1 / 39

The Theory of Biological Evolution

Explore the theory of evolution and how populations change over time. Learn about natural selection, genetic change, and the diversity of life forms.

msingh
Download Presentation

The Theory of Biological Evolution

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Happy Tuesday! • Submit The Peppered Moth WS • Title a new page in your notebook: The Theory of Biological Evolution • Finish Presentations (Per 4 and 6 only) • Evidence Projects group scores @ end of class. Can someone set an alarm for 3 minutes before the bell? Thank you!

  2. Discuss! A volcano erupted on an island. The ash released from the volcano changed the acidity (pH) of the soil from the level it had been for hundreds of years. This significant change resulted in new environmental pressures on species in the soil. Which of the following is a likely outcome of these pressures? • Some species will disappear from the soil because they do not have individuals with traits that allow them to survive in more acidic soil. • Only some species will generate the needed mutations to adapt to the change in pH; other species will become extinct. • Most species gain additional genetically-based traits, and this increase in complexity allows them to live in the more acidic soil. • Individuals in each species will evolve the traits necessary to survive under these new conditions.

  3. A ship that had been used for many years in arctic exploration was sold and moved to a harbor in the warm waters of the Caribbean. Worms that had lived on the ship bottom crawled off in the warm waters and attempted to attach to other ships in this tropical area where there were no similar worms. Some of the worms were able to survive and reproduce. What would you expect to happen to this group of worms over many generations in this new environment? • The worms will mate and produce offspring just as they did in their previous environment, and the group’s traits will likely remain unchanged after many generations. • The worms will gain new, more complex traits through natural selection that will help them better adapt to the warmer waters because natural selection leads to more complex and better adapted organisms. • Worms possessing genetic variations that help them to survive and thrive in the new environment will leave more offspring than others lacking those traits. Over time, the proportion of the worm population with these adaptive traits will likely increase. • The mutation rate will increase in this group of worms in order to promote evolution.

  4. The Theory of Biological Evolution

  5. The Theory of Evolution, defined: “All living species are descendants of ancestral species and are different from present day ones due to the cumulative change in the genetic composition of a population” • In a nutshell: Populations of living things came from other life – but look and behave differently because of genetic change.

  6. Charles Darwin (1809-1882) • Father of the theory of Evolution • Suggested that natural selection is the mechanism by which species evolve over geologic time. • Proposed Descent with Modification: • All organisms on Earth are related through some unknown ancestral type that lived long ago.

  7. History of Evolution Theory • As with any scientific theory, Evolution Theory has been developed through many generations of scientists interpretingnew evidence to refine and expand our understanding of biological change across time. • Darwin and Wallace (Evolution) • Gregor Mendel (Genetics) • Franklin, Watson & Crick (Genetics)

  8. The Nuts and Bolts of Evolution • Populations change, not individuals. • Evolution is like a tree. Many branches emerged from a common beginning, some branches died off (extinction), others branched multiple times (diversity)

  9. The Nuts and Bolts of Evolution • Niche: • A job or activity that is very suitable for someone. “I have my dream job. I have found my niche in society” • An environment that has all the things that a particular form of life needs in order to live. “The arctic fish have found their niche in cold waters due to the adaptations in their cell membranes” • The great diversity of life is the result of over 3.5 billion years of evolution, filling every available niche with life forms.

  10. Niche: An environment that has all the things that a particular form of life needs in order to live. • Discuss with a neighbor a possible niche for a/an: • Elephant • Whale • Bacterium • Cactus • Why are these life forms able to fill these niches? • How have these life forms filled these niches?

  11. The Origin of Species Darwin developed two main ideas: • Evolution explains life’s unity and diversity • Natural selection is a cause of adaptive evolution

  12. Sirenia (Manatees and relatives) Loxodonta africana (Africa) Elephas maximus (Asia) Loxodonta cyclotis (Africa) Hyracoidea (Hyraxes) Years ago Stegodon Mammut Mammuthus Deinotherium Platybelodon Millions of years ago Barytherium Moeritherium Figure 22.7 Darwin’s Tree of Life Is there a connection to this?

  13. Factors involved in Biological Evolutioninterpreted through Observations and Inferences from On the Origin of Species

  14. Overproduction* • Most species can (and do!) produce far more offspring than are needed to maintain the population. • Populations remain more or less constant (“stable”) because a small fraction of offspring live long enough to reproduce.

  15. Competition* • Living space and food are limited, so offspring from each generation must compete among themselves in order to live.

  16. (Genetic) Variation* • Characteristics in individuals in any species are not exactly alike. • Example: Differences for Homo sapiens can be exact size or shape of body, strength in running, or resistance to disease.

  17. Natural Selection* • Nature (“environment”) selects for living organisms with better suited inherited traits to survive and reproduce in that particular environment. • “Survival of the Fittest” – what does fitness mean? • Fitness = likelihood of survival AND reproduction. Both factors must be at play.

  18. Polar Bear Sun Bear • For the sun bear (native to SE Asia), long fur is harmful because the bear will overheat. • What does long fur do to a sun bear’s fitness? • Polar bears use long fur to absorb heat in the cold arctic environment. • What does long fur do to a polar bear’s fitness?

  19. Think about color… • What is the best color for absorbing heat? • What is the best color for reflecting heat? • Traits balance out, resulting in the best fitness possible. • Why can’t polar bears be black, even though they would be warmer? • Why can’t a sun bear be white, to keep it more cool? • The ability to hunt is MORE valuable than color of fur for keeping the bear alive.

  20. Polar Bear Sun Bear Helpful mutations over many generations = “Adaptations” This is why species appear to be adapted to their environment.

  21. Adaptation • An adaptation is an inherited trait that increases an organisms’ chance of survival and reproduction in a given environment. • Note: This is where the verbal shortcut of the term “adapt” is used (painfully) incorrectly.

  22. Speciation • Over many generations, favorable adaptations (for a particular environment) gradually accumulate in a species and “bad” (unfavorable) ones disappear. • Eventually, accumulated changes become so great, the result is a new species. • Takes many generations. Does that mean it takes a lot of time? Why or why not?

  23. What’s next? • Natural selection does not move in a pre-determined direction! The changing earth determines what will and can survive.

  24. The four factors (*) Biological evolution is a consequence of 4 factors working together. Without all factors, species change will not occur. • Overproduction • Competition • Genetic Variation • Natural Selection

  25. Pencils down for a class quiz!Which factors of evolution are depicted in the following pictures?

  26. Diagram 1

  27. Diagram 2

  28. Diagram 3

  29. Diagram 4

  30. Key!

  31. Competitionor Overpopulation

  32. Variation

  33. Speciation

  34. Adaptation

  35. Your Task • Begin the Lecture Review Questions. You can work with a group or partner, but write down your own answers (i.e., in your own words). Use your notes to help you. • Due on the day of test review. Don’t procrastinate!

  36. Modeling Natural Selection through the Evolution of Lemurus hypotheticus

  37. The Evolution of Lemurus hypotheticus Population: The species, Lemurus hypotheticus. Environment: Floornchair Rainforest Resources: Food = Landing on a Chair Variation: The slight differences between individuals brought to you by mutation and genetic recombination (aka sexual reproduction)

  38. Simulation:The Evolution of Lemurus hypotheticus No variation Monopeds Opti-nots Audio-nots Vertically challenged Bad SOD Tunnel Vision Manual Nots PITN Lotsamass

More Related