Phylogeography of the New Zealand giraffe weevil Lasiorhynchus barbicornis (Coleoptera: Brentidae): A comparison of biogeographic boundaries

摘要

Historic geological and climatic events such as tectonic activity, volcanism and glaciation have significantly impacted the distribution and genetic signature of organisms. In New Zealand, glacial cycles during the late Pliocene and throughout the Pleistocene caused the loss of large areas of forest habitat and many species are proposed to have been restricted to refugia during this period. Here we use mitochondrial DNA (COI, COII) to reconstruct phylogenetic relationships between haplotypes in association with several hypothetical biogeographical lines to determine the impact that past climatic conditions had on the giraffe weevil (Lasiorhynchus barbicornis), an endemic brentine weevil found in native forests across New Zealand. Our analyses revealed that populations in northern New Zealand have higher genetic diversity than those in the south. We compared evidence for genetic structure in relation to four biogeographical lines: Northland Line, Kauri Line, Taupo Line and Cockayne's Line. Although, there was significant difference in genetic variation north and south of all the proposed biogeographic lines, we found most support for the Kauri Line. These results support our hypothesis that giraffe weevils had a restricted range during the Pleistocene, predominantly pushed north into refugia, which was followed by range expansion following glacial retreat.