Mostrando recursos 1 - 4 de 4

  1. Quantitative genetics of functional characters in Drosophila melanogaster populations subjected to laboratory selection

    Teotónio, H; Matos, M; Rose, MR
    What are the genetics of phenotypes other than fitness, in outbred populations? To answer this question. the quantitative-genetic basis of divergence was characterized for outbred Drosophila melanogaster populations that had previously undergone selection to enhance characters related to fitness. Line-cross analysis using first-generation and second-generation hybrids from reciprocal crosses was conducted for two types of cross, each replicated fivefold. One type of cross was between representatives of the ancestral population, a set of five populations maintained for several hundred generations on a two-week discrete-generation life cycle and a set of five populations adapted to starvation stress. The other type of...
    - 08-jul-2016

  2. Genetic variation for outcrossing among Caenorhabditis elegans isolates

    Teotónio, H; Manoel, D; Phillips, PC
    The evolution of breeding systems results from the existence of genetic variation and selective forces favoring different outcrossing rates. In this study we determine the extent of genetic variation for characters directly related to outcrossing, such as male frequency, male mating ability, and male reproductive success, in several wild isolates of the nematode Caenorhabditis elegans. This species is characterized by an androdioecious breeding system in which males occur with hermaphrodites that can either self-fertilize or outcross with males. We find genetic variation for all characters measured, but also find that environmental variation is a large fraction of the total phenotypic...
    - 08-jul-2016

  3. Selection against males in Caenorhabditis elegans under two mutational treatments

    Manoel, D; Carvalho, S; Phillips, PC; Teotónio, H
    Within populations with mixed mating systems, selfing is expected to be favoured over outcrossing unless a countervailing process such as severe inbreeding depression is present. In this study, we consider the relationship between the expression of deleterious alleles and the maintenance of outcrossing in the nematode species, Caenorhabditis elegans. This species is characterized by an androdioecious breeding system composed of males at low frequency and self-fertilizing hermaphrodites that can only outcross via males. Here, we find that experimentally increasing the mutational load in four different isogenic wild isolates using 10 generations of Ethylmethane sulphonate (EMS) and UV irradiation mutagenesis significantly...
    - 08-jul-2016

  4. Experimental evolution reveals natural selection on standing genetic variation

    Teotónio, H; Chelo, IM; Bradic, M; Rose, MR; Long, AD
    Evolution depends on genetic variation generated by mutation or recombination from standing genetic variation. In sexual organisms, little is known about the molecular population genetics of adaptation and reverse evolution(1-11). We carry out 50 generations of experimental reverse evolution in populations of Drosophila melanogaster, previously differentiated by forward evolution, and follow changes in the frequency of SNPs in both arms of the third chromosome. We characterize the effects of sampling finite population sizes and natural selection at the genotype level. We demonstrate that selection has occurred at several loci and further that there is no general loss or gain of...
    - 07-jul-2016

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