scholarly journals Phenotypic Selection in Natural Populations: What Limits Directional Selection?

2011 ◽  
Vol 177 (3) ◽  
pp. 346-357 ◽  
Author(s):  
Joel G. Kingsolver ◽  
Sarah E. Diamond
Keyword(s):  
Natural Populations ◽  
Phenotypic Selection ◽  
Directional Selection

Analysis of phenotypic selection among locations in Impatiens pallida and Impatiens capensis

1990 ◽  
Vol 68 (5) ◽  
pp. 1098-1105 ◽  
Author(s):  
Jonathan T. Brassard ◽  
Daniel J. Schoen
Keyword(s):  
Quantitative Traits ◽  
Environmental Heterogeneity ◽  
Light Availability ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Directional Selection ◽  
Impatiens Capensis ◽  
Selection Analysis ◽  
Sib Families ◽  
Selection Of

Selection analysis of a set of quantitative traits was carried out in environmentally similar quadrats within natural populations of Impatiens capensis and Impatiens pallida to examine whether spatially heterogeneous directional selection is detectable when the range of environmental variation is restricted. While 25 of 96 different estimates of directional selection were significantly different from zero, there was only one instance in which directional selection of a quantitative trait was spatially heterogeneous among quadrats within species. The discovery of a low level of spatially heterogeneous selection supports previous results showing that spatially heterogeneous selection in these species is likely due to heterogeneity in abiotic features of the habitat, such as water and light availability, or to environmental factors correlated with these features. Measurements of the same set of characters examined in the selection analysis for 33 self-sib families of I. pallida indicate significant among-family variation in all instances. The evolutionary implications of these findings are discussed. Key words: natural selection, environmental heterogeneity, genetic variation, Impatiens pallida, Impatiens capensis.

scholarly journals The ‘algebra of evolution’: the Robertson–Price identity and viability selection for body mass in a wild bird population

2020 ◽  
Vol 375 (1797) ◽  
pp. 20190359 ◽  
Author(s):  
G. K. Hajduk ◽  
C. A. Walling ◽  
A. Cockburn ◽  
L. E. B. Kruuk
Keyword(s):  
Phenotypic Diversity ◽  
Additive Genetic Variance ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Relative Fitness ◽  
Price Equation ◽  
Genetic Covariance ◽  
Selection Gradient ◽  
Viability Selection ◽  
Temporal Correlations

By the Robertson–Price identity, the change in a quantitative trait owing to selection, is equal to the trait's covariance with relative fitness. In this study, we applied the identity to long-term data on superb fairy-wrens Malurus cyaneus , to estimate phenotypic and genetic change owing to juvenile viability selection. Mortality in the four-week period between fledging and independence was 40%, and heavier nestlings were more likely to survive, but why? There was additive genetic variance for both nestling mass and survival, and a positive phenotypic covariance between the traits, but no evidence of additive genetic covariance. Comparing standardized gradients, the phenotypic selection gradient was positive, β P = 0.108 (0.036, 0.187 95% CI), whereas the genetic gradient was not different from zero, β A = −0.025 (−0.19, 0.107 95% CI). This suggests that factors other than nestling mass were the cause of variation in survival. In particular, there were temporal correlations between mass and survival both within and between years. We suggest that use of the Price equation to describe cross-generational change in the wild may be challenging, but a more modest aim of estimating its first term, the Robertson–Price identity, to assess within-generation change can provide valuable insights into the processes shaping phenotypic diversity in natural populations. This article is part of the theme issue ‘Fifty years of the Price equation’.

scholarly journals Evolution of the additive genetic variance–covariance matrix under continuous directional selection on a complex behavioural phenotype

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151119 ◽  
Author(s):  
Vincent Careau ◽  
Matthew E. Wolak ◽  
Patrick A. Carter ◽  
Theodore Garland
Keyword(s):  
Covariance Matrix ◽  
Adaptive Response ◽  
Genetic Variance ◽  
Environmental Changes ◽  
Wheel Running ◽  
Additive Genetic Variance ◽  
Phenotypic Selection ◽  
Directional Selection ◽  
Genetic Covariance ◽  
Variance Covariance Matrix

Given the pace at which human-induced environmental changes occur, a pressing challenge is to determine the speed with which selection can drive evolutionary change. A key determinant of adaptive response to multivariate phenotypic selection is the additive genetic variance–covariance matrix ( G ). Yet knowledge of G in a population experiencing new or altered selection is not sufficient to predict selection response because G itself evolves in ways that are poorly understood. We experimentally evaluated changes in G when closely related behavioural traits experience continuous directional selection. We applied the genetic covariance tensor approach to a large dataset ( n = 17 328 individuals) from a replicated, 31-generation artificial selection experiment that bred mice for voluntary wheel running on days 5 and 6 of a 6-day test. Selection on this subset of G induced proportional changes across the matrix for all 6 days of running behaviour within the first four generations. The changes in G induced by selection resulted in a fourfold slower-than-predicted rate of response to selection. Thus, selection exacerbated constraints within G and limited future adaptive response, a phenomenon that could have profound consequences for populations facing rapid environmental change.

