CHIASMA FREQUENCIES AND DISTRIBUTIONS IN GOMPHOCERINE GRASSHOPPERS - A COMPARATIVE-STUDY BETWEEN SEXES

Frequency and position of chiasmata at metaphase I were studied in spermatocytes and oocytes from six species of gomphocerine grasshoppers (2n♂ = 16 + XO; 2n♀ = 16 + XX), namely: Omocestus panteli, Euchorthippus pulvinatus, Euchorthippus chopardi, Chorthippus vagans, Chorthippus parallelus and Chorthippus jucundus. In the latter species mean cell chiasma frequency was similar in both sexes. However in the remainder chiasma frequencies were higher in males than in females. Within each species different bivalents are responsible for the sex chiasma differences that can be interpreted as a relatively simple bivalent based system of chiasma control. Chiasmata were non-localised in both sexes of all species analysed but females showed altered chiasma distributions compared with males, with fewer proximal chiasmata and more interstitial and distal chiasmata. © 1990 The Genetical Society of Great Britain.