Essential Questions: What is evolution? What types of evidence supports the theory of evolution ? Evolution- changes in species over long periods of time

Geologic Time-Earth’s history and revealed by layer of rock (4.5 billion). Fossil Record-collection of fossils that provide clues to the history of earth’s organisms.

Evidence of Evolution Fossils- remains or traces of organisms that once lived.

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Essential questions: What is comparative anatomy? What are homologous structures ? Comparative Anatomy-comparing body structures of plants and animals. Comparative Anatomy-comparing body structures of plants and animals. Homologous structures:  Similar in structure but different in function. Exs. Wing of a bat and flipper of a whale.  Indicates a common ancestor

Comparative Anatomy

Comparative Embryology -comparing the similarities among vertebrate embryos. Exs. Chicken/fish/man—gill slits 2-chambered heart, tail

Comparative Embryology

Comparative Biochemistry- comparing chemicals in organisms. Exs. Blood, DNA Lion and cats are closely related because of similarities in protein structures.

Theories of Evolution Spontaneous Generation- a. concept that living things came from nonliving things Exs. Toads come from mud (flies from rotting animals) b. Disproved by Louis Pasteur.

Theory of Use and Disuse-Lamarck –Proposed in the early 1800’s by Jean Lamarck. –Theory states that organisms were able to develop new structures because they needed the structures. Size of an organ is determined by how much the organism used. Exs. Ballet dancers, basketball players

Theory of Use and Disuse Lamarck also believed in the “inheritance of acquired characteristics”. A trait produced in an individual’s lifetime can be passed on to its offspring. This was disproved in that late 1800’s by August Weismann.

Weismann’s Experiment

Charles Darwin

Darwin’s Finches

Essential Question? What is Darwin’s theory of Natural Selection? Theory of Natural Selection: Theory proposed by naturalist Charles Darwin in the 1850’s. Stated evolution occurs because of natural selection. Nature(environment) acts as the selecting agent of an organism’s trait.

Theory of Natural Selection Theory contains the following main concepts: Overproduction

Theory of Natural Selection Competition-for food, habitat, mate, light, etc.

Theory of Natural Selection Variations-members of a population show differences in traits that make certain individuals better adapted to survive. Exs. Size, color, structure Survival of the fittest Natural Selection variations that are more helpful are a natural selection agent against organisms that can’t adapt. A population evolves not the individual

Adaptive Value-any trait that helps the organisms survives and reproduces under a given set of environmental conditions. Ex. Coloration of rabbits.

Essential Question: What is the modern theory of evolution 1. Mutation Theory -Hugo DeVries.. a. Inherited mutations cause variations b. Mutations occur randomly and those that are favorable are passed on to offspring. b. Mutations occur randomly and those that are favorable are passed on to offspring. 2. Modern Theory -combined Darwin’s ideas of variation, natural selection with mutations, DNA, chromosomes, and sexual reproduction.

Genetic Shuffling- sorting and random recombination of genes during meiosis and fertilization. Ex. Shuffling of cards.

Essential Question: What are some examples of evolution in our time? Evolution in our Time: Exs. Black flies in the Adirondack Mountain

Revenge of the Black Fly

Examples of Evolution in Our Time Staphylococcus bacteria that is resistant to antibiotics. English peppered moth for over 100 years in Manchester England.

Essential Questions: What is geographic and reproductive isolation? How does it affect speciation? Geographic Isolation: Occurs when population is physically separated into a smaller populations by geographic barriers. Occurs when population is physically separated into a smaller populations by geographic barriers. Geographic Barriers: Exs. Mountains ranges, desert, rivers, shopping, malls. Geographic Barriers: Exs. Mountains ranges, desert, rivers, shopping, malls.

Geographic Barriers

Speciation- production of a new species. Reproductive isolation-population can’t interbreed even if barriers are removed. Exs. Kaibab and Albert squirrels in the Grand Canyon

Adaptive radiation-process by which many new species of organisms evolved from a common ancestor. Ex. Finches of the Galapagos Islands.(13 different types). types).

Darwin’s Finches

Patterns of Change: Changes in species are often related to environmental change. Changes in species are often related to environmental change. Species with short reproductive cycles that produce many offspring tend to evolve more quickly than species with long lifespan and few offspring. Species with short reproductive cycles that produce many offspring tend to evolve more quickly than species with long lifespan and few offspring. The failure to adapt to a changing environment may result in the death of the species. The failure to adapt to a changing environment may result in the death of the species.

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Time Frame for Evolution:  While the essentials of Darwin’ theory of evolution, variation and natural selection are generally accepted by the scientific community, considerable discussion exists within this community as to the time frame in which evolution occurs.  The current theories have been proposed to explain the time frame: Gradualism Punctuated Equilibrium

Gradualism Gradualism Evolutionary change is slow, gradual and continuous. Evolutionary change is slow, gradual and continuous. Supported by fossils that show slight changes between adjacent rock layers and greater amounts of change between bottom and top layers

Punctuated Equilibrium Punctuated Equilibrium: 1. Proposes that species have long periods of stability (several million years) interrupted by brief periods of significant changes during which new species may evolve. 2.Supported by fossil records that there is very little change, but sudden bursts of changes are observed between some adjacent layers.

Gradualism Versus Punctuated Equilibrium

Essential Question: What is the heterotroph hypothesis? Heterotroph Hypothesis-explanation for how the early life forms may have evolved on the primate earth. Steps in the Process of Formation of the Earth:  Earth is composed of a sea of hot thin soup, containing N2, CO2, NH3, H2 and H20.  Energy from the sun and radioactive sources caused the formation of organic compounds.  Eventually these compounds became able to reproduce and use CO2, anaerobic bacteria.  These bacteria evolved into aerobic bacteria and could undergo photosynthesis. Ex. Blue-green algae

Miller’s Experiment