Cytogenetics of two interspecific synthetic hybrids of the grasshopper genus Euchorthippus

Abstract

The spermatogenesis of two synthetic hybrid individuals of the grasshopper genus Euchorthippus was studied by C-banding methods. One resulted from the cross Euchorthippus pulvinatus ♂ × Euchorthippus chopardi ♀ (p/c), whereas the other one was produced in the cross E. chopardi ♂ × E. pulvinatus ♀ (c/p). The two parental sets of chromosomes were always recognized according to their different C-banding patterns. Chiasma frequency was decreased in both hybrids when compared with the parental species, this decrease being more accentuated in the hybrid individual c/p, where univalents at metaphase I were frequent. Chiasmata were formed between homoeologous chromosomes, and only two multivalent associations were observed. Polyploid spermatids and some micronuclei were a common feature in both hybrids. It is suggested that C-heterochromatin differences do not play any important role in the speciation process: genie differences between parental genomes are probably more important.Key words: synthetic hybrid, Euchorthippus, C-heterochromatin, meiotic pairing, reproductive isolating mechanisms.