Organic Evolution is the change in the inherited characteristics.
From one generation to the next, These changes could be positive, they could be negative or it could be a change that really doesn’t have an effect at all. It could be neutral.
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These changes can occur for several reasons. One reason is due to mutations and genetic mutations are random changes in the sequence of DNA base pairs.
Another reason variation could occur is recombination. The offspring of organisms that reproduce sexually contain random mixtures of their parent’s chromosomes and that happens through recombination. Each parent has certain characteristics and in the offspring, those characteristics are kind of mixed up and combined.
Another reason variations can occur is epigenetic factors and epigenetic factors are factors involved when genes are turned on or off, due to changes in the organism’s environment and there is no change to the DNA at this point.
Another reason variations can occur is gene flow. Gene flow occurs when genes are exchanged between populations or between species. Examples of that are movements of creatures between habitats or seeds being blown by the wind through different areas.
Another reason variations can occur is genetic drift and that is the change in the frequency of a particular gene variant known as an allele. Alleles may disappear completely or become fixed as the only allele or the only option for a certain gene.
Other variations can occur is through natural selection so the process by which genetic mutations that enhance reproduction and survival, become and remain more common in successive generations. Those genetic mutations that help an organism more, are going to become more prevalent and the individuals with those traits are going to be the ones more likely to survive.
Those traits can become more common in future generations.
You can see that organic evolution can occur due to several different factors, but the thing to remember is that organic revolution is that change and inherited characteristics from one generation to the next.