Abstract:

Aim: Revealing the mechanisms that determine species coexistence is of great importance for the development of community ecology theoretical concepts/ which is one of the hot spot for biodiversity and conservation biology research. Niche separation is an important reason for the coexistence of sympatric species.

Methods: To determine the dietary composition of six sympatric small mammals at the Laojunshan Nature Reserve, Sichuan, the animal samples were trapped and the luminal stomach contents were collected. We used two DNA metabarcoding assays (chloroplast RbcL and mitochondrial COI region sequences) to better understand their dietary diversity, niche breadth and overlap.

Results: (1) Lepidoptera (relative abundance: 3.76%-42.33%) and Diptera (2.59%-62.63%) were the prey items identified, while Poales (0.02%-45.33%) and Fabales (0.19%-38.95%) were the taxa that constituted the majority of plant-derived foods. In addition to this, inter-specific differences in relative abundance of these main food items were observed. (2) We found that there was a significant trophic overlap (O_jk = 0.63) of animal derived diet between Rattus tanezumi and Blarinella griselda. A certain degree of food niche overlap was found between the other sampled species, yet there were still significant differences in the composition and proportion of predominant food items. (3) A certain inter-specific difference in α diversity of animal derived food between the six small mammals was detected, while almost no differences in α diversity of plant derived foods were found between the six small mammals. Niviventer confucianus had the highest dietary diversity, with higher niches breadth (8.2-11.1) of both plant- and animal-derived diets than those of the other five species.

Conclusion: These results suggest that, although the dietary overlap is observed in six small mammals, they can reduce foods competition and achieve long-term coexistence through separating the types and proportions of the main food items. Furthermore, this study reveals the mechanism of maintaining the diversity of various small mammal species at the Laojunshan Nature Reserve. This study also contributes to the ecological management of rodent-like animals in this area. Considering the limitations of our sample size and time scale of sampling, we believe that increasing sample size and time span can be more effective at identifying inter-specific relationship through DNA metabarcoding.

Key words: sympatric co-existence, dietary composition, DNA metabarcoding, trophic niche