Download Lesson 3, Ecosystems, Natural Selection

Ecosystems:
Lesson 3: Natural Selection
Textbook pages NC2-NC6
Critical Vocabulary: Natural Selection, Adaptation, Overproduction, Variation, Selection.
Critical Content:
 Natural Selection: The process through which members of a species that are best suited to their environment
survive and reproduce at a higher rate than other members of the species. There are 4 basic principles involved in
natural selection:
o Overproduction: When most plants or animals reproduce, they usually produce more offspring than can
possibly survive.
o Variation: Within a species there are natural differences or variations in traits. Such differences result from
differences in the genetic material of the species. Variations are passed from one generation to the next.
o Adaptation: A change in an individual’s genetic material is referred to as a mutation. Sometimes a
mutation occurs that makes an individual better able to survive than other members of a population. An
adaptation is any inherited trait that gives an organism an advantage in its environment.
o Selection: Because individual organisms with a particular adaptation are more likely to survive and
reproduce, the adaptation becomes more likely in the next generation. As this process repeats, more and
more members of a species show the adaptation. Scientists say the environment is selecting this trait.
 Charles Darwin: Charles Darwin proposed the theory of natural selection based on his observation of the
differences between similar animal species in the Galapagos Islands, where he spent five years as a researcher for
the British navy.
Lesson Body:
(needed materials: textbooks, Eco Geeks video file on snails, computer with an internet connection, data projector.)
 Begin by showing the United Streaming video on the Marine Iguana (saved in folder on computer desktop). It
introduces an animal that developed interesting characteristics because of the unique habitat that it lived in.
 While showing the video the first time, do not get into content. Use it as a hook activity to draw student attention.
 Next, have students work in small groups to complete the Problem Based Investigation on Natural Selection found
in the textbook on pages NC 2- NC 6. Review answers as a class.
 Consider having students create mini posters advertising one of the four principles of Natural Selection that
includes an image, bulleted text and an engaging title.
 Optional: Finally, reshow the United Streaming video on the Marine Iguana. Discuss the principles of natural
selection that influenced the development of the unique characteristics of the Marine Iguana in the video.
Section Assessment Question (optional):
Can you think of any examples of natural selection that take place in middle school? What about in fashion or music
trends? Do some video games get “selected?” Do some brands of clothing “adapt?” Do companies ever “Over
produce,” hoping to find an “adaptation” that will succeed with kids?