Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands,but the causative mechanism of grazing on demographic parameters,particularly the age structure and sex ratio,i...Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands,but the causative mechanism of grazing on demographic parameters,particularly the age structure and sex ratio,is rarely investigated.In this study,we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt’s vole(Lasiopodomys brandtii)in Inner Mongolia of China by using large manipulative experimental enclosures during 2010-2013.Our results indicated that sheep grazing significantly decreased the proportion of the spring-born cohort,but increased the proportion of the summer-born cohort.Grazing increased the proportion of males in both spring and summer cohorts.In addition,we found a negative relation between population density and the proportion of the overwinter cohort.Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing.展开更多
Group size and composition of blue sheep(Pseudois nayaur)were studied in the Helan Mountains, Ningxia Autonomous Region from November to December 2003.We scanned mountain slopes with binoculars and observed with 20-60...Group size and composition of blue sheep(Pseudois nayaur)were studied in the Helan Mountains, Ningxia Autonomous Region from November to December 2003.We scanned mountain slopes with binoculars and observed with 20-60× spotting-scope. A total of 310 herds of blue sheep and 1 336 individuals were observed during the study period. Blue sheep were frequently seen in small herds of 2 to 8 individuals, which represent 94.8% of total herds observed. Herds consisting of 9 individuals or more represented 5.2%. The largest herd we observed numbered 51 individuals. Mean group size was 4.2 individuals. Blue sheep herds can be divided into three types: male herds (composed solely of males), female herds (consisting of females with or without juveniles of both sexes), and mixed herds (including adult males, females, and subadults).Among the 310 herds, female herds were counted 150 times(48.4%), mixed herds 154 times(49.7%), and male herds 6 times(1.9%). Of 1 336 blue sheep classified by sex and age, adults, subadults and juveniles composed 64.1%,20.8%, and 15.1% respectively. The female:male ratio of adults was 1∶0.73. The ratio of adult females to juveniles was 1∶0.56, which is higher than the ratio recorded in spring (1∶0.43) or summer (1∶0.44).The results showed that the Helan Mountains State Nature Reserve has succeed in protecting blue sheep.展开更多
Background： Genetic factors are the main cause of early miscarriage. This study aimed to investigate aneuploidy in spontaneous abortion by fluorescence in situ hybridization （FISH） using probes for 13, 16, 18, 21, ...Background： Genetic factors are the main cause of early miscarriage. This study aimed to investigate aneuploidy in spontaneous abortion by fluorescence in situ hybridization （FISH） using probes for 13, 16, 18, 21, 22, X and Y chromosomes. Methods： A total of 840 chorionic samples from spontaneous abortion were collected and examined by FISH. We analyzed the incidence and type of abnormal cases and sex ratio in the samples. We also analyzed the relationship between the rate of aneuploidy and parental age, the rate of aneuploidy between recurrent abortion and sporadic abortion, the difference in incidence of aneuploidy between samples from previous artificial abortion and those from no previous induced abortion. Results： A total of 832 samples were finally analyzed. 368 （44.23%） were abnormal, in which 84.24% （310/368） were aneuploidies and 15.76% （58/368） were polyploidies. The first was trisomyl6 （121/310）, followed by trisomy 22, and X monosomy. There was no significant difference in the rate ofaneuploidy in the advanced maternal age group （≥35 years old） and young maternal age group （〈35 years old）. However, the rate oftrisomy 22 and the total rate of trisomies 21, 13, and 18 （the number oftrisomy 21 plus trisomy 13 and trisomy 18 together） showed significantly different in two groups. We found no skewed sex ratio. There was no significant difference in the rate of aneuploidy between recurrent miscarriage and sporadic abortion or between the samples fi＇om previous artificial abortion and those from no previous artificial abortion. Conclusions： Aneuploidy is a principal factor of miscarriage and total parental age is a risk factor. There is no skewed sex ratio in spontaneous abortion. There is also no difference in the rate of aneuploidy between recurrent abortion and sporadic abortion or between previous artificial abortion and no previous induced abortion.展开更多
基金supported by the State Basic Research Program of the Ministry of Science and Technology(2007CB109100)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB11050000).
文摘Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands,but the causative mechanism of grazing on demographic parameters,particularly the age structure and sex ratio,is rarely investigated.In this study,we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt’s vole(Lasiopodomys brandtii)in Inner Mongolia of China by using large manipulative experimental enclosures during 2010-2013.Our results indicated that sheep grazing significantly decreased the proportion of the spring-born cohort,but increased the proportion of the summer-born cohort.Grazing increased the proportion of males in both spring and summer cohorts.In addition,we found a negative relation between population density and the proportion of the overwinter cohort.Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing.
文摘Group size and composition of blue sheep(Pseudois nayaur)were studied in the Helan Mountains, Ningxia Autonomous Region from November to December 2003.We scanned mountain slopes with binoculars and observed with 20-60× spotting-scope. A total of 310 herds of blue sheep and 1 336 individuals were observed during the study period. Blue sheep were frequently seen in small herds of 2 to 8 individuals, which represent 94.8% of total herds observed. Herds consisting of 9 individuals or more represented 5.2%. The largest herd we observed numbered 51 individuals. Mean group size was 4.2 individuals. Blue sheep herds can be divided into three types: male herds (composed solely of males), female herds (consisting of females with or without juveniles of both sexes), and mixed herds (including adult males, females, and subadults).Among the 310 herds, female herds were counted 150 times(48.4%), mixed herds 154 times(49.7%), and male herds 6 times(1.9%). Of 1 336 blue sheep classified by sex and age, adults, subadults and juveniles composed 64.1%,20.8%, and 15.1% respectively. The female:male ratio of adults was 1∶0.73. The ratio of adult females to juveniles was 1∶0.56, which is higher than the ratio recorded in spring (1∶0.43) or summer (1∶0.44).The results showed that the Helan Mountains State Nature Reserve has succeed in protecting blue sheep.
文摘Background： Genetic factors are the main cause of early miscarriage. This study aimed to investigate aneuploidy in spontaneous abortion by fluorescence in situ hybridization （FISH） using probes for 13, 16, 18, 21, 22, X and Y chromosomes. Methods： A total of 840 chorionic samples from spontaneous abortion were collected and examined by FISH. We analyzed the incidence and type of abnormal cases and sex ratio in the samples. We also analyzed the relationship between the rate of aneuploidy and parental age, the rate of aneuploidy between recurrent abortion and sporadic abortion, the difference in incidence of aneuploidy between samples from previous artificial abortion and those from no previous induced abortion. Results： A total of 832 samples were finally analyzed. 368 （44.23%） were abnormal, in which 84.24% （310/368） were aneuploidies and 15.76% （58/368） were polyploidies. The first was trisomyl6 （121/310）, followed by trisomy 22, and X monosomy. There was no significant difference in the rate ofaneuploidy in the advanced maternal age group （≥35 years old） and young maternal age group （〈35 years old）. However, the rate oftrisomy 22 and the total rate of trisomies 21, 13, and 18 （the number oftrisomy 21 plus trisomy 13 and trisomy 18 together） showed significantly different in two groups. We found no skewed sex ratio. There was no significant difference in the rate of aneuploidy between recurrent miscarriage and sporadic abortion or between the samples fi＇om previous artificial abortion and those from no previous artificial abortion. Conclusions： Aneuploidy is a principal factor of miscarriage and total parental age is a risk factor. There is no skewed sex ratio in spontaneous abortion. There is also no difference in the rate of aneuploidy between recurrent abortion and sporadic abortion or between previous artificial abortion and no previous induced abortion.
