Biology / Unit 1 Bio 0056 short lesson, about 20 seconds
Natural Selection
Captions available
The idea
Natural selection is the mechanism by which individuals whose traits better fit their environment survive and reproduce at a higher rate, shifting allele frequencies over time.
In practice
Moths with a coloring that better matches tree bark are eaten less often and leave more offspring behind.
Where people slip
A single organism does not undergo natural selection in its lifetime; only a reproducing population does, across generations.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology