Lesson 2 - Natural Selection and Examples

Lesson Objectives

A. Content Objective: Be able to explain how natural selection occurs using evolution-specific language and describe how natural selection using a specific example.

B. Language Objective: Using a visual notes format or Cornell format, create a set of notes explaining one example of evolution using the following guidelines:

Is there selection pressure, such as competition for resources or abiotic factors?
Is there an overproduction of offspring?
What phenotypic variations exist?
Which phenotypes were better adapted?
What happened to the individuals’ number of offspring that were better adapted?
What happens to the allele frequency over time?

C. Syllabus Statements:

D4.1.1—Natural selection as the mechanism driving evolutionary change - "Students should appreciate that natural selection operates continuously and over billions of years, resulting in the biodiversity of life on Earth."

D4.1.2—Roles of mutation and sexual reproduction in generating the variation on which natural selection acts - "Mutation generates new alleles and sexual reproduction generates new combinations of alleles."

D4.1.3—Overproduction of offspring and competition for resources as factors that promote natural selection - "Include examples of food and other resources that may limit carrying capacity."

D4.1.4—Abiotic factors as selection pressures - "Include examples of density-independent factors such as high or low temperatures that may affect survival of individuals in a population."

D4.1.5—Differences between individuals in adaptation, survival and reproduction as the basis for natural selection. "Students are required to study natural selection due to intraspecific competition, including the concept of fitness when discussing the survival value and reproductive potential of a genotype."

D4.1.6—Requirement that traits are heritable for evolutionary change to occur - "Students should understand that characteristics acquired during an individual’s life due to environmental factors are not encoded in the base sequence of genes and so are not heritable. Students are not required to know the term “Lamarckism” but it may be useful when discussing falsified theories about evolution by inheritance of acquired traits."

D4.1.7—Sexual selection as a selection pressure in animal species - "Differences in physical and behavioural traits, which can be used as signs of overall fitness, can affect success in attracting a mate and so drive the evolution of an animal population. Illustrate this using suitable examples such as the evolution of the plumage of birds of paradise."