Natural selection is one of the central mechanisms of evolutionary change and is the process responsible for the evolution of adaptive characteristics. Credit for this astonishing discovery must be given to the man known as the father of evolution and heredity, Charles Darwin, who expounded his theory of evolution in 1859. Natural selection is one of the principles that govern heredity . The first generally refers to the fact that evolution has occurred in such a way that organisms living today are different from their ancestors. Natural selection is the evolutionary process that explains the correspondence, or adaptation, between the characteristics of organisms and the environments in which they live. This principle implies that if evolution were explained as a car, then the theory of natural selection would be its driving force. The theory states that it is nature that controls and selects organisms, which tend to have characteristics favorable to survival and at the same time eliminate inferior species. This research paper examines Darwin's four main ideas of evolution, its relation to the current problem of antibiotic resistance in bacteria, and its description in terms of the 20th century "modern evolutionary synthesis". Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Darwin's theory is significantly a very important reference point in the process of evolution and origin of species. The principle is considered the key to the formation of new and superior species from old and existing ones. This means that nature selects superior traits, which are transmitted to offspring independently of each other. The main explanation behind this theory is that a superior allele tends to be dominant over others, mixing a genetic composition and traits that influence a certain segregated trait during the growth and development of the organism. There are many “evolutionary forces”. Natural selection is specifically the design of fittest species and traits that survive and reproduce. It is impossible to imagine evolution without natural selection. It was originally thought of as the primary mechanism of evolution and is still conceived as the dominant driving force of change in the modern evolutionary synthesis. Natural selection can be thought of as a way to shape or guide evolution. It does this in several ways. Directional selection occurs when the environment eliminates an allele from dominant position in a population. Disruptive selection selects the two extreme expressions of a trait. Stabilizing selection occurs when extremes are less adaptive and intermediate phenotypes work better. There would be no theory of evolution without natural selection. It is a process of change necessary for synthesis. While some controversy surrounds evolution as applied to human populations, Darwin's theory applies to all organic species. The basic principles of evolution are simple and seem obvious to the modern reader. However, before Darwin, no scientist had put all the pieces together. Variation in populations: In every species there is variation. This variability also occurs between related individuals. Siblings vary in color, height, weight and other characteristics. Other characteristics rarely vary, such as the number of limbs or eyes. The observer must be careful when making generalizations about a population. Some populations show more variation than others, particularly in geographically isolated areas such as Australia, the Galapagos, Madagascar, and so on. The organisms present in these areas can berelated to those in other parts of the world. However, due to very specific conditions in the surrounding environment, these species evolve very distinct characteristics. Hereditary Traits: Each species has traits determined by heredity. Hereditary traits passed from parents to offspring determine the characteristics of the offspring. Inherited traits that improve your chances of survival are more likely to be passed on to subsequent generations. Of course, some characteristics, such as weight and muscle mass, can also be influenced by environmental factors such as food availability. But characteristics developed through environmental influences will not be passed on to future generations. Only traits passed on by genes will be inherited. For example, if an organism inherits the genes for a larger skeletal mass but lack of nutrition prevents the individual from growing to that size, and if the individual survives and reproduces, the genes for the larger skeleton will be passed on . Each year species produce more offspring than the environment can support. This high birth rate results in competition among members of the species for the limited natural resources available. The struggle for resources determines the mortality rate within a species. Only surviving individuals reproduce and pass on their genes to the next generation. Survival of the fittest: Some individuals survive the struggle for resources. These individuals reproduce, adding their genes to subsequent generations. The traits that helped these organisms survive will be passed on to their offspring. This process is known as “natural selection”. Environmental conditions determine the survival of individuals with specific traits that are transmitted through inheritance to the next generation. Today we call this process “survival of the fittest”. Darwin used this phrase, but attributed the source to a fellow biologist, Herbert Spencer. The bacteria grow and multiply quickly and can reach large numbers. When bacteria multiply, one cell divides into two cells. Every time the bacterium goes through this process there is the possibility (or risk, depending on the final outcome) that errors will occur; the so-called mutations. These mutations are random and can be located anywhere in the DNA. While some mutations are harmful to bacteria, others can provide an advantage given the right circumstances. This is where Darwin's theory of natural selection comes into play. If a mutation gives the bacterium an advantage in a particular environment, this bacterium will grow better than its neighbors and can increase in number: this is why it is selected for. Mutations are one way that bacteria become resistant to antibiotics. Some spontaneous mutations (or genes acquired from other bacteria through horizontal gene transfer) can make the bacterium resistant to an antibiotic. If we treated the bacterial population with that specific antibiotic, only resistant bacteria will be able to multiply; the antibiotic selects for them. These bacteria can now increase in number and the end result is a population composed mainly of resistant bacteria. The process of natural selection of resistant bacteria. Antibiotics kill sensitive bacteria, but any resistant bacteria will survive. When competition from other bacteria disappears, these resistant bacteria can increase in number. It is important to understand that selection for antibiotic-resistant bacteria can occur anywhere an antibiotic is present in a selective concentration. When we treat an infection, selection can occur anywhere in the body that the antibiotic reaches. Therefore, the antibiotic can.