Dating the time of origin of major clades dating while legally separated in north carolina
In addition, multiple calibrations can overcome negative effects from errors in dating and placement of single fossils .
In the genus , a rich fossil record exists, with the first fossil appearing in the Early Cretaceous [3, 4].
However, despite the detailed chloroplast data and the availability of potential fossil calibration points, comprehensive time-calibrated molecular phylogenetic trees remain lacking.
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].
We currently lack a dated molecular phylogeny that makes use of the rich pine fossil record, and this study is the first to estimate the divergence dates of pines based on a large number of fossils (21) evenly distributed across all major clades, in combination with applying both node and tip dating methods. Our age estimates vary significantly between the different dating approaches, but the results generally agree on older divergence times.
In addition to older divergence times in , our results also indicate that node age estimates in pines depend on dating approaches and the specific fossil sets used, reflecting inherent differences in various dating approaches.
However, there is no objective way to define the calibration densities and researchers have used different approaches to define them [19, 37, 38, 40].
The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.) is widely accepted and a robust gene tree based on entire plastome sequences exists.Besides Mesozoic pine fossils [3, 4, 23–26], numerous fossils have been described from the Cenozoic era and were placed within various pine clades [27–32].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 ).Many studies have focused on this genus, particularly with regard to its phylogenetic relationships [1, 5–10], ecology [11, 12], biogeography [13, 14], and the timing of diversification events .There exists a wealth of molecular, morphological and fossil data on the genus.