Differential developmental programs in two closely related Hawaiian crickets

Hawaiian crickets in the genus Laupala Otte have emerged as a model system in the study of several evolutionary processes, such as the differentiation of signaling phenotypes, the evolution female preferences, and the phylogeographic patterns of speciation. However, very little is understood concerning the basic biology of species within this genus. Here, we document the postembryonic timing of developmental events in two closely related Hawaiian crickets in the genus Laupala. Laupala kohalensis Otte and Laupala paranigra Otte are closely related, exhibit widely divergent pulse rates of the male calling song, and are members of a rapid, recent, and extensive diversification of Hawaiian crickets. In this article, we used morphometric image analysis of developing individuals, from hatching through to adult maturation, to delineate instars in each species. We found that instar duration was consistent across both species, but the number of juvenile ecdysis events differed. L. kohalemis consistently exhibited eight instars. In contrast, L. paranigra exhibited a maximum of seven instars; moreover, half of the individuals experienced only six instars before maturation. A molecular mechanism linking the evolution of song pulse rate and developmental rate is discussed.