3.1 Overview of taxonomic assignment and dietary diversity
In the 24 stomach samples analyzed over all seasons, the mean number of MOTUs in animal species was 38±6 for spring, 30±5 for summer, 32±18 for autumn and 4±1 for winter (Table 1). In plant food items, the mean number of MOTUs was 95±28 for spring, 57±24 for summer, 87±41 for autumn and 120±42 for winter (Table 1). In total, we identified 38 potential animal food items (spanning 26 families and 15 orders) (Supplementary Table 1) and 113 plant food items (spanning 39 families and 23 orders) (Supplementary Table 2) at species level that are consumed by Chinese mole shrew. Seasonal dietary changes were detected in A. squamipes with a general shift toward low dietary diversity in winter. As expected, the number of animal food items at species level decreased significantly in winter (Figure 1A). Peak consumption of animal food items was detected in spring and summer, which were significantly higher than those in autumn and winter. However, we found no significant seasonal differences in the number of plant food items at genus level (Figure 1A), suggesting that potential plant food items were constant throughout the year.
Alpha diversity indices (Chao1, Shannon, and Simpson) indicated seasonal differences in the diversity of animal food items. There was a greater Chao1 diversity index in spring and summer compared to winter (Figure 2A). A higher Shannon diversity index was observed in autumn relative to winter. Overall, our analysis showed a lower alpha diversity of animal food items in winter. However, the dietary alpha diversity of plant food items did not differ significantly between seasons (Figure 2B), suggesting that the availability of plant-derived foods were not affected by seasons.
The PCoA plot (Figure 3) revealed seasonal differences in animal-derived diets. Animal food items in spring, summer and autumn weakly clustered together and were separate from diets in winter (Figure 3A). In addition, there was dispersion within winter animal food items, suggesting a high degree of intergroup variability. We also observed a cluster of plant food items in autumn that was separated from those in other seasons with apparent dispersion (Figure 3B). The dominant family (Poaceae) in autumn likely contributed to this separation.