Tag evolution-rate [11 articles]

Abstract

BACKGROUND: A sudden emergence of Influenza A Virus (IAV) infections with a new pandemic H1N1 IAV is taking place since April of 2009. In order to gain insight into the mode of evolution of these new H1N1 strains, we performed a Bayesian coalescent Markov chain Monte Carlo (MCMC) analysis of full-length neuraminidase (NA) gene sequences of 62 H1N1 IAV strains (isolated from March 30th to by July 28th, 2009). RESULTS: The results of these studies revealed that the expansion population growth ...

Abstract

We introduce the Bayesian skyline plot, a new method for estimating past population dynamics through time from a sample of molecular sequences without dependence on a prespecified parametric model of demographic history. We describe a Markov chain Monte Carlo sampling procedure that efficiently samples a variant of the generalized skyline plot, given sequence data, and combines these plots to generate a posterior distribution of effective population size through time. We apply the Bayesian skyline plot to simulated data sets and show ...

Abstract

One of the most widely accepted explanations for floral diversification in angiosperms is the pollinator-shift model developed by Verne Grant and Ledyard Stebbins. According to this model, the most profound changes in floral traits (such as morphology, color, patterning and scent) occur when plants undergo adaptive shifts between pollinator classes. We tested this model through investigations of geographical variation in floral form and pollinator assemblages in the South African annual daisy Gorteria diffusa. This species has elaborate insect-like ornaments on the ...

Abstract

10.1073/pnas.0805039105 Gradual evolution is a common phenomenon in the fossil record of marine microplankton, yet no theoretical model has so far been presented to explain the observed pattern of unidirectionality in trait evolution lasting over tens of millions of generations. Recent molecular genetic data show that the majority of microfossil-producing plankton groups harbors substantial cryptic diversity. Here, we examine the effect of cryptic diversity on apparent rates of lineage evolution. By using a theoretical approach, we show that under resource competition, ...

Abstract

The rate of protein evolution varies more than 1000-fold and, for the past 30 years, it was thought that the rate was determined by protein function. Drummond and co-workers have now shown that a single factor underlying mRNA expression, protein abundance and synonymous codon usage is the chief causal agent of protein evolutionary rate in yeast. It will be interesting to see whether this is shown to be a universal rule for all biological systems. ...

Abstract

We develop models of the rates of evolution at sex-linked and autosomal loci and of the rates of fixation of chromosomal rearrangements involving sex chromosomes and autosomes. We show that the substitution of selectively favorable mutations often proceeds more rapidly for X- or Y-linked loci than for the autosomes, provided that mutations are recessive or partially recessive on the average. Selection acting on a quantitative character is expected to result in similar long-term rates of gene substitution for X-linked and autosomal ...

Abstract

Many phylogenetic comparative methods that are currently widely used in the scientific literature assume a Brownian motion model for trait evolution, but the suitability of that model is rarely tested, and a number of important factors might affect whether this model is appropriate or not. For instance, we might expect evolutionary change in adaptive radiations to be driven by the availability of ecological niches. Such evolution has been shown to produce patterns of change that are different from those modelled by ...

Abstract

Using an appropriately designed and replicated study of a latitudinal influence on rates of evolution, we test the prediction by K. Rohde [(1992) Oikos 65, 514-527] that the tempo of molecular evolution in the tropics is greater than at higher latitudes. Consistent with this prediction we found tropical plant species had more than twice the rate of molecular evolution as closely related temperate congeners. Rohde's climate-speciation hypothesis constitutes one explanation for the cause of that relationship. This hypothesis suggests that mutagenesis ...

Abstract

A recent hypothesis suggests that resting metabolic rate, measured as energy expended per unit body mass per unit time, might be implicated in the rate of nucleotide substitution in animals. Using relative rate tests on DNA-DNA hybridization data from birds, we show that generation time is significantly correlated with genetic distance between members of an ingroup and an outgroup taxon, but that neither metabolic rate nor body mass explain variation consistent with the hypothesis, either alone or with generation time. ...