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Evolution

Explore the concepts of evolution through fossils, dating methods, comparative studies, and theories like Natural Selection. Learn about adaptation, speciation, and the different types of evolution that shape the diversity of life on Earth.

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Evolution

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  1. Evolution Changes in types of organisms over a period of time

  2. Fossils • A fossil is some remnant of an organism that proves its existence • Imprints of bacteria, leaves or footprints • Insects, pollen, or flower parts in amber • Tools or pottery shards • Bones of organisms in sedimentary rock • Cave drawings

  3. Determining fossil age • Relative dating • Oldest fossils are in the deepest sedimentary rock layers • Younger layers hold newer, more complex fossils

  4. Absolute dating • Can be used to determine a precise age in years • Use the decay rate of radio-isotopes like carbon 14 • The oldest known fossils are approximately 3 billion years old

  5. Comparative studies • Researchers use comparative studies to establish evolutionary relationships between organisms

  6. Comparative anatomy • Comparing specific body structures • Analogous structures have a similar function but the structure is different • Ex the wing of an insect and the wing of a bird

  7. Homologous structures are similar in structure but may have different functions • Ex) human hand, cat paw, whale flipper, bat wing

  8. Vestigial structures are reduced in size and have no known function • They resemble structures in other organisms • Ex) the human appendix or the pelvis bone in a whale

  9. Comparative embryology • The comparison of embryonic development • Early development is similar in many species • The closer the relationship between species the more similar is development

  10. Comparative cytology • Observing similarities in cell structures • All cells have some common organelles that perform identical functions • Plasma membrane, cytoplasm, and ribosomes

  11. Comparative Biochemistry • Similarities involving proteins, enzymes and nucleic acids • All organisms share genetic codes • Transcription and translation • All organisms carry on cell respiration in the same way • All autotrophs carry on photosynthesis in the same way

  12. Theories of Evolution

  13. J.B. Lamarck • Use and disuse • Organisms can change their body structure over the course of a lifetime • ATROPHY – structure decreases in mass with disuse • HYPERTROPHY – structure increases in mass with use

  14. Lamarck believed that ACQUIRED TRAITS could then be passed to the offspring • Example) the neck of the giraffe

  15. August Weissman • Disproved Lamarck’s theory of use and disuse • He cut off the tails of mice then mated them • All of the offspring had long tails • This experiment was repeated for 22 generations • All of the mice were born with long tails!

  16. Charles Darwin • Theory of Natural Selection • Darwin served as a geologist, botanist, zoologist, and general man of science aboard the H.M.S. Beagle from 1831-1836

  17. Overproduction – organisms produce more offspring than can possibly survive • Struggle for existence – there are only limited resources available • Not all offspring will survive • Natural selection – those organisms with advantages in a given environment are most likely to survive and reproduce • Those who survive and reproduce are the FITTEST

  18. Variation – offspring tend to be different from their parents and each other • Speciation – after many generations are involved in natural selection • A population may be so different from the original population that it can be classified as a different species • SPECIES= organisms who can mate and produce fertile offspring

  19. Speciation • Involves isolation • Anything which prevents two groups within a species from interbreeding

  20. Geographic isolation • A population is divided by a natural barrier • mountains • Deserts • Body of water • Landslide cause by an earthquake • Geographic isolation can instigate a speciation event—but genetic changes are necessary to complete the process

  21. Reproductive isolation • Differing selection pressures on the new environments can complete the differentiation of the new species.

  22. the differences between the isolated groups become so great that they can no longer interbreed

  23. Microevolution • Small, gradual changes which are detectable within a few generations

  24. Industrial Melanism – changes in the colors of a population as a result of human industrial activity

  25. Macroevolution • Long term changes that make a new species

  26. General patterns for evolution • Divergent evolution – different groups evolve from one ancestor

  27. Convergent evolution – two or more different groups evolve so that they resemble one another strongly

  28. Adaptive radiation – organisms spread into new environments and become adapted through natural selection

  29. Adaptations • an anatomical structure, physiological process or behavioral trait of an organism that has evolved over a period of time by the process of natural selection • it increases the expected long-term reproductive success of the organism

  30. Organisms that are adapted to their environment are able to: • obtain air, water, food and nutrients • cope with physical conditions such as temperature, light and heat • defend themselves from their natural enemies • reproduce • respond to changes around them

  31. Camouflage and mimicry are adaptations some animals use as protection from predators. • An animal that uses camouflage looks like things in its environment. It might look like a leaf, a twig, or a rock.

  32. http://oncampus.richmond.edu/academics/education/projects/webunits/adaptations/mimicry.htmlhttp://oncampus.richmond.edu/academics/education/projects/webunits/adaptations/mimicry.html • Animals that use mimicry use colors and markings to look like another animal. • Example) the Monarch Butterfly and the Viceroy

  33. Symbiosis • Two species live in close association with each other • In symbiosis, at least one member of the pair benefits from the relationship. The other member may be • injured = parasitism • relatively unaffected = commensalism • may also benefit = mutualism

  34. Mutualism = (+) (+) • Both organisms benefit

  35. Moray eel and cleaner fish • The eel gets clean • The fish gets food • Both organisms benefit

  36. Parasitism = (+) (-) • the parasite benefits while the host is harmed

  37. (1) The hookworm latches on the walls of the colon with its sharp teeth where it feeds on blood. • (2) The tapeworm is the longest parasite. A mature adult can lay a million eggs a day. • (3) Tapeworm eggs embedded in the colon. • (4) The roundworm can grow to be 20 inches (50 cm) long and lay 200,000 eggs per day. • (5) Pinworms migrate outside the colon during the night to lay their eggs around the anus. This causes the nightly itching of many unsuspecting victims.

  38. Commensalism = (+) (0) • One organism benefits while the other is neither helped or harmed

  39. Heterotroph Hypothesis • 1920-30s • Formulated by a small group of scientists • Suggests a probable sequence in which organisms appeared

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