Evolution and taxonomic significance of the copulatory apparatus in Ensifera (Orthoptera). Part 1: General concepts and origin

Abstract

The importance of using copulatory characters in generic and higher taxonomy (not only in species taxonomy) is discussed in the light of the recent “genital clock” concept which should partly replace the old “lock-and-key” theory. This concept assumes that evolutional changes in the copulatory apparatus (if it is sufficiently complicated) follow after genetic drift, and that these processes occur at a more uniform rate than changes in the characters of external morphology, ecological properties and many other biological traits, since structure of this apparatus is less dependent upon the situation in the ecosystem. Evolution of the copulatory apparatus in the suborder Ensifera and in its ancestors may be divided into three hypothetical stages reflected in some morphological features: 1) a highly hypothetical stage without copulation and without a copulatory apparatus in the most ancient (extinct) orthopteroid insects; 2) the appearance of different organs in early Orthoptera serving for fixation of partners during copulation and for insertion of the spermatophore in the female genital chamber; 3) the development of complicated organ with consolidation of these functions.