Modern Synthetic Theory of Evolution includes the following 5 factors:-
1. Mutation: Alteration in the chemistry of gene (DNA) is able to change its phenotypic effect this is called point mutation or gene mutation.
2. Variation or Recombination: new genotypes from already existing genesis of several types :
(1) the production of gene combinations containing the same individual two different alleles of the same gene, or the production of heterozygous individuals (meisois);
(2) the random mixing of chromosomes from two parents during sexual reproduction to produce a new insdividual;
(3) the exchange between chromosomal pairs of particular alleles during meiosis, called crossing over, to produce new gene combinations. Chromosomal mutations such as deletion, duplication, inversion, translocation and polyploidy also result in variation.
3 Heredity: The transmission of variations from parent to offspring is an important mechanism of evolution.
4 Natural selection: It brings about evolutionary change by favouring differential reproduction of genes which produces change in gene frequency from one generation to the next. Natural selection creates new adaptive relations between population and environment by favouring some gene combinations, rejecting others and constantly modifying and moulding the gene pool.
5 Isolation: Isolation of organisms of a species into several populations or groups under psychic, physiological or geographical factors is supposed to be one of the most significant factors responsible for evolution.
In addition, three accessory factors affect the working of these five basic factors; Migration of individuals from one population to another as well as hybridization between races or closely related species both increase the amount of genetic variability available to a population. The effects of chance acting on small populations may alter the way in which natural selection guides the course of evolution .
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Amar Kumar 8 years, 5 months ago
Modern Synthetic Theory of Evolution includes the following 5 factors:-
1. Mutation: Alteration in the chemistry of gene (DNA) is able to change its phenotypic effect this is called point mutation or gene mutation.
2. Variation or Recombination: new genotypes from already existing genesis of several types :
(1) the production of gene combinations containing the same individual two different alleles of the same gene, or the production of heterozygous individuals (meisois);
(2) the random mixing of chromosomes from two parents during sexual reproduction to produce a new insdividual;
(3) the exchange between chromosomal pairs of particular alleles during meiosis, called crossing over, to produce new gene combinations. Chromosomal mutations such as deletion, duplication, inversion, translocation and polyploidy also result in variation.
3 Heredity: The transmission of variations from parent to offspring is an important mechanism of evolution.
4 Natural selection: It brings about evolutionary change by favouring differential reproduction of genes which produces change in gene frequency from one generation to the next. Natural selection creates new adaptive relations between population and environment by favouring some gene combinations, rejecting others and constantly modifying and moulding the gene pool.
5 Isolation: Isolation of organisms of a species into several populations or groups under psychic, physiological or geographical factors is supposed to be one of the most significant factors responsible for evolution.
In addition, three accessory factors affect the working of these five basic factors; Migration of individuals from one population to another as well as hybridization between races or closely related species both increase the amount of genetic variability available to a population. The effects of chance acting on small populations may alter the way in which natural selection guides the course of evolution .
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