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Seasonal variation of population and individual dietary niche in the avivorous bat, Ia io

Citation

Gong, Lixin; Jiang, Tinglei (2022), Seasonal variation of population and individual dietary niche in the avivorous bat, Ia io, Dryad, Dataset, https://doi.org/10.5061/dryad.bzkh1899m

Abstract

The variation in niche breadth can affect how species respond to environmental and resource changes. However, there is still no clear understanding of how seasonal variability in food resources impacts the variation of individual dietary diversity, thereby affecting the dynamics of a population’s dietary niche breadth. Optimal foraging theory (OFT) and the niche variation hypothesis (NVH) predict that population niche breadth will expand with food resource limitation stemming from increased within-individual dietary diversity and individual specialization. Here, we used DNA metabarcoding to examine the composition and seasonality of diets of the avivorous bat Ia io. Furthermore, we investigated how the dietary niches changed among seasons and whether the population niche breadth broadened when the availability of food resources was reduced in autumn compared with spring and summer to test the predictions of OFT and the NVH. We found that there was differentiation in dietary niches among seasons and a low degree of overlap, and the decrease of insect resource diversity and the emergence of ecological opportunities of nocturnal migratory birds might drive dietary niche expansion toward birds in I. io. However, the population’s dietary niche breadth did not broaden by increasing the within-individual dietary diversity or individual specialization when food resources were scarce in autumn. Our findings were not consistent with the predictions of OFT or NVH, because birds as prey for bats provided extremely different resources from those of insects in size and nutritional value. Our results also showed that bats’ individual body mass, dietary diversity, and ecological opportunity influence individual dietary specialization. Our work highlights the importance of size and quality of prey resources along with other factors (i.e., physiological, behavioral, and life-history traits) in dietary niche evolution.

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