The answers to many biological questions depend on accurate dating methods. In recent years, molecular clocks have been used frequently to establish biological divergence dates. However, their application has been controversial ever since the idea was first introduced by Pauling and Zuckerkandl more than 30 years ago. One of the major problems with molecular clock-estimates is that we know that DNA often does not evolve in a clock-like manner. New Bayesian techniques have recently become available that allow molecular dating even when evolution is not clock-like. These techniques are only now being tested. The New Zealand cicadas provide an excellent system for exploring these methods for many reasons. First, we now have well-supported molecular trees for the five endemic NZ genera and their Australian and New Caledonian relatives, as well as for the 14 species in the genus Maoricicada and for most of the 22 species in the genus Kikihia. Second, the roots of these trees are better established than those in most taxonomic groups. Third, landscape and climatic changes in NZ are dramatic, well-studied and provide potential calibration points for molecular dating. The fourth and most important advantage is that Kikihia and Maoricicada lineages can be calibrated independently to give estimates of the date of arrival of their ancestors. Initial analyses suggest that these genera diverged from each other approximately 9-10 +/- 3 MYA and that they arrived in NZ shortly before this. The molecular data strongly support the hypothesis that the closest relatives of these NZ cicada genera are New Caledonian. This fits well with a third independent piece of geological information suggesting that an island connection between NZ and NC was broken in the Mid-Miocene approximately 14-20 MYA.
Keywords: Cicadas New Zealand
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA