Study On The Relationship Between Anatomical Characteristics And Climatic Factors Of The Endemic Species Of The Rana Kukunoris On The Qinghai-Tibet Plateau

Rana kukunoris,an endemic species of the Qinghai-Tibet Plateau,originally belonged to R.chensinensis,and now belongs to the genus Ranidae of the family Ranidae of the order Anura of Amphibia.It mainly distributed in the east of the Qinghai-Tibet Plateau at an altitude of 2000 4400 m.In order to reveal the biological mechanism of how the R.kukunoris adapts to the harsh environment of the Qinghai-Tibet Plateau,this study will examine whether there are geographical variations in the three key anatomical characteristics of the alpine frogs.If exists,further identifying the key environmental factors which influence the geographical variations in the anatomical characteristics of their populations.The alpine frogs were collected from adult breeding individuals at seven different altitudes in the eastern Qinghai-Tibet Plateau from March to April 2012,totaling 331(183?,148?).In the project,three anatomical characteristic data of the R.kukunoris were obtained by field investigation and dissecting in laboratory.Then we measured and calculated the characteristics of the R.kukunoris and obtained the following three research results:1.Geographical variation in the length of the digestive tract: by analyzing the data of 7populations,the total length and weight of the digestive tract and the length of the intestinal tract possessed significant inter-population difference,and the weight of the digestive tract possessed gender difference.The intestinal length of the male frogs is consistent with the prediction theory of digestive tract length,but contrary to that of the females.The reason may be that different gender use different micro-habitats and possess different predation ability,which leads to different types and quantities of food caught.When the temperature is low,the male frogs are smaller and more flexible than the females,and its predation ability may be stronger than that of the females.At this time,the activity of digestive enzymes is low,and it takes longer intestine to digest more food.However,when the temperature is high,the variety and quantity of food increase,and the female frogs need longer intestines to digest these foods.At this time,for the male frog,because of its small size,the amount of food needed is limited,and the increased enzyme activity makes up for the shorter intestine.It can be seen that the variation of the intestinal length of the male frog is more conducive to adapting to the harsh living environment of the plateau.2.Geographical variation of skin thickness: the results show that the dorsal and ventral skin thickness of the R.kukunoris showed significant inter-populations difference but no gender difference.The results also showed that the skin thickness of both sexes increases with the decrease of temperature,which indicates that increasing the skin thickness in cold places is beneficial to resisting cold,especially increasing the possibility of spending a long hibernation period.Moreover,in a dehydrated environment,increasing skin thickness is one of the effective ways against desiccation for amphibians.3.Geographical variation in brain size: the results showed that absolute brain size showed significantly inter-population differences and gender differences;and the relative brain size remains significant inter-population differences,but no gender differences.The lower the temperature,less rainfall or less actual annual evapotranspiration will generally lead to the decrease of food types,quantity and available habitats,and the risk of predation will increase simultaneously.At this time,the increase of olfactory bulb and telencephalon will help visual search for food and suitable habitats and avoid natural enemies.Besides,when food is in short supply,energy is preferentially distributed to telencephalon to meet cognitive and energy needs.The development of olfactory nerve of the male frog is consistent with that of olfactory bulb,which increases olfactory nerve in water-deficient environment.On the other hand,the olfactory nerve development of female frog is opposite to that of olfactory bulb.The higher the temperature and sufficient rainfall,the larger the olfactory nerve.Usually,climate factors can directly or indirectly affect amphibians' cognitive needs,food types,predation risks,energy requirements in brain evolution and other factors.Therefore,the changes of brain size and the gender differences of R.kukunoris are closely related to these climate factors.