Download Evidence of Evolution - Yorkville High School

Evidence of Evolution
What is evolution?
• Definition:
– The gradual change in a
species over time
• Takes a Looooong time
• Results from a change in
the GENETIC material of
an organism
– Not acted on at the
individual level
– Passed on from one
generation to the next
What is a theory?
• Based on a careful examination of facts
• Well supported explanation of some aspect of
the natural world based on knowledge that has
been repeatedly confirmed through
observation and experimentation.
What evidence do we have for
evolution?
• Similarities of structures in living things
– Analogous Structures
– Homologous Structures
– Embryo development (early stages)
– Vestigial Organs
• Shared Ancestry
– The fossil record
– Biogeography
Analogous Structures
• Similar function
– Ex. Used to fly
• Different structure
– Ex. Different
arrangement of
bones
• Different origins
– Do not have a
common ancestor
Homologous Structures
• Different function
– Adapted to different
purposes
– Humans arm is used
differently than a whales fin
• Similar structure
– Same basic arrangement of
bones
• Same origin
– Common ancestor
Embryology
• Embryos develop similarly in many vertebrates
Vestigial Structures
• Inherited structures that no longer serve a
function for the organism
• Examples
– Hipbone in dolphin/whale
– Our appendix
– Our wisdom teeth
Shared Ancestry
• Shared Ancestry
– The fossil record
– Biogeography
The Fossil Record
• Found fossils that show slow progression of
change
• More found since Darwin
Biogeography
• Found animals in isolated islands or
environments that ended up being perfect for
that area after generations
• Where they are now compared to then
– Patterns in different places tell how organisms evolved
– Populations on different islands all look different…
• Originate from a mainland
• Ever hear of the Galapagos Islands?
Ex: Galapagos Islands
South America
Darwin = populations on islands evolved from mainland species
Change over time…
• Depending on the food source and
environment, different birds survived and
changed to best fit each island
Situations
• One of the islands on the
Galapagos has a relatively
large mountain system on it.
Because of it, there is a lot of
crack and tight spaces things
fit in. As for seeds birds eat,
they often fall into the think
cracks. Which bird is most
likely the one that thrives
there? Why?
Natural Selection
• Darwin’s Finches
– Beak specialties
– Common ancestor
– Natural selection takes place frequently and rapidly
– Variation increases chance of adaptation