Name: Date:
Student Exploration: Rainfall and Bird Beaks
Vocabulary: adaptation, beak depth, directional selection, drought, evolution, natural selection,range,
stabilizing selection
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
During the voyage of the HMS Beagle (1831–1836), the young Charles Darwin collected severalspecies of
finches from the Galápagos Islands. Two of Darwin’s finches are shown below.
1. Which species do you think is best adapted to a diet of small, delicateseeds?
Explain why you think so.
Geospiza fortis, because it has a smaller beak with a fine point thatcould
pick up delicate seeds.
2. Which species do you think is best adapted to a diet of large, tough-to-
crack seeds? Explain.
Geospiza magnirostris, because it has a larger, stronger beak thatcrush the
seed shells easily.
Gizmo Warm-up
Darwin’s finches are one of many types of animals on the Galápagos
Islands that have unique adaptations, or traits that help an organism
survive in its environment. The Rainfall and Bird Beaks Gizmo™
allows you to explore how rainfall influencesthe range of beak shapes
found in a single finch species.
1. The beak depth of a finch is the distance from the top of the beak to the bottom, as shown.
A. What is the current average beak depth in the Gizmo? 10.04 mm
B. Select the HISTOGRAM tab. Do all the finches have the same beak depth? No!
2. Click Play ( ) and let the simulation play for five years with average rainfall (12.5
cm/yr). Select the GRAPH tab and view the Finches vs time and Beak depth vs timegraphs.
A. How does the finch population change? The population varies in an almost
sinusoidul shape, with the population going down in number and then up again.
, B. Does the beak depth change significantly? Yes, the beak depth decreases
significantly. The beak depth went from 10mm to 7.5 on average over the 5 years.
Student Exploration: Rainfall and Bird Beaks
Vocabulary: adaptation, beak depth, directional selection, drought, evolution, natural selection,range,
stabilizing selection
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
During the voyage of the HMS Beagle (1831–1836), the young Charles Darwin collected severalspecies of
finches from the Galápagos Islands. Two of Darwin’s finches are shown below.
1. Which species do you think is best adapted to a diet of small, delicateseeds?
Explain why you think so.
Geospiza fortis, because it has a smaller beak with a fine point thatcould
pick up delicate seeds.
2. Which species do you think is best adapted to a diet of large, tough-to-
crack seeds? Explain.
Geospiza magnirostris, because it has a larger, stronger beak thatcrush the
seed shells easily.
Gizmo Warm-up
Darwin’s finches are one of many types of animals on the Galápagos
Islands that have unique adaptations, or traits that help an organism
survive in its environment. The Rainfall and Bird Beaks Gizmo™
allows you to explore how rainfall influencesthe range of beak shapes
found in a single finch species.
1. The beak depth of a finch is the distance from the top of the beak to the bottom, as shown.
A. What is the current average beak depth in the Gizmo? 10.04 mm
B. Select the HISTOGRAM tab. Do all the finches have the same beak depth? No!
2. Click Play ( ) and let the simulation play for five years with average rainfall (12.5
cm/yr). Select the GRAPH tab and view the Finches vs time and Beak depth vs timegraphs.
A. How does the finch population change? The population varies in an almost
sinusoidul shape, with the population going down in number and then up again.
, B. Does the beak depth change significantly? Yes, the beak depth decreases
significantly. The beak depth went from 10mm to 7.5 on average over the 5 years.
