Sample Essay on the Four Forces of Evolution

Evolution is a process by which individuals, species or populations change their biological or inherited traits over time. The evolution has led to diversity among species or individuals and has given rise to species or individuals with characteristics that are adaptive to ever changing environmental conditions. Individuals with common ancestors share many characteristics and are similar, they can interbreed and gives rise to fertile offspring. Changes in climatic and environmental conditions however has resulted in variation among individuals or species.

Species is the largest group of individuals who can freely met sexual and reproduce fertile offspring.Population on the other hand is the total number of species or individuals with the same characteristics who reside in a particular location and are able to interbreed freely and produce offspring. This means individual or specie pair can met sexual under normal conditions to give rise fertile offspring. Variation is the difference between cells, individual or organisms resulting from genetic difference or environmental conditions. Variation resulting from genetics are caused by change in the number or structure of genes. These changes will lead to changes in eye colour, body structure and disease among others. Climatic conditions, availability of food and interference by other organisms cause environmental variation. Environmental variation are not inherited from one individual to another as is the case in genetic variation. Some of these changes do not last for long but disappear after a certain period of time.

Evolution and biodiversity can best be explained by four forces of evolution namely; mutation, gene flow, genetic drift, and natural selection. Mutation is a process that permanently changes the genetic constitution of and individual. This process is random and impacts on individual life from body appearance to physiology among others. Internal and external factors are known to cause mutation. Internal factors include erroneous changes in DNA composition while external factors are environmental factors which include smoking, radiation among others. Gene flow is the passing of genes from one individual to another over generations. Gene flow involves movement of genes to a place or population where the genes were non-existent. Genetic drift, on the other hand, is change in the sequence of gene as a result of choosing of individuals randomly with genes resembling those of their parents. The individual survival in this particular case is based on probability and correlation of the genes with those of the parent. Genetic drift is caused by upcoming population and reduction in the number of organisms necessitating start of a new population. Lastly, natural selection is a process by which individual who are well used or adapted to environment produce offspring who in return will carry inherited traits from their parents onto their offspring. Natural selection causes changes in genetic composition of an individual giving rise to an individual who can fit harmoniously in a particular environment. Individuals who are adaptive are fit and survives irrespective of harsh conditions.

Isolation refers to separation of individuals who share common characteristics. Speciation on the other hand is a process by which individuals who have common characteristics and similarities change over time resulting in new species. Environmental conditions and genetics are major causes of speciation.

In summary, understanding both environmental factors and genetics will give a clear understanding of changes in physical appearance of individuals and how well they can adapt to unfriendly environment.