Reviewed: one independent reader; copy check clear.
direct selection
direct selection In historical evolutionary discussion, direct selection means selection that acts immediately on the trait or material in question, rather than producing it indirectly as a by-product of other changes.
In historical evolutionary discussion, direct selection means selection that acts immediately on the trait or material in question, rather than producing it indirectly as a by-product of other changes. In the passage, it is contrasted with Darwin’s view that some features, such as mutual sterility, arise incidentally instead of being directly selected.