根据基于17个样品Cyt6基因全序列的系统发育树和遗传变异以及地理分布，这些岩羊样品聚为5支，根据地理区划和本文分析结果，四川的岩羊可分为摩天岭、川西、川西北、川西南和川北5个种群。基于17个样品Cyt6基因1137bp的编码区，共定义了岩羊的16种单元型，在5个种群间未发现共享的单元型。     

Molecular phylogeny and phylogeography of genus Pseudois (Bovidae,Cetartiodactyla): New insights into the contrasting phylogeographic structure

Blue sheep, Pseudois nayaur, is endemic to the Tibetan Plateau and the surrounding mountains, which are the highest‐elevation areas in the world. Classical morphological taxonomy suggests that there are two subspecies in genus Pseudois (Bovidae, Artiodactyla), namely Pseudois nayaur nayaur and Pseudois nayaur szechuanensis. However, the validity and geographic characteristics of these subspecies have never been carefully discussed and analyzed. This may be partially because previous studies have mainly focused on the vague taxonomic status of Pseudois schaeferi (dwarf blue sheep). Thus, there is an urgent need to investigate the evolutionary relationship and taxonomy system of this genus. This study enriches a previous dataset by providing a large number of new samples, based on a total of 225 samples covering almost the entire distribution of blue sheep. Molecular data from cytochrome b and the mitochondrial control region sequences were used to reconstruct the phylogeny of this species. The phylogenetic inferences show that vicariance plays an important role in diversification within this genus. In terms of molecular dating results and biogeographic analyses, the striking biogeographic pattern coincides significantly with major geophysical events. Although the results raise doubt about the present recognized distribution range of blue sheep, they have corroborated the validity of the identified subspecies in genus Pseudois. Meanwhile, these results demonstrate that the two geographically distinct populations, the Helan Mountains and Pamir Plateau populations, have been significantly differentiated from the identified subspecies, a finding that challenges the conventional taxonomy of blue sheep.     

基于线粒体Cyt b 和核基因ZFY 探讨羊族物种之间的系统发生关系

为了阐明羊族物种之间的系统发生关系并解决岩羊属中矮岩羊物种的有效性问题,本文测定了来自金沙江河谷地区栖息于林线以上岩羊和林线以下矮岩羊共226 份粪便DNA 样品的线粒体Cyt b 基因全序列(1 140 bp)和核基因ZFY 部分序列(612 bp),结合从GenBank 中检索到的羊族物种同源DNA 序列进行比较,利用最大简约法和最大似然法构建分子系统发育树,根据获得的拓扑结构初步探讨它们的系统进化关系。结果表明,绵羊属的绵羊与山羊属、塔尔羊属、岩羊属各物种亲缘关系最远,喜马拉雅塔尔羊和岩羊属、山羊属的亲缘关系最近。在进化树的岩羊属这一分支中,金沙江河谷地带岩羊和矮岩羊与内蒙古、青海、四川其它地理种群的岩羊聚为一支,同时分布在这一区域的部分岩羊和矮岩羊在Cyt b 基因和ZFY 基因单倍型上存在共享现象。历史上的气候事件可能造成金沙江河谷地带岩羊和矮岩羊种群之间相互迁移,偏雄性扩散促进了各地理种群之间的基因交流。因此不支持矮岩羊为独立的物种,建议将金沙江河谷地带的岩羊和矮岩羊都划分到岩羊四川亚种(Pseudois nayaur szechuanensis)。由于它们的形态和生态上存在一定的分化,建议将林线以下矮岩羊作为一个独立的管理单元进行保护与管理。     

New aspects of an old discussion - phylogenetic relationships of Ammotragus and Pseudois within the subfamily Caprinae based on comparison of the 12S rDNA sequences

A mitochondrial 12S rDNA fragment was amplified by PCR and directly sequenced from eight members of the Caprinae ( Ammotragus lervia, Capra aegagrus, Ovis ammon, O. musimon, O. nivicola, O. orientalis, O. vignei and Pseudois nayaur ). Multiple alignment of the sequences and genetic distance calculation with the'distance of Taijama and Nei and the algorithms of Saitou and Nei (neighbour-joining - NJ) showed that Pseudois is grouped together with Capra and Ammotragus . All members of the genus Oxis formed a second cluster. Phylogenetic analyses supported these results. NJ-analyses and maximum parsimony (MP) trees did not support the present phylogenetic classification. Bootstrap values of 95% (NJ) and 96% (MP) confirms the grouping of P. nayaur and C. aegagrus . Another clade, O. ammon and O. orientalis supported weakly by bootstrap values of 65% (MP) and 70% (NJ) and the clade O. musimonand O. vignei had bootstrap values of 50% (MP) and 60% (NJ). So the phylogenetic relationship within the genus Oxis is still unsafe. But the parsimony analyses lead to the conclusion that Ammotragus represents an old lineage that diverged from ancestral caprines together with true sheep a long time ago and that both true goats and blue sheep forms represent one evolutionary lineage.     

