Chapter 11: The Evolution of Populations

Sources of Variation

Narrated slideshow discussing how mutations and recombination produce variation in a population

(Main Ideas: Genetic variation in a population increases the chance that some individuals will survive. Genetic variation comes from several sources.)



Disruptive Selection

Animations illustrating how natural selection favors short legs or long legs in subpopulations of Anolis lizards in the Carribbean (watch each in succession)

(Main Ideas: Natural selection acts on a distribution of traits. Natural selection can change the distribution of a trait in one of three ways.)



Genetic Drift

Simulation showing what happens to allele frequency in a population over time

(Main Idea: Genetic drift is a change in allele frequencies due to chance.)



Sexual Selection

Video describing how sexual selection explains the long, brightly colored tails of peacocks

(Main Idea: Sexual selection occurs when certain traits increase mating success.)



Mating Strategies

Game show in which you try to guess which “contestant” is the right species based on answers to species-specific courtship and mating questions

(Main Idea: Sexual selection occurs when certain traits increase mating success.)



Hardy-Weinberg Equation

Interactive tutorial showing how genotype frequency and phenotype frequency in a population are related

(Main Idea: The Hardy-Weinberg equation is used to predict genotype frequencies in a population.)




Tutorial explaining what speciation is and how it can occur

(Main Idea: The isolation of populations can lead to speciation.)



Behavioral Isolation

60-second podcast describing a population of birds that may separate into two distinct species based on differing feeding behaviors

(Main Idea: Populations can become isolated in several ways.)



Convergent Evolution

Map with illustrations showing organisms with similar morphological features that have evolved independently from one another

(Main Idea: Evolution through natural selection is not random.)



Evolutionary Arms Race

Video about a newt that has evolved poison skin, and its predator, a snake that has evolved the ability to eat it

(Main Idea: Species can shape each other over time.)




Site discussing the possible causes of mass extinction events on Earth. This is part of a larger, interactive timeline of Earth’s history.

(Main Idea: Species can become extinct.)


Adaptive Radiation

Interactive tutorial explaining adaptive radiation in honeycreeper birds

(Main Idea: Speciation often occurs in patterns.)