Īrenas, Trends in substitution models of molecular evolution, Front. Availability and implementation All datasets are deposited in Figshare. Therefore, the bias introduced by the use of the GTR + Γ model to analyze datasets, in which the time-reversibility and stationarity assumptions are violated, is likely not large and can be reduced by applying multiple calibrations. Confidence and credibility intervals from GTR + Γ analysis usually contained correct times. The use of only a few calibrations reduced these biases considerably (∼5%). Divergence times obtained using a GTR + Γ model differed only slightly (∼3% on average) from the expected times for NR datasets, but the difference was larger for NS datasets (∼10% on average). We tested Bayesian and RelTime approaches that do not require a molecular clock for estimating divergence times. Results We quantified the bias on time estimates that resulted from using the GTR + Γ model for the analysis of computer-simulated nucleotide sequence alignments that were evolved with non-stationary (NS) and non-reversible (NR) substitution models. Many reports have quantified the impact of violations of these underlying assumptions on molecular phylogeny, but none have systematically analyzed their impact on divergence time estimates. Frequently the same General Time Reversible (GTR) model across lineages along with a gamma (+Γ) distributed rates across sites is used in relaxed clock analyses, which assumes time-reversibility and stationarity of the substitution process. No software tools for molecular dating allow researchers to relax these two assumptions in their data analyses. By now, racing Skylines had straight-six, turbocharged engines, which in racing trim would push out some 500bhp.Abstract Motivation As the number and diversity of species and genes grow in contemporary datasets, two common assumptions made in all molecular dating methods, namely the time-reversibility and stationarity of the substitution process, become untenable. For the public, the R32 Skyline GT-R introduced an all-wheel-drive system – the catchily-titled Advanced Total Traction Engineering System for All-terrain with Electronic Torque Split, better known as ATTESA ET-S. Together with the RB26DETT 2.6-litre twin-turbo engine (officially with 276bhp but often with much more), this system formed a template that can still be found in the latest GT-R, mixing bags of power with torque and traction at whatever end of the car you needed it. Skyline GT-R – The standard car, sold from 1989 Power and grip would become hallmarks of the GT-R name. Skyline GT-R Nismo – A homologation model built in 1990 to satisfy racing regulations. They featured a Nismo bodykit, different turbochargers and no ABS. Nissan also offered Nismo components to owners so they could upgrade their standard car to Nismo spec.įor others though, the R33’s timeline coincided very nicely with the release of a videogame with which the GT-R badge would later become synonymous. Sony’s Gran Turismo had been five years in the making and was unveiled in 1997. For many, it brought the Skyline into their bedroom and gave a huge boost to a name that had previously been largely the preserve of JDM nerds. The R33 has been a mainstay of every GT game since. Skyline GT-R LM Limited – In 1996, Nissan celebrated its return to the 24 Hours of Le Mans by building 188 special edition R33s. The LM Limited cars were spread over standard and V-Spec models, all with Champion Blue paint and commemorative stickers, as well as extra bodywork on the front and a carbon fibre spoiler. Skyline GT-R Great Britain V-Spec – Sold only in the UK, 97 V-Spec models were made and modified by the UK dealer, Middlehurst of St Helens. These cars had extra cooling for the gearbox, rear diff and transfer box, UK-spec bumpers to house the legally required indicators, sidelights and so on, and UK-spec headlights.