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 Variation in oleoresin yield and anatomical traits among Sindora glabra populations in Hainan, China

Trees ◽  
2020 ◽  
Vol 34 (5) ◽  
pp. 1323-1334
Author(s):  
Niu Yu ◽  
Qiongqiong Li ◽  
Jinchang Yang ◽  
Guangtian Yin ◽  
Rongsheng Li ◽  
...  
Keyword(s):  
Quantitative Traits ◽  
Natural Populations ◽  
Wet Season ◽  
Tree Diameter ◽  
Anatomical Analysis ◽  
Tropical Plant ◽  
Increasing Trend ◽  
Secretory Canals ◽  
Major Factors ◽  
Selection Of

Key message Geography and tree diameter were the major factors in determining oleoresin yield in Sindora glabra. The tangential diameter and area of secretory canals are reliable indicators of the oleoresin amount. Abstract Sindora glabra is a native tropical plant of China that exudes copious amounts of oleoresin from wounds on the stem. Elucidation of the mechanism affecting the oleoresin yield is of particular importance for development and selection of superior germplasm. In this study, the variation in oleoresin yield and anatomical traits of the stem of S. glabra were investigated in four main natural populations in Hainan. The results showed that annual oleoresin yield varied considerably among populations. The oleoresin yield exhibited an increasing trend with the increment of tree stem diameter until the diameter was over 80 cm. Moreover, oleoresin production in the wet season was higher than in dry season. The analysis of oleoresin chemical composition indicated that the four populations belong to the same chemotype despite the amount of four types of sesquiterpenes varying greatly among areas. Anatomical analysis revealed that quantitative traits of secretory canals including tangential diameter, area, density and frequency were significantly different among populations and tree diameters. Furthermore, the tangential diameter and area of secretory canals were positively correlated with oleoresin yield. These results suggested that the tangential diameter and area of secretory canals are reliable indicators of the oleoresin amount and can be used for selection purposes in S. glabra.

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

scholarly journals Effects of linkage on response to directional selection from new mutations

1983 ◽  
Vol 42 (2) ◽  
pp. 193-206 ◽  
Author(s):  
P. D. Keightley ◽  
W. G. Hill
Keyword(s):  
Quantitative Traits ◽  
Directional Selection ◽  
Small Populations ◽  
Additive Effects ◽  
Steady Rate ◽  
Mutant Genes ◽  
Mutational Variance ◽  
Rate Of Response ◽  
Selection Of ◽  
New Mutations

SUMMARYThe influence of linkage on the rates of response to continued directional selection of quantitative traits deriving from variation contributed by new mutations in finite populations is investigated. Mutant genes are assumed to have additive effects which are randomly sampled from a symmetric distribution, and to be randomly located on the chromosome. Results were obtained by Monte Carlo simulation.The expected steady rate of response, when variability from new mutations is balanced by that lost by drift and selection, is reduced the tighter the linkage, but the reduction is small unless there are few, short chromosomes. For a given rate of new mutational variance per haploid chromosome set per generation, greater effects of linkage are obtained in large than in small populations, because more mutants segregate. The response and influence of linkage are essentially the same whether the new variance is due to many genes of small effect or few of large effect.The variability of response between replicates and generations was investigated, and the contribution to this of new mutants or recombination of existing mutants compared. Usually most genetic variability was due to the occurrence of a new favourable mutant of large effect.

scholarly journals MULTIPLICATIVE GENOTYPE-ENVIRONMENT INTERACTION AS A CAUSE OF REVERSED RESPONSE TO DIRECTIONAL SELECTION

Genetics ◽  
1986 ◽  
Vol 114 (1) ◽  
pp. 333-343
Author(s):  
A Gimelfarb
Keyword(s):  
Sudden Change ◽  
Phenotypic Selection ◽  
Directional Selection ◽  
Quantitative Character ◽  
Environment Interaction ◽  
Response To Selection ◽  
Random Drift ◽  
Genotype Environment Interaction ◽  
Possible Cause ◽  
Selection Of

ABSTRACT In experiments with directional selection on a quantitative character a "reversed response" to selection is occasionally observed, when selection of individuals for a higher (lower) value of the character results in a lower (higher) value of the character among their offspring. A sudden change in environments or random drift is often assumed to be responsible for this. It is demonstrated in this paper that these two causes cannot account for the reversed response at least in some of the experiments. Multiplicative genotype-environment interaction is discussed as a possible cause of a reversed response to directional selection. Such interaction entails either disruptive or stabilizing genotypic selection, even when the phenotypic selection is directional.

