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adaptations over time

ideas about evolution
by

jason clarkson

on 20 January 2011

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Transcript of adaptations over time

What do you already Know about evolution?
Today's Goals
Describe Lamarck's theory of acquired characteristics and Darwin's theory of evolution
Identify why variations in organisms are impotant
Compare and contrast gradualism and Punctuated equilibrium
Early Models of evolution
characteristics of a species are inherited
when they pass from parents to offspring
species- group of organisms that share similar
characteristics and can reproduce amongst themselves
changes in these inherited characteristics is called
Evolution
Jean Baptiste de Lamarck
1809 - hypothesis of acquired characteristics
traits or characteristics developed
during a parent organisms lifetime are
inherited by its offspring
Is this true?
NO! If you develop strong muscles, they
don't get passed to your offspring
evidence does not support this idea
Darwin's Model
in 1831, darwin explored off the coast of South America onboard his ship the HMS Beagle.
He made observations of the plants and animals he saw. He was amazed by the variety of life he saw on the Galapogs Islands.
Darwin's Observations
He saw 13 species of finches
they all looked similar except for difference in body size, beak shape, and eating habits
He also noted that the finches looked similar to a finch species found on the South American Coast.
What conclusion do you think he made?
all 13 finches evolved from the South American Species
Competition and survival
-all living organisms produce more offspring
than can survive. Why?
it ensures that their traits will be passed on to other generations
Darwin noticed that in just a few years, a pair of finches could produce a large population
population - all the members of a single species, living in the same area
Members of a large population compete for
living space
food
other resources
Those that are best able to survive are more likely to pass on their traits to the next generation.
what about the finches?
Darwin reasoned that
the finches must have had to compete for food. finches with the beak shape that allowed them to eat the available food
survived longer and reproduced more offspring

after many generations, these groups of finches became separate species
Natural Selection
Darwin didn't stop after the Galapagos islands. He studied dog breeds and flowers

in the mid 1800's, he developed the theory of evolution that is accepted by most scientists today. He described his theory in a book titled "On the Origin of Species"
principles of natural selection
organisms produce more offspring than can survive
differences or variations occur among individuals of a species
variations are passed to offspring
some variations are helpful. individuals with helpful variations survive and reproduce better than those without them
over time, the offspring of the individuals with the helpful variations make up more of a population and eventually become a new species
Variation and adaptation
variation - an inherited trait that makes an organism different from other members of its species

adaptation - any variation that makes an organism better suited to its environment
variations result from permanent changes or mutations in an organisms genes. if organisms with these variations survive, they will pass the traits on. what is the result?
over many generations a new species can evolve
adaptations can involve color, shape, behavior, or chemical makeup. camouflage is a good example
changes in the sources of genes - over time, the genetic makeup of a species might change its appearance
example: as the genetic makeup of the seed eating galapagos finch changed, so did the size and shape of its beak.
many environmental factors bring about changes. when animals move into or out of an area, they might bring in or remove genes and variations.
geographic isolation
-small groups of organisms are isolated from the rest of the species. over several generations, variations that dont exist in the larger population, might become more common in the isolated population.

over time the populations may become so different that they can no longer reproduce amongst each other.

ex. canary island rabbits

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Full transcript