Transcript Opening Activity - Western Sierra Collegiate Academy

Describe the variation pictured above. Speculate as to how
natural selection in different environments has produced such
large differences.
Brainstorm a situation where the ideas of variation, natural selection, and
adaptation apply to non-living things. Share your answer with a partner and be
prepared to explain to the class.
NOVEMBER 19, 2010
Homologous structures are structures which are similar even in widely differing
species. It is evidence of divergence from a common ancestor. The form is similar
even though the function may not be.
Tool user
Runner
itc.gsw.edu/.../histgeol/paleo2/homol1.htm
Pouncer
Flyers
Swimmer
The ancestor started with four primitive but functional wings.
How have the form and function diverged in contemporary insects?
http://www.press.uchicago.edu/books/gee/carroll4.html
http://evolution.berkeley.edu/evosite/lines/images/homology.gif
•The pitcher plant and venus fly trap live in environments with poor soil and need extra nutrients.
•The poinsetta has to attract insects in order to promote pollination.
•The cactus has to protect its moisture from pests.
Describe a possible variation as a first evolutionary step from a regularly shaped leaf toward each of these
specialized homologous structures.
http://8e.devbio.com/article.php?ch=18&id=178
Describe the form and function of the pictured structures (antennae and leg).
Compare them, and use the vocabulary word homologous in your sentence.