Abstract:
Bothrometopus huntleyi is a flightless weevil endemic to the volcanically-formed sub-Antarctic
Prince Edward Islands archipelago that arose approximately 0.5 million years ago (m.y.a.). Since
emergence, a series of volcanic and glaciation events have occurred on Marion Island, whilst Prince
Edward Island, the second island constituting the archipelago, has remained largely unaffected by
glaciation. Cytochrome oxidase I gene analyses indicate that major historical dispersal events in this species
are linked to the geologically discrete histories of these islands and underlie the high haplotype diversity
(0.995) recovered for the Prince Edward Islands archipelago. The estimated time to haplotype coalescence
of,0.723 m.y.a. is in keeping with estimated dates of island emergence, and the majority of individuals
appear to have descended from a relict, high-altitude population that is still present on Marion Island. The
first major inter-island dispersal event occurred,0.507 m.y.a., coinciding with the oldest dated rocks on
Marion Island. Apart from this early inter-island colonization, only one other between-island dispersal
event was detected. The genetically discrete B. huntleyi complexes on each of the islands of the Prince
Edward Islands archipelago together with the low levels of inter-island gene flow reaffirm the need to
control alien invasive mice, which are restricted to Marion Island, and which prey on this weevil species.
