Data from: Inflation of molecular clock rates and dates: molecular phylogenetics, biogeography, and diversification of a global cicada radiation from Australasia (Hemiptera: Cicadidae: Cicadettini)

Dated phylogenetic trees are important for studying mechanisms of
diversification, and molecular clocks are important tools for studies of
organisms lacking good fossil records. However, studies have begun to
identify problems in molecular clock dates caused by uncertainty of the
modeled molecular substitution process. Here we explore Bayesian
relaxed-clock molecular dating while studying the biogeography of ca. 200
species from the global cicada tribe Cicadettini. Because the available
fossils are few and uninformative, we calibrate our trees in part with a
cytochrome oxidase I (COI) clock prior encompassing a range of literature
estimates for arthropods. We show that tribe-level analyses calibrated
solely with the COI clock recover extremely old dates that conflict with
published estimates for two well-studied New Zealand subclades within
Cicadettini. Additional subclade analyses suggest that COI relaxed-clock
rates and maximum-likelihood branch lengths become inflated relative to
EF-1α intron and exon rates and branch lengths as clade age increases. We
present corrected estimates derived from (1) an extrapolated EF-1α exon
clock derived from COI-calibrated analysis within the largest New Zealand
subclade, (2) post-hoc scaling of the tribe-level chronogram using results
from subclade analyses, and (3) exploitation of a geological calibration
point associated with New Caledonia. We caution that considerable
uncertainty is generated due to dependence of substitution estimates on
both the taxon sample and the choice of model, including gamma category
number and the choice of empirical versus estimated base frequencies. Our
results suggest that diversification of the tribe Cicadettini commenced in
the early- to mid-Cenozoic and continued with the development of open,
arid habitats in Australia and worldwide. We find that Cicadettini is a
rare example of a global terrestrial animal group with an Australasian
origin, with all non-Australasian genera belonging to two distal clades.
Within Australia, we show that Cicadettini is more widely distributed than
any other cicada tribe, diverse in temperate, arid and monsoonal habitats,
and nearly absent from rainforests. We comment on the taxonomic
implications of our findings for thirteen cicada genera.