Abstract
IntroductionOur purpose was to assess how pairs of sibling horseshoe bats coexists when their morphology and echolocation are almost identical. We collected data on echolocation, wing morphology, diet, and habitat use of sympatric Rhinolophus mehelyi and R. euryale. We compared our results with literature data collected in allopatry with similar protocols and at the same time of the year (breeding season).ResultsEcholocation frequencies recorded in sympatry for R. mehelyi (mean = 106.8 kHz) and R. euryale (105.1 kHz) were similar to those reported in allopatry (R. mehelyi 105–111 kHz; R. euryale 101–109 kHz). Wing parameters were larger in R. mehelyi than R. euryale for both sympatric and allopatric conditions. Moths constitute the bulk of the diet of both species in sympatry and allopatry, with minor variation in the amounts of other prey. There were no inter-specific differences in the use of foraging habitats in allopatry in terms of structural complexity, however we found inter-specific differences between sympatric populations: R. mehelyi foraged in less complex habitats. The subtle inter-specific differences in echolocation frequency seems to be unlikely to facilitate dietary niche partitioning; overall divergences observed in diet may be explained as a consequence of differential prey availability among foraging habitats. Inter-specific differences in the use of foraging habitats in sympatry seems to be the main dimension for niche partitioning between R. mehelyi and R. euryale, probably due to letter differences in wing morphology.ConclusionsCoexistence between sympatric sibling horseshoe bats is likely allowed by a displacement in spatial niche dimension, presumably due to the wing morphology of each species, and shifts the niche domains that minimise competition. Effective measures for conservation of sibling/similar horseshoe bats should guarantee structural diversity of foraging habitats.
Highlights
Our purpose was to assess how pairs of sibling horseshoe bats coexists when their morphology and echolocation are almost identical
This study shows that R. mehelyi and R. euryale exhibit similar ecologies in sympatry yet showing subtle but significant differences
The most pronounced ecological difference is their divergent use of foraging habitats that contrasts with the low divergence in diet
Summary
Our purpose was to assess how pairs of sibling horseshoe bats coexists when their morphology and echolocation are almost identical. According to the ecomorphological paradigm, species with similar morphology should exhibit similarities in behaviour and ecology [1] This prediction, raises the possibility of competition between such species when they occur in sympatry. Removal or demographic response experiments, if adequately designed, may demonstrate a cause-effect relationship between niche differentiation and inter-specific competition [4,5] These experiments are inappropriate for rare, elusive, K-selected, or endangered species, and currently, non-disruptive, more inductive approaches are the only practical alternatives. These alternative approaches usually compare morphology, behaviour, and ecology of two (or more) species which occur under allopatric and sympatric conditions and assume that any niche displacement is directly associated with competition [6]
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