IB Biology Topic D4.1.10 Allele Frequencies of Geographically Isolated Populations Revision Notes (HL)

IB Biology Topic D4.1.10 Allele Frequencies of Geographically Isolated Populations Revision Notes (HL) | RevisionDojo

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Isolated Populations Drift Apart Until They May Become New Species

Definition

Allele frequency

Allele frequency refers to how common a particular allele is within a population. It is expressed as a proportion or percentage of all alleles for a specific gene.

When a species splits into populations that cannot interbreed, gene flow between them stops.
Selection, mutation, and genetic drift then act independently in each population, so their allele frequencies move apart.
Given enough time, the populations can diverge so far that they can no longer interbreed, which is allopatric speciation.

What Cuts Off Gene Flow

Geographic barriers
1. New rivers, rising mountains, changing sea levels, or expanding deserts separate populations.
Founder effect
1. A small group is cut off, such as insects blown to an island, and starts with only a subset of the original gene pool.

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Note

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Excepteur sint occaecat cupidatat non proident

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Isolated Populations Drift Apart Until They May Become New Species

Definition

Allele frequency

Allele frequency refers to how common a particular allele is within a population. It is expressed as a proportion or percentage of all alleles for a specific gene.

When a species splits into populations that cannot interbreed, gene flow between them stops.
Selection, mutation, and genetic drift then act independently in each population, so their allele frequencies move apart.
Given enough time, the populations can diverge so far that they can no longer interbreed, which is allopatric speciation.

What Cuts Off Gene Flow

Geographic barriers
1. New rivers, rising mountains, changing sea levels, or expanding deserts separate populations.
Founder effect
1. A small group is cut off, such as insects blown to an island, and starts with only a subset of the original gene pool.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D4.1.10: Allele Frequencies of Geographically Isolated Populations Notes

Isolated Populations Drift Apart Until They May Become New Species

What Cuts Off Gene Flow

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

Isolated Populations Drift Apart Until They May Become New Species

What Cuts Off Gene Flow

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics