1.  Variation refers to a variety or diversity of traits (different kinds) within any given population.  variations occur in human populations & in populations of plants, animals, birds, insects, fish, bacteria etc. Variation in Populations Three causes of variation 1) Diversity of genetic traits from sexual reproduction 2) Diversity of genetic traits that result from mutations 3) Changing environmental conditions Variation in populations Tennessee SPI Objective: Analyze data on levels of variation within a population to make predictions about survival under particular environmental conditions.

2.  The Galapagos Islands are located in the Pacific Ocean about 600 miles west of Ecuador (see picture below). Variation in Populations  At some point in the past, a small population of Finches (birds) were blown from South American to these islands. South American Finch  Each island has a slightly different ecosystem, and these finches adapted accordingly. This lead to significant variation in the shapes and sizes of their beaks.

3.  Over time the finches developed different beak shapes and sizes in order to eat the local food (structural adaptations). narrow-pointed beak for eating insects Moderately wide beak with a sharp point for cracking nuts and eating insects Very wide beak for only eating nuts Food Source Only Bugs Food Source Nuts & Bugs Food Source Only Nuts Variation in Populations

4. Review Questions Note: Termination refers to the percentage of bugs that were killed

5. Review Questions