贺兰山同域分布岩羊和马鹿发情季节的生境选择差异

2007年和2008年9—12月,在宁夏贺兰山国家级自然保护区和内蒙古贺兰山国家级自然保护区利用痕迹检验法和直接观察法对同域分布的岩羊和马鹿发情季节生境选择进行研究。通过在选定的15条沟段里进行调查,分别测定了岩羊和马鹿的177个和154个样方的18种生态因子。结果表明,发情季节岩羊和马鹿在植被类型、地形特征、优势乔木、坡向、坡位、灌木密度、灌木高度、植被盖度、坡度、海拔高度、距水源距离、人为干扰距离、距裸岩距离和隐蔽级等生态因子选择上存在极显著差异(P0.01),乔木高度存在显著差异(P0.05),而其余生态因子无显著差异(P0.05),相对于马鹿选择的生境而言,岩羊发情季节更偏爱选择地势陡峭的山地疏林草原带,优势乔木以较高的灰榆为主,灌木密度低但高度较高,植被盖度较低,坡度较大的阳坡中上部,海拔较低,接近水源和裸岩,隐蔽程度低的生境。典则系数显示发情季节岩羊和马鹿的生境选择几乎完全分离,Wilk’sλ值也显示发情季节岩羊和马鹿的生境选择具有很高的差异性(Wilk’sλ=0.123,χ2=679.172,df=10,P0.001)。发情季节岩羊和马鹿的Fisher线性判别函数分别为:F岩羊=3.638×乔木高度+0.242×乔木距离+7.766×灌木高度+0.663×灌木距离+0.232×植被盖度+0.191×坡度+0.001×距水源距离+0.008×距裸岩距离+0.307×隐蔽级-31.078;F马鹿=4.850×乔木高度+0.321×乔木距离+12.024×灌木高度+0.929×灌木距离+0.192×植被盖度+0.482×坡度+0.002×距水源距离-0.001×人为干扰距离-0.003×距裸岩距离+0.511×隐蔽级-50.787。逐步判别分析表明在区分发情季节岩羊和马鹿生境方面有一系列生态因子发挥作用,依照贡献值的大小依次为坡度、人为干扰距离、隐蔽级、距裸岩距离、乔木高度、乔木距离、距水源距离、灌木高度、灌木距离和植被盖度,由这10个变量构成的方程对发情季节岩羊和马鹿生境的正确区分率达到99.7%。     

基于细胞色素b基因的中国岩羊不同地理种群遗传差异分析

为了揭示中国岩羊不同地理种群的遗传差异,探讨岩羊亚种分化的分子机制,采用中国岩羊不同地理种群的细胞色素b(Cyt b)基因的全序列,分析了碱基变异情况、遗传距离以及核苷酸序列差异。用最大似然法和贝叶斯法构建分子系统树并对获得的拓扑结构进行分析。结果发现,西藏亚种与四川亚种Cyt b基因平均序列差异为4.2%(±0.007),处于偶蹄目亚种的序列差异范围内,支持了目前对岩羊西藏亚种的分类地位。四川亚种内部各地理种群之间的遗传距离(0.033±0.0 111)与它们分别到西藏种群的遗传距离(0.042±0.007)差异不显著(t=1.824,P=0.084),说明四川亚种内部各地理种群间已经发生较显著的遗传分化。其中,四川、甘肃和青海种群亲缘关系较近,并与四川亚种内部的其它种群已产生了显著的遗传分化。因此认为四川亚种内部各地理种群的种下分化需要深入研究。     

