Species status and population genetic structure of the flightless chafer beetles Prodontria modesta and P. bicolorata (Coleoptera; Scarabaeidae) from South Island, New Zealand


  • This paper is part of a PhD thesis by Brent Emerson at the Department of Zoology, University of Otago. Research is being carried out to investigate the phylogenetic relationships within the flightless genus Prodontria and relating these to the biogeographic patterns seen in other southern New Zealand plant and animal groups. Graham Wallis is a lecturer in genetics at the above address. He leads an evolutionary genetics research team with interests centred around the genetic analysis of hybrid zones, the biogeography and phylogenetic relationships of New Zealand endemics, and molecular analysis of co-evolution.


This study uses isozyme electrophoresis to investigate the systematic status of two rare flightless chafer beetle species, Prodontria modesta and P. bicolorata, currently distinguished solely on the basis of colour. Seven polymorphic loci were analysed for the species in sympatry and allopatry. In sympatry, gene frequencies imply no genetic barrier between the two colour forms. Wright's hierarchical F-statistics were calculated to determine how the genetic variation is partitioned across the geographic range of the two species. Strong geographic structuring occurs at the population level but there is little genetic differentiation attributable to species. Comparisons of morphological measurements are in support of the electrophoretic results. The systematic significance of the two distinct colour forms is thus questionable. Under the biological, recognition or phylogenetic species concepts, the genetic data suggest that there is only one species, polytypic for a colour pattern. Most of the genetic diversity of this group of beetles lies within and among populations, which differ quite markedly over their geographic range, rather than between the two named species.