Evolution SC.912.L.15.1 Explain how the scientific theory of evolution is supported by the fossil record, comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary change
Darwin wasn’t the only one Lamarck Changes in a phenotype occur because of an environmental need Giraffe Modifications were passed onto the next generation Inheritence “need” was dictated by environmental change and that change involved movement towards perfection
Now we know No evidence that changes in environment can initiate changes in organisms that can be passed on to future generations Change originates in the process of gamete formation Environment does not create these variations it determines the survival of these variations
“Decent with Modification” Organic Evolution: “Decent with modification” - Charles Darwin Species change gradually through adaptation. Chance FLASH CARD ALERT ADAPTATION: A single individual has a random mutation/trait that creates a change in phenotype, which increases the organism’s chance of successful reproduction. Leads to: NATURAL SELECTION
FLASH CARD ALERT: NATURAL SELECTION: The adapted individual is able to survive and reproduce in the new environment better than others Then: The adapted individual reproduces, creating more individuals with the same adaptations. These adaptations become predominant in the population, thus altering the genetic makeup of the entire population… OR… A new species arises that co-exists with the ancestor
THE STEPS OF EVOLUTION 1. Random mutation. A single individual has a random mutation/trait that is beneficial in its environment. 2. Natural selection: The adapted individual is able to survive and reproduce in the new environment better than others
3. Reproduction of adaptive trait: The adapted individual reproduces, creating more individuals with the same adaptations.
4. These adaptations become predominant in the population, thus altering the genetic makeup of the entire population… OR…
5. A new species arises that co-exists with the ancestor
Flightless Birds: Penguin
Random Mutation: Can be advantageous (adaptation) neutral, or maladaptive Adaptation: characteristics that increase the potential of an organism to successfully reproduce in a specified environment Adaptations are characteristics that increase an individual's evolutionary fitness.
FLASH CARD ALERT: EVOLUTIONARY FITNESS: measure of the capacity for successful reproduction in a given environment relative to others of that same species.
How Natural Selection Works All organisms have a far greater reproductive potential than is ever realized Starfish Struggle of survival: Not enough resources to go around Changes in the environment: climate change, food shortages, environmental stressors. Inherited Variations exist Genetic mutation & recombination
These genetic changes MAY BE an advantage Chance. Because individuals with maladaptive traits are less likely to reproduce the maladaptive traits become less frequent and are eventually eliminated