1 / 70

Evolution

Evolution. Charles Darwin. Basic premises for this discussion. Evolution is not a belief system. It is a scientific concept. It has no role in defining religion or religious beliefs Evolution is a theory…but you don’t get any better than that in science. Some basic definitions.

byron-gay
Download Presentation

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. Evolution Charles Darwin

  2. Basic premises for this discussion • Evolution is not a belief system. It is a scientific concept. It has no role in defining religion or religious beliefs • Evolution is a theory…but you don’t get any better than that in science www.carlwozniak.com

  3. Some basic definitions • Theory:a well-substantiated explanation that incorporates facts, laws, inferences and tested hypotheses. In science, you don’t get any better than a theory. www.carlwozniak.com

  4. So what does the definition mean? • Evolutionis a change in the number of times specific genes that code for specific characteristics occur within an interbreeding population • Individuals don’t evolve, populations do www.carlwozniak.com

  5. So what does the definition mean? • Things don’t change because organisms want or need them to www.carlwozniak.com

  6. Definition problems • Part of the problem is that a number of different definitions for evolution can be found both within and without the scientific community. These can easily confuse laypeople. www.carlwozniak.com

  7. Definition problems "evolution: ...the development of a species, organism, or organ from its original or primitive state to its present or specialized state; phylogeny or ontogeny" - Webster's "evolution: The gradual process by which the present diversity of plant and animal life arose from the earliest and most primitive organisms, which is believed to have been continuing for the past 3000 million years." -Oxford Concise Science Dictionary "evolution: ...the doctrine according to which higher forms of life have gradually arisen out of lower." - Chambers www.carlwozniak.com

  8. A brief history of Evolution Charles Darwin was born on February 12, 1809 in Shrewsbury, England. From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world. He observed much variation in related or similar species of plants and animals that were geographically isolated from each other. These observations were the basis for his ideas. www.carlwozniak.com

  9. www.carlwozniak.com

  10. A brief history of evolution Contrary to popular belief, Darwin was not the first person to describe the concept of evolution, but he was the one who gave it its driving force. www.carlwozniak.com

  11. A brief history of evolution Darwin presumed that populations of individuals changed over time, and, in 1844, he developed the concept of the driving force for evolution. It wasn’t until many years later that he published his idea in a book called “The Origin of Species” www.carlwozniak.com

  12. Fossils • Any evidence of an organism that lived long ago. www.carlwozniak.com

  13. Types of Fossils • Cast • Mold • Trace fossils • Imprints • Petrified fossils • Frozen or Amber www.carlwozniak.com

  14. Dating Fossils • Relative Dating • Rock layers are put down in order • Oldest on bottom, youngest layers on top • Radiometric Dating • Carbon-14 (50,000 years or less) • Potassium-40 (1.3 billion years – 50,000 years) www.carlwozniak.com

  15. Why Use Fossils? • Scientists have used the fossil record to construct a history of life on Earth. • Earth’s life forms appeared 3.5 billion years ago • Fossil record is not complete, but pretty good for general information www.carlwozniak.com

  16. Fossils shape ideas about evolution • When geologists provided evidence indicating that Earth was much older than many people had originally thought, biologists began to suspect that species change over time, or evolve www.carlwozniak.com

  17. Evolutionary theory. • Darwin became convinced that the Earth was old and continually changing • He concluded that living things also change, or evolve over generations • He also stated that living species descended from earlier life-forms: descent with modification www.carlwozniak.com

  18. Primate Evolution

  19. Primates are mammals that have: • Opposable thumbs • Large brain • Good, stereoscopic vision • Flexible elbows for hand rotation • Grasping feet www.carlwozniak.com

  20. Primates are mammals that have: • Opposable Thumbs... The first digit can be moved so that it can touch each of the other digits. www.carlwozniak.com

  21. Early Primates • Appeared 60-65 million years ago • Prosimian • Small bodies • Lemurs, Tarsiers • Anthropoids • Human-like primates • Evolved in Africa www.carlwozniak.com

  22. Hominid Evolution • Hominids developed 5-8 million yrs ago • Hominids are bipedal • First hominids were in genus Australopithecus • “Lucy” most famous fossil hominid • More modern hominids were in genus Homo www.carlwozniak.com

  23. More recent humans • Homo sapiens • (developed 400,000 years ago) • Neanderthals • Europe arrival (100,000 years ago) www.carlwozniak.com

  24. More recent humans • Homo sapiens • (developed 400,000 years ago) • Cro-Magnon • Europe arrival (40,000 years ago) • Americas arrival (12,000 years ago) www.carlwozniak.com

  25. Natural Selection Darwin knew nothing of genes, but what he did have were two observations and a little inference that provided the motive force for evolution. www.carlwozniak.com

  26. Natural Selection Observation 1: Organisms generally have more offspring than can survive to adulthood. Observation 2: Offspring are not identical. There is variation in their appearance, size, and other characteristics. www.carlwozniak.com