Is mahogany dysgenically selected?

2005 ◽  
Vol 32 (2) ◽  
pp. 129-139 ◽  
Author(s):  
J.P. CORNELIUS ◽  
C.M. NAVARRO ◽  
K.E. WIGHTMAN ◽  
S.E. WARD
Keyword(s):  
Conservation Status ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Poor Quality ◽  
Selective Logging ◽  
Selected Traits ◽  
Selection Event ◽  
Selection Differentials

One concern in the ongoing debate over the conservation status of mahogany has been the possibility that selective logging, as a form of negative phenotypic selection, might have led to deterioration in the genetic quality of populations. The incidence and degree of such ‘dysgenic’ effects is discussed, based on a consideration of mahogany logging practices, their expected genetic effects and empirical data on phenotypic selection in forest trees. Loggers have tended to avoid diseased, small, very large and poorly-formed individuals, and consequently logging has tended to increase the proportion of poor quality phenotypes relative to that before logging; in at least some conditions, selection differentials have been strongly negative. However, the upper limit for heritability of logger-selected traits in naturally-regenerated mahogany is probably no more than c. 0.1. Consequently, and assuming relatively extreme but realistic negative selection differentials of 50%, the maximum negative dysgenic response to a single logging-mediated phenotypic selection event is expected to be relatively small, i.e. ≤5%. This expectation is consistent with the empirical information from mahogany and other taxa. The implications of any dysgenic effects depend very much on the use and the future of dysgenically-selected populations. In managed populations, dysgenic effects could be reversed through positive selection. In the case of exploited but currently unmanaged natural populations, dysgenic selection is primarily of importance insofar as it affects fitness. As a threat to mahogany conservation and long-term sustainable production, it is probably insignificant in comparison with other genetic and non-genetic factors.

scholarly journals Selection in natural populations V. Indian Rats (Rattus Rattus)

1966 ◽  
Vol 8 (3) ◽  
pp. 261-267 ◽  
Author(s):  
Leigh Van Valen ◽  
Robin Weiss
Keyword(s):  
Environmental Effects ◽  
Rattus Rattus ◽  
Natural Populations ◽  
Directional Selection ◽  
Stabilizing Selection ◽  
Selection Intensity ◽  
Average Difference ◽  
Age Classes ◽  
Tooth Width ◽  
The Difference

In samples of sixteen populations of Rattus rattus from southern India, the oldest individuals have less variable molar widths than the younger ones. This is probably due to stabilizing selection by mortality. There is no detectable heterogeneity between sexes or teeth or among populations in this selection. Although there is no average difference between age classes in mean tooth width, the difference between age classes is heterogeneous among populations. This heterogeneity may reflect heterogeneity in directional selection or in direct environmental effects. The selection intensity on the variance is about 0·04.

scholarly journals Phenotypic selection in common toad (Bufo bufo)

2007 ◽  
Vol 59 (4) ◽  
pp. 327-333 ◽  
Author(s):  
Dragana Cvetkovic ◽  
Natasa Tomasevic ◽  
I. Aleksic ◽  
Andjelka Crnobrnja-Isailovic
Keyword(s):  
Natural Populations ◽  
Phenotypic Selection ◽  
Bufo Bufo ◽  
Leg Length ◽  
Regression Approach ◽  
Selection For ◽  
Correlated Characters ◽  
Toad Bufo ◽  
Toad Bufo Bufo ◽  
Selection Differentials

One of the most important problems for evolutionary biologists is to investigate the patterns and strength of phenotypic selection acting on quantitative traits in natural populations. Measurement of selection is complicated by the presence of correlations between characters; selection on a particular trait produces not only a direct effect, but indirect effects as well. Despite the growing body of phenotypic selection studies in a variety of taxa, studies on amphibians are still sparse. The aim of this study was to estimate patterns and strength of selection acting on a set of correlated characters in a natural population of Bufo bufo from the vicinity of Belgrade, Serbia. Morphological traits (body length, fore- and hind leg length) were measured, while fitness was assayed as fecundity and gonad weight for females and males, respec?tively. The regression approach was used to estimate selection differentials and gradients. Selection patterns differed between the sexes - linear selection differentials showed significant total directional selection for body size in females, but not in males. In males, differentials were significant for both fore- and hind leg lengths. Sample size did not permit identification of significant nonlinear (quadratic) selection.

