Nodes, estimated ages

Divergence Time Estimates Showing Estimated Ages of Nodes Supported by 95% or Higher Posterior Probability in the Phylogenetic Analyses... 

One way to assess the placement of ambiguous taxa on the GAC is to attempt to date each event in each taxon-area cladogram and then place ambiguous nodes and taxa in accordance with those estimated ages. At this point, we begin to enter a new level of consilience studies, one in which we look to minimise the difference between data and model, between reason and experience, and between what is and what ought to be. This is because our means of dating evolutionary events rely on inference, models of reason, rather than direct experience. 

Mastocytosis is a disorder characterized by increased numbers of mast cells in the skin, bone marrow, gastrointestinal tract, Uver, spleen, and lymph nodes [9,10]. The prevalence is unknown the incidence has been roughly estimated to be 3-7 new patients per million per year [9]. Most cases are sporadic with only a limited number (50-100) of cases with mastocytosis reported to pass from generation to generation [11], Mastocytosis presents at any age, although most cases occur during the first 2 years of life (childhood-onset) or after puberty (adult-onset) [9]. Mastocytosis in childhood often is self-limited and involves only the skin, whereas the course in patients with adult-onset disease is normally chronic and includes systemic involvement. 

Note Node numbers correspond to those on the chronogram (Figure 17.1). Point estimates are from analyses of the all-compatible majority rule consensus tree and posterior probability values are rep ted. The Mode value represents the most likely divergence lime value under the specified model (obtained by local density estimation calculated over the 100 random frees drawn from the posterior distribution of trees and parameters), and the HPD values limits the confidence interval for the estimates. ( node constrained j age estimates show bimodal distribution across the 100 random trees > age distribution with a pronounced right tail across the 100 random frees)... 

The majority of the moss fossil record cannot provide us with useful information about the possible ages of nodes, for the most part being too recent or too poorly characterized to be used as constraints or to contribute much to our understanding of the timing and sequence of evolutionary events (Krassilov and Schuster, 1984 Miller, 1984). However, our age estimates can possibly suggest something about our interpretation of the fossils. Only fossils credibly considered to be pleurocarpous are discussed here (see also Ignatov and Shcherbakov, Chapter 16). 

Recent theoretical developments (e.g. Sanderson, 1997,2002 Near and Sanderson, 2004 Thome et al., 1998 Thome and Kishino, 2002 Lavin, Chapter 19) can place an estimated dimension of absolute time on phylogenetic trees dmved from DNA sequaice data, and potentially distinguish between recent evolutionary radiations and older events (see Lavin, Chapter 19). If an age can be assigned to a single node in a phylogenetic tree using external evidence, these methods can estimate the ages of all other... 

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