  27. Natural Selection Inference: Those organisms that are better adapted to their environment have a greater likelihood of surviving to adulthood and passing these characteristics on to their offspring. Survival of the “fittest.” www.carlwozniak.com

  28. Darwin’s dilemma Darwin was hesitant to publish his theories because of the backlash that previous authors received. If this book is true, “religion is a lie, human law a mass of folly and a base injustice; morality is moonshine.” -Adam Sedgwick’s response to Robert Chamber’s 1844 book, Vestiges of the Natural History of Creation, in which Chamber’s hinted that organic creation was the result of natural laws, not God’s intervention. www.carlwozniak.com

  29. Adaptations: Evidence for Evolution • an adaptation is any variation that aids an organism’s chances of survival in its environment. • According to Darwin’s theory, adaptations in species develop over many generations • Learning about adaptations in mole-rats can help you understand how natural selection has affected them. www.carlwozniak.com

  30. Structural adaptations arise over time • The ancestors of today’s common mole-rats probably resembled African rock rats. www.carlwozniak.com

  31. Structural adaptations arise over time • Some ancestral rats may have avoided predators better than others because of variations such as the size of teeth and claws. www.carlwozniak.com

  32. Structural adaptations arise over time • Ancestral rats that survived passed their variations to offspring. • After many generations, most of the population’s individuals would have these adaptations. www.carlwozniak.com

  33. Structural adaptations arise over time • Over time, natural selection produced modern mole-rats. • Their blindness may have evolved because vision had no survival advantage for them. www.carlwozniak.com

  34. Structural adaptations arise over time • Mimicry is a structural adaptation that enables one species to resemble another species. • Predators may learn quickly to avoid any organism with their general appearance www.carlwozniak.com

  35. Structural adaptations arise over time • camouflage, an adaptation that enables species to blend with their surroundings. • Because well-camouflaged organisms are not easily found by predators, they survive to reproduce. www.carlwozniak.com

  36. Evidence for Evolution • Physiological resistance in species of bacteria, insects, and plants is direct evidence of evolution. • However, most of the evidence for evolution is indirect, coming from sources such as fossils and studies of anatomy, embryology, and biochemistry. www.carlwozniak.com

  37. Evolution in the Classroom • Once upon a time, the State of Tennessee passed a statute prohibiting the teaching of evolution. • In 1925 the Tennessee legislature passed the Butler Act which made it a misdemeanor to teach the evolution of only one species—mankind—in the public schools. • Violation of the statute (the Butler Act) was punishable by fine and/or imprisonment. www.carlwozniak.com

  38. John Scopes • John Scopes a young and earnest high school biology teacher in Dayton, Tennessee was arrested as he was teaching evolution in his classroom. He was the victim of a fundamentalist witch hunt. Click here for a video clip from ITW. www.carlwozniak.com

  39. Extinction www.carlwozniak.com

  40. Extinction The Definition and Causes

  41. What is Extinction? • Extinction occurs when the last existing member of a given species dies • In other words…there aren’t any more left! www.carlwozniak.com

  42. Causes of Extinction • Genetics and Demographics • Small populations = increased risk • Mutations • Causes a flux in natural selection • Beneficial genetic traits are overruled • Loss of Genetic Diversity • Shallow gene pools promote massive inbreeding www.carlwozniak.com

  43. Some Causes • Habitat Degradation • One of the most influential • Has many causes • Some due to humans • Some due to other factors www.carlwozniak.com

  44. Habitat Degradation • Toxicity • Kills off species directly through food/water • Indirectly via sterilization • Can occur in short spans (a single generation) • Can occur over several generations • Increasing toxicity • Increasing competition for habitat resources www.carlwozniak.com

  45. Habitat Degradation • Destruction of Habitat • “Save the Rainforests!” • Elimination of living space • Change in habitat • Rainforest to pasture lands • Leads to diminishing resources • Increases competition • Can be caused by natural processes • Volcanoes, floods, drought, etc… www.carlwozniak.com

  46. Causes Con’t. • Predation • Competition • Disease • Coextinction • Mass Extinction • Planned Extinction www.carlwozniak.com

  47. Predation • Introduction of predators • Invasive alien species • Transported by humans • Cattle, rats, zebra muscles, etc… • Sometimes on purpose, sometimes not • Can eat other species • Eat food sources • Introduce diseases www.carlwozniak.com

  48. Coextinction • The loss of one species leads to the loss of another • Chain of extinction • Can be caused by small impacts in the beginning • A predator looses its food source • Affected by interconnectedness in nature www.carlwozniak.com

  49. Mass Extinction • Aka: an extinction event • A sharp decrease in the number of species on Earth in a short period of time • Coincides with a sharp drop in speciation • The process by which new biological species arise • There have been at least 5 • Last one was 65M years ago www.carlwozniak.com

  50. Mass Extinction • Nearly 2/3rds (or more) of all animal species that ever existed on the planet are now gone. • With contemporary extinction being attributed to HUMAN activity. • Numerous factors go into the extinction of a specific species. • Though all point the finger to climate change. www.carlwozniak.com

More Related