Dating dispersal and radiation in the gymnosperm gnetum
S2 ), a result that is consistent with the effects of undersampling observed elsewhere (47).
Because BEAST allows more complex nucleotide-substitution models than do the other two dating approaches, and because dates from the 56-taxon matrix might be less accurate because of undersampling, the following discussion focuses on the results obtained with the 144-taxon matrix analyzed using BEAST (Fig. S27,000 nucleotides of plastid DNA (144-taxon dataset).
A phylogeny was generated for 122 representatives covering all genera, using up to 10,000 nucleotides of plastid, mitochondrial, and nuclear sequence per species.
Relying on 16 fossil calibration points and three molecular dating methods, we show that Cupressaceae originated during the Triassic, when Pangea was intact.
Nonrandom sampling arises when phylogenies include at least one species per genus but not all congenerics, thereby overrepresenting deep nodes (diversification events) in the tree.
Cupressaceae occur on all continents except Antarctica and comprise 162 species in 32 genera (see Table S2 for subfamilies, genera, and species numbers).
The family has a well-studied fossil record going back to the Jurassic (32–36).
Yellow lines represent species occurring in Africa south of the Sahara. Gray bars represent 95% HPD intervals for nodes 1–10.
Gray (run 1) and purple (run 7) normal distributions represent the posterior for the BEAST age estimate of node 7 when uniform or lognormal priors were applied to calibration points.