Reversible Plasticity in the Communication System of the Cricket <i>Gryllus rubens</i>

ABSTRACT Many animals display phenotypic plasticity in various traits. The induced changes can lead to the evolution of novel traits. The evolutionary potential of plasticity is heightened if traits are involved that affect reproduction. In many instances, however, it is not known if phenotypic changes are permanent or reversible. I tested if the plastically induced changes in mating songs and song preferences of the cricket, Gryllus rubens were permanent or reversible. This species has two generations per year (spring and fall) and songs and preferences change in parallel between generations as the result of the thermal environment. I reared males and females as juveniles until adulthood at one temperature (“cool” or “warm”), recorded males and tested female preferences for the songs, and then kept the animals for 1 week at the other temperature (“warm” or “cool”) and rerecorded males and retested females to test if the initially induced songs and preferences changed after exposure to the other temperature. The pulse rate of male songs increased significantly after increasing the rearing temperature from “cool” to “warm” and decreased significantly when decreasing the temperature from “warm” to “cool.” Female preference changed significantly and in parallel with the songs, that is, female attraction for the “warm” song increased and that of the “cool” song decreased after increasing the rearing temperature from “cool” to “warm” for 1 week. Females displayed the opposite attraction pattern to the stimuli when reducing the temperature from “warm” to “cool.” Reversible plasticity in G. rubens ' communication could be adaptive to keep it functional in the face of thermal fluctuations within and between reproductive generations. In more general terms, parallel plasticity of songs and preferences allows communication systems to acquire phenotypic variation necessary to evolve, despite the need for both to remain matched.