Biology / Unit 8 Bio 1677 short lesson, about 20 seconds
"Organisms Evolve Because They Need To"
Captions available
The idea
Organisms do not evolve a trait because they need it, the mechanism-level expansion of Unit 1's Bio 0057 — variation must already exist before any pressure appears.
In practice
Antibiotic-resistance genes already existed at low frequency before antibiotic exposure, which then selected for their carriers.
Where people slip
An environmental change does not summon a new adaptation on demand — it only selects among variation already present.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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