Search results for "evolutionary"
showing 10 items of 4392 documents
Signals of major histocompatibility complex overdominance in a wild salmonid population
2009
The major histocompatibility complex (MHC) contains the most variable genes in vertebrates, but despite extensive research, the mechanisms maintaining this polymorphism are still unresolved. One hypothesis is that MHC polymorphism is a result of balancing selection operating by overdominance, but convincing evidence for overdominant selection in natural populations has been lacking. We present strong evidence consistent with MHC-specific overdominance in a free-living population of Arctic charr (Salvelinus alpinus) in northernmost Europe. In this population, where just two MHC alleles were observed, MHC heterozygous fish had a lower parasite load, were in better condition (as estimated by a…
Signals from the deep-sea: Genetic structure, morphometric analysis, and ecological implications of Cyclothone braueri (Pisces, Gonostomatidae) early…
2020
Abstract Cyclothone braueri (Stomiiformes, Gonostomatidae) is a widely distributed fish inhabiting the mesopelagic zone of marine tropical and temperate waters. Constituting one of the largest biomasses of the ocean, C. braueri is a key element in most of the ecological processes occurring in the twilight layer. We focused on the ecological processes linked to early life stages in relation to marine pelagic environmental drivers (temperature, salinity, food availability and geostrophic currents) considering different regions of the Central Mediterranean Sea. A multivariate morphometric analysis was carried out using six parameters with the aim of discerning different larval morphotypes, whi…
Identifying gene-environment interactions in schizophrenia: contemporary challenges for integrated, large-scale investigations
2014
European Community Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G x E), however, so far, thorough replication of findings is rare and G x E research still faces several conceptual and methodological challenges. in this article, we aim to review these recent developments and illustrate h…
"Table 4" of "Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV"
2014
Integrated elliptic flow at sqrt(sNN) = 2.76 TeV for centrality 20-30%.
Harmonizing circumpolar monitoring of Arctic fox: benefits, opportunities, challenges and recommendations.
2017
Source at http://dx.doi.org/10.1080/17518369.2017.1319602 The biodiversity working group of the Arctic Council has developed pan-Arctic biodiversity monitoring plans to improve our ability to detect, understand and report on long-term change in Arctic biodiversity. The Arctic fox (Vulpes lagopus) was identified as a target of future monitoring because of its circumpolar distribution, ecological importance and reliance on Arctic ecosystems. We provide the first exhaustive survey of contemporary Arctic fox monitoring programmes, describing 34 projects located in eight countries. Monitored populations covered equally the four climate zones of the species’ distribution, and there were large dif…
Forward Kinematic Modelling with Radial Basis Function Neural Network Tuned with a Novel Meta-Heuristic Algorithm for Robotic Manipulators
2022
The complexity of forward kinematic modelling increases with the increase in the degrees of freedom for a manipulator. To reduce the computational weight and time lag for desired output transformation, this paper proposes a forward kinematic model mapped with the help of the Radial Basis Function Neural Network (RBFNN) architecture tuned by a novel meta-heuristic algorithm, namely, the Cooperative Search Optimisation Algorithm (CSOA). The architecture presented is able to automatically learn the kinematic properties of the manipulator. Learning is accomplished iteratively based only on the observation of the input–output relationship. Related simulations are carried out on a 3-Degrees…
Evolutionary selection and variation in family businesses
2011
PurposeThis qualitative study attempts to understand what kinds of evolutionary selection and variation occur in family businesses during the preparation of a managerial and ownership succession.Design/methodology/approachThe study was conducted by interviewing members of one family business in Louisiana, USA and one in Finland in order to contribute to the understanding of succession preparation in small family businesses with two generations. Evolutionary economics was adapted for this interdisciplinary study to explain evolutionary changes in a family business succession.FindingsThe findings indicate that both selection and variation can take place through different routes during the pre…
Chance and Necessity
2015
In Chance and Necessity Monod masterfully spans the divide between humanities and sciences. For Monod, unlike subsequent renowned popularisers, science was one thing but what science evoked was quite another; he claimed that we should take the logic of science as far as it allowed. In this chapter, I revisit Monod’s reflections on Bergson —as did the famous evolutionary biologist Mayr —and I suggest that this philosopher’s vitalist theory should be reconsidered in the light of modern Biology, as should Driesch’s Embriology. The thesis on the need to give similar importance to both the parts of a biological entity as to the interactions between them is discussed within a wider context.
Prenatal androgen exposure modulates cellular and humoral immune function of black-headed gull chicks
2005
Avian eggs contain considerable amounts of maternal yolk androgens, which have been shown to beneficially influence the physiology and behaviour of the chick. As androgens may suppress immune functions, they may also entail costs for the chick. This is particularly relevant for colonial species, such as the black-headed gull (Larus ridibundus), in which the aggregation of large numbers of birds during the breeding season enhances the risk of infectious diseases for the hatching chick.To test the effect of maternal yolk androgens on the chick's immune function, we experimentally manipulated, in a field study, yolk androgen levels within the physiological range by in ovo injection of either a…
Experimental introgression to evaluate the impact of sex specific traits onDrosophila melanogasterincipient speciation
2019
ABSTRACTSex specific traits are involved in speciation but it is difficult to determine whether their variation initiates or reinforces sexual isolation. In some insects, speciation depends of the rapid change of expression in desaturase genes coding for sex pheromones. Two closely related desaturase genes are involved inDrosophila melanogasterpheromonal communication:desat1affects both the production and the reception of sex pheromones whiledesat2is involved in their production in flies of Zimbabwe populations. There is a strong asymmetric sexual isolation between Zimbabwe populations and all other “Cosmopolitan” populations: Zimbabwe females rarely copulate with Cosmopolitan males whereas…