On Adaptive Accuracy and Precision in Natural Populations

Abstract

Adaptation is usually conceived as the fit of a population mean to a fitness optimum. Natural selection, however, does not act only to optimize the population mean. Rather, selection normally acts on the fitness of individual organisms in the population. Furthermore, individual genotypes do not produce invariant phenotypes, and their fitness depends on how precisely they are able to realize their target phenotypes. For these reasons we suggest that it is better to conceptualize adaptation as accuracy rather than as optimality. The adaptive inaccuracy of a genotype can be measured as a function of the expected distance of its associated phenotype from a fitness optimum. The less the distance, the more accurate is the adaptation. Adaptive accuracy has two components: the deviance of the genotypically set target phenotype from the optimum and the precision with which this target phenotype can be realized. The second component, the adaptive precision, has rarely been quantified as such. We survey the literature to quantify how much of the phenotypic variation in wild populations is due to imprecise development. We find that this component is often substantial and highly variable across traits. We suggest that selection for improved precision may be important for many traits.

Mechanisms underlying parallel reductions in aerobic capacity in non-migratory threespine stickleback (Gasterosteus aculeatus) populations

“…However, evolutionary theory (e.g. Garland, 1998;Hansen et al, 2006) and recent intraspecific empirical studies (e.g. Gonzalez et al, 2006;Chappell et al, 2007;Gębczynski and Konarzewski, 2011) argue that this is not the case.…”

The effect of inbreeding on fluctuating asymmetry of wing veins in two laboratory strains of Drosophila melanogaster

“…Hansen et al (2006) Inbreeding and asymmetry of Drosophila wing veins AJR Carter et al were unable to do. The relative magnitude of the error terms are too low to account for a full 50% reduction and the full cause of these lower V d values remains unclear.…”

“…The coefficient of variation (CV; standard deviation divided by the mean) of FA provides a measure of variation in DI, if CV(FA) exceeds 75.6% then real differences in DI between individuals is implied (Palmer and Strobeck, 2003). To compare the amounts of phenotypic variance that is due to FA with those found in other studies, we computed the between-individual variance among wings that is due to differences between wings on the same individual (V d ) as (Hansen et al, 2006). This value measures the importance of DI; dividing V d by overall phenotypic variance makes the impact of DI comparable with genetic and environmental factors.…”

“…Reviews of natural and laboratory populations (Lajus et al, 2003;Hansen et al, 2006) have shown that variance in the realized trait due to different levels of DI account for a mean of 31 or 15% of the overall trait variance, respectively. Differences in population DI may affect the evolutionary potential of populations by influencing their phenotypic variances in a manner that is neither directly environmental nor caused by genotypic variation for the mean value of the trait in question.…”

Adaptive accuracy of temperature oviposition preferences in newts

“…oviposition rates) and developing embryos. In this study, we used the recent concept of adaptive accuracy (the deviation of phenotype from its local optimum) proposed by Hansen et al (2006), as well as the method of quantifying predictability in a temperature time series by decomposing its total variation into predictable and non-predictable components (Měráková and Gvoždík 2009), to test the following two predictions: (1) Preferred oviposition temperatures fit closely to phenotypic optima at the water surface rather than to optima at the maximum depth (hereinafter bottom), and (2) surface temperatures provide more reliable cues about future thermal environment than the bottom temperatures at the time of oviposition.…”