Abstract:
Bats play important ecological roles in tropical systems, yet how
these communities are structured is still poorly understood.
Our study explores the structure of African bat communities
using morphological characters to define the morphospace
occupied by these bats and stable isotope analysis to define
their dietary niche breadth. We compared two communities,
one in rainforest (Liberia) and one in savannah (South Africa),
and asked whether the greater richness in the rainforest
was due to more species ‘packing’ into the same morphospace
and trophic space than bats from the savannah, or some other
arrangement. In the rainforest, bats occupied a larger area
in morphospace and species packing was higher than in
the savannah; although this difference disappeared when
comparing insectivorous bats only. There were also differences
in morphospace occupied by different foraging groups (aerial,
edge, clutter and fruitbat). Stable isotope analysis revealed
that the range of d13C values was almost double in rainforest
than in savannah indicating a greater range of utilization of
basal C3 and C4 resources in the former site, covering primary productivity from both these sources. The ranges in d15N, however, were similar between the two
habitats suggesting a similar number of trophic levels. Niche breadth, as defined by either
standard ellipse area or convex hull, was greater for the bat community in rainforest than in
savannah, with all four foraging groups having larger niche breadths in the former than the latter.
The higher inter-species morphospace and niche breadth in forest bats suggest that species packing
is not necessarily competitive. By employing morphometrics and stable isotope analysis, we have
shown that the rainforest bat community packs more species in morphospace and uses a larger
niche breadth than the one in savannah.
