Evolution

Evolution is a theory in Biology that explains the changes in flora, fauna, and other living things on Earth and that this depends on the process of evolution. At the time of birth, the genes are passed on from parent to offspring. Factors are a manifestation of these genes. Different characteristics exist in a given number of species due to genetic variation or due to mutations. Over time, these traits become more common or less common in certain species of animals.

History

Evolutionary science theory using the method of natural selection was presented by 'Charles Darwin' and 'Alfred Russel Wallace'. This happened in the 19th century. The theory presented is commonly called Darwin's Theory of Evolution.

Darwin also authored a book on Evolution entitled ‘On the Origin of Species’. According to Darwin's view of natural selection, interest rates are higher than ever, but survival rates are low.

There are three observations regarding this idea:

In all species of animals, characteristics vary in their physiology, morphology, and behaviour.

Survival and fertility rates depend on a factor in the past.

Symptoms can be passed on from generation to generation.

We can therefore say that with each passing generation the offspring usually survives the genetic predisposition of the parents and alters their traits and characteristics in relation to certain natural conditions which usually enable them to adapt to a particular given habitat.

This is how an evolution evolved from one generation to another

Any species that exists today on Earth has the Last Universal Common Ancestor (LUCA) that used to live about 3.5 billion to 4 billion years ago. This can also be explored by studying the fossil records that usually include Biogenic Graphite in living things or other evolutionary data incorporated into each passing generation that can provide details about almost every living thing in history.

The study of the existing pattern of biodiversity is divided into 3 categories:

Speciation (the formation of new species over time)

Anagenesis (mutations that occur between certain species in relation to each passing generation)

Extinction (extinction of any species of dinosaur-like animals)

Greek philosophers such as the Empedocles and Anaximander of prehistoric times also believed in the possibility of the evolution of species. This idea even prevailed in Roman times. During the mediaeval period people followed the ideas of Aristotle who was considered the father of the western mind, however, much of the controversy over ancient data people believed that anything in nature had something to do with divinity in the universe. Thus, this understanding was introduced under Christian teaching. However, the examples that Aristotle set out as the basis for new species were still being considered.

Then came the era before Darwin, when modern philosophy rebuffed the ideas of Aristotle. They only accept the explanation of natural phenomena regarding the laws of nature. The name ‘Species’ was coined by John Ray in some unchanging natural species. Biological division was introduced by Carl Linnaeus in 1735. Later, Erasmus Darwin proposed that all living things on earth evolve from a tiny organism.

The first theory of Evolution dates back to the 19th century (1744-1829) when Jean Baptiste Lamarck proposed the 'Transmutation of species' theory.

Role of Genes in Evolution

The Evolution process takes place at the Genomic level. Genetics are the basic unit of inheritance. Gene is made up of DNA. Any changes in the DNA sequence will affect the structure and affect the way genes are expressed. Our ancestral history and evolutionary data are embedded in DNA. When two different species have the same DNA and the same Gene, we may predict that those species may share the same ancestry. For example, humans are said to evolve from apes. Over time, DNA changes. While some changes are beneficial to the living person and help them to adapt to a better environment and environment, some changes may be especially dangerous if there is a mistake involved as this mistake can be passed onto future generations. Some genes remain as they are throughout Evolution.

Heredity

Genetics depends on two key factors, namely Genotype and Phenotype.

There are certain aspects that are controlled by Gene. This is called a Genotype.

For example, some of the facial features,hair type and eye colour are inherited from one of the parents. To be precise, if one of the parents has a blue eye colour and he/she is inherited from the offspring then it is basically called the 'blue eye feature'.

The set of human traits in relation to their interactions between their genotype and environment is called Phenotype. Because of this feature, many aspects of human phenotype are not inherited. Phenotype appears naturally. There is a strong combination of Gene and nature that expresses the appearance and behaviour of living things. Various examples can be counted on that, from the size of the bird's beak, the lashes on the animal's back, and the colour of the hair, etc.

NCERT Books Link:

• NCERT book for class 11 Biology.
• NCERT book for class 12 Biology

Gene Flow

The flow of genes is also called migration. This is nothing more than carrying a human gene from one figure to another. This migration occurs through a number of factors such as pollination flying from one place to another, mating between people of different races and ethnicities will produce offspring bearing the characteristics of both parents. For example, an Indian person is moving to the USA, and those who are married to an American person will dedicate children to the traits of both parents.

The genetic flow between different species occurs in two ways;

Vertical genetic transfer: The flow of genes between two genes of the same species is affected by the migration and further reproduction, thus the transfer of genes from parents to offspring occurs.

Horizontal gene transfer: This is a genetic transfer between two different types. Genetics can be transferred from the lower extremities to the upper extremities or genetic transfer occurs from the Endosymbiont to the host.

Genetic diversity depends on the flow of Gene. The flow of genes can be prevented between certain species of animals by placing barriers between isolated populations and thus preserving the unique identity of a specific population.

NCERT Notes Subject Wise Link:

• NCERT notes Class 12 Maths
• NCERT notes Class 12 Physics
• NCERT notes Class 12 Chemistry
• NCERT notes Class 12 Biology

Natural selection

Darwin's proposed natural selection theory has four main components:

Inheritance: a few aspects are permanently transferred from parent to children while a few factors have an environmental impact and Habitat.

Variety: Even within the same population each person exhibits different differences such as colour, body size, features, etc. although they are of the same type.

High rate of population growth: Few species have more children each year than the number of resources available to them. This leads to a resource struggle between people.

Different survival and reproduction: Those creatures with a genetic predisposition to survival will lead to reproduction and thus provide additional offspring for future generations.

NCERT Solutions Subject wise link:

• NCERT solutions for class 12 Physics.
• NCERT solutions for class 12 Chemistry.
• NCERT solutions for class 12 Mathematics.
• NCERT solutions for class 12 Biology.

NCERT Exemplar Solutions Subject wise link:

• NCERT exemplar solutions for class 12 Physics.
• NCERT exemplar solutions for class 12 Chemistry.
• NCERT exemplar solutions for class 12 Mathematics.
• NCERT exemplar solutions for class 12 Biology.