Darwin Natural Selection Unit 6 Evolution Chapter 15
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Darwin & Natural Selection Unit 6: Evolution Chapter 15
Theory of Evolution ▪ Evolution: The process of change over time • Specifically, a change in the frequency of a gene or allele in a population over time
Charles Darwin ▪ Father of Evolution ▪ Proposed a mechanism for evolution, natural selection ▪ Darwin went on a 5 -year trip around the world on the ship, the HMS Beagle • As the ship’s naturalist, he made observations of organisms in South America and the Galapagos Islands • Wrote a book, “Origin of the Species”
Darwin’s Finches
Natural Selection ▪ Natural Selection: Organisms that are best adapted to an environment survive and reproduce more than others
▪ Darwin’s Theory of Natural Selection occurs in four steps: • • Overproduction Variation Competition Selection
1. Overproduction ▪ Each species produces more offspring that can survive
2. Variation ▪ Each individual has a unique combination of inherited traits. ▪ Adaptation: an inherited trait that increases an organism’s chances of survival
What adaptations do you see?
What adaptations do you see?
Why is Variation Important? ▪ Because the environment changes. ▪ The more variation within a species, the more likely it will survive • EX: If everyone is the same, they are all vulnerable to the same environmental changes or diseases ▪ The more variation of types of species in an habitat, the more likely at least some will survive • EX: Dinosaurs replaced by mammals
Which community has a better chance of surviving a natural disaster? Community A Community B
3. Competition ▪ Individuals COMPETE for limited resources: • Food, water, space, mates ▪ Natural selection occurs through “Survival of the fittest” ▪ Fitness: the ability to survive and reproduce ▪ Not all individuals survive to adulthood
4. Selection ▪ The individuals with the best traits / adaptations will survive and have the opportunity to pass on it’s traits to offspring. • Natural selection acts on the phenotype (physical appearance), not the genotype (genetic makeup) • Ex: When a predator finds its prey, it is due to the prey’s physical characteristics, like color or slow speed, not the alleles (BB, Bb)
▪ Individuals with traits that are not well suited to their environment either die or leave few offspring. ▪ Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.
Peppered Moth A ▪ Which moth will the bird catch? B
Descent with Modification ▪ Descent with Modification – each living species has descended, with changes, from other species over time. ▪ Common Descent – all living organisms are related to one another
Evidence for Evolution: ▪ ▪ ▪ Fossil Record Homologous Body Structures Vestigial Organs Embryology Biochemical Evidence
The Fossil Record ▪ Fossils: a record of the history of life on Earth
Archaeopteryx ▪ Missing link between reptiles and birds
Homologous Body Structures ▪ Homologous Body Structures: similar anatomy in different types of animals because of common ancestor
Vestigial Organs • Vestigial Organs: “leftover” traces of evolution that serve no purpose
Embryology ▪ Embryology: embryos of all vertebrates are very similar early on
Biochemical Evidence ▪ Biochemistry: DNA with more similar sequences suggest species are more closely related • EX: Humans and chimpanzees share more than 98% of identical DNA sequences
Learning Goals ▪ 1. Define "Evolution" & "Natural Selection". ▪ 2. Describe the 4 steps of Natural Selection, giving an example of each. ▪ 3. Explain the importance of "Variation". ▪ 4. Does Natural Selection act on an organism phenotype or genotoype? Explain! ▪ 5. List the 5 evidences that support the Theory of Evolution.
Coral Snake (Poisonous) Milk Snake (Not poisonous)
Stick Mantid
Flower Mantid
- Chapter 15 darwin's theory of evolution section 15-1
- Www.bf.tku.edu.tw/files/news chapter 17
- Chapter 15 darwin's theory of evolution section 15-1
- Chapter 15 darwin's theory of evolution section 15-1
- Natural selection
- 3 types of natural selection
- Natural selection vs evolution
- Natural selection vs evolution
- What is evolution and natural selection
- Similarities
- Natural selection vs artificial selection
- Difference between continuous and discontinuous variation
- Stabilizing selection
- Natural selection vs artificial selection
- Darwin and evolution
- Charles darwin theory of evolution
- Bat wing
- Darwin's theory of evolution
- Chapter 15 section 1 darwins theory of natural selection
- Types of selection
- Balancing selection vs stabilizing selection
- K selected
- Clumped dispersion
- Two way selection and multiway selection
- Multiway selection
- Mass selection and pure line selection
- Sympatric speciation example
- P**n
- 4 principles of natural selection
- Stabilizing selection graph
- Genetic drift
- Natural selection 3
- How big are jaguars teeth
- Aids basketball player
- 3 types of natural selection
- Bird beak natural selection lab answers
- Selección natural
- Natural selection
- Natural selection ted ed
- Genetic drift vs gene flow vs natural selection
- Natural selection
- 3 types of natural selection
- Natural selection foldable
- The different types of natural selection
- Artificial selection
- 4 principles of natural selection
- Natural selection project ideas