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Heredity of phenotypic traits: a father and son with prominent ears and crowns. DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix. In humans, eye color is an example of an inherited characteristic: an individual might inherit the "brown-eye trait" from one of the parents. [1]
It is this genetic variation that underlies differences in phenotype. An example is the ABO blood type antigens in humans, where three alleles govern the phenotype. [100] Some traits are governed by only a single gene, but most traits are influenced by the interactions of many genes.
The mechanisms of genetic and ecological inheritance are also different; whereas genetic inheritance depends on reproduction (e.g., sexual and asexual) where genes are transmitted in one direction from parent to offspring in the same species, the modified environment and its selective pressures caused by ecological inheritance can be handed ...
The observation that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. [7] [8] The modern science of genetics, seeking to understand this process, began with the work of the Augustinian friar Gregor Mendel in the mid-19th century.
In genetics, the phenotype (from Ancient Greek φαίνω (phaínō) 'to appear, show' and τύπος (túpos) 'mark, type') is the set of observable characteristics or traits of an organism. [ 1 ] [ 2 ] The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological ...
In humans, for example, eye colour is an inherited characteristic and an individual might inherit the "brown-eye trait" from one of their parents. [21] Inherited traits are controlled by genes and the complete set of genes within an organism's genome (genetic material) is called its genotype. [22]
The social insects provide good examples of organisms with what appear to be kin selected traits. The workers of some species are sterile, a trait that would not occur if individual selection was the only process at work. The relatedness coefficient r is abnormally high between the worker sisters in a colony of Hymenoptera due to haplodiploidy.
Many traits are produced by the interaction of several genes. Traits controlled by two or more genes are said to be polygenic traits. Polygenic means "many genes" are necessary for the organism to develop the trait. For example, at least three genes are involved in making the reddish-brown pigment in the eyes of fruit flies. Polygenic traits ...