Biology subjects

Adam Eyre-Walker

Publications and source records attributed to Adam Eyre-Walker.

3 recordsLinked to original sources

bioRxiv2016

Mito-nuclear Incompatibilities and Mitochondrial Replacement Therapy

Mitochondrial replacement therapy (MRT) is a human reproductive technology by which the mitochondria of a recipients eggs are effectively replaced by those of a donor, potentially eliminating harmful mitochondrial mutations carried by the recipient. However, concerns have been raised that MRT may lead to problems due to incompatibilities between the nuclear genome of the recipient and mitochondrial genome of the donor. Whether this is likely to be a problem is investigated using 226 estimates, taken from the literature, of the effect of replacing the \"native\" by a \"foreign\" mitochondrial DNA (mtDNA) from the same species in a variety of animals. In approximately half of the cases (45%), strains with the foreign mtDNA have higher fitness than those with the native mtDNA, and on average the native strains are only 3% fitter. Based on these results it is argued that incompatibilities between the mitochondrial and nuclear genomes are not likely to be a problem for MRT.

Genetics↗

bioRxiv2015

Adaptive evolution is substantially impeded by Hill-Robertson interference in Drosophila

It is known that rates of mutation and recombination vary across the genome in many species. Here we investigate whether these factors affect the rate at which genes undergo adaptive evolution both individually and in combination and quantify the degree to which Hill-Robertson interference (HRi) impedes the rate of adaptive evolution. To do this we compiled a dataset of 6,141 autosomal protein coding genes from Drosophila, for which we have polymorphism data from D. melanogaster and divergence out to D. yakuba. We estimated the rate of adaptive evolution using a derivative of the McDonald-Kreitman test that controls for the slightly deleterious mutations. We find that the rate of adaptive amino acid substitution is positively correlated to both the rates of recombination and mutation. We also find that these correlations are robust to controlling for each other, synonymous codon bias and gene functions related to immune response and testes. We estimate that HRi reduces the rate of adaptive evolution by [~]27%. We also show that this fraction depends on a genes mutation rate; genes with low mutation rates lose [~]11% of their adaptive substitutions while genes with high mutation rates lose [~]43%. In conclusion, we show that the mutation rate and the rate of recombination, are important modifiers of the rate of adaptive evolution in Drosophila.

Evolutionary Biology↗

bioRxiv2015

Molecular evolutionary consequences of island colonisation

Island endemics are likely to experience population bottlenecks; they also have restricted ranges. Therefore we expect island species to have small effective population sizes (Ne) and reduced genetic diversity compared to their mainland counterparts. As a consequence, island species may have inefficient selection and reduced adaptive potential. We used both polymorphisms and substitutions to address these predictions, improving on the approach of recent studies that only used substitution data. This allowed us to directly test the assumption that island species have small values of Ne. We found that island species had significantly less genetic diversity than mainland species; however, this pattern could be attributed to a subset of island species that had undergone a recent population bottleneck. When these species were excluded from the analysis, island and mainland species had similar levels of genetic diversity, despite island species occupying considerably smaller areas than their mainland counterparts. We also found no overall difference between island and mainland species in terms of effectiveness of selection or mutation rate. Our evidence suggests that island colonisation has no lasting impact on molecular evolution. This surprising result highlights gaps in our knowledge of the relationship between census and effective population size.

Evolutionary Biology↗