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.