A Study On The Siberian Weasel (Mustela Sibirica Sibirca) Fur Heat Transfer Property And Impacted Factors

Mammals have a perfect thermoregulation mechanism, they maintain body temperature by physiologically adjusting the balance of heat production and dissipation. The pelage is a critical surface between the body and environment, which plays an important role in thermal balance and provide morphological strategies for adapting to circumstances variety. Siberian weasel have (Mustela sibirica) a strong adaptability, widely distribute in different geographical environment, and even the same geographical population can adapt to various habitat types. The pelage morphological structure of weasel is complicated and high diversity,the characteristics of pelage of weasels from different habitat type show obvious differentiation, which provide a ideal object for researching adaptive evolution of animal by the morphological structure and characteristics of pelage. Thermal property of fur is an inherent attribute in heat transfer process, so different morphological characteristics certainly will show different thermal property. Therefore, to find the relation between pelage characteristic and fur thermal property.The thermal property of fur influenced by different ecological factors were measured, thermal property of fur of different ecotype were compared. These provide evidence for the further research in influence of fur on thermoregulation.In this research, summer fur and winter hair of forest ecotype, hill ecotype and plain ecotype of Siberian weasel (M.s.sibirca) distributed between Zhangguangcai Moutains and Songnen Plains were chosen. The hair colour, hair length, hair diameter, hair density, and medulla index of hairs of there ecotypes were studied. The thermal flux and overall heat transfer coefficient of fur from three ecotypes were measured under different air temperature, wind speed, relative air humidity by testing platform based on heat transfer property of pelage builted by ourselves. All data were analyzed by SPSS, and the results are as following:1. For forest ecotype, the hair color of summer fur is chocolate and that of winter fur is dark orange; for plain ecotype, color of winter fur is peru. The vertical Anatomical surface of pelage showed obvious color layering, which could be related to absorb the radiant heat from the sun and improve the heat-insulating property of the fur.2. There are significant differences in skin thickness and hair density among the three ecotypes, of which the forest ecotype is the highest, plain ecotype is the lowest, hill ecotype is medium.3. For forest ecotype, skin thickness of summer fur is significantly higher than that of winter fur morphological characteristic such as hair density, hair length, medulla width and medulla index of gurd hair 4. The dimorphism is significant for fur morphological characteristic. For all ecotypes, the skin thickness, hair density, hair length, hair diameter, and medulla index all showed significant difference between male and female.5. Among three ecotypes, the fur overall heat transfer coefficient and thermal flux of forest ecotype is the lowest, and that of plain ecotypes is the highest. Regression analysis showed that hair density,hair length and medulla index of guard hair is the main factors that influences the heat transfer property.6. Ambient air temperature has a significant impact on fur thermal flux. The thermal flux of plain ecotype is the highest, that of hill ecotype is medium, that of forest ecotype is the lowest, and the difference between each other is highly significant. The air temperature has highly significant impact on fur thermal flux between summer and winter, and between male and female. Air temperature showed no significant impact on fur overall heat transfer coefficient.7. The fur thermal flux increased significantly with the increase of wind speed. The heat transferred from hair to environment increased by1.72times when wind speed increased from0m·s to5m·s. Under the impact of gradient wind speed, fur thermal flux of plain ecotype is the highest, that of hill ecotype is medium, that of forest is the lowest, and fur thermal flux between each ecotype is significantly different. The impact of wind speed on fur is significant between seasons and between genders.8. Wind direction has no significant impact on fur thermal flux in male weasel, but significant in female. Wind direction has no significant impact on overall heat transfer coefficient in both sexes.9. Air relative humidity has no significant impact on fur thermal flux and overall heat transfer coefficient, of which increased significantly when the fur was wetting. The hair significantly promoted the evaporation of water.Base on the analysis above, we can conclude that:1. Among three ecotypes, the heat-insulating property of fur of forest ecotype is the highest, and the impact of ecological factors on heat transfer property is the minimum; followed by hill ecotype and plain ecotype.2. The thermal property of fur from three ecotypes showed distribution of vertical zonality that forest ecosystem transit to plain ecosystem gradually.3. The fur thermodynamic property of weasel explains the biological significance of different morphological characteristics, reflects the response of fur characteristics to different ecological factors changes, and incarnates the adaptability that the morphology and function of animal fur highly unify.