Background/Question/Methods How plateau-endemic species adapt to altitudes is a basic question to understand the spread, adaptation and evolution of mammals. Plateau-endemic mammals usually have a large distribution range along altitude, namely thousands of meters. But previous researches on plateau-endemic mammals mostly focused on their survival at high altitude, studies that test how they adapt to wide altitude ranges are limited. The challenges of the species living in different elevation include different energy demand and various food resources. Thus, diet, food preference, and gut microbiota could have strong connection with the differences of resources or energy demand along elevation. Unfortunately, no studies have been conducted to calculate these factors simultaneously and quantitatively over successive elevation gradients. For better understandings of how diet, food preference and gut microbiota contribute and influence the altitude adaptation of mammals. Three basic questions should be answered:1) whether dietary flexibility is important for altitude adaptation, 2) whether dietary flexibility is a passive response to resource differences or an active selection by the animal, 3) the role that gut microbita plays in this diet adaptation. The plateau pika (Ochotona curzoniae) is a generalist primary consumer which has continuous geographical distribution in Qinghai-Tibetan Plateau and has a large elevational fitness range (3000~5500m ASL). Here we simultaneously investigated the quantitative structure of diet, food preference, plant community (as food resources) and gut microbiota of plateau pika along an elevation gradient from 3000m to 5000m (200~250m apart). Plant communities were achieved by field survey plots, diets and microbiota communities were achieved by high-throughput sequencing and DNA-barcode, and food preferences were calculated from diet abundance divided by resources abundance. We used multiple regression models for distance matrices (MRM) to test the relationships between each variable matrix and altitude gradients. Results/Conclusions Results show that the communities’ structures of diet, plant resources, food preference and gut microbiota have significantly different among altitudes and have correlation with altitudes. Among them gut microbiota showed more significant correlation than diet with altitudes. Moreover, food preferences have higher contribution than plant resources in the explanation of diet difference. Specifically, we concluded: 1) plateau pika distributed along a large altitude range by having elevational plastic diets, 2) the differences in diet at altitude gradients could be mainly attributed to pika’s active food preference adaptation rather than passive response to plant resources, 3) in the above processes, gut microbiota plays a role in improving the potential flexibility of diet.
