Data from: The roles of morphological traits, resource variation and resource partitioning associated with the dietary niche expansion in the fish-eating bat Myotis pilosus

Niche expansion and shifts are involved in the response and adaptation to
environmental changes. However, it is unclear how niche breadth evolves
and changes toward higher-quality resources. Myotis pilosus is both an
insectivore and a piscivore. We examined the dietary composition and
seasonality in M. pilosus and the closely related Myotis fimbriatus using
next-generation DNA sequencing. We tested whether resource variation or
resource partitioning help explain the dietary expansion from insects to
fish in M. pilosus. While diet composition and diversity varied
significantly between summer and autumn, the proportion of fish-eating
individuals did not significantly change between seasons in M. pilosus.
Dietary overlap between M. pilosus and M. fimbriatus during the same
seasons was much higher than within individual species across seasons. We
recorded a larger body size, hind foot length, and body mass in M. pilosus
than in M. fimbriatus and other insectivorous trawling bats from China.
Similar morphological differences were found between worldwide fishing
bats and non-fishing trawling bats. Our results suggest that variation in
insect availability or interspecific competition may not play important
roles in the dietary expansion from insects to fish in M. pilosus. M.
pilosus has morphological advantages that may help it use fish as a diet
component. The morphological advantage promoting dietary niche evolution
toward higher-quality resources may be more important than variation in
the original resource and the effects of interspecific competition.