Sentences with phrase «effective population size»
Together with analyses of mtDNA protein evolution, these data suggest that the long - term effective population size of Neandertals was smaller than that of modern humans and extant great apes.
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Changes to dn / ds in some of these domestic / wild animal comparisons may be the result of reductions in effective population size leading to relaxation in selective forces.
Many higher order vertebrates have low effective population sizes resulting from reduced efficiency of selection [10], suggesting that neutral or mildly deleterious mutations such as some transposon insertions can easily reach fixation.
The Kennel Club quotes the findings of the Food & Agriculture Organisation of the United Nations, «Breeding strategies for sustainable management of animal genetic resources» (2010) in expressing the relationship between effective population size and the sustainability of breeds thus:
The rate at which new mutations appear in a genome (sizes of circles) is inversely proportional to the so - called effective population size of the species.
Applying high - throughput sequencing technologies to obtain sequences from most of the genome, we calculated that the passenger pigeon's effective population size throughout the last million years was persistently about 1/10, 000 of the 1800's estimated number of individuals, a ratio 1,000 - times lower than typically found.
Using the SLAC algorithm implemented in HyPhy [34], the island group had a substantially higher mean dN / dS ratio (0.40) than mainland only (0.10), suggesting a signal of positive selection or the relaxation of selective forces associated with a decline in effective population size [35].
McGowen explained that this feature «has been connected to mammals with similar life histories, such as species with large generation times, large parental investment, and small effective population size.
Comparison of these sequences with present day humans suggests that Neandertals had a long term low effective population size.
However, this method entails many uncertainties, such as the extent of ancestral polymorphisms, effective population size, and generation time.
Today, 7.6 billion people inhabit Earth, but population geneticists focus on the effective population size, which is the number of people it took to produce the genetic variation seen today.
In 2008 a federal recovery plan stated that the white abalone «was driven to such low levels during the height of the commercial fishery that adults do not occur in high enough densities to successfully reproduce, contributing to repeated recruitment failure and an effective population size near zero.»
As a wildlife conservationist, I am very interested in understanding what makes an «effective population size»: that fraction of a population that is fertile, actively reproducing, and able to produce the next generation.
This could result from neutral processes if the effective population size of males is reduced relative to females due to a higher variance in the number of offspring from males than from females.
We estimated the neutral mutation parameter (4Neμ for autosomal loci and 3Neμ for X-linked loci), where Ne is the effective population size and μ is the mutation rate per site per generation, using two estimators: Watterson's θw [67], the proportion of segregating sites in a sample, and π [68], the average number of pairwise differences per sequence in a sample.
Effective population sizes (Ne) in rabbits are on the order of 106 [21].
Since males of N. giraulti tend to mate more frequently with their sisters than males of N. longicornis [87], [88], a smaller effective population size is expected for N. giraulti.
The increase in genetic diversity that Rogers and his colleagues found corresponds to a roughly tenfold increase in effective population size.
In population genetics, effective population size is not a direct measure of the total number of people that lived at a given time.
However, in such cases, the effective population size may be much smaller due to the level of correlations between neurons, which could affect the ability to average out noise across neuronal populations [17 — 20], and due to the relationship between the average neuronal firing rate and the time window over which stimuli are processed, which could affect the ability to temporally average out noise [21].
The figures are: out of 152 breeds with annual registrations above 50 dogs, 84 (55 %) have an effective population size (Ne) of less than 100, and 36 (24 %) have a Ne of less than 50.
Conservation biologists have recently raised the Ne (effective population size) from 50 to 100 unrelated individuals needed to maintain a sustainable breeding population.
Conditions not relating directly to breed standards account for over 75 % of all inherited disorders in pedigree dogs [24] and have been attributed to breed formation and small effective population size, the repeated use of popular sires and inbreeding.
In addition, by eliminating some animals from breeding, a reduction in the effective population size will occur, thus risking higher levels of inbreeding, potential founder effects and genetic bottlenecks.
The island populations differ in two variables that affect genetic variation: effective population size and duration of isolation.
We estimate that the effective population size of foxes on the islands varies from approximately 150 to 1,000 individuals.