Is a polygenic trait a continuous trait?
Traits that display a continuous distribution, such as height or skin color, are polygenic. The inheritance of polygenic traits does not show the phenotypic ratios characteristic of Mendelian inheritance, though each of the genes contributing to the trait is inherited as described by Gregor Mendel.
Why do phenotypes of polygenic characteristics show continuous variation?
Most characteristics are controlled by more than one gene and are described as being polygenic . Polygenic characteristics have phenotypes that can show a wide range of values, with each value following on from the value before. This is described as continuous variation .
What is continuous trait?
A continuous trait displays a range of expression (such as weight, height, etc.) rather than an all-or-none appearance (such as white or red). Continuous traits are usually under polygenic control and subject to substantial environmental influence in expression.
What is a continuous phenotype?
Continuous traits: Distribution of phenotypes in the population. varies along a continuum. Individuals differ by small degrees. (examples include height, blood pressure, reaction time, learning ability) Polygenic quantitative or multifactorial.
What are examples of discontinuous variation?
Examples of discontinuous variation include a person’s blood group or the color of a species of bird. These variations can exist for two major reasons. They could be purely random genetic changes, or they can be traits that have been influenced and selected by the environment.
How does the environment interact and affect phenotypes?
Environment Can Impact Phenotype
Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed, which ultimately affects the animal’s phenotype.
What is continuous variation biology?
Continuous variation is the combined effect of many genes (known as polygenic inheritance) and is often significantly affected by environmental influences.
What are the causes of continuous variation?
Characters influenced by many genes are called polygenic characters. Differences in external environmental conditions also produce continuous variation. In nature, each character will be influenced by many environmental variables, some tending to increase it, others to decrease it.
Why do some traits show continuous variation instead of discrete categories?
Discrete variation is either/or and is often caused by the presence or absence of a small number if genes. … The involvement of a variety of genes in the determination of an organism’s features is known as polygenic inheritance. This more complex cause brings about what is known as continuous variation.