Food for everyone: differential feeding habits of cryptic bat species
inferred from DNA metabarcoding
Abstract
Ecological theory postulates that the niche of co-occurring species must
differ along some ecological dimensions in order to allow their stable
coexistence. Yet, many biological systems challenge this competitive
exclusion principle. For instance, insectivorous bats from the Northern
Hemisphere typically form local assemblages of multiple species sharing
highly similar functional traits and pertaining to identical feeding
guilds. Although their trophic niche can be accessed with unprecedented
details using genetic identification of prey, the underlying mechanisms
of resource partitioning remain vastly unexplored. Here, we studied the
differential diet of three phenotypically and phylogenetically
closely-related bat species of the genus Plecotus in an area of
sympatry and throughout their entire breeding season (April-October)
using DNA metabarcoding. Even at such a small geographic scale, we
identified strong seasonal and spatial variation of their trophic niche
at both intra- and inter-specific levels. Indeed, while the different
bats fed on a distinct array of prey during spring, they showed higher
niche overlap during summer and fall, when all three bat species
switched their hunting behavior to feed on few temporarily abundant
moths. Furthermore, by considering the ecological traits of prey
species, we inferred from the menu of each bat species that feeding
grounds and hunting techniques differed suggesting that niche
partitioning was primarily habitat-driven. As predicted by their
phylogenetic relationships, the two most-closely related bat species
exhibited the most distinct foraging habitat preferences, while the
third, more distantly-related species was more generalist. These results
highlight the need of extensive samples to fully understand species
coexistence.