Friday, April 17, 2015

Lab Meeting on Quantitative Genetics

This week in lab meeting we will have a discussion on quantitative genetics. Anna Nordén will present some preliminary results from her PhD work in the hermaphroditic worm, Macrostomum lignano. She is conducting a quantitative genetics study in which she investigated the heritability of fitness through female and male sex roles. Additionally, I suggest that we discuss the following paper that attempts to synthesize quantitative genetic studies with studies of DNA sequence variability in Drosophila.

Hope to see you there! I'll bring fika.

Figure from Bank et al. 2014: Two hypothetical Distributions of fitness effects (DFE) of all possible new mutations.

Causes of natural variation in fitness: Evidence from studies of Drosophila populations

Brian Charlesworth

    DNA sequencing has revealed high levels of variability within most species. Statistical methods based on population genetics theory have been applied to the resulting data and suggest that most mutations affecting functionally important sequences are deleterious but subject to very weak selection. Quantitative genetic studies have provided information on the extent of genetic variation within populations in traits related to fitness and the rate at which variability in these traits arises by mutation. This paper attempts to combine the available information from applications of the two approaches to populations of the fruitfly Drosophila in order to estimate some important parameters of genetic variation, using a simple population genetics model of mutational effects on fitness components. Analyses based on this model suggest the existence of a class of mutations with much larger fitness effects than those inferred from sequence variability and that contribute most of the standing variation in fitness within a population caused by the input of mildly deleterious mutations. However, deleterious mutations explain only part of this standing variation, and other processes such as balancing selection appear to make a large contribution to genetic variation in fitness components in Drosophila.

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