The first one is natural selection. The first thing we think about natural selection is Charles Darwin , the Galápagos Islands, and only the strong survive. While the first two are correct, the third one is incorrect. Instead of only the strong survive it is the most adaptable survive. Three things are really important to natural selection. They are variation of genes in population, the variations to be heritable, and differential reproductive success. An example of natural selection would be a green caterpillar and a blue caterpillar on a green leaf the green caterpillar will blend in while the blue one will be easier for predators to spot. Therefore the green caterpillar will survive to reproduce more than the blue caterpillar will.
Mutations or any change in the DNA is also a mechanism. Not all mutations are relevant to evolution. Only the mutations that will occur in gamete or sex cells can lead to evolution.
The third mechanism is recombination. Recombination is mostly about crossing over that occurs during meiosis. The new gene combinations can be helpful and harmful to the organism.
Gene Flow or migration is the fourth mechanism. Gene flow is one an organism leaves and takes their traits with them. When an organism leaves one population and goes to the other and reproduces their it takes its genes that the population had not been introduced to yet and includes them in the gene pool of the population.
Genetic drift is chance changes in a population. It is entirely random and doesn't necessarily lead to the best or most adaptable organisms surviving.
Artificial selection is the sixth mechanism of evolution. It is called this because instead of the organism choosing who to mate with humans do. This is very common in livestock animals. Breeders breed the biggest and best animals to wi the shows.
Non- Random mating or sexual selection is the fact that not all individuals have the same chance of mating. Not always a good thing as it can lead to organism being more visual sexual selection happens in peacocks, some birds, and flys.
The last mechanism is reproductive isolation. Reproductive isolation occurs when a species is separated and then become two different species. This happened on the Galápagos Islands. Most cormorants are able to fly except for a type of cormorant that is found on the Galápagos Islands. 
Thank you for always putting so many important points in your blog. It helps me to know you have an understanding of the subject, because you can summarize and rewrite your thoughts.
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