Morphological Differentiation among Neighboring Populations in the Brachypterous Grasshopper Parapodisma subastris (Orthoptera : Acrididae)

This study examined morphological differentiation of the brachypterous grasshopper Parapodisma subastris among three neighboring populations, using univariate and multivariate analyses. Functionless fore and hind wings exhibited a larger variability than did other characters. The length of male cerci, a part of genitalia, varied less among populations than did that of female cerci. This low variability in male genitalia may be ascribed to stabilizing selection acting on male genitalia. Factor analysis suggested that genitalia and degenerated wings were distinguished from the other characters in the intensity of correlations. In spite of the vicinity of the populations, discriminant analysis showed that 94%-100% of population members were correctly classified into the populations to which they belonged. This suggests that the opportunities of migration among the populations are limited enough to lead to genetic differentiation.