Darwin & Natural Selection

Presentación del tema: "Darwin & Natural Selection"— Transcripción de la presentación:

1 Darwin & Natural Selection http://www.wuhsd.org/site/handlers/filedownload.ashx?moduleinstanceid=3044&dataid=22517&FileName=DarwinNatural%20Selection11.ppt

2 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 genotype? Explain! 5.List the 5 evidences that support the Theory of Evolution. 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 genotype? Explain! 5.List the 5 evidences that support the Theory of Evolution.

3 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  Evolution: The process of change over time  Specifically, a change in the frequency of a gene or allele in a population over time

4 Charles Darwin  Father of Evolution natural selection  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  Father of Evolution natural selection  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”Wrote a book, “Origin of the Species”

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6 Darwin’s Finches

7 Natural Selection  Natural Selection: Organisms that are best adapted to an environment survive and reproduce more than others

8  Darwin’s Theory of Natural Selection occurs in four steps:  Overproduction  Variation  Competition  Selection  Darwin’s Theory of Natural Selection occurs in four steps:  Overproduction  Variation  Competition  Selection

9 1. Overproduction  Each species produces more offspring that can survive

10 2. Variation  Each individual has a unique combination of inherited traits.  Adaptation: an inherited trait that increases an organism’s chances of survival  Each individual has a unique combination of inherited traits.  Adaptation: an inherited trait that increases an organism’s chances of survival

11 What adaptations do you see? http://www.eveboo.com/wp-content/uploads/2013/05/snow-wolf-wallpaper.jpg

12 What adaptations do you see? http://i.imgur.com/HZTh8ZG.jpg

13 Why is Variation Important?  Because the environment changes. variation within a species survive  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 variation of types of species some will survive  The more variation of types of species in an habitat, the more likely at least some will survive  EX: Dinosaurs replaced by mammals  Because the environment changes. variation within a species survive  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 variation of types of species some will survive  The more variation of types of species in an habitat, the more likely at least some will survive  EX: Dinosaurs replaced by mammals

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15 3. Competition  Individuals COMPETE for limited resources:  Food, water, space, mates Survival of the fittest  Natural selection occurs through “Survival of the fittest”  Fitness: the ability to survive and reproduce  Not all individuals survive to adulthood  Individuals COMPETE for limited resources:  Food, water, space, mates Survival of the fittest  Natural selection occurs through “Survival of the fittest”  Fitness: the ability to survive and reproduce  Not all individuals survive to adulthood

16 4. Selection best traits / adaptations will survive and have the opportunity to pass on it’s traits  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) best traits / adaptations will survive and have the opportunity to pass on it’s traits  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)

17  Individuals with traits that are not well suited to their environment either die or leave few offspring. good traits build up in a population bad traits are eliminated by the death of the individuals  Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.  Individuals with traits that are not well suited to their environment either die or leave few offspring. good traits build up in a population bad traits are eliminated by the death of the individuals  Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.

18 Peppered Moth  Which moth will the bird catch? A B

19 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  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

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21 Evidence for Evolution:  Fossil Record  Homologous Body Structures  Vestigial Organs  Embryology  Biochemical Evidence  Fossil Record  Homologous Body Structures  Vestigial Organs  Embryology  Biochemical Evidence

22 The Fossil Record  Fossils: a record of the history of life on Earth

23 Archaeopteryx  Missing link between reptiles and birds

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25 Homologous Body Structures  Homologous Body Structures: similar anatomy in different types of animals because of common ancestor

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27 Vestigial Organs  Vestigial Organs: “leftover” traces of evolution that serve no purpose

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29 EmbryologyEmbryology  Embryology: embryos of all vertebrates are very similar early on

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31 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  Biochemistry: DNA with more similar sequences suggest species are more closely related  EX: Humans and chimpanzees share more than 98% of identical DNA sequences

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33 Coral Snake (Poisonous) Milk Snake (Not poisonous)

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40 Stick Mantid

41 Flower Mantid