The importance of evolution as a scientific concept cannot be denied. Since its development in the 19th Century, it has been accepted by the scientific community as the theory behind how species have developed and changed over the ages. The principle of evolution involves four basic driving forces: natural selection, genetic drift, gene flow, which is also called genetic migration, and mutation. Together, these four forces have created the wide variety of species that exist on the planet today and in the past. This paper will explain the four forces of evolution, as well as additional important terms, such as species, population, isolating mechanisms, and speciation.
In order to fully understand the forces of evolution, it is important to establish a basic understanding of the concept of a species. The term species refers to the lowest level of the taxonomic ranking. Species share the vast majority of characteristics. While they may have different colorings and some markings, the distinctions are not enough to be of primary concern to taxonomists. Most importantly, the term species indicates that two members of the species can successfully reproduce and produce an offspring. This offspring is fertile, as opposed to sterile. There have been times when two different species have been successfully mated in that an offspring was produced. However, the offspring is sterile and cannot continue its line on its own.
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"The Four Forces of Evolution".
A population refers to a group of species that shares genetic material. This is usually because they live within a geographic area that allows them to do this. For instance, elephants are found in both Southeast Asia and in Africa. However, it is highly unlikely that an Asian elephant will have the opportunity to share genetic material with an African one. This is because they live in different populations. As such, the different populations all belong to the same gene pool, where the genetic material is passed on to later generations. The importance of a gene pool cannot be understated in understanding evolution. The health of a gene pool can help to determine if a species survives. For instance, if a gene pool has a large amount of alleles that do not enhance the ability of a species to respond to its environments, particularly the threats, the species likely will not survive. This often happens with species in different populations; they have limited genetic material available for offspring. This often tends to weaken a population and make it susceptible to a number of genetic conditions. This if seen in humans; when a group of humans tends to isolate itself, they often develop genetic conditions. For instance, royalty tended to intermarry for generations. As such, hemophilia is a condition that is associated with them.
There are ways to increase the variation of genetic material, and therefore the variation in the offspring. Genes or alleles may change on their own. This is called mutation. Mutations may occur for a number of reasons. DNA must replicate by copying one of the strands. Mistakes can and do happen. They mutations may be of no importance, or they may result in the strengthening or weakening of the offspring.
Migration, or genetic flow, is another way in which the diversity of DNA is increased. Individual species do migrate from one population to another. When this occurs, the new members of the population bring new genetic material to the population. This can help to lead to new genetic combinations.
It must be noted that some of evolution is random. When two parents reproduce, the offspring inherits a copy of the gene from each parent. The combination of the genes determine many qualities about the offspring. This is a random occurrence and cannot be predicted. In order to develop many genetic conditions, a person must inherit two recessive genes. If both parent has one copy, there is a one out of four chance the offspring will inherit both copies of the defective gene.
Populations often become isolated from other populations. This decreases the chances that they will share genetic material through migration. For instance, the elephants of Asia and Africa were once much closer geographically. However, with continental drift, the populations were isolated increasingly. This is called an isolating mechanism. It is not the only type of isolating mechanism. There are biological isolating mechanisms as well. For instance, an elephant and a human cannot reproduce because of simple biology. This isolates the species from sharing their DNA as well.
When enough of these factors work together to begin changing enough characteristics of a population’s species, a new species may develop. This is called speciation. For instance, the African elephant and the Asian elephant are two different species. From a distance, they might appear quite similar. However, upon closer examination, it appears that they have significant differences in their structure and appearance. This is due to their separation from each other many generations ago. Changes and mutations that developed in each population eventually led to two different species.
Evolution is a critical concept to understand. It helps us to recognize how various species developed over time and also why species become extinct. It also helps science to understand how long it might take for a new species to develop based upon the forces of evolution. These forces work together to help make a species stronger and better able to adapt to its environment. However, if a species’ changes make it less likely to adapt to the environment, it will eventually become extinct. This is Darwinism.
