IB Biology Topic A4.1.9 Adaptive Radiation as a Source of Biodiversity Revision Notes (HL)

IB Biology Topic A4.1.9 Adaptive Radiation as a Source of Biodiversity Revision Notes (HL) | RevisionDojo

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Adaptive Radiation Turns One Ancestor Into Many Niche-Specialised Species

In adaptive radiation, a single ancestral species diversifies relatively rapidly into many species, each adapted to a different ecological niche.
Because it generates many new species in a short evolutionary time, it is a major source of biodiversity.

Definition

Adaptive radiation

Adaptive radiation is the evolutionary process by which a single ancestral species rapidly diversifies into many species, each specialized to exploit a different ecological niche.

Note

Adaptive radiation is a pattern of speciation, not a separate mechanism; the underlying allopatric and sympatric processes are covered in A4.1.6 and A4.1.8.

Four Features Define an Adaptive Radiation

Common ancestry: all the species descend from one shared ancestor.
Rapid speciation: many species arise in a short evolutionary timeframe.
Ecological specialisation: each species occupies a distinct niche, which reduces competition.
Morphological divergence: species evolve distinct traits suited to their niche, such as different beak shapes.

Case study

The Galapagos finches, roughly 18 species, descend from one ancestral species that reached the islands from South America.
They radiated within about one to two million years, which is rapid on an evolutionary scale.
Each species evolved a beak suited to a different food source.
- The large ground finch uses a robust beak to crack hard seeds.
- The cactus finch has a long, pointed beak for feeding on cactus flowers.
- The warbler finch uses a slender beak to catch insects.
These distinct niches reduced competition and let the species coexist on the same islands.

Radiation Fills Vacant Niches and Reduces Competition

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Adaptive Radiation Turns One Ancestor Into Many Niche-Specialised Species

In adaptive radiation, a single ancestral species diversifies relatively rapidly into many species, each adapted to a different ecological niche.
Because it generates many new species in a short evolutionary time, it is a major source of biodiversity.

Definition

Adaptive radiation

Adaptive radiation is the evolutionary process by which a single ancestral species rapidly diversifies into many species, each specialized to exploit a different ecological niche.

Note

Adaptive radiation is a pattern of speciation, not a separate mechanism; the underlying allopatric and sympatric processes are covered in A4.1.6 and A4.1.8.

Four Features Define an Adaptive Radiation

Common ancestry: all the species descend from one shared ancestor.
Rapid speciation: many species arise in a short evolutionary timeframe.
Ecological specialisation: each species occupies a distinct niche, which reduces competition.
Morphological divergence: species evolve distinct traits suited to their niche, such as different beak shapes.

Case study

The Galapagos finches, roughly 18 species, descend from one ancestral species that reached the islands from South America.
They radiated within about one to two million years, which is rapid on an evolutionary scale.
Each species evolved a beak suited to a different food source.
- The large ground finch uses a robust beak to crack hard seeds.
- The cactus finch has a long, pointed beak for feeding on cactus flowers.
- The warbler finch uses a slender beak to catch insects.
These distinct niches reduced competition and let the species coexist on the same islands.

Radiation Fills Vacant Niches and Reduces Competition

Definition

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Duis aute irure dolor in reprehenderit

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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.

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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.
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 A4.1.9: Adaptive Radiation as a Source of Biodiversity Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Adaptive Radiation Turns One Ancestor Into Many Niche-Specialised Species

Four Features Define an Adaptive Radiation

Radiation Fills Vacant Niches and Reduces Competition

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

Adaptive Radiation Turns One Ancestor Into Many Niche-Specialised Species

Four Features Define an Adaptive Radiation

Radiation Fills Vacant Niches and Reduces Competition

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