The environment picks
Variations do not all survive equally.
A heat wave
A group of bacteria has some variation. Some of them can withstand heat better than others. A heat wave arrives.
Which bacteria are likely to survive better?
What this lesson covers
The idea
Variations have unequal chances of survival: depending on their nature they give different advantages, and selection of variants by environmental factors forms the basis for evolutionary processes.
A heat wave
A group of bacteria has some variation. Some of them can withstand heat better than others. A heat wave arrives.
Which bacteria are likely to survive better?
- The ones that can withstand heat
- The ones that cannot withstand heat
- All of them survive equally well
Heat wave
Press Next step.
Selection
The heat did not treat all the bacteria alike. The variation that helped in the heat gave an advantage. This is how the environment selects variants.
Variations have unequal chances of survival: depending on their nature they give individuals different advantages. Selection of variants by environmental factors forms the basis for evolutionary processes.
Notes
Variations have unequal chances of survival. Selection of variants by the environment forms the basis for evolution.
Check yourself
Do all the variations in a species have equal chances of surviving in their environment?
In a heat wave, which bacteria survive better?
What forms the basis for evolutionary processes?
- Yes, all variations have equal chances. Depending on the nature of the variation, different individuals have different kinds of advantages.
- No, different variations give different advantages — correct. Yes!
- No, because every variation harms the individual. Some variations give an advantage. For example, bacteria that can withstand heat survive better in a heat wave.
- Those that cannot withstand heat. A variation that lets bacteria withstand heat is the advantage in a heat wave.
- All bacteria survive equally well. Bacteria that can withstand heat have an advantage, so they survive better.
- Those that can withstand heat — correct. Yes!
- Selection of variants by environmental factors — correct. Yes!
- Equal survival of all variants. Variants do not have equal chances of surviving. The environment selects among them.
- Individuals without any variants. Variants exist, and selection of variants by environmental factors forms the basis for evolutionary processes.