give salient features of lamarck theory

Dear student,
Jean-Baptiste Lamarck's theory, also called as Lamarckism possess following features:

• Use and disuse of organs: The organs which are used continuously increase in size, develop and become more functional whereas the organs which are not used often gets degenerated and become lost.
• The ecological conditions in which an organism lives results in requirement of certain needs. These needs are fulfilled by production of new organs or degeneration of unused organs or modification of old organs.
• Character changes in an individual due to the inhabiting environment becomes hereditary and are transmitted to next generation.
• For example- long neck of the modern giraffe. During food scarcity, the short-necked giraffes needed to stretch their necks to get leaves from higher trees. This resulted in stretching of their necks and passing of this trait to next generations. Thus it became genetically fixed and giraffes today have longer necks.

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