Meaning & use
directional selection
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Meaning
noununcountablebiology
A type of natural selection where individuals with one extreme version of a trait survive and reproduce better than others, so the trait shifts in that direction over generations.
Grammar: Used as a mass noun; no plural form is needed.
Patterns
- directional selection for something
- directional selection against something
- directional selection in a population
In a population of birds, directional selection favored longer beaks because the seeds available were deep in hard shells.
The fossil record shows directional selection for larger body size during cold periods.
When a new predator arrives, directional selection can quickly change the average color of a prey species.
Common combinations
- strong directional selection
- Strong directional selection for drought tolerance left only the deepest-rooted plants.
- directional selection pressure
- The changing climate created a directional selection pressure on flowering time.
- directional selection for
- The researchers found directional selection for smaller body size in warmer years.
- directional selection against
- Directional selection against bright plumage made duller males more common.
- act of directional selection
- The shift in beak size is a classic act of directional selection.
Synonyms and how they differ
- positive selection
- This term often refers to selection that favors a beneficial new trait, which can be a form of directional selection, but it is not always limited to a shift toward one extreme.
- adaptive evolution
- A broader term for any genetic change that improves survival; directional selection is one specific pattern that can cause it.
Opposites
Word family
- directional adjective
- Relating to a direction or movement toward a point.
- selection noun
- The process by which certain individuals survive and reproduce more than others.
- select verb
- To choose something or someone from a group.
Commonly confused: directional selection or disruptive selection? directional selection or stabilizing selection?
directional selection vs disruptive selection
Disruptive selection favors both extremes of a trait and can split a population, while directional selection favors only one extreme.
directional selection vs stabilizing selection
Stabilizing selection favors the average trait value and reduces variation, which is the opposite of a directional shift.
Practice
Which sentence correctly uses 'directional selection'?
Choose one answer.
Option 1 is correct because directional selection favors one extreme, here smaller body size. Option 0 describes stabilizing selection, option 2 describes disruptive selection, and option 3 describes artificial selection, not natural directional selection.
Make it your own
Write a sentence using “directional selection”, then check it and compare it with the examples above.