Search results for "selection"
showing 10 items of 1940 documents
Mitochondrial DNA effects on fitness in Drosophila subobscura
2011
We tested different fitness components on a series of conspecific mtDNA haplotypes, detected by RFLPs in Drosophila subobscura. Additionally, haplotype VIII, endemic to the Canary Islands, was tested upon its own native nuclear DNA background and upon that of the rest of mtDNAs tested herein. We found that both nuclear and mitochondrial DNA can have a significant effect upon their hosts' fitness, and that negative selection is one of the mechanisms that can intervene in this species' mtDNA haplotype pattern. We discuss the importance of this mechanism in relation to genetic drift, in the form of periodic population bottlenecks, and how the latter can enhance the former. We also detected a s…
Molecular and ecological signs of mitochondrial adaptation: consequences for introgression?
2013
The evolution of the mitochondrial genome and its potential adaptive impact still generates vital debates. Even if mitochondria have a crucial functional role, as they are the main cellular energy suppliers, mitochondrial DNA (mtDNA) introgression is common in nature, introducing variation in populations upon which selection may act. Here we evaluated whether the evolution of mtDNA in a rodent species affected by mtDNA introgression is explained by neutral expectations alone. Variation in one mitochondrial and six nuclear markers in Myodes glareolus voles was examined, including populations that show mtDNA introgression from its close relative, Myodes rutilus. In addition, we modelled prote…
Assortative mating and fertility in two Drosophila subobscura strains with different mitochondrial DNA haplotypes.
2003
The mating pattern and female fertility on the two main mitochondrial DNA haplotypes (I and II) of Drosophila subobscura were studied, in an attempt to find possible differences between them in relation to sexual selection or isolation that could explain the populational dynamics and the co-existence of these two strains in nature. The mating pattern indicated an assortative mating in population cages, where couples of the same haplotype, mainly those of haplotype I, mated more often. However, the significations detected in laboratory conditions disappeared in wild populations, where random mating was the rule. The female fertility also showed differences in the laboratory compared to the w…
Mining parasite data using genetic programming.
2005
Genetic programming is a technique that can be used to tackle the hugely demanding data-processing problems encountered in the natural sciences. Application of genetic programming to a problem using parasites as biological tags demonstrates its potential for developing explanatory models using data that are both complex and noisy.
Not Only for Egg Yolk—Functional and Evolutionary Insights from Expression, Selection, and Structural Analyses of Formica Ant Vitellogenins
2014
Vitellogenin (Vg), a storage protein, has been extensively studied for its egg-yolk precursor role, and it has been suggested to be fundamentally involved in caste differences in social insects. More than one Vg copy has been reported in several oviparous species, including ants. However, the number and function of different Vgs, their phylogenetic relatedness, and their role in reproductive queens and nonreproductive workers have been studied in few species only. We studied caste-biased expression of Vgs in seven Formica ant species. Only one copy of conventional Vg was identified in Formica species, and three Vg homologs, derived from ancient duplications, which represent yet undiscovered…
Generic Inhibition of the Selected Movement and Constrained Inhibition of Nonselected Movements during Response Preparation
2014
Abstract Previous studies have identified two inhibitory mechanisms that operate during action selection and preparation. One mechanism, competition resolution, is manifest in the inhibition of the nonselected response and attributed to competition between candidate actions. The second mechanism, impulse control, is manifest in the inhibition of the selected response and is presumably invoked to prevent premature response. To identify constraints on the operation of these two inhibitory mechanisms, we manipulated the effectors used for the response alternatives, measuring changes in corticospinal excitability with motor-evoked potentials to TMS. Inhibition of the selected response (impulse …
Towards a resolution of the lek paradox
2001
Genetic benefits in the shape of 'good genes' have been invoked to explain costly female choice in the absence of direct fitness benefits. Little genetic variance in fitness traits is expected, however, because directional selection tends to drive beneficial alleles to fixation. There seems to be little potential, therefore, for female choice to result in genetic benefits, giving rise to the 'lek paradox'. Nevertheless, evidence shows that genetic variance persists despite directional selection and genetic benefits of female choice are frequently reported. A theoretical solution to the lek paradox has been proposed on the basis of two assumptions: that traits are condition-dependent, and th…
Genome-wide patterns of selection in 230 ancient Eurasians
2015
Mathieson, Iain et al.
Mate choice for optimal (k)inbreeding.
2011
Mating between related individuals results in inbreeding depression, and this has been thought to select against incestuous matings. However, theory predicts that inbreeding can also be adaptive if it increases the representation of genes identical by descent in future generations. Here, I recapitulate the theory of inclusive fitness benefits of incest, and extend the existing theory by deriving the stable level of inbreeding in populations practicing mate choice for optimal inbreeding. The parsimonious assumptions of the model are that selection maximizes inclusive fitness, and that inbreeding depression is a linear function of homozygosity of offspring. The stable level of inbreeding that…
Validation of clinical scoring systems ART and ABCR after transarterial chemoembolization of hepatocellular carcinoma.
2016
Abstract Purpose To perform an external validation of the Assessment for Retreatment with Transarterial Chemoembolization (ART) and α-fetoprotein (AFP), Barcelona Clinic Liver Cancer (BCLC), Child–Pugh, and response (ABCR) scores and to compare them in terms of prognostic power. Materials and Methods From 2000 to 2015, 871 patients with hepatocellular carcinoma underwent transarterial chemoembolization at a tertiary referral hospital, and 176 met all inclusion and exclusion criteria for both scores and were analyzed. Nineteen percent (n = 34) had BCLC stage A disease and 81% had stage B disease. Thirty-nine patients (22%) presented with elevated AFP levels. Overall survival was calculated. …