Comparing fossil and extant beetles in central North Island forests, New Zealand

Restoration efforts around New Zealand provide safe havens for native species that have been seriously compromised since the arrival of people and introduced mammals approximately 750 yrs ago. Maungatautari in the Waikato is currently the largest area of almost (except for mice) mammal-free estate on the New Zealand mainland. We examined attributes, such as beetle size variation, dispersal ability and trophic structure, of the beetle community at Maungatautari and compared it with the fossil beetle assemblage from two central North Island sites where forest was preserved under up to 2 m of tephra and volcanic ash from the Taupo eruption (232 ± 5 AD (1718 ± 5 cal. yr BP)) prior to the introduction of mammals. A total of 334 fossil, and 206 extant, beetle species were found. No difference was observed between the trophic composition and dispersal ability of taxa within the beetle communities sampled from pre-mammal ecosystem compared with Maungatautari. Greater numbers of large species were found at Maungatautari compared to the two fossil sites. However, this disguised the loss of several large flightless ground-dwelling weevil species that were found as fossils but are now considered extinct. Surprisingly, only 1.2% of the fossil beetle species identified are now thought to be extinct. The fossil beetle assemblages from the central North Island are invaluable datasets that describe the pre-mammal beetle fauna and provide an important benchmark for assessing restoration outcomes in New Zealand forest ecosystems.