The Processes of Evolution
Evolution, in a nutshell, is the process by which the organisms that surround us today came to be from our ancient ancestors. Why do we look like we do? How come certain species die off, and new ones evolve? What factors determine how certain organisms are able to adapt to certain environments? These are only a few, out of an infinite amount, of questions that evolution has scientists wondering. Because evolution is constantly happening, these questions will never cease, but the process by which it happens will be better and better understood.
Evolution is often described as descent with modification, it can only occur when there is a change in an allele frequency within a population over time. Evolution may constantly be at work, but it is only noticeable over long periods of time. Long term change is what really matters in evolution. What are some of the causes of change? Mutation, for one, is a change in a cell’s DNA sequence. It commonly happens due to error in replication or repair, and it is the ultimate source of genetic variation.
Genetic variation has three primary sources: mutation, gene flow, and reproduction. A single mutation can have a large impact, but since long term change is most important in evolution, it is usually an accumulation of numerous mutations that cause evolutionary change. Mutation is completely random and can be beneficial or harmful to an organism, or may not effect that organism at all. Mutation that occurs in non-reproductive cells are called somatic mutations and do not even get passed onto offspring, which in turn do not even matter to evolution. Most mutations that do matter often occur naturally. A naturally-occurring mutation could happen after a cell divides, and makes a copy of its DNA, and the DNA does not come out quite right. The small difference produced in that cell’s copy of its DNA is a mutation. Other causes of mutation occur when a cell is exposed to specific chemicals...