Dating the time of origin of major clades Cam 2 cam nude caht
Despite a rich fossil record, most recent time calibrations of pine divergences have used very few (usually 1–3) fossils [11, 13, 15, 16, 18] (but see ).Some of these fossils are controversial regarding their phylogenetic assignment and age (e.g. belgica as discussed in ), leading to inconsistent age estimates of the origin of pines and divergence times of subsections therein.Sound estimations of divergence times within phylogenetic trees benefit from using many fossils that are evenly distributed across the tree, a strategy that better accounts for rate variation when using relaxed molecular clock models [19–21].In addition, multiple calibrations can overcome negative effects from errors in dating and placement of single fossils .No conclusion has been reached to date as to whether estimated divergence times are in agreement between the two methods [44–46].
The sets of dated phylogenetic trees of pines presented here provide a way to account for uncertainties in age estimations when applying comparative phylogenetic methods.
However, there is no objective way to define the calibration densities and researchers have used different approaches to define them [19, 37, 38, 40].
Recently, the fossilized birth-death (FBD, hereafter) method has been introduced as a new approach for time calibration of molecular phylogenetic trees [41, 42].
We find the origin of crown Pinus is likely up to 30 Myr older (Early Cretaceous) than inferred in most previous studies (Late Cretaceous) and propose generally older divergence times for major clades within Pinus than previously thought.
Our age estimates vary significantly between the different dating approaches, but the results generally agree on older divergence times.
Subsequent studies have improved phylogenetic resolution, but have mostly focused on specific subclades (e.g.  and provided better resolution for much of the tree.