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Divergent trophic levels in two cryptic sibling bat species
Björn M Siemers1, Stefan Greif, Ivailo Borissov
1Sensory Ecology Group, Max Planck Institute for Ornithology, Seewiesen, Germany. siemers@orn.mpg.de
Oecologia
|February 23, 2011
Summary
Closely related bat species with similar morphology forage at different trophic levels. Stable isotope analysis revealed Myotis myotis consumes more secondary consumers, while Myotis blythii oxygnathus primarily eats primary consumers, impacting ecosystem roles.
Area of Science:
- Ecology
- Zoology
- Biogeochemistry
Background:
- Dietary shifts drive niche specialization in animal species.
- Foraging behavior divergence can alter an animal's trophic position and ecosystem impact.
Purpose of the Study:
- To investigate how foraging behavior divergence affects trophic levels in two closely related bat species.
- To test the hypothesis that Myotis myotis and Myotis blythii oxygnathus occupy different trophic positions based on their diets.
Main Methods:
- Conducted a laboratory validation experiment to measure isotopic discrimination in insectivorous bats.
- Utilized stable isotope analyses (¹⁵N enrichment) in field populations in Bulgaria.
- Employed a Bayesian mixing model to determine dietary composition.
Main Results:
- Myotis myotis consumed a mixed diet of 50% primary and 50% secondary consumers.
- Myotis blythii oxygnathus predominantly consumed primary consumers (98%).
- Secondary consumer arthropods were significantly more enriched in ¹⁵N than primary consumers, supporting the trophic level hypothesis.
Conclusions:
- Morphologically similar, sympatric sibling species can forage at divergent trophic levels.
- Divergent foraging strategies lead to different roles in ecosystem processes.
- Stable isotope analysis is a valuable tool for elucidating trophic relationships in closely related species.
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