Echolocation by Insect-Eating Bats

[ "Hans-Ulrich Schnitzler () is professor and head of the Lehrstuhl Tierphysiologie of the University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany."]; [ "Elisabeth Kalko is professor and head of the Abteilung Experimentelle Ökologie of the University of Ulm, Albert Einstein Allee 11, D89069 Ulm. E. Kalko is a staff member and H.-U. Schnitzler is a research associate of the Smithsonian Tropical Research Institute, Panama. E. Kalko is also a research associate at the National Museum of Natural History in Washington, DC."]
BioScience (Impact Factor: 4.74). 09/2009; DOI: 10.1641/0006-3568(2001)051[0557:EBIEB]2.0.CO;2
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    ABSTRACT: Phylogeny, ecology, and sensorial constraints are thought to be the most important factors influencing echolocation call design in bats. The Molossidae is a diverse bat family with a majority of species restricted to tropical and subtropical regions. Most molossids are specialized to forage for insects in open space, and thus share similar navigational challenges. We use an unprecedented dataset on the echolocation calls of 8 genera and 18 species of New World molossids to explore how habitat, phylogenetic relatedness, body mass, and prey perception contribute to echolocation call design. Our results confirm that, with the exception of the genus Molossops, echolocation calls of these bats show a typical design for open space foraging. Two lines of evidence point to echolocation call structure of molossids reflecting phylogenetic relatedness. First, such structure is significantly more similar within than among genera. Second, except for allometric scaling, such structure is nearly the same in congeneric species. Despite contrasting body masses, 12 of 18 species call within a relatively narrow frequency range of 20 to 35 kHz, a finding that we explain by using a modeling approach whose results suggest this frequency range to be an adaptation optimizing prey perception in open space. To conclude, we argue that the high variability in echolocation call design of molossids is an advanced evolutionary trait allowing the flexible adjustment of echolocation systems to various sensorial challenges, while conserving sender identity for social communication. Unraveling evolutionary drivers for echolocation call design in bats has so far been hampered by the lack of adequate model organisms sharing a phylogenetic origin and facing similar sensorial challenges. We thus believe that knowledge of the echolocation call diversity of New World molossid bats may prove to be landmark to understand the evolution and functionality of species-specific signal design in bats.
    PLoS ONE 01/2014; 9(1):e85279. · 3.73 Impact Factor
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    ABSTRACT: Patterns of interspecific and intraspecific variation in the three endemic species of Malagasy Triaenops bats were investigated using morphology and bioacoustics. Adult bats were captured at different localities across the island, measured, and their echolocation calls recorded. On average, male T. auritus and T. furculus have shorter forearms (47.0 and 44.0 mm, respectively) and emit higher frequency calls (107.8 and 113.1 kHz, respectively) than females (47.5 and 45.7 mm and 95.6 and 98.2 kHz, respectively), representing a form of reversed sexual dimorphism (females larger than males). However, T. menamena shows typical patterns of sexual size dimorphism with males having a longer forearm (51.7 mm) and lower frequency echolocation calls (82.3 kHz) than females (49.0 mm and 93.5 kHz, respectively). When segregated by sex, there was a strong allometric relationship between forearm length, used as a measure of body size, and the resting frequency in these three species, as well as two African hipposiderids (T. afer and Cloeotis percivali). Triaenops auritus males and both sexes of T. furculus deviated from the relationship between these two variables. Hypotheses are explored to explain the drivers of these sexual dimorphism patterns. On the basis of the allometric relationship, the strong correlation is in parallel to other groups of bats and is probably associated with ecological constraints. Recent phylogenetic analyses showed a separation of Afro-Malagasy Triaenops into two sister clades: T. auritus/T. furculus (suggested to be placed in a new genus, Paratriaenops) and T. menamena/T. afer. The patterns of sexual dimorphism in these taxa are congruent with clade membership. Further studies are needed to understand strategies used by these taxa when in sympatry to share habitat and ecological niches.
    Acta Chiropterologica 12/2013; 15(2):431–439. · 0.89 Impact Factor


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