POLYGENIC INHERITANCE OF A BEHAVIORAL PHENOTYPE: INTERSPECIFIC GENETICS OF SONG IN THE HAWAIIAN CRICKET GENUS LAUPALA.

The Hawaiian cricket genus Laupala (family Gryllidae) is one of several native genera of flightless crickets found in rain-forest habitat across the Hawaiian archipelago. Species in this genus are morphologically quite similar, but the songs produced by adult males are acoustically distinct. I examined the nature of song variation found within Laupala paranigra and between Laupala kohalensis and L. paranigra, both endemic to the island of Hawaii. Variation within and among species was most notable in the temporal structure of the song, as quantified by the pulse rate. The variation in pulse rate present in natural populations of L. paranigra bred true through the F1 laboratory generation, suggesting that the intraspecific variation in this species has a genetic basis. Interspecific hybridizations between L. kohalensis and L. paranigra successfully produced F1 , F2 , and backcross generations. Hybrid F1 males from reciprocal crosses sang with significantly different pulse rates, implicating an X chromosomal contribution to the phenotypic difference between these species. Interspecific patterns of inheritance are most consistent with a type-I genetic architecture. Polygenic inheritance of the interspecific pulse-rate variation was observed, and approximately eight genetic factors were estimated to underlie the difference in pulse rate between L. kohalensis and L. paranigra. © 1996 The Society for the Study of Evolution.