Courtship and agonistic sounds by the cichlid fish Pseudotropheus zebra
Comparison between spectra of laboratory background noise recorded in a stock tank, placed on top of a thin layer of expanded polystyrene and in an experimental tank, placed on top of a thick layer of rockwool. Amplitude levels (dB) are relative to the maximum value of the spectra. Sampling frequency , 2048 point FFT, filter bandwidth , Hamming window, and 50% overlap.
(Color online) Oscillogram, sonogram, and power spectrum of a Pseudotropheus zebra male courtship sound, representing some of the acoustic parameters measured: mean pulse period of the first five pulses, is an example of a pulse) number of pulses, and sound duration in and peak frequency 1 (PF1) and 2 (PF2) in . Sampling frequency , 2048 point FFT, filter bandwidth , Hamming window, and 50% overlap.
Variation of courtship sound parameters in Pseudotropheus zebra males during lead swim (LS), quiver (Q), sounds produced with no apparent body movement (X), and circle (C). Groups that are significantly different are indicated by different letters (results from Tukey tests). Both “Mean PP” and “Initial PP” refers to mean values of pulse periods; whereas the first is the mean of the pulse periods throughout the entire sound, the second indicates the mean of the first five pulses. Note that comparisons considered data pooled for all males due to the small sample sizes obtained for LS, X, and C. Only a subsample of quiver sounds was considered for the analyses (see methods).
Variation of the acoustic parameters of quiver sounds emitted in courtship (male–female) and agonistic interactions (male–male and female–female) by Pseudotropheus zebra. Groups that are significantly different are indicated by different letters (results from Dunn tests).
Oscillograms of sounds produced associated with different contexts and gender: male courtship quiver, circle, male agonistic quiver, and female agonistic quiver. Sampling frequency .
Oscillograms of a courtship sound produced by a Pseudotropheus zebra male recorded at a distance of (a) and (b) from the hydrophone, in this case, sound attenuation was approximately . Sampling frequency .
Characteristics of sounds produced by . zebra males and females during quiver in inter- and intrasexual interactions (male–female—courtship interactions; male–male and female–female—agonistic interactions). Means, SD, and range are based on fish means. Coefficients of variation represent intraindividual variability of the acoustic parameters. Results for one-way ANOVA testing differences between males for courtship quiver acoustic parameters, and testing differences between sounds made during different contexts and gender are presented.
Characteristics of courtship sounds made by P. zebra during lead swim, quiver, with no associated display and circle. Data are pooled for all recorded individuals due to the small sample size (for quiver sounds only a subsample of 4 sounds per male was considered in the analyses—see Sec. II). Coefficients of variation are also given: . Results for Kruskal–Wallis statistics testing differences between sounds associated with different courtship behaviors are presented.
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