Evolution and Selection of Quantitative Traits

2018 ◽  
Author(s):  
Bruce Walsh ◽  
Michael Lynch
Keyword(s):  
Mathematical Models ◽  
Quantitative Genetics ◽  
Complex Traits ◽  
Evolutionary Biology ◽  
Quantitative Traits ◽  
Specific Gene ◽  
Real World Data ◽  
Holistic Treatment ◽  
Genetics And Genomics ◽  
Selection Of

Quantitative traits—be they morphological or physiological characters, aspects of behavior, or genome-level features such as the amount of RNA or protein expression for a specific gene—usually show considerable variation within and among populations. Quantitative genetics, also referred to as the genetics of complex traits, is the study of such characters and is based on mathematical models of evolution in which many genes influence the trait and in which non-genetic factors may also be important. Evolution and Selection of Quantitative Traits presents a holistic treatment of the subject, showing the interplay between theory and data with extensive discussions on statistical issues relating to the estimation of the biologically relevant parameters for these models. Quantitative genetics is viewed as the bridge between complex mathematical models of trait evolution and real-world data, and the authors have clearly framed their treatment as such. This is the second volume in a planned trilogy that summarizes the modern field of quantitative genetics, informed by empirical observations from wide-ranging fields (agriculture, evolution, ecology, and human biology) as well as population genetics, statistical theory, mathematical modeling, genetics, and genomics. Whilst volume 1 (1998) dealt with the genetics of such traits, the main focus of volume 2 is on their evolution, with a special emphasis on detecting selection (ranging from the use of genomic and historical data through to ecological field data) and examining its consequences. This extensive work of reference is suitable for graduate level students as well as professional researchers (both empiricists and theoreticians) in the fields of evolutionary biology, genetics, and genomics. It will also be of particular relevance and use to plant and animal breeders, human geneticists, and statisticians.

Genetic markers and the selection of quantitative traits in forage grasses

Euphytica ◽  
1994 ◽  
Vol 77 (3) ◽  
pp. 269-275 ◽  
Author(s):  
M. D. Hayward ◽  
N. J. Mcadam ◽  
J. G. Jones ◽  
C. Evans ◽  
G. M. Evans ◽  
...  
Keyword(s):  
Genetic Markers ◽  
Quantitative Traits ◽  
Forage Grasses ◽  
Selection Of

scholarly journals Hybrid dysgenesis-induced quantitative variation on the X chromosome of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 627-636
Author(s):  
C Q Lai ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Quantitative Traits ◽  
Natural Populations ◽  
Quantitative Variation ◽  
Hybrid Dysgenesis ◽  
X Chromosomes ◽  
Bristle Number ◽  
Seven Generations ◽  
Polygenic Variation

Abstract To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.

scholarly journals Genetic variation in the dietary sucrose modulation of enzyme activities in Drosophila melanogaster

1984 ◽  
Vol 43 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Billy W. Geer ◽  
Cathy C. Laurie-Ahlberg
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Enzyme Activities ◽  
Glycogen Synthesis ◽  
Krebs Cycle ◽  
Natural Populations ◽  
Substitution Lines ◽  
Chromosome Substitution Lines ◽  
High Sucrose Diet ◽  
Selection Of

SUMMARYGenetic variation in the modulating effect of dietary sucrose was assessed in Drosophila melanogaster by examining 27 chromosome substitution lines coisogenic for the X and second chromosomes and possessing different third isogenic chromosomes derived from natural populations. An increase in the concentration of sucrose from 0·1% to 5% in modified Sang's medium C significantly altered the activities of 11 of 15 enzyme activities in third instar larvae, indicating that dietary sucrose modulates many, but not all, of the enzymes of D. melanogaster. A high sucrose diet promoted high activities of enzymes associated with lipid and glycogen synthesis and low activities of enzymes of the glycolytic and Krebs cycle pathways, reflecting the physiological requirements of the animal. Analyses of variance revealed significant genetic variation in the degrees to which sucrose modulated several enzyme activities. Analysis of correlations revealed some relationships between enzymes in the genetic effects on the modulation process. These observations suggest that adaptive evolutionary change may depend in part on the selection of enzyme activity modifiers that are distributed throughout the genome.

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