111
2000 ; Zosterisessor opiocephalus , Malavasi et al. 2003 ; Pomatoschistus pictus ,
Pedroso et al. 2013 ) and lower dominant frequencies ( C. gobio , Ladich 1989 ; Z.
ophiocephalus , Malavasi et al. 2003 ). The mechanical basis for the amplitude relationship is that sonic muscle size determines the force of contraction and correlates
positively with body size (Connaughton et al. 2000 ). Lower dominant frequency of
larger individuals can be explained by longer contraction durations of larger muscles (Connaughton et al. 2000 ).
However, size does not always predict sound dominant frequency; no relationship is found between dominant frequency and male size in the gobies P. pictus , P.
minutus , and P. bonelli (Torricelli et al. 1990 ; Amorim and Neves 2008 ; Pedroso
et al. 2013 ). Where sounds are sustained and harmonic, the dominant frequency
may be determined by the pulse repetition rate, which is controlled by central pattern generators, and may therefore be less sensitive to body size infl uences than
sounds in which pulses can be individually distinguished (Bass and McKibben
2003 ). Similarly, harmonic plainfi n midshipman hums and Mormyrid “moans”
show no correlation between dominant frequency and size (Crawford et al. 1997 ;
Bass and McKibben 2003 ).
Calling rate has been linked to female mate choice in benthic cavity spawning
fi shes. Two recent sets of studies conducted on Pomatoschistus gobies and the
Lusitanian toadfi sh ( Halobatrachus didactylus ) found that call rates were correlated
with male size and/or somatic condition, and were also predictive of female mate
choice. Condition factor (Fulton’s K) was related positively to total drumming
sound output in Pomatoschistus pictus and Pomatoschistus minutus (Amorim et al.
2013a ; Pedroso et al. 2013 ), and female P. pictus mated with males presenting high
courtship effort, which corresponds with a high number of drumming sounds
(Amorim et al. 2013a , b ). Similarly, Halobatrachus didactylus calling rate and calling effort were correlated with male size, lipid stores, and liver mass (Amorim et al.
2010 ; Vasconcelos et al. 2012) and positively predicted number of eggs in the nest
(Vasconcelos et al. 2012). Sonic muscle mass is strongly related to body size and
liver size in H. didactylus (Amorim et al. 2009 ), and similar relationships have been
found between drumming muscles mass and body size and condition in cod, Gadus
morhua (Rowe and Hutchings 2004 ).
6.2 Social Context
In addition to internal predictors of acoustic variation, the social context may elicit
changes in sound duration and dominant frequency; however, the patterns of association between these parameters and social context are variable across species. More
generally in fi shes, call durations are longer and pulse repetition rate is higher in
courtship contexts than agonistic contexts (Amorim 2006 ). In the goby Pomatoschistus
pictus , drum durations were longer in agonistic contexts than courtship contexts,
although drumming rates were higher in courtship than agonistic contexts (Bolgan
et al. 2013 ). Similarly, Padogobius bonelli aggressive sounds were longer in duration
Convergent Aspects of Acoustic Communication in Darters, Sculpins, and Gobies
2000 ; Zosterisessor opiocephalus , Malavasi et al. 2003 ; Pomatoschistus pictus ,
Pedroso et al. 2013 ) and lower dominant frequencies ( C. gobio , Ladich 1989 ; Z.
ophiocephalus , Malavasi et al. 2003 ). The mechanical basis for the amplitude relationship is that sonic muscle size determines the force of contraction and correlates
positively with body size (Connaughton et al. 2000 ). Lower dominant frequency of
larger individuals can be explained by longer contraction durations of larger muscles (Connaughton et al. 2000 ).
However, size does not always predict sound dominant frequency; no relationship is found between dominant frequency and male size in the gobies P. pictus , P.
minutus , and P. bonelli (Torricelli et al. 1990 ; Amorim and Neves 2008 ; Pedroso
et al. 2013 ). Where sounds are sustained and harmonic, the dominant frequency
may be determined by the pulse repetition rate, which is controlled by central pattern generators, and may therefore be less sensitive to body size infl uences than
sounds in which pulses can be individually distinguished (Bass and McKibben
2003 ). Similarly, harmonic plainfi n midshipman hums and Mormyrid “moans”
show no correlation between dominant frequency and size (Crawford et al. 1997 ;
Bass and McKibben 2003 ).
Calling rate has been linked to female mate choice in benthic cavity spawning
fi shes. Two recent sets of studies conducted on Pomatoschistus gobies and the
Lusitanian toadfi sh ( Halobatrachus didactylus ) found that call rates were correlated
with male size and/or somatic condition, and were also predictive of female mate
choice. Condition factor (Fulton’s K) was related positively to total drumming
sound output in Pomatoschistus pictus and Pomatoschistus minutus (Amorim et al.
2013a ; Pedroso et al. 2013 ), and female P. pictus mated with males presenting high
courtship effort, which corresponds with a high number of drumming sounds
(Amorim et al. 2013a , b ). Similarly, Halobatrachus didactylus calling rate and calling effort were correlated with male size, lipid stores, and liver mass (Amorim et al.
2010 ; Vasconcelos et al. 2012) and positively predicted number of eggs in the nest
(Vasconcelos et al. 2012). Sonic muscle mass is strongly related to body size and
liver size in H. didactylus (Amorim et al. 2009 ), and similar relationships have been
found between drumming muscles mass and body size and condition in cod, Gadus
morhua (Rowe and Hutchings 2004 ).
6.2 Social Context
In addition to internal predictors of acoustic variation, the social context may elicit
changes in sound duration and dominant frequency; however, the patterns of association between these parameters and social context are variable across species. More
generally in fi shes, call durations are longer and pulse repetition rate is higher in
courtship contexts than agonistic contexts (Amorim 2006 ). In the goby Pomatoschistus
pictus , drum durations were longer in agonistic contexts than courtship contexts,
although drumming rates were higher in courtship than agonistic contexts (Bolgan
et al. 2013 ). Similarly, Padogobius bonelli aggressive sounds were longer in duration
Convergent Aspects of Acoustic Communication in Darters, Sculpins, and Gobies