Extinction

1. Extinction Unit of Study

2. Major Topics • Extinction of a species is common. • The majority of Species that have existed on the Earth are extinct. (95-97%) • Environmental changes and poor adaptation characteristics of species may lead to extinction.

3. What is extinction? • When all members of a species no longer exist. • Does not apply to individuals. • Extinction has been and will continue to be a common event on Earth. • Part of Earth’s natural processes, like weather.

4. Species • A group of organisms that share similar characteristics and can reproduce among themselves. • These organisms can have different variations.

5. Organism Needs • Organisms need to gather and process resources, grow, reproduce, and maintain stable internal conditions while the external environment constantly changes • Sometimes these needs are met and sometimes they are not.

6. Natural versus Unnatural • Concerned about increase in the extinction rate. • Was estimated to be about 40,000 species a year. • Human activity contributing to the increase. • No longer natural.

7. Human Activity • Habitat disturbance and elimination. • Increase in housing and commercial development. • Commercial hunting. • Valuable fur • Food • Pest and Predator Control. • Protect livestock & crops.

8. Human Activity • Collecting specimens for pets, zoos, and research. • Pollution • Accidental or deliberate introduction of a new competing or predatory species into an ecosystem.

9. Endangered Species There are so few individuals left in the population that the species are on the verge of extinction. May not be able to save them. Threatened Species There is still a large enough population of a species for survival, but the number of organisms is declining over time. Can be saved with enough time and effort on our part. Pre- Extinction Categories

10. Threatened Species • American Bald Eagle • Haliaeetusleucocephalus • Killed to protect livestock. • Has not adjusted well to human activity. • Numbers are increasing due to current programs in the state and nationally.

11. Endangered Species • Peregrine Falcon • Falcoperegrinus • Suffered from habitat destruction and pesticide use in Kentucky. • Current program to reintroduce this species into various areas of the state where it is missing.

12. Endangered Species in Kentucky • http://animals.about.com/od/onlinecourses/a/esa_kentucky.htm

13. Evidence That Extinction is Common • Fossil Record • Look at all the fossils already uncovered. • Earth History • Life on Earth for about 350 million years. • Billions of organisms have become extinct. • Most did not even leave fossils behind! • Can see results of their existence

14. Catastrophe Variable due to size of population. Can include the following: Asteroid Impact Volcanic Activity Drought Other Natural Disasters Natural Processes Regularly occurring phenomena. Examples Evolution Disease Competition Reproductive Changes Methods of Extinction

15. Humanity • Into which category does humanity fit? • The answer is both! • We are a part of the world and its natural processes. • We also perform activities that have catastrophic effects on other species.

16. Feed at high trophic levels Large Size Low reproductive rate Specialized nesting or breeding areas Fixed migratory patterns Specialized feeding habits Certain behavioral patterns Intolerant of human presence Preys on livestock or humans Valuable body parts Found in only one place or region Extinction-Prone Characterisitcs

17. What are fossils? • Fossils are the remains of organisms that are no longer alive. • Three types of fossilized remains: • Casts and molds • Trace fossils • Preserved fossils (amber or ice) Fossils can tell us how life has changed through time Fossils can also tell us the age and environment in which an organism lived.

18. Fossil Formation • The body of a dead organism must be protected from scavengers and bacteria. • Covered by sediment. • Organisms have a better chance of being preserved if they have hard parts such as bones, shells or wood. • Mostly found in sedimentary rock. Metamorphic and igneous destroy material due to heat and pressure. • http://www.classzone.com/books/earth_science/terc/content/visualizations/es2901/es2901page01.cfm

19. Petrification Remains are buried below sediment. Sediment hardens over time to rock. Water removes remains, leaving a mold. Mold fills with minerals, forming a cast that we call a fossil. Depends on the type of fossil. Organism dies or becomes trapped in a very cold environment. Small organisms get trapped in amber. Sap of trees that hardens over time. How are fossils formed?

20. How Old Is This Thing? • We determine a fossils age in two ways. One is by looking at the layer of soil it is in and comparing it to another organisms in that layer. This is called Relative Dating. • The farther down in the soil you go, the older the rock and the older the fossil. • Another way we tell a fossil’s age is by testing it’s radioactive decay. The more it has decayed, the older it is. • Index Fossil- Fossil of an organisms that existed a short time. Used to help identify the age of organisms found in the same rock layer.

21. Why Teachers are NOT Fossils! • Law of Superposition- older rock layers in sedimentary rock are beneath younger rock layers. • Unconformity- missing rock layers • Where fossils are in the layers tells scientists when they existed. • Pile of Clothes example. • Absolute Age- Exactly how old something is. • Relative age- is an age compared to an object or event. (Like learning to ride a bike) • http://www.youtube.com/watch?v=R9e9NAq20X0

22. What Do Fossils Tell Us About Earth’s History? • How organisms looked and behaved. (Dinosaur nests) • What they ate. (Meat or veggies?) • Geography (Pangaea) • Adaptations (Giraffe necks) • Climate • Kentucky was once covered by a shallow sea • Antarctica has tropical fossils

23. Pangaea

24. Eras of Earth’s History • Precambrian • Beginning of Earth until first life form. • Paleozoic • Dominated by invertebrates • Mesozoic • Age of Reptiles. • Cenozoic • Dino extinction to now.

