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Edexcel IAL Biology 5.24 Isolation and speciation

Use the map or organism evidence to identify the barrier, explain reduced interbreeding and trace divergent selection to reproductive isolation and speciation.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
A2

Exam points

  • Distinguish allopatric and sympatric speciation from locations or diagrams.
  • Use map evidence to explain how separation reduces gene flow between populations.
  • Explain reproductive isolation through different habitats, seasons or mating times.

5.24—Isolation, gene flow and speciation question 1

[Maximum number: 4]

Madagascar is a large island off the southeast coast of mainland Africa.
Lemurs are endemic to Madagascar.

There are many different species of lemur, all of which evolved from one common ancestor. This common ancestor is thought to be a primate that was carried across the sea from mainland Africa on a raft of vegetation.

The photographs show two different species of lemur, Sifaka and Indri, found in the same region of Madagascar.

Sifaka

Sifaka

Indri

Indri

The diet of Sifakas is mostly seeds but also includes fruits, flowers and some types of leaves. The diet of Indri is mainly leaves.

Explain the types of speciation that have taken place in the evolution of Sifakas and Indri in this region of Madagascar.

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