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Evolution by gene duplication is an event by which a gene or part of a gene can have two identical copies that can not be distinguished from each other. This phenomenon is understood to be an important source of novelty in evolution, providing for an expanded repertoire of molecular activities.
Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution.It can be defined as any duplication of a region of DNA that contains a gene.
Repeated sequences (also known as repetitive elements, repeating units or repeats) are short or long patterns that occur in multiple copies throughout the genome.In many organisms, a significant fraction of the genomic DNA is repetitive, with over two-thirds of the sequence consisting of repetitive elements in humans. [1]
The upper DNA molecule differs from the lower DNA molecule at a single base-pair location (a G/A polymorphism) In genetics and bioinformatics, a single-nucleotide polymorphism (SNP / s n ɪ p /; plural SNPs / s n ɪ p s /) is a germline substitution of a single nucleotide at a specific position in the genome.
Duplications can occur within a lineage (e.g., humans might have two copies of a gene that is found only once in chimpanzees) or they are the result of speciation. For example, a single gene in the ancestor of humans and chimpanzees now occurs in both species and can be thought of as having been 'duplicated' via speciation.
The name derives from the 2 rounds of duplication originally hypothesized by Ohno, but refined in a 1994 version, and the term 2R hypothesis was probably coined in 1999. Variations in the number and timings of genome duplications typically still are referred to as examples of the 2R hypothesis.
Unequal crossing over is the process most responsible for creating regional gene duplications in the genome. [1] Repeated rounds of unequal crossing over cause the homogenization of the two sequences. With the increase in the duplicates, unequal crossing over can lead to dosage imbalance in the genome and can be highly deleterious. [1] [2]
A diagram that summarizes all well-known paleopolyploidization events. Ancient genome duplications are widespread throughout eukaryotic lineages, particularly in plants. . Studies suggest that the common ancestor of Poaceae, the grass family which includes important crop species such as maize, rice, wheat, and sugar cane, shared a whole genome duplication about