First published online August 8, 2008
Journal of Experimental Biology 211, 2609-2616 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.019612
Phonotactic selectivity in two cryptic species of gray treefrogs: effects of differences in pulse rate, carrier frequency and playback level
H. Carl Gerhardt
Division of Biological Sciences, University of Missouri, Columbia, MO
6521, USA
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Fig. 1. (A) Oscillograms showing the gross temporal structure of standard synthetic
advertisement calls of H. chrysoscelis (top) and H.
versicolor (bottom). (B) Oscillograms with an expanded time base showing
two pulses from six synthetic calls. Left column: H. chrysoscelis
with the 2.4 kHz carrier frequency; pulse rates were (from top to bottom): 40,
50 (the standard rate) and 75 pulses s–1. Right column:
H. versicolor with the 2.2 kHz carrier frequency; pulse rates were
(from top to bottom): 15, 20 (the standard rate) and 30 pulses
s–1.
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Fig. 2. Comparisons of pulse-rate preferences using different carrier frequencies
at a playback level of 85 dB SPL (sound pressure level). Data for bimodal
spectra were published previously
(Gerhardt, 2005a ) and are
re-plotted here. (A) Preferences of females of H. chrysoscelis; (B)
preferences of females of H. versicolor. Error bars are 95% credible
intervals, and statistically significant, post-hoc comparisons of
least-square means between the proportions of females choosing the standard
call depending on carrier frequency are indicated by asterisks
(*P<0.05; ***P<0.001). See
Materials and methods and Results for details about the statistical analyses.
N=number of female choices (one per female in each test).
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Fig. 3. Intensity dependence of pulse-rate preferences in tests between standard
calls and alternatives with pulse rates at the low- and high-cutoff values
(see text for definition). (A) Preferences of H. chrysoscelis; (B)
preferences of H. versicolor. Error bars are 95% credible intervals,
and statistically significant, post-hoc comparisons of least-square
means between the proportions of females choosing the standard call depending
on carrier frequency are indicated by asterisks
(*P<0.05; **P<0.01). See
Materials and methods and Results for details about the statistical analyses.
N=number of female choices (one per female in each test).
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Fig. 4. Intensity dependence of pulse-rate preferences in tests between standard
calls and alternatives with other pulse rates. (A) Preferences of H.
chrysoscelis; pulse-rate differences were less than those between the
standard call and alternatives at the low- and high-cutoff values in tests at
85 dB SPL with stimuli having a bimodal spectrum
(Gerhardt, 2005a). When these
data were combined with those plotted in
Fig. 3, there were highly
significant effects of pulse rate. See text for details. (B) Preferences of
H. versicolor in tests with an alternative with a lower pulse rate
(10 pulses s–1) than the low-cutoff value and with
alternatives with higher pulse rates (35 and 40 pulses s–1)
than the high-cutoff value. Error bars are 95% credible intervals.
N=number of female choices (one per female in each test).
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© The Company of Biologists Ltd 2008