scholarly journals The effectiveness of phenotypic selection in natural populations: a case study from the Peruvian Amazon

2011 ◽  
Vol 60 (1-6) ◽  
pp. 205-209 ◽  
Author(s):  
J. P. Cornelius ◽  
C. Sotelo Montes ◽  
L. J. Ugarte-Guerra ◽  
J. C. Weber
Keyword(s):  
Good Practice ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Poor Quality ◽  
Seed Collection ◽  
Minimum Quality Standards ◽  
Case Selection ◽  
First Case ◽  
Minimum Quality

AbstractPhenotypic selection is commonly used in agroforestry, both in genetic improvement and as a component of “good practice” in seed collection. In the first case, the aim is to secure genetic gain. In the second case, selection is used to ensure that seed supplies meet given minimum quality standards, or that poor quality sources are avoided. Here we examine the effectiveness of phenotypic selection in natural forest stands of the Amazonian timber and multipurpose treeCalycophyllum spruceanumBenth.. We ask (a) whether mothertrees with high estimated annual height and diameter increments had faster growing progeny than mothertrees with low values; (b) whether forked mother-trees tended to have higher proportions of forked progeny than unforked trees; (c) whether spatially isolated mother-trees tend to produce slower growing progeny than mother-trees growing together with conspecifics. In each case, we found no evidence of differences between the respective groups. We offer explanations for these findings and discuss their implications for tree improvement and seed collection.

scholarly journals Genomic basis of fishing-associated selection varies with population density

2021 ◽  
Vol 118 (51) ◽  
pp. e2020833118
Author(s):  
Amélie Crespel ◽  
Kevin Schneider ◽  
Toby Miller ◽  
Anita Rácz ◽  
Arne Jacobs ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Population Density ◽  
Brain Function ◽  
Natural Populations ◽  
Phenotypic Selection ◽  
Selective Pressures ◽  
Experimental Fish ◽  
Growth Metabolism ◽  
Evolutionary Consequences ◽  
Genomic Basis

Fisheries induce one of the strongest anthropogenic selective pressures on natural populations, but the genetic effects of fishing remain unclear. Crucially, we lack knowledge of how capture-associated selection and its interaction with reductions in population density caused by fishing can potentially shift which genes are under selection. Using experimental fish reared at two densities and repeatedly harvested by simulated trawling, we show consistent phenotypic selection on growth, metabolism, and social behavior regardless of density. However, the specific genes under selection—mainly related to brain function and neurogenesis—varied with the population density. This interaction between direct fishing selection and density could fundamentally alter the genomic responses to harvest. The evolutionary consequences of fishing are therefore likely context dependent, possibly varying as exploited populations decline. These results highlight the need to consider environmental factors when predicting effects of human-induced selection and evolution.

scholarly journals Climate variability slows evolutionary responses of Colias butterflies to recent climate change

2015 ◽  
Vol 282 (1802) ◽  
pp. 20142470 ◽  
Author(s):  
Joel G. Kingsolver ◽  
Lauren B. Buckley
Keyword(s):  
Climate Variability ◽  
Climate Warming ◽  
Fitness Function ◽  
Natural Populations ◽  
Directional Selection ◽  
Climate Data ◽  
Egg Survival ◽  
The Past ◽  
Recent Climate ◽  
Mean Climate

How does recent climate warming and climate variability alter fitness, phenotypic selection and evolution in natural populations? We combine biophysical, demographic and evolutionary models with recent climate data to address this question for the subalpine and alpine butterfly, Colias meadii , in the southern Rocky Mountains. We focus on predicting patterns of selection and evolution for a key thermoregulatory trait, melanin (solar absorptivity) on the posterior ventral hindwings, which affects patterns of body temperature, flight activity, adult and egg survival, and reproductive success in Colias . Both mean annual summer temperatures and thermal variability within summers have increased during the past 60 years at subalpine and alpine sites. At the subalpine site, predicted directional selection on wing absorptivity has shifted from generally positive (favouring increased wing melanin) to generally negative during the past 60 years, but there is substantial variation among years in the predicted magnitude and direction of selection and the optimal absorptivity. The predicted magnitude of directional selection at the alpine site declined during the past 60 years and varies substantially among years, but selection has generally been positive at this site. Predicted evolutionary responses to mean climate warming at the subalpine site since 1980 is small, because of the variability in selection and asymmetry of the fitness function. At both sites, the predicted effects of adaptive evolution on mean population fitness are much smaller than the fluctuations in mean fitness due to climate variability among years. Our analyses suggest that variation in climate within and among years may strongly limit evolutionary responses of ectotherms to mean climate warming in these habitats.

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