The Evolution of Genetic Architecture

Abstract

Genetic architecture, the structure of the mapping from genotype to phenotype, determines the variational properties of the phenotype and is instrumental in understanding its evolutionary potential. Throughout most of the history of evolutionary biology, genetic architecture has been treated as a given set of parameters and not as a set of dynamic variables. The past decade has seen renewed interest in incorporating the genotype-phenotype map as a dynamical part of population genetics. This has been aided by several conceptual advances. I review these developments with emphasis on recent theoretical work on the evolution of genetic architecture and evolvability.123 Annu. Rev. Ecol. Evol. Syst. 2006.37:123-157. Downloaded from www.annualreviews.org by University of Sussex on 10/02/12. For personal use only.

Genetic analysis of an ephemeral intraspecific hybrid zone in the hypervariable tree, Metrosideros polymorpha, on Hawai‘i Island

“…Finally, the lack of a genetic correlation between leaf length and width for var. glaberrima suggests that leaf shape in this variety should be more flexible in response to selection (Hansen, 2006). This conclusion is consistent with the purported evolution of the stenophyllous (that is, narrow)-leaved, riparian var.…”

“…Within species, genetic architecture can be shaped by selection operating on key adaptive traits, and it contributes significantly to the evolutionary trajectories of complex phenotypes (Sinervo and Svensson, 2002;Hansen, 2006). For example, taxa with broad ecological niches (for example, generalists) may have greater phenotypic and genetic variation and lower genetic correlations than specialists in which selection has favored stronger genetic correlations among key traits (Grant and Grant, 1994;Sinervo and Svensson, 2002).…”

“…For taxa with contrasting genetic correlational structures, introgression is expected to weaken genetic correlations within taxa (Grant and Grant, 1994). Overall, hybridization can increase population evolvability through elevated genetic variation and altered genetic architectures (Hansen, 2006) while facilitating ecological diversification through the generation of novel combinations of adaptive traits (Grant and Grant, 1994;Seehausen, 2004).…”

Evolving neural fields for problems with large input and output spaces

“…Although duplication can generate modular and redundant structures, it increases the genome size. The other way of generating repeated structure, called cooption, is to employ a gene or groups of genes in new contexts (Hansen, 2006). This does not increase genome size significantly.…”

The Effects of Stabilizing and Directional Selection on Phenotypic and Genotypic Variation in a Population of RNA Enzymes

“…However, this is not necessarily the case. Whether it does depends on several factors, including the shape -convex or concave -of the fitness function (Layzer 1978), the distribution of trait values (Bürger 1991;Hansen 1992), whether a trait optimum fluctuates with time, the presence and kind of genotype-by-environment interactions (Hermisson and Wagner 2004), the existence of epistatic interactions among loci (Hansen 2006), and the extent of phenotypic canalization before the onset of directional selection (de Visser et al 2003;Hermisson and Wagner 2004). The change in phenotypic variance caused by periods of stabilizing selection is no easier to predict.…”