贺兰山同域分布岩羊和马鹿的夏季食性

2008年78月贺兰山对同域分布的岩羊和马鹿粪便进行采集,利用粪便显微分析法对二者夏季食性进行了研究。从10个沟系中一共收集了297堆岩羊和305堆马鹿粪便,每堆中捡拾2粒粪粒,组成40个复合样本进行分析。结果表明,夏季在岩羊采食的19科35种(属)植物中,针茅(29.74%)、早熟禾(18.82%)、内蒙古邪蒿(10.30%)、灰榆(7.76%)、冰草(7.47%)是其主要食物,针茅是岩羊夏季的大宗食物;夏季在马鹿取食的11科18种(属)植物中,小红柳(36.26%)、山杨(23.10%)、灰榆(16.84%)等是其主要食物,小红柳为马鹿夏季的大宗食物。夏季岩羊采食植物中,乔木占8.67%,灌木占3.97%,禾本科草本占69.43%,非禾本科草本占17.94%;马鹿采食植物中,乔木占89.61%,灌木占5.38%,禾本科草本占1.03%,非禾本科草本占3.99%。从食物多样性和食物生态位宽度来看,岩羊的Shannon-Wiener指数高于马鹿,而马鹿的Pielou均匀性指数和食物生态位宽度指数高于岩羊,岩羊和马鹿共有9种食物重叠,生态位重叠指数为65.17%。     

从细胞色素b 基因全序列分析岩羊和山羊、绵羊的系统发生关系

本文测定了来自四川和青海岩羊的细胞色素b 基因全序列(1 140 bp) , 结合从GenBank 中检索获得的山羊、北山羊、绵羊和盘羊4 个近缘种细胞色素b 核苷酸同源区序列进行比较, 分析了碱基组成和变异情况以及核苷酸序列差异。分别采用简约法和距离矩阵法构建分子系统树, 得到了基本相同的拓扑结构, 从分子水平初步探讨了岩羊的系统起源问题。岩羊与山羊属的山羊、北山羊有着比绵羊属的绵羊、盘羊更近的亲缘关系。岩羊与山羊、北山羊的分歧时间大约在3～6 百万年, 而与盘羊、绵羊的分歧时间大约在6～8 百万年。     

贺兰山岩羊冬季对卧息地的选择

2003 年11～12月, 在贺兰山采用样带法对岩羊冬季卧息地的选择性进行了研究。共观察到94 个岩羊的卧息地, 结果表明岩羊对优势乔木的利用有选择性( x² = 17.01 , df = 5 , P < 0.05) , 偏好利用灰榆占优势的卧息地, 避免选择油松和青海云杉占优势的卧息地; 对坡向选择性利用( x²= 30.69, df =2, P < 0.05) , 偏好位于阳坡的卧息地, 避免利用阴坡; 对植被类型、坡位和风向的利用无选择性。对卧息地样方与在样带中随机设置的样方进行比较, 发现卧息地具有乔木密度低、食物丰富度低、隐蔽程度高、接近水源、接近裸岩、风速低和雪覆盖浅等特征。贺兰山的岩羊经常选择岩洞作为卧息地, 占总卧息地的62.77 %。对59 个岩洞和35 个非岩洞卧息地进行比较, 表明岩洞卧息地的坡度大、隐蔽程度高、风速低、保温性好、食物丰富度低和无雪覆盖。岩羊通常选择较宽的、深度和高度适中的岩洞作为卧息地。对各种生境因子的主成分分析表明前7 个特征值的累积贡献率已经达到了80.09%, 可以较好地反映岩羊卧息地的生境特征, 第1 主成分中隐蔽级、风向、风速、距裸岩距离和雪深具有重要作用, 其余6 个主成分中优势乔木、坡向、坡位和坡度也很重要。     

Fatal Sarcoptes scabiei infection of blue sheep (Pseudois nayaur) in Pakistan

Sarcoptes scabiei was detected for the first time in skin scrapings, hair pluckings, and histologic sections from a blue sheep (Pseudois nayaur) from the Shimshali Pamir in the Karakorum range of the western Himalaya in Pakistan (36 degrees 28'N, 75 degrees 36'E). Local reports suggest many hundred animals have been affected by a severe skin disease over a 10-yr period, but the shy nature of this species and the extreme climate that they inhabit meant only a single affected animal was available for detailed evaluation. The severe skin lesions were confined to the forelegs and brisket, and many Sarcoptes scabiei mites were present in all the samples examined. Histologic preparations of the skin showed hyperkeratotic and parakeratotic hyperkeratosis of the epidermis with a severe exudative dermatosis with many polymorphonuclear neutrophils and gram-positive cocci, yet no eosinophils. These findings might suggest the lack of an appropriate immune response to the parasite or other coping strategies because there has been no abatement of the clinical signs in affected animals over several years. Treatment options are limited due to the behavior of the species and its habitat. The blue sheep is a primary source of prey for the endangered snow leopard (Panthera uncia) and continued depletion could have serious consequences for the survival of the latter.     

