MYP Biology Topic Natural Selection Revision Notes

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MYP Biology Topic Natural Selection Revision Notes | RevisionDojo

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Why Do Some Traits Become More Common Over Time?

Natural selection is the process by which individuals with advantageous traits are more likely to survive and reproduce.
These traits are passed to offspring and become more common in the population over generations.

Definition

Natural selection

A process where individuals with advantageous traits survive and reproduce more successfully than others.

Tip

While inheritance creates variation, natural selection acts on that variation.

How Does Natural Selection Work?

Natural selection follows a predictable sequence explaining how populations change over time:

Variation exists Individuals differ in traits such as size, color, behaviour, or physiology.
Some variations give advantages: certain traits improve survival or reproduction under specific environmental conditions.
Individuals with advantageous traits survive longer, escaping predators, finding food more easily, resisting disease, or tolerating stress.
As these individuals reproduce more, they pass their alleles to more offspring.
The trait becomes more common over generations, increasing the frequency of these advantageous alleles.

Analogy

A population is like a sieve: only traits that fit the environment pass through to the next generation.

What Creates the Variation That Natural Selection Acts On?

Variation is generated through genetic processes described previously:
1. Meiosis shuffles alleles
2. Fertilization combines alleles
3. Mutations create new alleles
4. Polygenic traits produce continuous variation
Again, you must understand natural selection does not create variation; it filters existing variation.

Common Mistake

Thinking organisms “develop traits because they need them” when they don't.
Only individuals already possessing advantageous traits survive to reproduce.

How Do Environments Decide Which Traits Succeed?

The environment “chooses” traits by rewarding individuals who already have traits that match current conditions.
In other words, the environment determines which traits are favorable, not an organism’s intentions.
These environmental factors include:

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MYP Biology Natural Selection Notes

Why Do Some Traits Become More Common Over Time?

How Does Natural Selection Work?

What Creates the Variation That Natural Selection Acts On?

How Do Environments Decide Which Traits Succeed?

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Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Why Do Some Traits Become More Common Over Time?

How Does Natural Selection Work?

What Creates the Variation That Natural Selection Acts On?

How Do Environments Decide Which Traits Succeed?

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Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Cells7 subtopics

Organisms7 subtopics

Processes10 subtopics

Metabolism4 subtopics

Evolution7 subtopics

Interactions with environment6 subtopics

Interactions between organisms5 subtopics

Human interactions with environments3 subtopics

Biotechnology3 subtopics

MYP Biology Natural Selection Notes

Cells7 subtopics

Organisms7 subtopics

Processes10 subtopics

Metabolism4 subtopics

Evolution7 subtopics

Interactions with environment6 subtopics

Interactions between organisms5 subtopics

Human interactions with environments3 subtopics

Biotechnology3 subtopics

Why Do Some Traits Become More Common Over Time?

How Does Natural Selection Work?

What Creates the Variation That Natural Selection Acts On?

How Do Environments Decide Which Traits Succeed?

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Why Do Some Traits Become More Common Over Time?

How Does Natural Selection Work?

What Creates the Variation That Natural Selection Acts On?

How Do Environments Decide Which Traits Succeed?

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account