Quantitative Trait Analysis

In this chapter, complex traits, or otherwise known as quantitative traits, were examined. Quantitative traits are determined numerically, as well as by different genes that are influenced by the surrounding environment. A few examples of these types of traits include, but not limited to, height, the rate of our ability to metabolize food, and the speed of a cheetah when chasing its prey. To begin, quantitative traits can be anatomical, physiological, and behavioral traits, as well as diseases. These types of traits are examined across a species rather than between species. These are typical traits of the species that every organism has in that species, but the traits can have different characteristics. For instance, each human has two eyes, …show more content…
Traits can be defined as continuous or meristic. Continuous traits are traits that aren’t able to fall into distinct categories, like weight for example. Meristic traits are traits that can be expressed numerically, like the different number of bristles Drosophila flies have. Both of these types of traits fall under the quantitative traits category of quantitative genetics because they display a range of phenotypic variation that follow a normal distribution pattern. This means that the traits being analyzed do not fall under discrete phenotypes, but instead there is a wide variety of different offspring that can be present across …show more content…
Polygenic inheritance refers to the transmission of a quantitative trait between two or more genes in a species. These polygenic, quantitative traits are on specific parts on a chromosome called quantitative trait locus, or QTL. These QTLs are then identified through different types of genetic mapping, which is either a single gene on a chromosome, or two or more genes very close to one another on the chromosome. QTL mapping is done via the association of the determined phenotypes and molecular markers, such as microsatellites or RFLPs. This is helps identify where the traits are on the gene because markers’ sites are already known. This idea of polygenic inheritance is an important part of quantitative genetics because it, coupled with different environmental factors, can help create even a greater variety of phenotypes. Some examples of these types of environmental conditions that affect the phenotypic frequencies include sunlight, soil composition, and dryness. All these can affect the genotype of the organism. An increase in the gene number and a variation in the environment can ultimately affect the overlap of the different types of genotypes and