Neo-Darwinism is the "modern synthesis" of Darwinian evolution through natural selection with Mendelian genetics, the latter specifying that evolution involves the transmission of characteristics from parent to offspring through the mechanism of genetic transfer, rather than the "blending process" of pre-Mendelian evolutionary science. Neo-Darwinism can also designate Charles Darwin's ideas of natural selection separated from his hypothesis of pangenesis as a Lamarckian source of variation involving blending inheritance.
As part of the disagreement about whether natural selection alone was sufficient to explain speciation, George Romanes coined the term neo-Darwinism in 1895 to refer to the version of evolution advocated by Alfred Russel Wallace and August Weismann with its heavy dependence on natural selection. 
Weismann and Wallace rejected the Lamarckian idea of inheritance of acquired characteristics that even Darwin took for granted. The term was first used to explain that evolution occurs solely through natural selection, and not by the inheritance of acquired characteristics resulting from use or disuse. The basis for the complete rejection of Lamarckism was Weismann's germ plasm theory. Weismann realised that the cells that produce the germ plasm, or gametes (such as sperm and egg in animals), separate from the somatic cells that go on to make other body tissues at an early stage in development. Since he could see no obvious means of communication between the two, he asserted that the inheritance of acquired characteristics was therefore impossible; a conclusion now known as the Weismann barrier.
From the 1880s to the 1930s, the term continued to be applied to the panselectionist school of thought, which argued that natural selection was the main and perhaps sole cause of all evolution. From then until around 1947, the term was used for the panselectionist followers of Ronald Fisher.
Modern evolutionary synthesis
Following the development, from about 1936 to 1947, of the modern evolutionary synthesis, now generally referred to as the synthetic view of evolution or the modern synthesis, the term neo-Darwinian is often used to refer to contemporary evolutionary theory. However, some have described such usage as incorrect; with Ernst Mayr writing in 1984 that "the term neo-Darwinism for the synthetic theory is wrong, because the term neo-Darwinism was coined by Romanes in 1895 as a designation of Weismann's theory."
Despite such objections, publications such as Encyclopædia Britannica use this term to refer to current evolutionary theory. Richard Dawkins and Stephen Jay Gould use the term in their writings and lectures.
- Developmental systems theory
- Evolutionary developmental biology
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- Gould 2002, p. 216
- Darwin 1872, p. 108
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- Pigliucci, Massimo (December 2007). "Do We Need An Extended Evolutionary Synthesis?" (PDF). Evolution. Hoboken, NJ: John Wiley & Sons for the Society for the Study of Evolution. 61 (12): 2743–2749. doi:10.1111/j.1558-5646.2007.00246.x. PMID 17924956.
- Mayr, Ernst (1984). "What is Darwinism Today?". PSA: Proceedings of the Biennial Meeting of the Philosophy of Science Association. Chicago, IL: University of Chicago Press on behalf of the Philosophy of Science Association. 2: 145–156. ISSN 0270-8647. JSTOR 192502. Volume Two: Symposia and Invited Papers (1984).
- "neo-Darwinism". Encyclopædia Britannica. Chicago, IL: Encyclopædia Britannica, Inc. 2015. Retrieved 2015-11-19.
- on YouTube. The video of the lecture was originally posted on May 5, 2010, at old.richarddawkins.net: "Lecture on Neo-Darwinism" at the Wayback Machine (archived December 1, 2014).
- Gould 2011, pp. 53–73
- Darwin, Charles (1872). The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (6th ed.). London: John Murray. OCLC 1185571.
- Gould, Stephen Jay (2002). The Structure of Evolutionary Theory. Cambridge, MA: Belknap Press of Harvard University Press. ISBN 0-674-00613-5. LCCN 2001043556. OCLC 47869352.
- Gould, Stephen Jay (2011). "Challenges to Neo-Darwinism and Their Meaning for a Revised View of Human Consciousness". In McMurrin, Sterling M. The Tanner Lectures on Human Values. 6. Salt Lake City, UT; Cambridge, UK: University of Utah Press; Cambridge University Press. ISBN 978-0-521-17647-7. OCLC 846869183. "Lecture delivered at Clare Hall, Cambridge University April 30 and May 1, 1984"