Génétique Quantitative

Abstract

La génétique quantitative est une branche de la génétique qui étudie la variation des caractéristiques complexes chez les individus et les populations, comme la taille, le poids, la croissance, la production laitière, la teneur en huile chez les plantes, etc. Ces caractéristiques sont également appelées traits quantitatifs, car elles varient continuellement plutôt que de se répartir en catégories distinctes. La génétique quantitative étudie la manière dont les traits quantitatifs sont hérités et influencés par l'environnement. Les caractéristiques quantitatives sont souvent polygéniques, ce qui signifie qu'elles sont influencées par plusieurs gènes. De plus, les caractéristiques quantitatives peuvent également être affectées par l'environnement, comme l'alimentation, la température, la lumière, le stress, etc. Les méthodes de la génétique quantitative permettent de mesurer l'héritabilité des traits quantitatifs, c'est-à-dire la proportion de la variance phénotypique observée qui est due à des différences génétiques entre individus. Les méthodes de la génétique quantitative peuvent également être utilisées pour identifier les régions du génome qui sont associées à des variations de traits quantitatifs, appelées QTL (Quantitative Trait Loci). La caractérisation des QTL permet de mieux comprendre les mécanismes génétiques sous-jacents à la variation des traits quantitatifs. Quantitative genetics is a branch of genetics that studies the variation of complex characteristics in individuals and populations, such as height, weight, growth, milk production, oil content in plants, etc. These characteristics are also called quantitative traits, because they vary continuously rather than falling into distinct categories. Quantitative genetics studies how quantitative traits are inherited and influenced by the environment. Quantitative characteristics are often polygenic, meaning that they are influenced by multiple genes. In addition, quantitative characteristics can also be affected by the environment, such as diet, temperature, light, stress, etc. The methods of quantitative genetics make it possible to measure the heritability of quantitative traits, that is, the proportion of the observed phenotypic variance that is due to genetic differences between individuals. Quantitative genetics methods can also be used to identify regions of the genome that are associated with variations in quantitative traits, called QTLs (Quantitative Trait Loci). The characterization of QTLs allows a better understanding of the genetic mechanisms underlying the variation in quantitative traits. Its history dates back to the beginning of the 20th century, when scientists such as Ronald Fisher, J.B.S. Haldane, and Sewall Wright began to develop statistical methods to analyze data on complex characteristics. They proposed that quantitative traits were governed by many genes with tiny effects, and that these genes were inherited in a polygenic manner. Over time, more advanced statistical methods have been developed to study quantitative traits, including linear regression and analysis of variance (ANOVA). These methods have led to a better understanding of how quantitative traits were inherited and how they were influenced by the environment. In the 1980s and 1990s, the use of genetic markers made it possible to identify regions of the genome that were associated with variations in quantitative traits, called QTLs (Quantitative Trait Loci). QTLs have provided a better understanding of the genetic mechanisms underlying the variation in quantitative traits and have paved the way for marker-assisted selection (MAS), a method of selecting individuals for specific characteristics using genetic markers. With the advent of high-throughput DNA sequencing technologies in the early 21st century, quantitative genetics has taken another leap forward. These technologies have made it possible to identify millions of genetic variations in the genome, and to discover new genes and new regions of the genome that influence quantitative traits. Today, quantitative genetics is used in many fields of biology, including agriculture, animal husbandry, medicine, and ecology. Recent advances in the field of quantitative genetics have opened new perspectives for understanding the complexity of quantitative traits and for their use in marker-assisted selection and synthetic biology