Feeding habitats of blue sheep (Pseudois nayaur) during winter and spring in Helan Mountains, China

The feeding habitat selection of blue sheep (Pseudois nayaur)was studied by direct observation method in the Helan Mountains,China during winter (from November to December)and spring (from April to June)from 2003 to 2004.We established 25 line transects to collect information on feeding habitats used by blue sheep.Blue sheep in the study area preferred mountain savanna forests,a habitat dominated by Ulmus glaucescens,with medium tree density (＜4 individuals/400 m2),moderate tree height (4-6 m),higher shrub density (＞5 individuals/100 m2),higher shrub (＞1.3 m),higher food abundance (＞50 g),moderate distance to human disturbance (＜500 m),and mild distance to bare rock (＜2 m).Such habitats characterized by 12 ecological factors were preferred as feeding areas by blue sheep during winter.Similar to habitat selection by the species during winter,blue sheep also showed a preference for mountain savanna with tree dominated by Ulmus glaucescens and medium tree density (＜4 individuals/400 m2)during spring.Nevertheless,blue sheep preferred medium tree height (＜6 m),moderate tree density (5-10 individuals/100 m2),medium shrub height (1.3-1.7 m),higher food abundance (＞100 g),moderate altitude (＜2 000 m),moderate distance to water resource (＜500 m),and medium hiding cover (50%-75%)during spring.Selection of the feeding habitats by sheep showed a significant difference in vegetation type,landform feature,dominant tree,tree height,shrub density,distance to the nearest shrub,food abundance,slope direction,slope degree,distance to water resource,and hiding cover between winter and spring.Results of principal components analysis indicated that the first principal component accounted for 24.493%of the total variance among feeding habitat variance during winter,with higher loadings for vegetation type,dominant tree,tree height,distance to the nearest tree,shrub density,shrub height,altitude,distance to water resource,and distance to human disturbance.In spring,the first principal components explained 28.777%of the variance,with higher loadings for vegetation type,distance to the nearest tree,shrub height,distance to the nearest shrub,food abundance,altitude,and distance to human disturbance.     

贺兰山岩羊冬春季取食生境的比较

2003年11～12月和2004年4～6月,在贺兰山设定了25条固定样线,采用直接观察法对岩羊冬春季的取食生境选择进行了研究。结果表明,岩羊冬季对12种取食生境生态因子有选择性,偏爱选择位于山地疏林草原带,优势乔木为灰榆,乔木密度〈4株、高度4～6m,灌木密度〉5株、高度〉1．3m,食物质量〉50g,人为干扰距离〈500m,距裸岩距离〈2m的地方取食。而春季对11种取食生境生态因子有选择性,偏爱选择山地疏林草原带,优势乔木为灰榆,乔木密度〈4株、高度〈6m,灌木密度5～10株、高度1．3～1．7m,食物质量〉100g,海拔高度〈2000m,距水源距离〈500m,隐蔽级50％～75％的地点。冬春季岩羊对植被类型、地形特征、优势乔木、乔木密度、乔木高度、灌木密度、灌木距离、食物丰富度、坡向、坡度、距水源距离、人为干扰距离和隐蔽级的选择存在显著差异。主成分分析表明,冬季第1主成分的贡献率达24．493％,其中绝对值较大的权系数出现在植被类型、优势乔木、乔木高度、乔木距离、灌木密度、灌木高度、海拔高度、距水源距离和人为干扰距离等生态因子：春季第1主成分的贡献率达28．777％,其中绝对值较大的权系数出现在植被类型、乔木距离、灌木高度、灌木距离、食物丰富度、海拔高度和人为干扰距离等生态因子。随着北方地区冬春季食物数量和质量的剧烈变化,贺兰山岩羊对取食生境的利用对策也将发生一定程度的改变,与其他分布区的岩羊相比,贺兰山独特的地理位置和特殊生境使其在取食生境选择上存在很大差异。     

