Chromosomal dynamics of Gastrimargus

Abstract

Chromosome number and morphology have been regarded as most constant properties of a species both within and between different individuals. This is also, true of short-horned grasshoppers The concept of absolute karyotypic stability entails an evolutionary cul-de-sac, and therefore a relative stability alone can afford scope for further genotypic change. Though it is known that spontaneous chromosomal mutations in stable genetic systems is low, yet chromosomal variations within an organism is as common as between organisms within a population. However, a re-organization of a karyotype to attain a better homeostatic stability depends not only on the incidence of structural and numerical anomalies but also on their subsequent survival. Such selective incorporation of anomalies are claimed in orthopterans. The incorporation of anomalies into a genetic system is as much a measure of karyotypic plasticity as it affords the starting point of further evolutionary change. Cytological examination of the two species of Gastrimargus, G. transversus and G. africanus orientalis (Family, Acrididae; Order, Orthoptera) collected locally (Mysore, India) has clearly shown the karyotypic dynamism.