PPT-Higher Biology Unit 3 3.7- Mass Extinctions and Biodiversity

Extinction When an organism is classed as extinct there are no living members of that species left Extinction is a natural process where organisms that are less suited to an environment die out Throughout the history of earth there have been several mass extinction events . Mass extinctions are global events characterized by unusually high rates of extinction The magnitude of these rates is usu ally unspecified but it is generally significantly higher than the rate of so called background extinctions that is extinc tio The struggle for life on earth. Mass Extinction - Definition. A significant proportion of species become extinct (between 30% and 95%) . The extinctions operate across a wide range of environments and . Overview. Extinctions are as important in the history of life as are the evolution of new species. Explaining extinctions is just as challenging a scientific question as explaining the evolution of new species. AP Environmental Science. Mr. Grant. Lesson . 38. Objectives:. Define . the terms . extinction. , . extirpation. and . mass extinction. .. Contrast . background extinction rates and periods of mass extinction.. entire branch.Global extinction re The Sixth Mass Extinction. Essential Questions. What is extinction?. Which species have become extinct in modern times? . What are the characteristics of past mass extinctions? . How do modern extinction rates compare with natural (background) rates?. The sixth . m. ass . e. xtinction. Objectives. Define . extinction.. Give examples of (1) past mass extinctions (2) and recent species . extinctions.. Compare current extinction rates with background extinction . Objectives:. Define the terms . extinction. , . extirpation. and . mass extinction. .. Contrast background extinction rates and periods of mass extinction.. Evaluate the primary causes of biodiversity loss.. Very general images. What is with the . zig. . zag. ? . Has the earth cooling-shows really deep time!. Shows Cambrian Explosion period.. Mentions algae and eukaryotic cells.. Has all groups! Nice sense of how things evolved. Not straight hard to follow. Hard to tell . 1) Geological Time Scale. 2) Major Episodes in History of Life. 3) Extinctions and Radiations. Today. ’. s OUTLINE:. Geology plays an Important role in Evolutionary Thinking. Patterns of extinctions and evolutionary change in the fossil record were among the main influences on. What is extinction? . Extinctions occur when the last individual of a species dies out. . Functional Extinctions occur when individuals remain but the odds of sustainable reproduction are low. i.e. the species is effectively extinct even though individuals remain. . Opportunities and. Adaptive Radiations. Overview. Extinctions. Adaptive Radiations—New Niches. Stem mammals survived and experience adaptive radiation.. Evolution of birds, feathers, flight, and flightlessness.. Saving the Siberian Tiger. Siberian tigers are one of five remaining tiger subspecies.. In the early 20th century, hunting and habitat loss reduced the wild population to just 20–30 animals.. Conservation efforts have helped the wild population rebound to 450–500 today.. A2 BIOLOGY UNIT 3. Maximum mark = 90. Mean mark = 37.6. Entry = 2150. A*. A. B. C. D. E. Grade boundary. 54. 46. 40. 34. 29. 24. Cumulative % at grade. 11.7. 27.9. 43.8. 60.7. 75.8. 87.3. Item level data.