auditory communication; genetic; neurobiology; neuroethology; crickets; behavior
Sexual dimorphism is exhibited across all cricket species and is a central aspect of the mating processes of these insects. Only male crickets possess wing structures and pattern generators in the central nervous system that allow them to produce a mating call that is unique to their species in order to attract conspecific females. Conspecific females possess an auditory feature detection circuit in the central nervous system that is capable of detecting the species-specific frequency and temporal pattern of sound pulses within a male call. In order for dimorphic differences in mating behavior to result in successful continuation of a species, it would seem that genetic control of the neurological mechanisms underlying the production and perception of mating behaviors in both sexes of a species must occur. Accordingly, previously conducted behavioral research on auditory production and perception in crickets has suggested that the neural mechanisms underlying these processes are genetically controlled in both males and females. A genetic analysis of male pattern generators in the central nervous system has been previously explored, however a genetic analysis of the feature detection circuit in female crickets has yet to be conducted.
Hybridization studies, where male and female crickets belonging to two similar yet distinct species are bred to produce hybrid offspring, have shown that within one generation the hybrid male offspring produce a mating call that is an intermediate hybrid between the calls of the two original parental males. They also demonstrated that within one generation hybrid females show a behavioral preference for these hybrid male calls over those of males from either of the two original parental species. Both of these findings strongly suggest that the mechanisms of production and perception of mating calls are completely genetically controlled, with no possibility of learned behavior playing a role in this phenomenon.
The ability for conspecifics to communicate through sound effectively implies that the sender and receiver must be coordinated in some way. The sender must produce a sound that is detectable by the receiver and any changes in the signal-generating mechanisms of the sender should be matched by parallel changes in the signal-recognition mechanisms of the receiver. Two main hypotheses regarding the mechanism that controls this necessary process are the “genetic coupling” and “coevolution” hypotheses. The existence of behavioral coupling in first generation hybrids supports the genetic coupling hypothesis; however, support for this theory is limited due to the lack of research regarding genetic mechanisms that might control the coupling of male production and female perception of sound.
The purpose of this project was to obtain funding in order to replicate two specific hybridization studies that support this genetic coupling hypothesis and to see if the behavioral results were comparable to those recorded in the original studies. The replication study would provide preliminary data that could be included in a second grant proposal for a study that would seek to determine the genetic mechanisms underlying the functioning of the auditory feature detection circuit in female crickets. This research, combined with existing genetic analyses of male pattern generators, would contribute to our understanding of the mechanisms that allow for conspecific male and female crickets to effectively communicate and may provide further support for the genetic coupling hypothesis, which is a possible explanation for the communication systems of multiple other animal species as well.