Ladich Friedrich, Schleinzer Günter
Department of Behavioural Biology, University of Vienna, Vienna, Austria.
Bioacoustics. 2018 Dec 18;29(2):123-139. doi: 10.1080/09524622.2018.1555773. eCollection 2020.
Croaking gouramis (genus , Anabantoidei) generate series of two-pulsed bursts (croaks) during agonistic interactions. Sex-specific differences are minor in which raises the question whether sexes differ in the other two species. The current study analyses sounds recorded in female , compares the sound characteristics to those of males investigated earlier and correlates these characteristics to female body size. Sex-specific differences were found in three out of six sound characteristics. In females, sounds were lower in burst number, burst period and SPL. Pulse period, dominant frequency and peak-to-peak amplitude ratios of pulses did not differ between sexes. Burst period and SPL increased significantly with female body weight, whereas dominant frequency decreased. The present acoustic data indicate the sex-specific differences are more pronounced in than . The results also demonstrate that both sexes are vocal, which remains to be shown for females of the third species, , which have poorly developed sonic organs. The evolution of the pectoral sound-producing mechanism in is most likely based on an exaptation process during which acoustic signals are generated by fin tendons initially related to other functions as is evident in closely related genera lacking this organ.
沼口斗鱼（沼口斗鱼属，攀鲈亚目）在争斗互动中会发出一系列双脉冲爆发声（叫声）。性别差异较小，这就引出了一个问题，即另外两个物种的性别是否存在差异。当前的研究分析了雌性沼口斗鱼记录的声音，将声音特征与之前研究的雄性沼口斗鱼的特征进行比较，并将这些特征与雌性沼口斗鱼的体型相关联。在六个声音特征中的三个发现了性别差异。在雌性沼口斗鱼中，叫声的爆发次数、爆发间隔和声压级较低。脉冲间隔、主频和脉冲峰峰值幅度比在两性之间没有差异。爆发间隔和声压级随雌性体重显著增加，而主频降低。目前的声学数据表明，沼口斗鱼的性别差异比另一种沼口斗鱼更明显。结果还表明，两性都会发声，而对于第三种沼口斗鱼的雌性，其发声器官发育不良，这一点还有待证实。沼口斗鱼胸鳍发声机制的进化很可能基于一种扩展适应过程，在此过程中，声学信号最初由与其他功能相关的鳍腱产生，这在缺乏该器官的近缘属中很明显。
