Dating the time of origin of major clades
However, our data cannot reject vicariance to explain South America-Australia disjunctions. There is a long-standing debate on the extent of vicariance and long-distance dispersal events to explain the current distribution of organisms, especially in those with small diaspores potentially prone to long-distance dispersal.
Phylogenetic analyses were performed using DNA sequences of nu LSU and mt SSU r DNA, and the protein-coding gave a rate two to four times higher than nu LSU and mt SSU.
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By providing a context for understanding the gaps in the angiosperm fossil record this technique lends credibility and support to the remainder of the angiosperm record and to its applications in understanding a variety of aspects of angiosperm history.
In effect, this methodology empowers the fossil record.
In contrast, a few authors have invoked plate tectonics and emphasized vicariance to explain distribution patterns of lichens, especially for species occurring in the Southern Hemisphere –.In view of these limitations, attempts to use the fossil record to corroborate phylogenetic hypotheses based on extensive comparisons among extant taxa may be misplaced.Instead we suggest a method—minimum age node mapping—for combining reliable fossil evidence with hypotheses of phylogeny.Divergence times of the major clades were estimated with partitioned BEAST analyses allowing different rates for each DNA region and using a relaxed clock model.Three calibrations points were used to date the tree: an inferred age at the stem of Lecanoromycetes, and two dated fossils: Parmelia in the parmelioid group, and Alectoria.