Restoration of meiotic stability following artificial hybridisation and selection in Teleogryllus (Orth., Gryllidae)

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Abstract
As part of a research project directed at the genetic control of Teleogryllus commodus (Wlk.) in Australia, hybridisation studies have been carried out between T. commodus and the sibling species T. oceanicus (Le Guillou). A cytological examination of a hybrid strain (male progeny of T. commodus × T. oceanicus backcrossed to T. oceanicus) was made in the F4 generation when meiotic stability had been reached. The karyotype was very similar to that of T. oceanicus, suggesting that only those combinations in which the chromosomes were structurally homologous to T. oceanicus survived. But the stridulation pattern of the hybrid males, intermediate between that of the two parental species, and a consistent sex ratio of 2:1 in favour of the males, indicate profound genetic differences from T. oceanicus. These effects are attributed to introgression, with chromosomal material from T. commodus being incorporated in the T. oceanicus genome as an outcome of the initial hybridisation of the two species.