Gene Pools and Speciation

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):

Natural Selection (unit 19)
Speciation (unit 21)

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.

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