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Publication
Social calls are subject to stabilizing selection in insular bats
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Advisor(s)
Abstract(s)
Aim Bats communicate by emitting social calls, and these often elicit reactions in
conspecifics. Many such vocalizations are species-specific so that unambiguous
signals can be transmitted and interpreted by conspecifics. In species-rich
assemblages, evolutionary pressures might prompt interspecific diversification of
call structure so that communication with heterospecifics is avoided. In species poor island communities, where no risk of miscommunication occurs, stabilizing
selection should prevail and preserve call structure and function. Call structure in
island bats might be inherited from colonizers from the mainland and be
maintained with little change in the absence of selection from heterospecifics. To
test this hypothesis we studied Pipistrellus maderensis, an insular taxon occurring on
the Madeira Archipelago, the Canary Islands and the Azores. It is closely related to
one of the most widespread European pipistrelles, Pipistrellus kuhlii. Pipistrellus
maderensis most probably evolved from a common ancestor shared with P. kuhlii,
or from founders of that taxon that colonized the islands. We hypothesized that on
Madeira Island, where no risk of ambiguous communication with heterospecifics
exists, the structure and function of social calls should have been preserved by
stabilizing selection. Echolocation calls, subject to different selection pressures, may
instead show more pronounced differences between P. maderensis and P. kuhlii.
Location Madeira Island (Portugal, Atlantic Ocean), central and southern Italy.
Methods We recorded social and echolocation calls from allopatric populations
of the two pipistrelles and explored interspecific differences in time and frequency
characteristics. We also conducted playback experiments by broadcasting
recordings of social calls from P. kuhlii and P. maderensis (taken respectively in
peninsular Italy and on Madeira) and monitoring the bats’ responses.
Results Social call structure showed a strong similarity between species, whereas
echolocation calls were markedly different and exhibited a mean divergence of
over 6 kHz in their frequency of maximum energy. On Madeira, P. maderensis
significantly reduced flight activity when we broadcast P. kuhlii signals, as did
P. kuhlii in Italy in response to P. maderensis calls.
Main conclusions Reliable interpretation of social calls provides benefits to
both the signaller and the receiver because signals help to optimize food
exploitation at foraging sites. In the absence of closely related species that can
emit similar calls, this advantage may have acted as a strong evolutionary
pressure, stabilizing social call structure in P. maderensis in insular ecosystems
with limited foraging resources.
Description
Keywords
Allopatry Bioacoustics Communication Echolocation Evolution Island evolution Italy Madeira (Portugal) Pipistrellus kuhlii Pipistrellus maderensis . Faculdade de Ciências da Vida
Citation
Russo, D., Teixeira, S., Cistrone, L., Jesus, J., Teixeira, D., Freitas, T., & Jones, G. (2009). Social calls are subject to stabilizing selection in insular bats. Journal of Biogeography, 36(12), 2212-2221.
Publisher
Wiley