Evolution is separated into microevolution and macroevolution. Microevolution is the smaller changes in a species, like changes in allele frequency. Macroevolution describes changes that occur over a long period of time, like the evolution of a new species.
Evolution is a two step process:
-The production and redistribution of variation
-Natural selection acting on that variation.
The processes of evolution that produce and redistribute variation are :
1. Mutation- When one allele changes to another and the gene itself is altered. This contributes to variation because that genetic change is passed on and spread to the next generation, where it changes the genetic makeup of the population over time. Mutation is the only way to produce new genes.
2. Gene Flow- Gene flow is the exchange of genes between populations. So when individuals of one population mate with those of another, their genes are mixed and offspring will have genes from both populations(meaning possible new traits to be passed down).
3. Genetic Drift- Evolutionary changes in allele frequencies that are produced by random factors in small populations. In a small population, if an allele is rare it may completely disappear if not passed down. Also, a rare allele could become more and more common as shown by the Founder Effect. This occurs when a small group forms a colony and mates within itself. The genes passed down are those of that small group of founders and something rare in the parent group may become common in the small new group.
4. Recombination-When members of chromosome pairs exchange DNA segments during meiosis. Genes sometimes are brought to new genetic environments and can be influenced by the alleles they are close to. This change in environment can change the way a gene acts and changes of gene function can be acted on by natural selection.
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