Life Cycle Origins, Speciation, and Related Phenomena in Crickets

Publisher Website
Google Scholar
Abstract
Seven general kinds of life cycles are known among crickets; they differ chiefly in overwintering (diapause) stage and number of generations/season, or diapauses/generation. Some species with broad north-south ranges vary in these respects, spanning wholly or in part certain of the gaps between cycles and suggesting how some of the differences originated. Species with a particular cycle have predictable responses to photoperiod and temperature regimes that affect behavior, development time, wing length, body size, and other characteristics. Some polymorphic tendencies also correlate with habitat permanence, and some are influenced by population density. Genera and subfamilies with several kinds of life cycles usually have proportionately more species in temperate regions than those with but 1 or 2 cycles, although numbers of species in all widely distributed groups diminish toward the higher latitudes. The tendency of various field cricket species to become double-cycled at certain latitudes appears to have resulted in speciation without geographic isolation in at least one case. Intermediate steps in this allochronic speciation process are illustrated by North American and Japanese species; the possibility that this process has also occurred in other kinds of temperate insects is discussed.

This publication has 1 reference indexed in Scilit: