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Edexcel A-Level Biology A2 5.24 Isolation Gene Flow and Speciation Questions

Explain how isolation, selection and reproductive barriers reduce gene flow and produce new species or subspecies over generations.

Syllabus
First assessment 2019
Course
Biology YBI11
Level
A2

Exam points

  • distinguish allopatric and sympatric speciation using geographic separation and shared habitats
  • explain how reproductive isolation through timing, behaviour or habitat prevents gene flow
  • explain how variation, selection and isolation produce new species or subspecies across generations

Edexcel A-Level Biology A2 5.24 Isolation Gene Flow and Speciation Questions 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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