How Does Natural Selection Affect Population Growth?

Charles Darwin was born in the city of Shrewsbury, England and was raised by a wealthy family and was the 5th child. His mother Susannah died when he was only eight and his father was a physician, poet, philosopher and naturalist. In 1825, Darwin graduated from the elite school at Shrewsbury. He then attended college at the University of Edinburgh to study medicine. In 1927 he dropped out and decided to study clergyman and entered the University of Cambridge. There he was introduced to Adam Sedgwick and John Stevens Henslowe. These two gentlemen showed Darwin how to observe natural phenomenon and collect specimens. Which when the opportunity arose, for him to be a member of the team, Darwin took the opportunity to travel on the survey ship,

The Beagle. Darwin started out on a five year trip around the world when he was 22. As the ships naturalist he spent his time on shore collecting thousands of plant and animal specimens and making observations. Darwin saw that the plants and animals that he found in temperate areas of South America were more similar to tropical South American species than they were to European species. During the voyage he read Lyell’s principles of Geology and kept his ideas in mind as he traveled. He became interested in distribution or organisms after visiting the Galapagos Islands. During his travel he realized that adaptation to the environment and the origin of new species were closely linked processes. During the 19th century, Americans and Europeans were first exposed to the concept of evolution. Darwin did not invent the idea, he conducted the necessary research to document that evolution has occurred. By doing this research he made the idea more acceptable to individuals.
Natural selection is the process in which living organism better adapt to their surrounding and environment, to survive and reproduce.

In Darwin’s Theory, he observed in the world around him, that organisms yield more offspring than is necessary to replace themselves. So populations should increase. For example, flies can lay up to 500 eggs in batches over a three to four day period. Through observation Darwin saw for himself, that numbers in population tend to stay at about the same levels. He confirmed this observation with others. So, why don’t the numbers go up? Resources, the major influence on populations would be things such as food, water, space. As stated by (Stephen Montgomery, 2009), “A simple conclusion, individuals compete with each other for scarce resources.” Another observation Darwin made was that individuals are unique and vary in almost every aspect but the differences are passed on from parent to offspring. So the idea behind his theory is that when an organism reproduces those that survive may have heritable traits that increase their chances of survival. They will pass those traits on and the frequency of those traits will increase. When an environment changes or when individuals move to a new environment, natural selection may result in adaptation to the new conditions, sometimes this results in a new species. Natural selection can only work on heritable traits. Acquired traits are not heritable and are not subject to natural

selection.
The main premise underlying evolution is the change in characteristic traits of biological population over a period of time or generations. On a bigger scale, evolution can be used to refer to the gradual appearance of all biological variety. As Darwin’s theories have proven in the past, as time goes by, a population can change by the natural changes in our resources. Darwin's use of the phrase "survival of the fittest" is frequently misunderstood. Many people assume that "the fittest" refers to the strongest, biggest, or smartest individuals. This may or may not be the case. From an evolutionary view, the fittest individuals are simply the ones who have the combination of traits that allow them to survive and produce more offspring that in turn survive to reproduce. In fact, they may be relatively weak, small, and not particularly intelligent. What makes an individual fit all depends on the environment at the time and the combination of traits that are most suited to flourishing in it.
Darwin proposed that all organisms have descended from a single ancestral form and came up with a branching tree called a phylogeny.

According to the, (Encyclopedia Britannica, 2014) Phylogeny, the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms. The phrase “descent with modification” summarizes Darwin’s view of how evolution works. All organisms descended from a common ancestor and similar species have diverged more recently. He also shared the similarities can be found at the molecular level. The genetic code is would be universal. Example, its like that all organisms descended from a common ancestor or different organisms share genes that have been inherited from a common ancestor. Darwin’s evolutionary tree of life can explain homologies, (Encyclopedia Britannica, 2014) similarity of the structure, physiology, or development of different species of organisms based upon their descent from a common evolutionary ancestor. The genetic code is shared by all species because it goes back into the ancestral past. Homologies result in a pattern, all life shares the deepest layer and each smaller group adds homologies to those the share. Darwin’s theory proposes that small differences accumulate over time producing the larger changes we see over geologic time. Certainly, this process is always at work, but probably doesn’t not account for all

changes.
The general idea of evolution dates back to the Greeks. The version of creationism was strongly reinforced by James Usshera a 17th century Anglican archbishop. Which believed that by counting the generations of the Bible and adding them to modern history, the date of creation was October 23, 4004 B.C. There were many theories before Darwin’s Theory, which included, Anaximander belief around 520 B.C. that life started as slime in oceans and moved to land. He also believed that species over time, evolved. John Ray in 1686 gave the first definition of species based on common descent. In 1735, Carolus Linnaeus came up with a way to classify organisms and believed that there was a divine order to all organisms that came from the hand of god. Between 1790’s and 1830’s Georges Cuvier made several contributions to science. He founded Vertebrate paleontology and developed a classification system for animals, but he did not believe in evolution. Lamarck was the first to suggest an explantions for evolution. Inheritance of acquired characteristics, but this did not hold up to testing. There have been many theories regarding evolution but the one person that backed up his theory was Charles Darwin, which took him until the age of 50.