Evolution is one of the complex phenomenon linked with heredity, environment, geographic location of the inhabitants and many other factors. Evolution is the gradual change in the inherited characteristics of individual species. Charles Darwin is well known as the father of evolution and his wok Darwinism has gained attention from many biologists around the world. Darwin`s work was based on the principles of genetics written by Mendel explained. Mendel framed the most popular theory of genetics. It is very difficult to express what precisely influence the evolution because each of us interact with the environment differently and behave in a certain way as a result individuals become unique over a period of time. Some of the underlying mechanisms of evolution are explained below.
Table of Contents
3. Gene flow
4. Genetic drift
5. Natural selection
7. Gradualism and rapidity
8. Hardy-Weinberg principle
9. A brief account of the evolution
Mutation is the key factor responsible for evolution. Although every mutation cannot be categorised as productive, a gradual and healthy mutation end up inheriting some useful traits in the progeny. Lesser the gap between the generations, greater the similarity. Mutation is a random change in an individual’s genetic makeup of the offsprings resulting in a set of useful variations. As a result of the random variation in the gene- pool, individuals obtain some In the short-term, mutations can be benign but they benefit in their long-term. One of the best examples is the evolution of human species for over centuries.
gene flow refers to how the genes transfer between different individuals. The genes transfer between the individuals under a variety of influences. One of them is the migration of individuals and groups from a place to another. When people migrate, there is a geographical mixing of individuals help in promoting the formation of unique breeds possessing many positive traits such as resistance against illnesses, being tall, attractive etc.
This is similar to gene flow. Genetic drift occurs when a small group of individuals relocates to a geographically isolated region. For instance, when we bring new species of fish from oceans to culture them in a private pond, there is the interchanging of genetic characters between the 2 species, as a result, better breeds are produced in both the inland and ocean fish population. This is becasue of genetic drift.
Natural selection is the differential survival and reproduction of individuals because of the differences in phenotype. It is pivotal for evolution resulting in the change of the heritable characteristic of a population over generations. Natural selection is by virtue of nature aid in testing the fitness of individuals to survive. There is survival of only the fittest.
This occurs when a particular population is isolated by geographic barriers, for example, desert in between 2 states, oceans between the continents. For example, the isolation of Australia, New Zealand, and the Galapagos Islands allowed many species to look for new habitats. Change in the habitat will obviously bring in many influences eventually resulting in the evolution.
Gradualism and rapidity
Darwin’s theory concluded that evolutionary changes take place slowly. In many cases, the fossil record shows that a species changed gradually over time but not instantly. The phenomenon of gradual evolution is known as gradualism.
Hardy-Weinbergprinciple uses a mathematical equation to calculate the genetic variation of a given population. In the year 1908, G. H. Hardy and Wilhelm Weinberg have postulated this. The equation states that the amount of genetic variation in a population will always remain constant from one generation to the next unless there are contamination factors. Take for example a genetic locus have 2 alleles namely, M and m. Based on the Hardy-Weinberg equation, the equation is written as: p2 + 2pq + q2 = 1 similar to (A+B)2. In the equation, p2 expresses the frequency of the homozygous genotype MM, q2 expresses the frequency of the homozygous genotype mm, and 2pq represents the frequency of the heterozygous genotype Mm. Here the sum total of the allele frequencies for all the alleles in this locus must be 1, so p + q = 1. If the p and q allele frequencies are known, then the frequencies of the 3 genotypes may be calculated using the Hardy-Weinberg equation. In population genetics studies, the Hardy-Weinberg equation can be used to measure whether the observed genotype frequencies in a population differ from the frequencies predicted by the equation.
A brief account of the evolution
1. Big Bang theory delineates the stages of how the earth and life forms have been formed. The first cellular forms of life appeared on earth was about 2000 million years ago. Gradually single-cellular organisms have evolved into many multi-cellular life forms.
2. 500 million years ago, invertebrates appeared gradually they had spilt into diverse categories through reproduction.
3. Around 350 mya, jawless fishes have evolved. Some of them were stout and few had strong fins. They were even able to move on land and go back to water when they wish. This indicates the fact that the fish population were amphibians instead of water creatures.
4. Some primitive seaweeds and plants were formed around 320 million years ago. the first organisms that invaded land were plants.
5. Reptiles of varied shapes, sizes, and life patterns started flourishing during 200mya.
6. Dinosaurs were known as the land reptiles existed at some point in time but they had undergone extinction. The period of extinction led to the evolution of many smaller reptiles, mammals, and human beings.