Variations In Visceral Organ Morphology And Adaptations To Habitat Alteration Of Main Rodents In Shennongjia

Rodents, one of the primary consumers in the food chain, are the regulator in theenergy flow and material transfer of ecosystem. The hoarding behavior of rodents assiststhe dispersal of plant diaspores and provides a safe shelter for seeds’ germination. Theythus play a vital role in plant recruitment, ecosystem functionality and the persistence ofbiodiversity. The behavior of rodents highly depends on the body size, energy absorptionand distribution and the later is achieved by the function of visceral organs. For furtherunderstanding the coexistence mechanism of rodents and their adaptation to habitatalteration, we investigated the food habits and visceral organ morphology of rodentcommunity among five different forest habitat types (primary forest, secondary forest,fuel-wood forest, Pinus armandii plantation forest, Larix kaempferi plantation forest) inLongmenhe National Forest Park, Shennongjia area. The main results are as follows.Niviventer confucianus, Niviventer andersoni, Apodemus chevrieri, Apodemus draco,Leopoldamys edwardsi, Typhlomys cinereus, Anourosorex squamipes, Dremomyspyrrhomerus, Rhizomys sinensis and Hystrix hodgsoni were sympatric in the Longmenhearea. The analysis of food habit showed that N. andersoni, N. confucianus, A. chevrieri andA. draco were omnivorous but the Chi-square test detected significant variation in dietarybiases. N. andersoni was primarily phyllophagous and seminivorous and the others wereprimarily seminivorous and carnivorous. The analysis of covariance of viscera organsshowed that while fresh weights of heart, lung and spleen and dry weight of spleen did notdiffer between rodents, other indices did exhibit significant variation with the highest valuefound in N. andersoni. In the analysis of digestive tract morphology, while length, freshand dry weight of caecum did not differ between rodents, fresh and dry weights of stomachand large intestine, fresh weights including stomach, caecum and large intestine contents,and length of large intestine did differ significantly with the highest value found in N.andersoni. Otherwise, the length, fresh and dry weight of small intestine, and fresh weightincluding small intestine contents also showed significant variations between species, withthe highest value found in N. confucianus.Variations in viscera organ morphology of N.andersoni compared to other species indicate that the segregation of food resourcescontributes to this species coexistence with other rodents. In order to adapt to differentavailability of food resources, the viscera organ and digestive tract morphology of N.andersoni show adaptable phenotypic plasticity. However, A. chevrieri and A. draco, both belonging to the genus Apodemus, do not exhibit differences in food habit, viscera organand digestive tract morphology, which implied that their coexistence may result from otherstrategies than resource allocation, such as habitat selection.Habitat alteration did not change the dietary of the dominated species N. confucianu.All the individuals in the five forest types were primarily seminivorous and carnivorous.By comparison, while spleen and kidney did not differ among different forests, heart, lungand liver mass exhibit variation between these forest habitats, with the highest massesfound in Pinus armandii plantation forest and Larix kaempferi plantation forest for heartand lung and the highest masses found in secondary forest for liver. As to digestive tract,while stomach mass did not differ among the forest types, fresh weight including caecumand large intestine contents, fresh weight without caecum and large intestine contents, dryweight of the caecum and large intestine did exhibit variation but with different trends. Dryweight of the small intestine in secondary forest is significantly higher than other foresttypes. Length of large intestine in secondary forest, which is similarity to other forest types,is longer than fuel-wood forest. Similarity food habits among different forests correlated toabundant food resources in autumn. The variation in viscera organ morphology of N.confucianus is matched to habitat alteration, with benefits for survival, reproduction andrecruitment dynamics.