25. Era Characteristics • Each of the last three eras had characteristic life forms. • Most if not all are currently extinct. • Some have managed to survive at a much reduced number.

26. Precambrian • Name means “before life” • Pre – before • Cambros - life • Began • Formation of the Earth • 4.6 billion years ago • The Earth was a suffocating place until oxygen in the atmosphere slowly began to climb.

27. Precambrian • Breathable air is thought to have been created by cyanobacteria, single-celled microbes living in the sea. • Ended 542 Million Years Ago • It's thought the final stages of Precambrian time were marked by a prolonged global ice age.

28. Paleozoic • Began • About 542 million years ago • When the most diverse life forms began to form. • Ex. Hard-shelled ocean animals, fish, land plants, amphibians and reptiles all began evolving here.

29. Paleozoic • Earth’s landmasses became a supercontinent and there were many swamps and forests which turned into our coal reserves. • Large extinction event: *About 95 percent of marine species and 70 percent of land animals were wiped out due to climate changes Paleozoic Era ended around 248 million years ago.

30. Mesozoic • Began • 248 million years ago • Ended • 65 million years ago • Dominant life form • Dinosaurs • Called “Age of Reptiles” • Pangaea breaks apart • First flowering plants form. • Ended with an asteroid impact. https://www.youtube.com/watch?v=Y8Ij9xboreA

31. Cenozoic • Began • 65 million years ago • End • ?, runs to present day • Dominant life forms • Age of Mammals • Primates first appear in trees. • Ice ages as recent as 10,000 years ago.

32. Adaptation or Extinction • The environment has changed numerous times in the 350 million years that life has been around. • Two options exist for organisms due to this continuous change: • Adaptation • Extinction

33. Adaptation • A characteristic of an organism that helps it to survive and reproduce. • Usually the adaptation was already present. • Did not aid in survival until environment changed.

34. Adaptations • All organisms have characteristics that can help or hurt their chances for survival. • Characteristics interact with environment. • If they are beneficial, they lead to survival.

35. Changing Earth • Changes include: • Plate Tectonics • Volcanoes • Erosion • Changing Sea Levels • Ice Ages • New Competitor or Predator

36. Variations • Animals of the same species have differences or variations • These variations are called adaptations if they aid survival. • These rarely occur overnight • Types of adaptations • Morphological-involve structures or anatomy (beaks) • Physiological- organisms functions (venom) • Behavioral- reactions to environment (migrations)

37. Natural Selection • Developed by Charles Darwin • Makes 4 points • Not only do species differ from one another, but individuals within the species have variations. • Most variation is inherited • Population produce more offspring than the environment can hold. • Only those individuals best adapted to their environment will survive. Scientists adopted this theory instead of Lamarck’s

38. Lamarck vs. Darwin • Lamarck said that organisms could pass on traits that they acquire during their lifetime. • Giraffes could stretch their necks and make them longer which could then be passed on to offspring. • Darwin said the difference in neck length of giraffes was based on a mutation. • Fossils support Darwin. We have fossils of short-necked giraffes, but none of the intermediate organisms.

39. Homologous Structures • In everyday life, people look like one another for different reasons. Two sisters, for example, might look alike because they both inherited brown eyes and black hair from their father. On the other hand, two people attending an Elvis impersonators’ convention may look alike because they are both wearing rhinestone studded suits and long sideburns. The similarity between the sisters is inherited, but the similarity between the Elvis impersonators is not.

40. Homologous Structures • It works the same way in biology. Some traits shared by two living things were inherited from their ancestor, and some similarities evolved in other ways. • HOMOLOGOUS STRUCTURES - traits inherited by two different organisms from a common ancestor that have the same structures, but different functions • EX: mammal forelimbs

41. Homologous Structures and Darwin

42. Homologous Structures and Darwin • Darwin theorized that today’s organisms have common ancestors based on the structure of their bones. • A whale and human have common bone structures in their arms (fins), so they may have developed from the same organism many generations ago. • Darwin used this evidence to support his theory of Evolution.

43. More Evidence of Evolution • Analogous Structures- Structures that have the same purpose but have no structural similarity. • These show no link to common ancestry.

44. Vestigial Structures • Gradual change through time reduces or removes the function of some body structure or organ. • Ex. appendix, eyes of a cave fish, leg bones of a snake.

45. Evidence From Embryology • Evolution occurs too slowly to see it in progress. So scientists will use the early stages of development to see these changes. • All vertebrates start out similar in appearance. • This leads scientists to think that all vertebrates have a common ancestor