Evolution – The Process – Lesson Summary

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Learning Objective

In this lesson we will learn about the processes involved in evolution by natural selection.

Learning Outcomes

By the end of this lesson you will be able to:

  • Outline the key stages in the evolutionary process.
  • Explain why genetic variation and reproductive isolation are required for the evolution of new species.
  • Discuss the role of mutation, natural selection and genetic drift in evolution.
  • Describe speciation and adaptive radiation.
  • Interpret a phylogenetic tree.

 
evolution the process lesson contents

(Image: fprose, Pixabay)

Lesson Topics

1 | Darwinian Evolution

2 | Overview of the Process of Evolution

3 | Genetic Variation in Populations

4 | Reproductive Isolation of Populations

5 | Natural Selection, Genetic Drift and New Mutations

6 | Speciation

7 | Phylogenetic Trees

8 | Some Misconceptions About Evolution

9 | Summary

Lesson Summary

  • Evolution is the gradual genetic change of populations over time, that results in different forms and new species.
  • Charles Darwin developed the theory of evolution by natural selection.
  • He concluded that all life on Earth evolved from a common ancestor as a result of natural selection.
  • Darwin’s theory provides a lens through which all biological processes can be viewed.
  • The evolutionary process includes several key stages:
  • Genetic variation.
  • Genetic variation is created by mutation – the source of all new alleles – and enhanced in populations by sexual reproduction and gene flow.
  • Reproductive isolation.
  • Reproductive isolation is the separation of populations, which results in independent genetic changes.
  • Natural selection, genetic drift and new mutations.
  • Natural selection is the favouring of more suitable alleles over others.
  • Genetic drift is the random change in allele frequencies due to chance.
  • New mutations arise very slowly over time.
  • Speciation.
  • Speciation is the gradual differentiation of isolated populations into separate species.
  • Adaptive radiation is the formation of multiple new species from a common ancestor.
  • A phylogenetic tree (evolutionary tree) is a branching diagram showing the evolutionary relationships between different species.

 
 
adaptive radiation darwin finches

Darwin’s observations of the Galapagos finches helped solidify his theory of evolution.

(Image: VectorMine, Adobe Stock)

(Header image: Maridav, Adobe Stock)