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SummaryThe epidemiological paradox and 'healthy migrant effect' refer to the favourable health outcomes in unprivileged groups under unfavourable socioeconomic conditions. Weight at birth is associated with the epidemiological paradox. However, differences in fertility structure (mainly mother's age and first maternity) might be the cause of the difference in weight at birth between children of immigrant and non-immigrant mothers. This paper aims to analyse the impact of the epidemiologic paradox by distinguishing between the factors related to fertility structure, in addition to other socio-cultural factors. The importance of fertility structure as the cause of weight-at-birth differences of the newborns of immigrant and non-immigrant women, and between those of subgroups of immigrant mothers, is tested. Based on data from birth registries for the period 1998–2009, a variance analysis was performed for Spanish mothers and for those of five major immigrant subgroups living in the region of Valencia, Spain, which experienced significant migrant inflows within a short period of time. A Scheffé test between pairs of nationalities was carried out. Finally, linear regression models were built. The results suggest that the most relevant factors are those related to fertility structure, and that consequently the epidemiological paradox does not apply for immigrant mothers as a whole, although Bolivian immigrant offspring may be an exception. This unexpected result requires further research to test to what extent this is due to the special adaptation of multigenerational high-altitude populations in pregnancy. The factors associated with fertility structure must be controlled when trying to relate birth weight differences between ethnic groups to socioeconomic factors.

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. The images in this article are included in the article's Creative Commons license, unless indicated otherwise in the image credit; if the image is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the image. ; The distribution of mutational fitness effects (DMFE) is crucial to the evolutionary fate of quasispecies. In this article we analyze the effect of the DMFE on the dynamics of a large quasispecies by means of a phenotypic version of the classic Eigen's model that incorporates beneficial, neutral, deleterious, and lethal mutations. By parameterizing the model with available experimental data on the DMFE of Vesicular stomatitis virus (VSV) and Tobacco etch virus (TEV), we found that increasing mutation does not totally push the entire viral quasispecies towards deleterious or lethal regions of the phenotypic sequence space. The probability of finding regions in the parameter space of the general model that results in a quasispecies only composed by lethal phenotypes is extremely small at equilibrium and in transient times. The implications of our findings can be extended to other scenarios, such as lethal mutagenesis or genomically unstable cancer, where increased mutagenesis has been suggested as a potential therapy. ; This work was partially funded by the Botin Foundation (JS, RVS), by the Spanish Secretaria de Estado de Investigacion, Desarrollo e Innovacion grants MTM2010-16425 (CS, RM) and BFU2012-30805 (SFE), by grant 2009-SGR-67 from the Catalan government (CS, RM), by grant NSF PHY05-51164 (JS, SFE), and by the Santa Fe Institute (RVS, SFE). ; Peer Reviewed

1 9 4 ; S Lengauer, C., Kinzler, K. W. & Vogelstein, B. Genetic instabilities in human cancers. Nature 396, 643–649 (1998). Cahill, D. P., Kinzler, K. W., Vogelstein, B. & Lengauer, C. Genetic instability and darwinian selection in tumours. Trends Cell. Biol. 9, M57–60 (1999). ; [EN] The distribution of mutational fitness effects (DMFE) is crucial to the evolutionary fate of quasispecies. In this article we analyze the effect of the DMFE on the dynamics of a large quasispecies by means of a phenotypic version of the classic Eigen's model that incorporates beneficial, neutral, deleterious, and lethal mutations. By parameterizing the model with available experimental data on the DMFE of Vesicular stomatitis virus (VSV) and Tobacco etch virus (TEV), we found that increasing mutation does not totally push the entire viral quasispecies towards deleterious or lethal regions of the phenotypic sequence space. The probability of finding regions in the parameter space of the general model that results in a quasispecies only composed by lethal phenotypes is extremely small at equilibrium and in transient times. The implications of our findings can be extended to other scenarios, such as lethal mutagenesis or genomically unstable cancer, where increased mutagenesis has been suggested as a potential therapy. We thank the members of the Complex Systems Lab as well as Phillip Gerrish, Susanna C. Manrubia, and Ernest Fontich for their helpful comments. The authors acknowledge the computing facilities of the Dynamical Systems Group (Universitat de Barcelona). This work was partially funded by the Botin Foundation (JS, RVS), by the Spanish Secretaria de Estado de Investigacion, Desarrollo e Innovacion grants MTM2010-16425 (CS, RM) and BFU2012-30805 (SFE), by grant 2009-SGR-67 from the Catalan government (CS, RM), by grant NSF PHY05-51164 (JS, SFE), and by the Santa Fe Institute (RVS, SFE). Eigen, M. Self-organization of matter and the evolution of biological macromolecules. Naturwiss. 58, 465–523 (1971). Eigen, M. & ...

