The Origin of Species · Chapter
II: Variation Under Nature explained
Darwin discusses the difficulty of defining 'species' and 'variety,' emphasizing that individual differences provide the raw material for natural selection.
What happens
Darwin discusses the difficulty of defining 'species' and 'variety,' emphasizing that individual differences provide the raw material for natural selection. He examines doubtful species, the arbitrary nature of classification, and the tendency for wide-ranging, common species to vary most. The chapter lays groundwork for the argument that varieties are incipient species.
Themes in this chapter
Variation and Inheritance
Central theme: individual differences are inherited and provide material for natural selection; varieties are incipient species.
Natural Selection and the Struggle for Existence
Referenced as the cumulative action that transforms varieties into species, though detailed explanation is deferred.
Characters to notice
- Charles Darwin
Author and narrator; presents his views on variation, species definitions, and the importance of individual differences.
- Mr. H. C. Watson
Provided data on British plants considered varieties by some botanists and species by others; assisted Darwin in tabulating varieties.
- Dr. Hooker
Reviewed Darwin's manuscript and tables; confirmed that wide-ranging species vary most.
- Mr. Wallace
Cited for his work on Malayan Archipelago Lepidoptera, classifying forms into variable forms, local forms, subspecies, and representative species.
- Mr. Wollaston
Mentioned regarding varieties of fossil land-shells in Madeira that endured as varieties for long periods.
- De Candolle
Noted for showing that plants with wide ranges often produce varieties.
Key passages
“No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species.”
There is no universally accepted definition of 'species,' but naturalists have an intuitive understanding of the term.
Highlights the subjective nature of species classification.
“I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety.”
The distinction between species and variety is arbitrary and based on convenience rather than a fundamental difference.
Key argument that species are not fixed, immutable categories.
“A well-marked variety may therefore be called an incipient species.”
A distinct variety is essentially a species in the early stages of formation.
Introduces the concept of varieties as stepping stones to new species.