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Session 6. Evolution and the Tree of Life
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Which skull is a lizard
and which is a snake? |
Learning Goals
During this session, you will have an opportunity to
build understandings to help you:
- Define what is meant by “species”
- Describe how new species evolve as a result of variation and
adaptation through natural selection
- Comprehend a tree of life as a model for depicting evolution
and the relatedness of species
Video Overview
What makes a snake a snake, and a lizard a lizard? What distinguishes
one type of lizard from another? And how did so many types of reptiles
come to be? Session 6 focuses on questions like these as we continue
our study of the fundamentals of evolution. Building upon key ideas
introduced last session – variation and adaptation through natural
selection – we focus upon what defines a species and how new
species evolve.
View this video==> 
Video Outline
Deep within the basement of the Museum of Comparative Zoology at
Harvard University, there is a treasure trove of life forms ready
for study. The program opens inside the reptile and amphibian collection,
where we begin to see part of what informs the work of evolutionary
biologists.
Dr. Karen Worth, representing the Insights
curriculum from the Educational Development Center (EDC), describes how the
study of evolution
can begin in the elementary grades. The fifth graders in Gail
Modugno’s
classroom in Springfield, Massachusetts give us a glimpse of what
this might look like as her students begin to connect similarities
among life forms to the possibility of relatedness. Our fourth
and fifth graders in the Science Studio connect us to research
on children’s
ideas throughout the program as they ponder the meaning of species,
adaptation, evolution, and relatedness.
Dr. Jim Hanken, from the
Museum of Comparative Zoology, helps us dig deeper by using snake
and lizard specimens to explore the meaning
of “species”. Dr.
Doug Causey, also from the museum, presents
us with a collection of “Darwin’s finches” to propose
a scenario for how new species might evolve through natural selection.
A tree of life is introduced as a model
that portrays how scientists think life on Earth evolved, and a
scenario for vertebrate
evolution is described. Dr. Paul Williams returns
to update us on the progress of Bottle Biology – highlighting
the results of an experiment that explores the fundamentals of
evolution.
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