Dating dispersal and radiation in the gymnosperm gnetum Show my self cam 2 cam sex with others free

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.Using ancient fossils to calibrate genetic distances in molecular phylogenies can be problematic, because the older a fossil is, the more likely it is to represent an extinct lineage that diverged somewhere along the line leading to the extant taxon with which it is being compared (37).However, probability distributions on fossil calibration ages allow some manipulation of this uncertainty (38), and judicious use of multiple fossils also may help circumvent calibration pitfalls (39).Around 160–138 million years ago (Ma) (1, 3), Pangea broke up into two supercontinents: Laurasia, comprising land that eventually gave rise to North America, Europe, and much of Asia, and Gondwana, made up of land that subsequently gave rise to South America, Africa, India, Antarctica, and Australia.Biostratigraphic data suggest that Late Triassic and Early Jurassic Pangea had a warm and equable climate without glaciation or sea ice and that it lacked significant geographic barriers from pole to pole (4).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).

Blue lines represent Cupressoideae restricted to the area of Laurasian continents.The fossil record shows that gymnosperms dominated the vegetation of Pangea but declined in dominance and abundance from the Mid-Cretaceous onwards (11, 12).Perhaps because of the extinction of entire clades, molecular-clock studies of gymnosperms consistently have inferred young, usually Oligocene, ages for the crown groups of living genera, e.g., –31).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.

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