贺兰山岩羊不同年龄和性别昼间时间分配的季节差异

2003年11月-2004年10月在宁夏贺兰山国家级自然保护区苏峪口国家森林公园,在每个月的11-20日采用瞬时扫描取样法,利用SJ-1型电子事件记录器观察记录岩羊的取食、休息、运动、站立和其他行为.冬季每天的观察时间为800-1700,春、秋季为700-1800,夏季为600-2000.采用非参数估计中的2个相关样本的Wilcoxon检验、2个独立样本的Mann-Whitney U检验和K个独立样本的Kruskal-Wallis H检验对岩羊不同性别、年龄以及季节变化进行了比较.结果表明,①岩羊行为的年时间分配,取食行为最高[(63.49±7.82)%];其次是休息[(19.32±6.79)%];运动和站立较低[分别占(8.03±0.91)%和(6.66±0.57)%];其他行为所占比例最低[(2.67±0.34)%];一年中7月取食行为最低,休息最高;而在2月取食最高,运动、站立和其他行为变化不大.②春夏秋3个季节的昼间取食行为均呈现2个(清晨和黄昏)明显高峰;冬季1天中取食均达到60%以上,其他行为明显高于另外3个季节.③不同年龄年取食行为成体和亚成体>幼体;休息成体和亚成体<幼体;运动和站立幼体<成体和亚成体;亚成体的运动高于成体,而站立低于成体.④不同性别月取食行为雄性在2月最高,其余月份均低于70%;而雌性虽然也是2月最高,但从11月-次年2月均超过70%;休息行为雌雄接近;运动行为雄性高于雌性.贺兰山岩羊的昼间时间分配与许多温带有蹄类动物一样,食物数量和质量的变化以及岩羊自身不同的生长阶段和生理时期是决定其昼间时间分配的主要因素.     

青海省玉树、果洛州岩羊的种群结构及生命表初探

本文根据野外发现的4470只岩羊,就其栖息地、种群大小和年龄组成进行分析。在已分辨性别的2168只岩羊中,成年雌雄性比为1：0.5。此外,我们还利用54架自然死亡的雄性岩羊头骨,初步探讨年龄分布、存活曲线和生命表。     

Chromosome evolution of the blue sheep/bharal (Pseudois nayaur)

A male dwarf blue sheep was collected 60 km south of Batang east to the Jinsha Jiang river, and a male Subei blue sheep (Greater form) was collected from Gansu, China, representing two geographically separated blue sheep forms. Chromosome preparations were prepared from fibroblast cultures. The dwarf blue sheep has a 2n = 54 and a karyotype with three biarmed formations that resulted from acrocentric chromosome fusions (based on the 2n = 60 Capra autosomal equivalents) 14p/5q, 27p/1q, and 29p/2q from the largest to the smallest biarmed chromosome, respectively. The 14p/5q fusion is metacentric, whereas the 27p/1q and 29p/2q are submetacentric. The Subei blue sheep had a 2n = 56, with only the 27p/1q and 29p/2q biarmed chromosome fusions. The remainder of the chromosomes in both blue sheep are acrocentric; the X is the largest acrocentric chromosome and the Y is a minute biarmed chromosome. Our observation is one evidence showing that chromosome evolution within blue sheep has followed a series of centric fusions resulting in the reduction of chromosome number, which is typical of all extant genera within the tribe Caprini.     

发情交配期贺兰山岩羊的集群特征

2003 年和2004 年的11 ～12 月,采用样线法和全事件取样法研究了贺兰山岩羊的集群特征。共观察到岩羊715 群,共计2 473只。发情前期平均群大小3.5±2.8 只(n = 241),发情期平均群大小3.4±3.2 只(n =297)。发情前期与发情期雄性群、雌性群、雌雄群、混合群及母子群大小间均无显著差异。发情前期到发情期群类型组成差异极显著,发情期雌雄群、混合群和独羊比例显著上升;雄性群、雌性群和母子群比例显著下降。发情前期到发情期,雄性岩羊在雄性群、雌雄群、混合群和独羊中的分布差异极显著,成年雌性岩羊在雌性群、雌雄群、混合群、母子群和独羊中的分布差异极显著。发情期4 个年龄等级雄性在雄性群、雌雄群、混合群和独羊中分布差异极显著,4 个年龄等级雄性岩羊都倾向分布于混合群。