DP Biology (last assessment 2024)
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10.3 Gene pools and speciation

Description

Nature of science:
Looking for patterns, trends and discrepancies—patterns of chromosome number in some genera can be explained by speciation due to polyploidy. (3.1)Understandings:

  • A gene pool consists of all the genes and their different alleles, present in an interbreeding population.
  • Evolution requires that allele frequencies change with time in populations.
  • Reproductive isolation of populations can be temporal, behavioural or geographic.
  • Speciation due to divergence of isolated populations can be gradual.
  • Speciation can occur abruptly.

Applications and skills:

  • Application: Identifying examples of directional, stabilizing and disruptive selection.
  • Application: Speciation in the genus Allium by polyploidy.
  • Skill: Comparison of allele frequencies of geographically isolated populations.

Guidance:

  • Punctuated equilibrium implies long periods without appreciable change and short periods of rapid evolution.

Theory of knowledge:

  • Punctuated equilibrium was long considered an alternative theory of evolution and a challenge to the long established paradigm of Darwinian gradualism. How do paradigm shifts proceed in science and what factors are involved in their success?

Utilization:

  • Many crop species have been created to be polyploid. Polyploidy increases allelic diversity and permits novel phenotypes to be generated. It also leads to hybrid vigour.

Syllabus and cross-curricular links:
Biology
Topic 5.1 Evidence for evolution

 

Directly related questions

Sub sections and their related questions

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