A Preliminary Analysis On The Population Viability For Small-tailed Han Sheep By Non-genetic Information And Microsatellite DNA

The small-tailed han sheep is one of the fine native breeds in Shandong, it is outstanding local varieties of resources in China. The small-tailed han sheep have many fine characteristics, such as big body-type, fast growth, high reproductive rate, strong adaptability, etc. The non-genetic information will get by our investigation and calculation, and the genetic variation of 5 microsatellite DNA in 100 small-tailed han sheep will get through laboratory work. Then in order to explore population dynamics and influencing factors in next 100 years, combining to the varieties of non-genetic information and microsatellite polymorphism information, this study simulated the population viability of small-tailed han sheep with VORTEX 9.72. The results are as follows:1. In ideal conditions (such as without catastrophes and inbreeding) the population of small-tailed han sheep have higher growth in next 30 years, and the maintaining stability gets nearly 8 million in later 70 years. However, the population of heterozygosity declined slightly, and inbreeding depression slightly increased.2. In simulation circumstances (with catastrophes and inbreeding), the probability of extinction of small-tailed han sheep population is 0, and gene heterozygosity dropped by 0.5% comparing to that in ideal conditions. The population growth trend would be inhibited. The growth rates of the small-tailed han sheep population with natural catastrophes and with inbreeding are 63.1% and 99.7% respectively. Thus compared to inbreeding catastrophe have a higher impact on the small-tailed han sheep population. The small-tailed han sheep dropped 9.5% with catastrophes and inbreeding. In these cases, catastrophes and inbreeding have synergism to the small-tailed han sheep population.3. Sensitivity analysis results: epidemic disease and excessive slaught are the most important factors that influenced the small-tailed han sheep population dynamics. When the epidemic disease is very serious or serious or more serious, the population growth rate was 7.76%, 11.3% and 12.3% respectively; when the frequency of excessive slaughter doubled or halved, the sensitivity index were 0.077 and -0.234, respectively. The second point was the proportion of breeding ewes and lambs died. When the proportion of breeding ewes increased and lamb death rates decreased, the sensitivity index increased. While the impact of inbreeding depression and environmental fluctuations on population dynamics is small, but they could slow down the growth of the small-tailed han sheep population. Therefore, suitable increase of the proportion of breeding ewes and reductionof excessive slaughter can maintain the population of small-tailed han sheep stability and development of Shandong in various degrees.Above all, in next 100 years, the survival probability of small-tailed han sheep population is 100%. According to the results of the simulation, combining non-genetic informations and microsatellite polymorphism information can get more accurate measures in the protection of the small-taied han sheep.