Topic 10.3: Gene Pools and Speciation

Essential Idea:  Gene pools change over time.
At SHS, Topic 10.3 is taught in the following class unit(s):

Statements & Objectives:

10.3.U1  A gene pool consists of all the genes, and their different alleles, present in an interbreeding population.​
  • Define gene pool.
  • Given data, calculate allele frequencies of genes in a gene pool.
  • Given data, calculate genotype frequencies for genes in a gene pool.
10.3.U2  Evolution required that allele frequencies change with time in populations.
  • Define evolution.
  • Outline five factors that can cause evolutionary change.
10.3.U3  Reproductive isolation of populations can be temporal, behavioral or geographic.​​
  • Compare allopatric and sympatric speciation.
  • Define reproductive isolation.
  • Explain temporal, behavioral and geographic isolation as mechanisms of speciation.
  • Describe an example of temporal, behavioral and geographic reproductive isolation.
  • Define speciation.
10.3.U4  Speciation due to divergence of isolated populations can be gradual.​
  • Outline a limitation of the idea of evolution through gradualism.
  • Identify gradualism from graphs of morphology changes over time.
  • Define gradualism.
10.3.U5  Speciation can occur abruptly.
  • Define punctuated equilibrium.
  • Outline a possible cause of rapid speciation events.
  • Identify punctuated equilibrium from graphs of morphology changes over time.
10.3.A1  Identifying examples of directional, stabilizing and disruptive selection.
  • Define stabilizing, disruptive and directional selection.
  • Use graphs to illustrate or identify stabilizing, disruptive and directional selection.
10.3.A2  Speciation in the genus Allium by polyploidy.​
  • Outline how polyploidy has led to many species of Allium.
  • List example species in the genus Allium (by common name)
10.3.S1 Comparison of allele frequencies of geographically isolated populations.​
  • Compare allele frequencies of two populations.
  • Describe how variations in the allele frequencies of a gene may be evidence of speciation.
10.3.NOS  Looking for patterns, trends and discrepancies- patterns of chromosome number in some genera can be explained by speciation due to polyploidy.​
  • Define polyploidy.
  • Outline causes of polyploidy.
  • Explain how polyploidy can lead to speciation.

In the News:
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911