Intraspecific karyotype variation is not concordant with allozyme variation in the Auckland tree weta of New Zealand, Hemideina thoracica (Orthoptera: Stenopelmatidae)

Abstract

Nine karyotypes are described within a single species of common New Zealand tree weta. Their diploid numbers range from 11 to 25. The distribution of the karyotypes suggests that each had a single origin except the 17-karyotype which was the most common karyotype and had a disjunct distribution. The overall level of allozyme diversity observed is similar to that seen within many widespread taxa. The distribution of allozyme alleles did not coincide with the distribution of karyotypes within this species and the Neighbour-Joining tree was not concordant with the chromosome based sub-divisions of the species. Thus, no evidence was found to suggest that chromosomal differentiation has been acting as a barrier to the flow of alleles within H. thoracica. The lack of concordance of genetic markers is thought to result from rapid chromosome radiation and reticulate evolution. Northland peninsula of North Island, New Zealand is a region of high chromosomal and allozymic diversity in H. thoracica. This may have resulted from geographic isolation during the Pliocene when Northland formed an archipelago of many small low-lying islands.