The summary is:
Nature 429, 612 - 613 (10 June 2004); doi:10.1038/429612a
Animal Behaviour: Eavesdropping on bats
BROCK FENTON AND JOHN RATCLIFFE
1 Brock Fenton is in the Department of Biology, University of Western Ontario, London, Ontario N6A 5B7, Canada.
e-mail: [EMAIL PROTECTED]
2 John Ratcliffe is in the Department of Zoology, University of Toronto at Mississauga, Ontario L5L 1C6, Canada.
e-mail: [EMAIL PROTECTED]
Two investigations into bat echolocation provide striking examples of the sophistication and the possible evolutionary and ecological consequences of variability in call design.
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The two articles are:
Nature 429, 657 - 661 (10 June 2004); doi:10.1038/nature02547
Echolocation signals reflect niche differentiation in five sympatric congeneric bat species
BJÖRN M. SIEMERS AND HANS-ULRICH SCHNITZLER
Animal Physiology, Zoological Institute, University of Tübingen, Morgenstelle 28, 72076 Tübingen, Germany
Correspondence and requests for materials should be addressed to B.M.S. ([EMAIL PROTECTED]).
Echolocating bats can be divided into guilds according to their preferred habitat and foraging behaviour1-4, which coincide with distinct adaptations in wing morphology5 and structure of echolocation signals6. Although coarse structuring of niche space between different guilds is generally accepted, it is not clear how niches differ within guilds7-10, or whether there is fine-grained niche differentiation reflected in echolocation signal structure11, 12. Using a standardized performance test, here we show clutter-dependent differences in prey-capture success for bats from five species of European Myotis. These species are morphologically similar, sympatric13, and all belong to the guild labelled "edge space aerial/trawling foragers"4. We further demonstrate a strong correlation between the prey-detection ability of the species and the respective search-call bandwidth. Our findings indicate that differences in echolocation signals contribute to within-guild niche differentiation. This is the first study relating sensory abilities of a set of potentially competing animal species to a direct measure of their respective foraging performance, suggesting an important role of sensory ecology in the structuring of animal communities.
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Nature 429, 654 - 657 (10 June 2004); doi:10.1038/nature02487
Harmonic-hopping in Wallacea's bats
TIGGA KINGSTON AND STEPHEN J. ROSSITER
1 Department of Geography, Boston University, Massachusetts 02215, USA
2 School of Biological Sciences, Queen Mary, University of London, London E1 4NS, UK
3 School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
* These authors contributed equally to this work
Correspondence and requests for materials should be addressed to T.K. ([EMAIL PROTECTED]). Accession numbers for new and published sequences are AY568637–AY568646, and AF065069–AF065073 and AF065090 (ref. 12), respectively.
Evolutionary divergence between species is facilitated by ecological shifts, and divergence is particularly rapid when such shifts also promote assortative mating. Horseshoe bats are a diverse Old World family (Rhinolophidae) that have undergone a rapid radiation in the past 5 million years. These insectivorous bats use a predominantly pure-tone echolocation call matched to an auditory fovea (an over-representation of the pure-tone frequency in the cochlea and inferior colliculus) to detect the minute changes in echo amplitude and frequency generated when an insect flutters its wings. The emitted signal is the accentuated second harmonic of a series in which the fundamental and remaining harmonics are filtered out. Here we show that three distinct, sympatric size morphs of the large-eared horseshoe bat (Rhinolophus philippinensis) echolocate at different harmonics of the same fundamental frequency. These morphs have undergone recent genetic divergence, and this process has occurred in parallel more than once. We suggest that switching harmonics creates a discontinuity in the bats' perception of available prey that can initiate disruptive selection. Moreover, because call frequency in horseshoe bats has a dual function in resource acquisition and communication, ecological selection on frequency might lead to assortative mating and ultimately reproductive isolation and speciation, regardless of external barriers to gene flow.
-- | Matt Heavner, Assistant Professor of Physics | University of Alaska Southeast | 11120 Glacier Highway, Juneau, AK 99801 | Phone: (907) 465-6403 | If Heisenberg was uncertain, why are you so sure?
