Question

Write any two pieces of evidence in favour of organic evolution. On the basis of any, prove the theory of organic evolution.

Answer 1

Hint: Evolution refers to the changes in a species which accumulate over several generations. Various factors like gene flow, mutation, natural selection, and genetic drift direct evolution.

Complete step-by-step answer:
Organic evolution is defined as changes in the genetic makeup of a species in a particular population. This occurs due to environmental changes. Accumulation of changes helps the organism survive the changing environmental conditions, thus facilitating better survival.

This process is a steady and slow process which takes a long time to occur over generations. These changes are tolerated by the organisms and maintain an equilibrium with the ecosystem.
Charles Darwin, Jean-Baptiste Lamarck, and Alfred Russel Wallace have proposed various theories of organic evolution.

Mechanisms of change, genetic drift, mutation, migration, etc cause organic evolution to occur. It also highlights the consequences of the reduction in the incidence of genetic variation and randomness of genetic drift.

Different pieces of evidence based on morphology, embryology, geography, geology, biochemistry, and physiology support organic evolution.
Fossils, homologous organs, analogous organs, vestigial organs, atavism, etc are a few examples that support organic evolution.

Vestigial organs appear smaller and functionless compared to homologous organs present in the ancestors. Snakes and whales consist of rudimentary bones in the former hind limbs. They provide anatomical changes in organisms as evolution progresses.
Fossils are well-preserved remains of organisms that get embedded into soil or water. This is due to the petrifaction, due to the replacement of organic matter by minerals like sand, oxides, lime, etc. Fossils provide geological evidence of morphological changes that occurred over a period of time across different organisms. Examples- fossils of Archaeopteryx, Eusthinopteron, Ayshaea, etc.

Note: Various factors that affect the process of evolution include non-random mating, mutations, the flow of genes, genetic variations, and population size.