Evolution

Evolution Evolution explains how variations in species have occurred over time Life on earth began more than 3 billion years ago The first living organisms were simple, single celled organisms that were most likely heterotrophs. Autotrophs came later.

Evolution Continued Over time, more complex single-celled creatures developed. Then, about a billion years ago, increasingly complex, multicellular organisms began to appear.

Life’s Natural History is a record of Successions & Extinctions mya Quaternary Tertiary Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian Ediacaran Precambrian, Proterozoic, & Archarozoic 1.5 Plants Birds 63 Mammals 135 Reptiles Seed Plants Flowering Amphibians Insects 180 Dinosaurs Teleost Fish Land Plants 225 Jawless Fish Molluscs Arthropods Chordates Multicellular Animals 280 Green Algae Photosynthetic Bacteria 350 Anaerobic Bacteria 400 430 500 570 700 4500 Life’s Natural History is a record of Successions & Extinctions

Life has changed & changed the Earth Living creatures have changed Earth’s environment, making other life possible

The Theory of Evolution The theory of evolution is accepted as the central theme of modern biology. Its helps biologists understand how the variations among individuals can lead to changes in an entire species of organisms.

So much evidence has been collected by thousands of scientists that evolution is now a theory, which is a concept that has been tested and confirmed in many different ways and can be used by scientists to make predictions about the world.

LaMarck Lamarke's Theory of Acquired Characteristics Lamarke thought that you would gain or lose features if you overused or didn't use them, and you could pass these new traits onto your offspring. Lamarck noted how well-adapted organisms were to their environments, and believed that fossils could be understood as less perfect forms which had perished in the struggle for increasing perfection. He explained adaptation as a result of change caused by environmental pressures.

This was known as the Inheritance of Acquired Characteristics. Example: A giraffe stretched its neck to reach higher leaves, and this stretched neck would be a trait inherited by its offspring Lamarke's Theory was eventually proven to be FALSE! Features gained during life are NOT passed on to children.

Darwin's Theory of Evolution by Natural Selection.

“On the Origin of Species by Means of Natural Selection” Voyage: 1831-1836 November 24, 1859, Darwin published “On the Origin of Species by Means of Natural Selection”

Darwin was a naturalist who observed many species Darwin was a naturalist who observed many species. He is famous for his trips to the Galapagos Islands, his observations of the finches (and other animals) and his theory of Natural Selection or Survival of the Fittest. 1. Variation exists among individuals in a species. 2. Individuals of species will compete for resources (food and space)

3. Some competition would lead to the death of some individuals while others would survive 4. Individuals that had advantageous variations are more likely to survive and reproduce.

Darwin’s finches Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous Vegetarian Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground Insect eaters Bud eater Seed eaters Cactus eater Warbler Tree finches Ground finches

This process he describes came to be known as Natural Selection The favorable variations are called adaptations  These variations could be passed on if the trait occurred in the sex cells

Evidence of Evolution Fossil Evidence Fossil record---creates a geologic time scale. Shows us that today’s organisms descended from ancestral species The fossil record is layers of sedimentary rock containing fossils

New layers cover older ones, creating a record over time Fossils within layers show that a variety of organisms have populated Earth throughout a long period of time

Fossil Record

Comparative embryology Embryos of different species develop almost identically Indicate presence of a common ancestors

Comparative embryology Shows how structures that are embryologically similar, but have different functions.

Homologous Structures Structures that are similar between different organisms.

Vestigial Organs--seemingly functionless parts, snakes have tiny pelvic and limb bones, humans have a tail bone. some snakes & whales show remains of the pelvis & leg bones of walking ancestors eyes on blind cave fish human tail bone

Hind leg bones on whale fossils

Biochemistry and DNA   Comparing DNA & protein structure. The closer the sequence of bases and amino acids the more closely related the organisms are every organism has a universal genetic code consisting of DNA and RNA

Comparative hemoglobin structure Human Macaque Dog Bird Frog Lamprey 8 32 45 67 125 10 20 30 40 50 60 70 80 90 100 110 120 Number of amino acid differences between hemoglobin (146 aa) of vertebrate species and that of humans

Which branching tree diagram best represents the information above ?

Which statement is a valid conclusion that can be drawn from the diagram on the left? (1) Snails appeared on Earth before corals. (2) Sponges were the last new species to appear on Earth. (3) Earthworms and sea stars have a common ancestor. (4) Insects are more complex than mammals.

Which statement is a valid inference based on the information in the diagram on the left? (1) Species A is the common ancestor of all life on Earth. (2) Species D is more closely related to species E than to species F. (3) Species B is the ancestor of species F. (4) Species C is the ancestor of species that exist at the present time.

Which statement is supported by the diagram on the left? (1) Species C is the ancestor of species B. (2) Species D and E evolved from species B. (3) Species X evolved later than species D but before species B. (4) Both species C and species D are related tspecies X.