Molecular clock dating
Our divergence estimates are congruent with other independent studies in dating Gondwanan geological events.Although different analyses retrieved similar results for the internal relationships within the Heterotardigrada, our results indicated that the molecular dating of tardigrades using genes coding for ribosomal RNA (18S and 28S r DNA) is a complex task, revealed by a very wide range of posterior density and a relative difficulty in discriminating between competing models.This theory also provided an important null model of molecular evolution, but was not without its critics.
Although Zuckerkandl and Pauling provided evidence for a linear relationship between the accumulation of amino acid differences and evolutionary time, they did not provide an explanation for “why” they observed this pattern.The origin of the Antarctic continental extant fauna is a highly debated topic, complicated by the paucity of organisms for which we have clear biogeographic distributions and understanding of their evolutionary timescale.To shed new light on this topic, we coupled molecular clock analyses with biogeographic studies on the heterotardigrade Mopsechiniscus genus.Several steps involve in Bayesian dating analysis, importantly including data partitioning, specifying evolutionary model, calibrating internal nodes or fossils, and setting priors for the tree and the molecular clock model. Hereby, I demonstrate the molecular clock dating functionalities in Mr Bayes 3.2 step by step, while focusing on total-evidence dating, using an example dataset truncated from the Hymenoptera data analyzed in Ronquist et al.
The ability of HIV-1 to escape from immune surveillance in many different directions is the driving force of molecular clock persistence.