Search results
Results from the WOW.Com Content Network
Mendelian traits behave according to the model of monogenic or simple gene inheritance in which one gene corresponds to one trait. Discrete traits (as opposed to continuously varying traits such as height) with simple Mendelian inheritance patterns are relatively rare in nature, and many of the clearest examples in humans cause disorders.
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
Complex traits are phenotypes that are controlled by two or more genes and do not follow Mendel's Law of Dominance. They may have a range of expression which is typically continuous. Both environmental and genetic factors often impact the variation in expression. Human height is a continuous trait meaning that there is a wide range of heights ...
Many traits are not discrete features (e.g. purple or white flowers) but are instead continuous features (e.g. human height and skin color). These complex traits are products of many genes. [52] The influence of these genes is mediated, to varying degrees, by the environment an organism has experienced.
Indeed, many organisms have traits whose inheritance works differently from the principles he described; these traits are called non-Mendelian. [44] [45] For example, Mendel focused on traits whose genes have only two alleles, such as "A" and "a". However, many genes have more than two alleles. He also focused on traits determined by a single gene.
Typically, QTLs underlie continuous traits (those traits which vary continuously, e.g. height) as opposed to discrete traits (traits that have two or several character values, e.g. red hair in humans, a recessive trait, or smooth vs. wrinkled peas used by Mendel in his experiments).
They can show either smooth, continuous gradation in a character, or more abrupt changes in the trait from one geographic region to the next. [2] A cline is a spatial gradient in a single specific trait, rather than in a collection of traits; [3] a single population can therefore have as many clines as it has traits, at least in principle. [4]
In the case where the trait instead takes non-discrete values, one must instead turn to a model where the trait evolves as some continuous process. Inference of ancestral states by maximum likelihood (or by Bayesian methods) would proceed as above, but with the likelihoods of transitions in state between adjacent nodes given by some other ...