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Speciation Open Response!
Do Now
Millions of years ago, seawater flooded part of the Mississippi River Valley. Scientists have
concluded that chorus frogs were affected by the flooding. The flooded areas formed
geographic barriers between chorus frog populations for millions of years.
1. Why is a river considered a “geographical barrier”?
2. Which of the following most likely occurred as a result of the seawater flooding?
A. The frogs lost the tadpole stage of their life cycle.
B. Isolated populations of frogs became separate species.
C. The frogs’ eggs were fertilized by sperm of marine species.
D. Frog populations were protected from all the predators in their areas.
3. How do you know if two organisms are separate species?
Reproductive Isolation and Speciation in Lizards Video – Use complete sentences!
1. The islands of the Caribbean are home to _________ different ___________________ of
anoles.
2. What is one way for populations to split into two?
3. If two species go through enough changes in their respective habitats, what will happen?
4. Why did some populations evolve over time to have darker dewlaps?
5. Over time, two different species will __________________________ for resources.
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Sequencing Speciation
DIRECTIONS: Put the following steps of speciation in order by writing the numbers 1 - 5 next to
their descriptions.
A geographic barrier such as a river, mountain, or volcano develops,
dividing the species.
Overtime, natural selection makes the two populations of species different.
ONE
A single species exists.
The single species is divided into two different habitats.
When the geographic barrier disappears, the two populations cannot
interbreed again because they are now two different species.
Open Response Rubric
Score
4
Description
Writing is in clear, complete sentences. The response includes important
details/ diagrams to support the answer. Scientific vocabulary is used
accurately.
3
Writing is mostly in clear, complete sentences. There are some relevant
details to support the answer. Some scientific vocabulary is included.
2
Writing partially explains the response to the questions. There is limited
evidence provided. Scientific vocabulary is used inaccurately/ not at all.
1
Writing gives a minimal response to the question. There is little/ no
evidence provided. Scientific vocabulary is used inaccurately/ not at all.
0
There is no answer written or the answer is irrelevant to the question.
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Open Response Practice
Marine (Ocean) iguanas, Genus(Amblyrhynchus) species(cristatus), live on the Galápagos
Islands. Scientists think these marine iguanas evolved from iguanas that spread out to the islands
from the South American mainland, about 900 km away.
a. Explain how geographic isolation on the Galápagos Islands caused the evolution of a new
iguana species.
b. Identify whether Amblyrhynchus cristatus and an ancient species of Iguana would be able
to mate and produce fertile offspring. Explain your answer.
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Open Response Peer Editing
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