The species has its unit, which reproduces only among itself and gives birth to fertile offspring like itself. Through this speciation and various biological changes, one organism is born into another organism in nature. Gene mutation and chromosomal aberrations play a substantial role in species evolution.
Role of Gene Mutation: Gene mutation is inherited. Many species of plants and animals usually arise through gene mutation. The role of gene mutation in species evolution is noted below:
Genes are arranged in straight lines within chromosomes. They are responsible for creating new features. Sexual reproduction involves the fusion of two types of gametes from organisms of opposite sexes, resulting in a new combination of chromosomes and genes in the male and female.
Mutations caused by the rearrangement of genes and chromosomes cause various changes including the arrangement of genes. As a result, the qualities of living things also change drastically.
Most gene mutations are either spontaneous or artificial and are harmful to organisms. Sometimes it can be fatal. The genetic and physiological structure of organisms is highly advanced. They can deal with any environmental hazard very easily. These characteristics later point toward the species.
Certain mutations such as duplication play an important role in evolution. Its role is particularly important in the evolution of new genetic material and the change of phenotype of organisms. Because through such mutation additional genes come into existence along with the previously existing complementary genes. Such mutations give rise to a small number of new species and are not capable of much evolutionary change.
In 1791, an English farmer named S. Wright found a male sheep in his flock. The legs of this sheep were quite short compared to other sheep. When this male sheep grows up he is crossed with a normal sheep. Two of the fifteen children had short legs. By crossing with short-legged sheep, he created short-legged flocks. Mutation of a recessive gene results in homozygous 'encon' males. Besides, it is possible to create other species of organisms through this method.
Role of Chromosome Aberrations: Sometimes genetic aberrations, genetic additions, and genetic substitutions occur in one or more chromosomes due to special reasons. These phenomena are called structural aberrations of chromosomes or chromosome aberrations. This results in a change in the physico-chemical structure of the chromosomes, which changes the phenotype of the organism.
A segment of a chromosome may break off, an additional segment with one or more new genes may be attached to the chromosome, a segment may exchange between two non-homologous chromosomes or a segment of the chromosome may break and turn 180° and rejoin in the opposite direction.
As a result of these, the karyotype of the organism changes, the linkage group changes; A position effect of gene action occurs, changing the phenotype of the organism. As a result, new species emerge. So these mutations play an important role in plant and animal life. Some chromosome mutations, such as haploidy, polyploidy, heteroploidy, and duplication, cause evolutionary changes in species.
Polypudiy is an important means of innovating new species.Physiological and biochemical properties of organisms are also altered or affected by polypoid mutations, more generally than in diploid plants.
Immediate speciation by chromosomal aberrations: In most cases, karyotype differences are more pronounced than morphological differences between closely related species. Chromosome numerical variation in different karyotypes, metacentric or acrocentric chromosome number, paracentric or paracentric inversion or supernumerary chromosome number, and roughly chromosomal.