Download Evolution

Biology
Wed, 3/4/15
Do Now
• Set up Notebook for new
heading: “Definition and
History of Evolution” (TOC and
RIGHT side)
• On your LEFT side, write your
understanding of the definition
of “Evolution”
Objective:
Understand theories and
hypotheses
Agenda:
• Definition and History
of Evolution
Homework:
• Revisit notes/work 10
minutes a night
Definition & History of Evolution
Evolution - a change in the characteristics of a
population of organisms over generations.
Remember the characteristics of life?
• All living things have the ability to change
over generations (this quality is describing
evolution)
Modern Understanding
of Evolution
• Evolution is a change in the frequency of a
gene within a population over generations.
• That evolution occurs is considered fact;
evolutionary theory describes how it occurs
and has occurred in the past.
http://pages.britishlibrary.net/charles.darwin/texts/beagle_voyage/beagle17.html
Wait a minute….Science word overload.
“…change in the frequency of a gene within a
population over generations.”
• Frequency - how often it happens
• Gene - Part of DNA that determines a
characteristic (like eye color) of an organism.
• Population - A group of organisms that can
interbreed.
• Generation - Length of time it takes from birth
to having babies. (humans ~30 years, E. coli –
20 minutes)
OLD Understandings of
Evolution
• Lamarck (early 1800’s) proposed: “The
inheritance of acquired characteristics”
• He proposed that by using or not using its
body parts, an individual tends to develop
certain characteristics, which it passes on
to its offspring
• Ex: A giraffe acquired its long neck
because its ancestor stretched higher and
higher into the trees to reach leaves, and
that the animal’s increasingly lengthened
neck was passed on to its offspring.
• Do you think this is true?
Test Lamarck’s Hypothesis
Weismann cut off the tails of mice for
successive generations.
Q. What should have happened if Lamarck’s
ideas were to be supported?
Q. What do you think did happen?
Charles Darwin
• Darwin set sail on the H.M.S. Beagle (18311836) to survey the south seas (mainly
South America and the Galapagos
Islands) to collect plants and animals.
• On the Galapagos Islands, Darwin
observed species that lived no where else in
the world.
• These observations led Darwin to write a
book in 1859 entitled “On the Origin of
Species by Means of Natural Selection”
Crash Course (natural selection)