Answer:
Darwinism and Neo-Darwinism are two terms that refer to different aspects of the theory of evolution by natural selection.
Darwinism is the original concept proposed by Charles Darwin in the 19th century, based on his observations of the diversity of life and the fossil record. Darwinism states that all living organisms share a common ancestor and that they have evolved over time through the process of natural selection. Natural selection is the mechanism that favors the survival and reproduction of individuals that are better adapted to their environment, and thus leads to the accumulation of inherited variations that increase the fitness of a population.
Neo-Darwinism is the modern synthesis of Darwinism and genetics, developed in the 20th century by various scientists, such as Ronald Fisher, Theodosius Dobzhansky, and Ernst Mayr. Neo-Darwinism incorporates the discoveries of Mendelian inheritance, mutation, gene flow, genetic drift, and speciation into the framework of Darwinism. Neo-Darwinism explains how the genetic variation that is the raw material for natural selection is generated and maintained, and how new species arise from the divergence of populations.
The basic difference between Darwinism and Neo-Darwinism is that Darwinism did not have a clear understanding of the source and nature of genetic variation, while Neo-Darwinism does. Darwinism also did not account for the role of other evolutionary forces besides natural selection, such as genetic drift and gene flow, while Neo-Darwinism does. Neo-Darwinism is considered to be a more comprehensive and accurate version of Darwinism, as it is supported by a wealth of empirical evidence from various fields of biology.