The Habitat and Phenetic Variation in Phymata Americana Melin (Heteroptera)

Abstract

Mason, L. G. (Dept. of Biol. Sciences, State Univ. of New York at Albany, Albany, N.Y. 12203) 1973. The Habitat and Phenetic Variation in Phymata americana Melin. Syst. Zool. 22:271-279.-In natural populations of Phymata americana year-to-year variation in a character measuring shape (i.e., amount of sculpturing of the exoskeleton) is slight or nonexistent in relatively undisturbed habitats similar to those in which the insects have presumably evolved. In areas associated with urbanization and agriculture, substantial (and statistically significant) year-to-year variation occurs. Year-to-year and locality-to-locality variation of thorax width (selected as a size measure) was more complicated, but again variation tended to be less predictable in disturbed than in undisturbed habitats. The interpretation put on these findings is that a stabilization of traits related to fitness (perhaps a more perfect canalization of traits) occurs in habitats to which the populations have become acclimated as regards genetic and developmental processes. Amounts of individual variation did not differ in the two types of habitats. A character chosen to represent the color pattern did not show the differences between habitat-types indicated for structural characters. The possible relationship between this result and the similar phenetic differences between geographically marginal and central populations of another insect species is discussed. [Phymata; habitat; variation.]