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In biology, evolution is the process of change in all forms of life over generations, and evolutionary biology is the study of how evolution occurs. Biological populations evolve through genetic changes that correspond to changes in the organisms ' observable traits .
Mosaic evolution – Evolution of characters at various rates both within and between species; Parallel evolution – Similar evolution in distinct species; Quantum evolution – Evolution where transitional forms are particularly unstable and do not last long; Recurrent evolution – The repeated evolution of a particular character
Dr. Dinesh Prasad Saklani is the director of NCERT since 2022. [2] In 2023, NCERT constituted a 19-member committee, including author and Infosys Foundation chair Sudha Murthy, singer Shankar Mahadevan, and Manjul Bhargava to finalize the curriculum, textbooks and learning material for classes 3 to 12. [4]
The mechanisms of evolution focus mainly on mutation, genetic drift, gene flow, non-random mating, and natural selection. Mutation: Mutation [12] is a change in the DNA sequence inside a gene or a chromosome of an organism. Most mutations are deleterious, or neutral; i.e. they can neither harm nor benefit, but can also be beneficial sometimes.
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
This mutationist view of evolution was later replaced by the reconciliation of Mendelian genetics with natural selection into a gradualistic framework for the neo-Darwinian synthesis. [10] It was the emergence of population thinking in evolution which forced many scientists to adopt gradualism in the early 20th century.
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]