Cytogenetics of the parthenogenetic grasshopper Warramaba virgo and its bisexual relatives

Abstract

Cloned highly repeated DNA sequences were used to investigate the origins of W. virgo. The chromosomal and genomic organization of these sequences in the parthenogenetic grasshopper W. virgo and its sexual relatives indicate that W. virgo has had two independent origins. Data from the cloned sequences together with that from rapidly renaturing DNA are consistent with a hybridization event between two sexual species for each origin of the parthenogenetic species. Previously published data on C-banding and other karyotypic features (White and Contreras 1981) strengthen the dual origin conclusion. — The cloned DNA sequences, pWv 1 and pWv 5, have differentiated northern and southern races in the sexual species P196. The southern race appears to have hybridized with another sexual species, P169, to give rise to the Boulder/Zanthus clones of W. virgo. The northern race of P196 may have crossed with a species similar to P169 to give rise to the remaining W. virgo clones which are now present in both eastern and western Australia. White (1980) proposed that the origin of W. virgo was in western Australia and that the eastern populations were established by migration. Consistent with this hypothesis is our finding that the cloned DNA sequences have identical genomic and chromosomal organisation in populations of W. virgo in the two disjunct areas.