Gradual definitely tending variation, such as may be observed in a group of organisms in the fossils of successive geological levels.
As now employed (first by de Vries), a sudden variation (the offspring differing from its parents in some well-marked character or characters) as distinguished from a gradual variations in which the new characters become fully developed only in the course of many generations. The occurrence of mutations, and the hereditary transmission, under some conditions, of the characters so appearing, are well-established facts; whether the process has played an important part in the evolution of the existing species and other groups of organisms is a disputed question.
The result of the above process; a suddenly produced variation.
The unique nature about the influenza virus is its great potential for changes, for mutation. Margaret Chan
The balance of evidence both from the cell-free system and from the study of mutation, suggests that this does not occur at random, and that triplets coding the same amino acid may well be rather similar. Francis Crick
A comparison between the triplets tentatively deduced by these methods with the changes in amino acid sequence produced by mutation shows a fair measure of agreement. Francis Crick
If you're the kind of person who likes numbers and statistics, I'm the long shot - the Lotto Powerball winner. I'm the mutation in the DNA that makes evolution a reality. I am the new black. Tracy Morgan
For the first time in history we can track the evolution of a pandemic in real time. Influenza viruses are notorious for their rapid mutation and unpredictable behaviour. Margaret Chan