I was interested in sharing this article because it is highly relevant to the material we've been covering in lecture. We've moved from talking mostly about proximate questions about animal communication to now learning about ultimate mechanisms in animal communication systems.



Insects make great models for studying the evolution of communication systems for many reasons that include their enormous fecundity, short generation time, and their ability to produce multiple generations of offspring in a single year. Teleogryllus oceanicus is a field cricket from the Hawaiian Islands that uses two mating strategies due to the presence of a phonotactic parasitoid fly that orients to the auditory signals that males use to attract females. Some males however, instead of making calls to attract females, move towards calling males and attempt to intercept the females that are attracted to sound. These satellite males are distinct from the calling males because they have a morphological mutation whereby their sound producing apparatus is non-functional.

Normally such a mutation might be selected against because it would typically inhibit those males carrying that mutation from attracting females. However, silent males move towards the sound of calling which is a behavioral adaptation that accompanies the mutation and probably allows the alleles that code for this morphological mutation to persist in populations of crickets. Scientists from the University of California Riverside have been investigating the relationship between the behaviors of the crickets and the flatwing mutation. They believed that the behavioral adaptation of silent males to move towards calling males (phonotactic satellite behavior) must have evolved previous to the mutation that rendered them unable to produce sound.

This hypothesis was tested by comparing the phonotactic behavior of silent males in the Hawaiian populations to crickets in the ancestral population (Australian islands) that do not coexist with the selection pressure presented by the deadly parasitoid fly. They found that all populations contained individuals with the satellite behavior and that even individuals without the morphological mutation that renders them silent were phonotactic. The authors conjecture that the satellite behavior likely has an adaptive value regardless of whether is it associated with the flatwing mutation.

Tinghitella, R. M. 2008. Rapid evolutionary change in sexual signal: genetic control of the mutation "flatwing" that renders male field crickets (Teleogryllus oceanicus) mute. Heredity 100: 261-267.

Tinghitella, R. M., Jeffery M. Wang and Marlene Zuk. 2009. Prexisting behavior renders a mutation adaptive: flexibility in male phonotaxis behavior and the loss of singing ability in the field cricket Teleogryllus oceanicus. Behavioral Ecology 20 (4): 722-728.

Posted by: Anna Rorkeski