Animals use a variety of signal modalities to communicate with other animals. Evolution of signals is constrained by the type of signal used (visual, acoustic, …), the medium in which it travels from sender to receiver (air, water, …), and need for honesty.
We have been investigating the role in communication and evolution of facial pigmentation patterns in Neolamprologus brichardi and sound production in Neolamprologus pulcher.
In the study of the facial pigmentation in Neolamprologus brichardi we have employed animal signaling theory, theoretical visual models and behavioral experimentation to show that this facial color pattern evolved stable chromatic conspicuousness for efficient transmission in the aquatic environment, while context-dependent plasticity in luminance of the horizontal black stripe element is used to signal switches in aggressive intent.
We further used experimental signal manipulation to demonstrate that social selection by receiver retaliation is the mechanism responsible for maintaining signal honesty. Given the impacts of social selection on the evolution of pigmentation patterns in Neolamprologus brichardi, it is likely that social selection can drive diversification dynamics in sexually monochromatic cichlid species, such as sexual selection does in sexually dichromatic ones.
Whether and how visual signals are perceived depends on several factors, including ocular (eye) media transparency. In cichlids there are two broad categories of eye transparency: UV-transmitting or UV-filtering, depending on whether they allow UV radiation through or not, respectively.
Visual signals are not the only way cooperatively breeding cichlids communicate with one another. We have recently discovered that Neolamprologus pulcher produces high frequency sounds, but not low frequency ones. Whether they can actually hear these sounds themselves, or whether these sounds have evolved in an interspecific context is to be determined.
Last updated: October 30th, 2018