Interspecific variation of calls in clownfishes: degree of similarity in closely related species

Abstract

BackgroundClownfishes are colorful coral reef fishes living in groups in association with sea anemones throughout the Indo-Pacific Ocean. Within their small societies, size hierarchy determines which fish have access to reproduction. These fishes are also prolific callers whose aggressive sounds seem to play an important role in the social hierarchy. Agonistic interactions being involved in daily behaviour suggest how acoustic communication might play an important role in clownfish group. Sounds were recorded and compared in fourteen clownfish species (some of which have never been recorded before) to evaluate the potential role of acoustic communication as an evolutionary driving force.ResultsSurprisingly, the relationship between fish size and both dominant frequency and pulse duration is not only species-specific; all the specimens of the 14 species are situated on exactly the same slope, which means the size of any Amphiprion can be predicted by both acoustic features. The number of pulses broadly overlaps among species, whereas the pulse period displays the most variation even if it shows overlap among sympatric species. Sound comparisons between three species (A. akallopisos, A. ocellaris and A. frenatus) having different types of teeth and body shape do not show differences neither in the acoustic waveform nor in the power spectrum.ConclusionSignificant overlap in acoustic features demonstrates that the sound-producing mechanism is highly conservative among species. Differences in the calls of some species are due to size dimorphism and the sound variation might be in this case a by-product. This morphological constraint does not permit a consideration of acoustic communication as the main driving force in the diversification of clownfishes. Moreover, calls are not produced to find mate and consequently are less subject to variations due to partner preference, which restricts the constraints of diversification. Calls are produced to reach and defend the competition to mate access. However, differences in the pulse period between cohabiting species show that, in some case, sounds can help to differentiate the species, to prevent competition between cohabiting species and to promote the diversification of taxa.

The cerato-mandibular ligament: a key functional trait for grazing in damselfishes (Pomacentridae)

“…agonistic interactions [33,34,48]. Similarities in dominant sound frequencies resulting from grazing and agonistic behaviors imply that the same basic underlying mechanism is used (i.e.…”

Trait decoupling promotes evolutionary diversification of the trophic and acoustic system of damselfishes

“…To test this hypothesis, we compared the sounds of 13 damselfishes: 11 species having the cmd ligament and two phylogenetically closely related species lacking it. The data for Amphiprion and Dascyllus species are from [45] and [46], respectively. Recordings of sound production in the new species followed the protocol of Colleye & Parmentier [23].…”

“…Recordings of sound production in the new species followed the protocol of Colleye & Parmentier [23]. Following previous acoustic studies in damselfishes [23,26,45], we carefully selected the sound parameters in our comparative study, because all (i.e. sound duration, number of pulses in a sound, pulse period, pulse length, dominant frequency and relative intensity) may not be relevant for interspecific comparisons.…”

Unusual sound production mechanism in the triggerfishRhinecanthus aculeatus(Balistidae)

“…Relationships between fish size and different acoustic characteristics have been shown in many species : sound level changes in a sciaenid (Connaughton et al, 2000) and in Forcipiger sp. (Boyle and Tricas, 2011), dominant frequency in most species studied (Amorim and Hawkins, 2005;Amorim et al, 2003;Bertucci et al, 2012;Colleye et al, 2011;Malavasi et al, 2003;Myrberg et al, 1993) and pulse duration in clownfish (Colleye et al, 2009(Colleye et al, , 2012 and Forcipiger sp. (Boyle and Tricas, 2011).…”