Post on 14-Jan-2016
description
Lamarck vs. Darwin
Introduction to change in organisms
What is a theory?
The most probable explanation for a large set of data based on the best available evidence
Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing
What is a species?What is a population?
Species – group of a single type of organisms that interbreed and are reproductively isolated
White-tailed deer
Population – refers to a group of organisms of a particular species living in a certain area.
White-tailed deer on Mt. Nebo
Lamarck’s Theory Jean Baptiste Lamarck: 1800’s
Believed: Change Occurs Over Time inheritance of acquired
characteristics acquired changes were passed
to offspring Law of Use and Disuse
If a body part were used, it got stronger
If body part NOT used, it deteriorated
Examples: Body builders or pierced ears
Lamarck’s Theory of Evolution Giraffes all had
SHORT necks originally
Giraffe’s Necks got LONGER from stretching for food
“Acquired” trait (long necks) then passed to offspring
Giraffe population became long-necked
Lamarck’s Theory of Evolution More examples
Traits Acquired During Ones Lifetime Would Be Passed To Offspring
Clipped ears and tails of dogs could be passed to offspring!
Lamarck’s Mistakes Was he correct??
NO! Traits are passed down from one
generation to the next by GENES, not by an individual’s life experiences or activities
Lamarck did NOT know how traits were inherited (Traits are passed through genes)
Genes Are NOT Changed By Activities In Life
Change Through Mutation Occurs Before An Organism Is Born
Voyage of the Beagle
Charles Darwin Born Feb. 12, 1809 Joined Crew of HMS
Beagle, 1831 Naturalist 5 Year Voyage
around world Astounded By
Variety of Life
Voyage of the Beagle
During His Travels, Darwin Made Numerous Observations And Collected Evidence That Led Him To Propose A Revolutionary Hypothesis About The Way Life Changes Over Time
Darwin’s Belief’s Survival of the fittest OR
natural selection Food and resources are
limitedSo organisms have to
COMPETE to get them (lions fight for food, space, mates …)
• OVER PRODUCE too many organisms
• Not all offspring will survive only the MOST FIT (not always the strongest!)
What happened to the giraffe’s? Survival of the fittest or natural
selection Natural selection said the giraffes
with short necks had less food to eat
Why? the food resources changed to leaves
only on the upper branches What happened?
short necks could not reach upper branches and did not survive (couldn’t pass on genes)
Long neck giraffes survived & reproduced because they were able to reach the food
• Evolution is the slow, gradual
change in a population of organisms
over time…
a looooooooong time!
Where do Where do
we see we see
this this
change?change?
When there is an unequal unequal ability of ability of individuals to survive and reproduce …individuals to survive and reproduce …
This leads This leads to a to a gradual change gradual change in a in a population with population with favorable characteristicsfavorable characteristics accumulating over generations accumulating over generations
Most fit “Most fit “naturallynaturally” selected” selected New species evolvesNew species evolves
Natural Selection
How does Selection occur? Selection of the most fit can occur
from several factors:Variations exist among
individuals in a populationCompetition for limited resourcesOverpopulationPredation/Disease
Example of Natural Selection
A classic example of natural selection is the Peppered moths during Industrial Revolution in Europe