AN UNUSUAL MITOCHONDRIAL-DNA POLYMORPHISM IN THE CHORTHIPPUS-BIGUTTULUS SPECIES GROUP (ORTHOPTERA, ACRIDIDAE)

Mitochondrial DNA restriction fragment patterns have been used to inve stigate the Chorthippus biguttulus group: a group of morphologically s imilar grasshopper species with very distinct male calling songs. Ten haplotypes were identified in 21 populations, representing six species . Haplotype diversity was as great within species, and in same case wi thin populations, as it was among species and no clear geographical pa tterns of haplotype distribution were revealed. In the light of grassh opper range changes since the last glaciation it is unlikely that thes e data can be explained entirely by the retention of ancestral polymor phism. This suggests that hybridization has occurred during periods of grasshopper range expansion since the last glacial maximum, allowing mtDNA transfer between populations that have previously diverged in al lopatry.