How do organisms adapt and change over time? What makes this flounder fish so unusual? And, how did...
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Transcript of How do organisms adapt and change over time? What makes this flounder fish so unusual? And, how did...
How do organisms adapt and change
over time?
What makes this flounder fish so
unusual? And, how did it get this way?
Vestigial Structures
Embryonic Structures
HomologousStructures
Fossils
NaturalSelection
Charles Darwin (1809-1882) Sailed around the world 1831-1836
Galapagos Turtles
Darwin’s Travels Revealed
• Lots of different species!
• These island observations led him to develop the theory of evolution!
Natural Selection• The process where plants/animals with
favorable traits survive and reproduce.
• Occur because of a mutation in the DNA or the environment.
Ex. Organisms adapt to their
environment.
Natural Selection is NOTSelective Breeding!
• Nature provides variation, humans select variations that are useful.
Ex a farmer breeds only his best livestock
Natural Selection
• Traits that help an organism survive in the environment are “selected”.
Example of Natural Selection
Peppered Moths Darwin’s Finches
• The isolation of the birds on an island caused the finches to develop lots of different kinds of beaks.
• A study of different colored moths disappearing and appearing in an area.
Summary of Darwin’s Theory
1. Organisms differ; variation is inherited
2. Organisms produce more offspring than survive
3. Organisms compete for resources
4. Organisms with advantages survive to pass those advantages to their children
5. Species alive today are descended with modifications from common ancestors
Is this a correct theory?
Mimicry
• Physically or actively looking like another organism.
Ex. A walking stick insect.
How do we know that organisms use natural
selection?
Fossil Records
• Solid remains or imprints of once-living organisms.
• Are formed from layers of sediment and minerals replacing bone.
Evidence of Evolution
• Shows that living things have evolved
• Show the history of life on earth and how organisms have changed over time.
Relative Dating
• Can determine a fossil’s relative age
• Date age comparing with other fossils
• Drawbacks – provides no info about age in years
Absolute Dating
• Can determine the absolute age in numbers
• Performed by radioactive dating – based on the amount of remaining radioactive isotopes
• Drawbacks - part of the fossil is destroyed during the test
Carbon-14 Dating
What do fossil records and skeletal records show
Similarities!
Vestigial Structures• Once useful structures that are still visible.
Ex. The hind-limb bones deeply embedded inside the whale or the changes in the horse.
Can you find the vestigial structures?
Homologous Structures
• Similar structures in different organisms.
Ex. Hand Bones
Homologous Body Structures
Embryonic Structures
• Embryos of vertebrates are not the same but look similar.
(And, grow into different organisms.)
How do organisms ensure the survival of there
species?
Natural Selection Must Haves:
• Overproduction of off-spring
• Inherited variation or differences
• Struggle to survive
• Successful reproduction
See the pictures and examples on Pg.162 +164
Possible Reasons for Natural Selection
• Variation In Genes
• Competition
• Pollution/Mutations
• Environmental Changes
• Separation
• Adaptation
• Division
So, why is it important that animals and plants adapt to
their environment?List and explain at least 3
reasons or examples you think animals might adapt.