Theory of Evolution

Evolution Inherited change over time, eventually causing creation of new species. Inherited change over time, eventually causing creation of new species.

Theories of Evolution Lamarck’s Theory Lamarck’s Theory 1.Tendency Toward Perfection - All organisms have innate tendency toward complexity and perfection -continually changing to help them live in their environment -Ex: over generations, bird’s urge and attempts to fly gave them big wings 2. Use and Disuse - Evolution occurs as structures develop with use, or disappear because of disuse -Ex: A giraffe’s neck 3. Inheritance of Acquired Traits - Acquired characteristics are passed on to offspring Ex: If you spent your life lifting weights and building muscle, your children would inherit big muscles as well.

Darwin In 1831, Darwin set sail from England aboard the H.M.S. Beagle for a voyage around the world. In 1831, Darwin set sail from England aboard the H.M.S. Beagle for a voyage around the world. Darwin went ashore and collected plant and animal specimens for his collection. Darwin went ashore and collected plant and animal specimens for his collection. OBSERVATIONS: OBSERVATIONS: -Many plants and animals were well suited to the environments they inhabited. -Grasslands in some regions were similar to one another but were inhabited by very different animals.

Observations (continued) Observations (continued) Fossils: some he collected resembled organisms that were still alive, others looked completely unlike any creature he had ever seen. Fossils: some he collected resembled organisms that were still alive, others looked completely unlike any creature he had ever seen. Galápagos Islands: They were close together but had very different climates. Galápagos Islands: They were close together but had very different climates. Characteristics of animals and plants greatly varied among the different islands. Characteristics of animals and plants greatly varied among the different islands. Example: Among tortoises, the shape of the shell corresponds to different habitats. Example: Among tortoises, the shape of the shell corresponds to different habitats. s sparse, high abundant, low vegetation vegetation vegetation vegetation Hood Island Tortoise Isabela Island Tortoise

Darwin wondered…Were animals living on different islands previously members of the same species? Darwin wondered…Were animals living on different islands previously members of the same species? Could these separate species have evolved from an original South American (Ecuador) ancestor species? Could these separate species have evolved from an original South American (Ecuador) ancestor species?

Naturally there is genetic variation (Mutations!) in a population allowing some to survive better than others. Naturally there is genetic variation (Mutations!) in a population allowing some to survive better than others. Any characteristic that gives the organism a REPRODUCTIVE advantage will become more common in a population. Any characteristic that gives the organism a REPRODUCTIVE advantage will become more common in a population. Over time, this process results in adaptations that specialize the organism for a particular ecological niche. Over time, this process results in adaptations that specialize the organism for a particular ecological niche.

Heritable traits that allow animals to better survive and reproduce in their environment become more common in a population over many generations. Heritable traits that allow animals to better survive and reproduce in their environment become more common in a population over many generations. Natural selection allows for Survival of the fittest. Natural selection allows for Survival of the fittest.

Darwin’s finches

Types of Evolution Convergent Evolution: Convergent Evolution: species that are NOT closely related look similar because they have evolved to live in the same environment Ex: Shark and Dolphin

Divergent Evolution: Divergent Evolution: species that are related begin to look different because they are adapting to different environments Ex: finches, tortoises Isabela Island Tortoise Hood (Espanola) Island Tortoise

Coevolution: Coevolution: two species evolve together Species= group of organisms that have similar characteristics and can reproduce fertile offspring Ex: Hummingbird and cardinal flower

Types of Natural Selection Directional Selection: Directional Selection: individuals in one extreme are selected to survive Ex: giraffe’s neck Neck size # of Giraffes in Pop Neck size # of Giraffes in Pop Peak shifts; average neck size increases

Stabilizing selection: Stabilizing selection: individuals with the average phenotype are selected to survive Ex: the weight of humans at birth Birth Weight Percentage of population Birth Weight Percentage of population Selection against extremes; curve in same place

Disruptive selection: Disruptive selection: individuals of both extremes are selected to survive Ex: Birds in a population where small and large seeds are common Beak size Percentage of population Beak size Percentage of population Selection against middle, curve peaks at the extremes

Evidence of Evolution Fossils (p ) Fossils (p ) a.Fossilized organisms in older rocks are different from those found in newer rocks. Use them to get an approximate date of when the organism existed. Use them to get an approximate date of when the organism existed. b.Can compare fossils to organisms alive today.

Anatomical Similarities A. Homologous Sturctures: (p.256) Different species have the same structures used for different functions. Evidence that these species evolved from a common ancestor. Ex: arm bones

B. Vestigial Structures: Structures or organs that we have but no longer use Evidence that species share a common ancestor who once used these structures/organs Ex: Appendix, wisdom teeth, tail bone

Embriological Similarities: (p. 257) Embriological Similarities: (p. 257) Similarities in the embryonic development of all vertebrates suggests that they evolved from a common ancestor. Embryo  An organism in the early stages of development and growth (usually before it is born) Vertebrate  An organism with a backbone

Biochemical Similarities: Biochemical Similarities: Organisms that share a common ancestor have similar DNA segments (amino acids and proteins) Ex: All organisms that use oxygen have the enzyme cytochrome c.

References finches2 finches2 finches2 finches2 pictures&fr=FP-tab-web- t&toggle=1&ei=UTF-8 pictures&fr=FP-tab-web- t&toggle=1&ei=UTF-8 pictures&fr=FP-tab-web- t&toggle=1&ei=UTF-8 pictures&fr=FP-tab-web- t&toggle=1&ei=UTF-8 _Natural_History/Birds_and_Animals/Animal s/Tortoises.html _Natural_History/Birds_and_Animals/Animal s/Tortoises.html _Natural_History/Birds_and_Animals/Animal s/Tortoises.html _Natural_History/Birds_and_Animals/Animal s/Tortoises.html als/species/2633.html als/species/2633.html als/species/2633.html als/species/2633.html vlect.html vlect.html