[EN] The distribution of mutational fitness effects (DMFE) is crucial to the evolutionary fate of quasispecies. In this article we analyze the effect of the DMFE on the dynamics of a large quasispecies by means of a phenotypic version of the classic Eigen's model that incorporates beneficial, neutral, deleterious, and lethal mutations. By parameterizing the model with available experimental data on the DMFE of Vesicular stomatitis virus (VSV) and Tobacco etch virus (TEV), we found that increasing mutation does not totally push the entire viral quasispecies towards deleterious or lethal regions of the phenotypic sequence space. The probability of finding regions in the parameter space of the general model that results in a quasispecies only composed by lethal phenotypes is extremely small at equilibrium and in transient times. The implications of our findings can be extended to other scenarios, such as lethal mutagenesis or genomically unstable cancer, where increased mutagenesis has been suggested as a potential therapy. ; We thank the members of the Complex Systems Lab as well as Phillip Gerrish, Susanna C. Manrubia, and Ernest Fontich for their helpful comments. The authors acknowledge the computing facilities of the Dynamical Systems Group (Universitat de Barcelona). This work was partially funded by the Botin Foundation (JS, RVS), by the Spanish Secretaria de Estado de Investigacion, Desarrollo e Innovacion grants MTM2010-16425 (CS, RM) and BFU2012-30805 (SFE), by grant 2009-SGR-67 from the Catalan government (CS, RM), by grant NSF PHY05-51164 (JS, SFE), and by the Santa Fe Institute (RVS, SFE). ; Sardanyes Cayuela, J.; Simó, C.; Martínez, R.; Solé, RV.; Elena Fito, SF. (2014). Variability in mutational fitness effects prevents full lethal transitions in large quasispecies populations. Scientific Reports. (4):1-9. doi:10.1038/srep04625 ; S ; 1 ; 9 ; 4 ; Eigen, M. Self-organization of matter and the evolution of biological macromolecules. Naturwiss. 58, 465–523 (1971). ; Eigen, M. & Schuster, P. The ...

The distribution of mutational fitness effects (DMFE) is crucial to the evolutionary fate of quasispecies. In this article we analyze the effect of the DMFE on the dynamics of a large quasispecies by means of a phenotypic version of the classic Eigen's model that incorporates beneficial, neutral, deleterious, and lethal mutations. By parameterizing the model with available experimental data on the DMFE of Vesicular stomatitis virus (VSV) and Tobacco etch virus (TEV), we found that increasing mutation does not totally push the entire viral quasispecies towards deleterious or lethal regions of the phenotypic sequence space. The probability of finding regions in the parameter space of the general model that results in a quasispecies only composed by lethal phenotypes is extremely small at equilibrium and in transient times. The implications of our findings can be extended to other scenarios, such as lethal mutagenesis or genomically unstable cancer, where increased mutagenesis has been suggested as a potential therapy. ; This work was partially funded by the Botín Foundation (JS, RVS), by the Spanish Secretaria de Estado de Investigación, Desarrollo e Innovación grants MTM2010-16425 (CS, RM) and BFU2012-30805 (SFE), by grant 2009-SGR-67 from the Catalan government (CS, RM), by grant NSF PHY05-51164 (JS, SFE), and by the Santa Fe Institute (RVS, SFE).