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Evolution theories, https://youtu.be/4HBdxDBqfHc, https://youtu.be/Me…
Evolution theories
Darwinism:is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits. Changes that allow an organism to better adapt to its environment will help it survive and have more offspring.
Darwin proceeded to work on the now well-understood concept that evolution is essentially brought about by the interplay of three principles: variation, heredity and the struggle for existence
Examples:
Plants evolve to become suited to their environment through natural selection. Some plants evolve flower colors to attract pollinators of a specific kind. 
Populations of bacteria exhibit very strong natural selection because they can multiply rapidly.
Lamarckism:based on the principle that physical changes in organisms during their lifetime—such as greater development of an organ or a part through increased use—could be transmitted to their offspring.
Propositions:
Change Through Use And Disuse:
The organs which are used frequently by the organism develop and the characteristics that are used seldom are lost in the succeeding generations.
Organisms Driven To Greater Complexity:
As the organisms adapted to their surroundings, they became increasingly complex from the simpler forms. Lamarck believed in the spontaneous generation of life.
Inheritance of Acquired Characters:
An individual acquires certain characteristics during its lifetime. These characters are inherited by their offspring as well. He explained this with an example of a blacksmith.
Effect of Environment and New Needs:
The environment influences all the organisms. A slight change in the environment brings about changes in the organisms. This gives rise to new needs which in turn produces new structures and changes the habits of the organisms.
Examples:
Aquatic birds such as ducks are believed to have evolved from terrestrial animals.
The snakes are believed to have evolved from lizard-like ancestors that have two pairs of limbs.
Neo darwinism:Theory of evolution that represents a synthesis of Charles Darwin’s theory in terms of natural selection and modern population genetics. This evolution is produced by a population and its genetic composition.
August Weismann, who asserted that his germ-plasm theory made impossible the inheritance of acquired characteristics and supported natural selection as the only major process that would account for biological evolution.
Examples:
The so-called industrial melanism, which is defined as the predominant color change as a consequence of the environmental change caused by industrial activity.
The ancestor of the horse does not have a hoof, if it did not have fingers, then centuries passed until it reached the hoof.
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