Introduction

Charles Darwin was an English naturalist in the nineteenth century.Charles Darwin (1809 – 1882) about evolution marks the beginning of an era in understanding of evolution.  At the age of 22 he lead the expedition tour on H.M.S.Beagle (1831), studied a variety of flora and fauna from different parts of globe, but found Galapagos Island most interesting, a “living laboratory of evolution”.

Darwin propounded Natural Selection as the basis of evolution – and all organisms including man have arisen as modified descendants.

He was influenced by the ideas of 

1.   T.R. Malthus (1799)       —   An Essay on Population
2.   Charles Lyell (1832)       —    Principles of Geology
3.   Herbert Spencer (1856) —    Idea of Survival of fittest

Later with the help of Lyell and Hooker Darwin published (1859) his complete book “Origin of New Species by Natural Selection” : “The Preservation of Races in the Struggle for Life”.

Alfred Russel Wallace (1823 – 19130) investigated the flora and fauna of South East Asia and South America.

• He came to a conclusion which was supported by Darwin in the paper “On the tendency of varieties to depart independently from the original type”
• Darwin and Wallace therefore produced a joint paper “On the tendency of species to form varieties and perpetuation of varieties and species and means of natural selection”
• In 1859, Darwin explained the theory of evolution in the back “On the origin of species by means of natural selection” popularly called “origin of species”

The “origin of species” (1859) holds an impressive amount of evidence in support of evolution by natural selection.

Carles Darwin is renowned as the “Father of Evolution” because of his role in the development of evolutionary theory. 

The Theory Of Evolution and the Elements of Natural Selection by Charles Darwin

 The resources of earth are limited. Therefore, populations of different species cannot increase beyond a certain limit, which leads to the struggle for existence.

 In the struggle for existence only those members survive which possess useful variation means nature selects fit individuals. This was called Natural selection

 This is the basis for formation of new species. Hence, he believed evolution as a slow gradual and longtime process.

  No two organisms are exactly alike. Under a given set of environment conditions certain individuals of a species possess variations tending to adjust them very advantageously to external conditions, whereas other individuals of the same species possess less favorable variations and thus are at a disadvantage in relation to the same set of environment factors.

  Variations are small morphological, physiological and behaviouristic differences among the individuals.

 Darwin claimed that species can evolve over time, that new species emerge from existing species and that all species have a common ancestor. 

The concept of Darvin’s theory was based on the following concepts:

• Traits are heritable
• To survive a creator produces more offspring
• The inheritable traits of offspring vary

The thoughts of Darwin regarding natural selection are as follows:-

• Species continue to evolve or change with time. Climate change also changes the conditions to survive and an organism needs to adapt to that habitat to survive. This peculiarity of changing throughout some undefined time frame according to the regular necessities is known as adaptation

• According to Darwin’s theory, superior changes are naturally selected and the others are eliminated from the environment. Along these lines, not all variations add to moderate advancement

• He studied the birds of the Galapagos Islands (Darwin’s finches) who developed various mouths or beaks according to the accessibility of their food. This demonstrated adaptability to radiation. He also noticed that Australian Marsupials showed various marsupials arising from some ancestors

• Practically all living beings share a common ancestral background with some creature. As per Darwin, all life forms had one ancestor and continued to diverge from that point onward. His evolutionary theories and hypotheses support the focused hypothesis

• As per Darwin, evolution is a long and gradual cycle. He reasoned that the conclusion occurred over a pervasive period. As we study the period of evolution, we generally refer to the changes that take place in billions of years. It is a highly consistent cycle as changes & adaptation consume most of the day to settle and lead to another species

Natural selection happens in four various ways

1. Reproduction

For natural selection to follow up on a given populace, that population should reproduce to make another new generation. Species regenerate themselves in order to maintain the continuity of their individual species on the earth. If the species stops reproducing, species will vanish after some time. The higher the reproduction pace of a populace, the higher the cutthroat strain is on an individual to survive.

2. Heredity

The passing of genetic factors from parents to offspring or from one generation to the next is referred to as heredity. The biological meaning of heredity may also refer to the link of a trait with an individual organism’s genetic constitution rather than environmental factors.

3. Variety in Characteristics

Natural selection can happen inside a populace when individuals from the populace have a variety of individual traits. For instance, a natural selection study on colour inside a populace requires various people to have changing tones. Without a variety in the attributes or traits, there will be no change in the characteristics for nature to “select” over others.

4. Variety in Fitness

In science, fitness has a more specialised significance than its standard definition. Inside the development setting, fitness is the capacity of a living being to survive and replicate by reproduction. Changing fitness degrees in individuals from a populace is essential for natural selection to happen. A few people should have traits that permit them to survive better and replicate more regularly than others.

Conclusion

So in this chapter, we learned about the father of evolution, Charles Darwin, and his theory of evolution. This theory states about the survival of the fittest. Here we have studied Darwin’s contribution definition. To survive and continue the species, human beings need to change and adapt themselves to the changes in the environment and keep on replicating and reproducing their offspring. By transfer of genes, the heredity goes on and thus, the theory of evolution continues in its way.