Environmental quality and evolutionary potential: lessons from wild populations

Abstract

An essential requirement to determine a population's potential for evolutionary change is to quantify the amount of genetic variability expressed for traits under selection. Early investigations in laboratory conditions showed that the magnitude of the genetic and environmental components of phenotypic variation can change with environmental conditions. However, there is no consensus as to how the expression of genetic variation is sensitive to different environmental conditions. Recently, the study of quantitative genetics in the wild has been revitalized by new pedigree analyses based on restricted maximum likelihood, resulting in a number of studies investigating these questions in wild populations. Experimental manipulation of environmental quality in the wild, as well as the use of naturally occurring favourable or stressful environments, has broadened the treatment of different taxa and traits. Here, we conduct a meta-analysis on recent studies comparing heritability in favourable versus unfavourable conditions in non-domestic and non-laboratory animals. The results provide evidence for increased heritability in more favourable conditions, significantly so for morphometric traits but not for traits more closely related to fitness. We discuss how these results are explained by underlying changes in variance components, and how they represent a major step in our understanding of evolutionary processes in wild populations. We also show how these trends contrast with the prevailing view resulting mainly from laboratory experiments on Drosophila. Finally, we underline the importance of taking into account the environmental variation in models predicting quantitative trait evolution.

Intraspecific genetic variation and competition interact to influence niche expansion

“…(b) Behavioural and evolutionary niche expansion Many studies show that genetic variation has a greater impact on population parameters under strong selection (reviewed in Wise et al 2002;Armbruster & Reed 2005;Charmantier & Garant 2005). Our results contribute to this literature by showing that the impact of genetic variation also depends on the degree of intraspecific resource competition.…”

Changes in the expression of genetic characteristics across cohorts in skeletal deformations of farmed salmonids

“…The most consistent explanation for this pattern is that genetic variation has not been effectively eroded by natural selection in the novel environment [4,17]. This may also apply to our observations, but it is difficult to relate these explanations to domestic animals with a short history in captivity.…”

“…Several studies have shown elevated genetic variation for continuously varying traits, such as body size, in stressful or novel environmental conditions, though opposite observations exist especially for wild populations (reviewed by [4,15,16]). The most consistent explanation for this pattern is that genetic variation has not been effectively eroded by natural selection in the novel environment [4,17].…”

Genetic analysis of tolerance to infections using random regressions: a simulation study

“…In contrast to pathogen-induced changes, changes in heritabilities due to other biotic (e.g. diet) and abiotic factors have been a focus of active research (Kause & Morin, 2001 ;Charmantier & Garant, 2005). The focus here was on the analysis of field data, but the statistical method presented is applicable to experimental treatments as well.…”