Study On Food Traceability And Trophic Niches Of Major Rodents In Alax Desert Area

Food is the material basis for animal survival and reproduction,and also an important dimension of trophic niche.Trophic niche can not only reflect the characteristics of species nutritional needs,but also reflect the nutritional level,functional status and nutritional relationship between species in the ecosystem.Dipus sagitta,Allactaga sibirica,Meriones meridianus and Phodopus roborovskii are the main rodents in the Alxa Desert Area.Due to the pressure of resource competition and evolutionary selection in nature,these reodents have long formed unique resource utilization strategies to maintain their species survival and population continuation.Four rodent species share similar habitats in the Alax Desert Area,but the mechanism of their coexistence remains unclear.In this study,four main rodents in Alxa Desert Area were investigated by trap-day method in different seasons of2021,the feeding habits and trophic niches of the main rodents in the Alax Desert Area were determined by combining DNA macrobarcoding with stable isotope techniques,the feeding strategy and coexistence mechanism of four sympatric rodents were revealed.The main findings are as follows :(1)In spring,Sarcozygium xanthoxylon,Salsola tragus and Caragana korshiinskii were the main feeding plants of the Dipus sagitta;The Allactaga sibirica mainly feeds on Ammopiptanthus mongolicus,Salsola tragus and Scorzonera divaricata;The Meriones meridianus mainly feeds on Salsola tragus,Sarcozygium xanthoxylon and Ammopiptanthus mongolicus;The Phodopus roborovskii mainly feeds on Salsola tragus,Sarcozygium xanthoxylon and Corispermum mongolicum;The trophic levels of the four rodents were significantly different(P<0.05),the trophic level of Allactaga sibirica is the highest,and the trophic level of Dipus sagitta is the lowest;The Dipus sagitta,Meriones meridianus and Phodopus roborovskii have greater competition for food resources and higher overlap of trophic ecological niches,the main plant species that generate competition are the Salsola tragus and the Sarcozygium xanthoxylon,Allactaga sibirica has less resource competition with the other three rodents.(2)In summer,Nitraria tangutorum,Scorzonera divaricata and Corispermum mongolicum are the main feeding plants for the Dipus sagitta;The Allactaga sibirica mainly feeds on Ammopiptanthus mongolicus,Convolvulus ammannii and Salsola tragus;The Meriones meridianus mainly feeds on Nitraria tangutorum,Scorzonera divaricata and Salsola tragus;The Phodopus roborovskii mainly feeds on Corispermum mongolicum,Oxytropis aciphylla and Nitraria tangutorum;The trophic levels of the four rodents were significantly different(P<0.05),the trophic level of Allactaga sibirica is the highest,and the trophic level of Meriones meridianus is the lowest;The Dipus sagitta,Meriones meridianus and Phodopus roborovskii have greater competition for food resources and higher overlap of trophic ecological niches,the main plant species that generate competition are the Nitraria tangutorum,Allactaga sibirica has less resource competition with the other three rodents.(3)In autumn,the main plants eaten by the Dipus sagitta are Corispermum mongolicum,Nitraria tangutorum and Scorzonera divaricata;The Allactaga sibirica mainly feeds on Salsola tragus,Ammopiptanthus mongolicus and Tribulus cistoides;The Meriones meridianus mainly feeds on Nitraria tangutorum,Salsola tragus and Ammopiptanthus mongolicus;The Phodopus roborovskii mainly feeds on Corispermum mongolicum,Oxytropis aciphylla and Ammopiptanthus mongolicus;Meriones meridianus compete with Allactaga sibirica and Dipus sagittas for resources of different strength and overlap in trophic ecological niches,the main plant species that competes with the Dipus sagitta is the Nitraria tangutorum,and the main plant species that competes with the Allactaga sibirica is the Salsola tragus.(4)The trophic level of the four rodent species varied significantly throughout the year.The Allactaga sibirica always has the highest trophic level and a unique food resource(Ammopiptanthus mongolicus).The Allactaga sibirica rarely competes directly with other rodents for food resources and overlaps in trophic niches.Ammopiptanthus mongolicus plays an important role in the year-round diet of the Allactaga sibirica;Sarcozygium xanthoxylon,Nitraria tangutorum,Salsola tragus are the main food items in the diet of the Dipus sagitta;and the Corispermum mongolicum plays an important role in the year-round food source of the Phodopus roborovskii.The feeding strategy and trophic niche changes of four rodents support the optimal foraging theory and niche differentiation hypothesis,the four achieve long-term co-existence in the desert area by adjusting the distribution pattern of food resources and the differentiation of trophic niche.