Morphological And Ecological Adaption Of Two Populations Of Nidirana Pleuraden

Under the influence of anthropogenic activities,amphibian populations have been declining rapidly worldwide.Local extinction of animal populations due to habitat changes caused by anthropogenic activities has become one of the main causes of biodiversity decline.Yunnan Music Frog(Nidirana pleuraden)is a common anuran species of Yunnan Plateau with wide distribution and well-adapted.Two populations of Nidirana pleuraden was found distributed in Xiaobaihu town and Sanchahe town,Luliang County,Yunnan province,which lived in different habitats with different intensities of anthropogenic activities.Other sympatric species of amphibian with the Nidirana pleuraden in Sanchahe town were local extinct,and only the Nidirana pleuraden was remained.To study how Nidirana pleuraden maintains its population in a changing environment,Xiaobaihu Town and Sanchahe Town in Luliang County were selected as the research sites.By comparing habitat environment the two population,analyzing the differences of populations in morph characteristics,skin structure,micronucleus rate of blood cell,and melanin-macrophages centers of the liver and spleen,unified with the habitat environment differences,the environmental adaptation in morphology,structure,genetic and physiology of Nidirana pleuraden was explored under different intensity of anthropogenic activity,which was expected to provide scientific evidence for the morphological and ecological adaptation evolution of amphibians.The results were as follows:1.There were significant differences in human population environment,water environment and biodiversity of amphibians in the two habitats of frog populations.The population density of Sanchahe is nearly 10 times that of Xiaobaihu.In water environment,the water conductivity of Sanchahe Town was significantly higher than that of Xiaobaihu.A total of 11 amphibian species were observed in the habitat of Xiaobaihu population,including 9 species of frogs,whereas there were only 2amphibian species in Sanchahe,which only 1 species of frog.The diversity of amphibian species in Xiaobaihu was significantly higher than that in Sanchahe.2.Sanchahe population was significantly larger than Xiaobaihu population in overall morphological characteristics,such as body weight,body length and head length,as well as most morphologic variables of head and appendages.The results showed that Sanchahe population was larger than Xiaobaihu population in terms of body size.The increase of body size was beneficial to improve the body volume surface area ratio and reduce skin water penetration,so as to adapt to the aquatic life in Sanchahe habitat.Most morphological characteristics of female frogs in Sanchahe population increased significantly,but the increase of male frogs was not significant,which may be related to female fertility selection.The relative value of morphological characteristics with snout-ventral length showed that the variation was concentrated in head,and the relative morphological characteristic value of the head of Sanchahe population was smaller than that of Xiaobaihu population,which might be related to food selection.2.The body condition index of Nidirana pleuraden depended on body weight,head size such as head length,head width and head height,hind limb length and limb thickness,etc.The load capacity of limbs was closely related to the length of forelimbs and hindlimbs.Head-wagging potential was related to head length and sensory organ size,such as eye diameter and eardrum length.The body condition index of Sanchahe population was significantly higher than that of Xiaobaihu population,which might be related to the food size of the two habitats.The different food drove the adaptive variation in Sanchahe population.4.The results of skin structure analysis showed that compared with Xiaobaihu population,the thickness of total skin and stratum spongiosum of adult in Sanchahe population were significantly thicker,and the number and size of mucus glands in stratum spongiosum were also significantly increased.The stratum spongiosum of Sanchahe population was thickened and could accommodate more capillaries,which was the result of adaptation to the increase of body size,more aquatic life and aquatic respiration.5.Micronucleus was found in the blood cells of both populations.Both in adults and tadpoles,the micronucleus rate of blood cells in Sanchahe population was higher than that in Xiaobaihu population.The correlation analysis between the micronucleus rate of blood cells and water environmental factors showed that the higher the water conductivity,the higher the micronucleus rate.The micronucleus rate was also negatively correlated with p H and dissolved oxygen in water.The higher ion concentration in water of the Sanchahe population habitat might lead to more DNA damage and higher micronucleus rate of blood cells.Observation on the structure of liver in the two populations showed that the liver cells of Sanchahe population had vacuolated,suggesting that the Sanchahe population was greatly affected by habitat environment.The number of melanin macrophage centers(MMCs)is an important indicator of frog immunity.Compared with Xiaobaihu population,the number of melanin macrophage centers in liver of Sanchahe population was significantly increased,which may be an immune adaptation to the changes in water environment caused by increased anthropogenic activities.6.Observation on the structure of liver in the two populations showed that the liver cells of Sanchahe population had vacuolated,suggesting that the Sanchahe population was greatly affected by habitat environment.The number of melanin macrophage centers(MMCs)is an important indicator of frog immunity.Compared with Xiaobaihu population,the number of melanin macrophage centers in liver of Sanchahe population was significantly increased,which may be an immune adaptation to the changes in water environment caused by increased anthropogenic activities.A comparative study on the morphology,ecology and habitat of the two populations of Nidirana pleuraden showed that the frogs adapted to the changes of habitat environment with increased anthropogenic activities by increasing body size,thickening skin and enhancing immunity.The Sanchahe population maintained the survival through multiple adaptive variations in external morphological characteristics,skin structure and immune system.The analysis of micronucleus rate of blood cells and melanin macrophage center of liver and spleen indicated that the immune system of Sanzhahe population was facing long-term water pressure caused by anthropogenic activities and habitat loss,and the population might be in a long-term decline trend.The results of this study might provide basic information for the adaptive variation of amphibians in human-disturbed environments,which was beneficial to the conservation of amphibians.