In this lesson, students explore a model of genetic drift in populations of varying sizes. The lesson uses the model to help students to understand the ramifications of population size and isolation on alleles in populations.
Learning Objectives:
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Describe how genetic drift influences the diversity (polymorphism) of alleles in a population
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Investigate the consequences of very small or very large populations for allele diversity.
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Compare the effects of genetic drift in isolated populations
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Apply these ideas to real-world populations of animals (including dog breeds and certain human ethnic groups)
Lesson Material:
Tempe, Arizona
Collective behavior
Whirligig beetle aggregation seen along the bank of the Missouri River in St. Charles, MO: an example of collective swarm behavior. Individual whirligig beetles strive to make it to a safe location in the middle of the swarm to avoid fish predation. Sometimes several different species of beetle will join the same swarm (as seen by the differently sized individuals here).
A time-lapse of some hissing cockroaches making a collective decision (20x speed). Four female roaches are presented with a choice of two shelters (one dark and the other bright). After assessing their environs, the group collectively choose the dark one.
A brief video showing the famous waggle dance of the honeybees. As discovered by the great researcher Karl von Frisch, honeybees communicate the location of resources (food sources and nests) using the waggle dance. For this discovery and other contributions to Ethology, von Frisch was awarded the Nobel Prize.
Close up footage of ants (Temnothorax rugatulus) exploiting a food source (green sugar water). Colonies can collectively choose the best (that is, most profitable) food source from among many. But it is the decisions and reactions of individual ants that adds up to this collective decision.
Much like the murmurations of starlings and other bird flocks, midges form swarms that are a wonderful example of collective behavior. In this video filmed in Phoenix, Arizona in May 2022, you can see this interesting phenomenon!
Social insect photos
