Species Diversity

1. Species Diversity • The species diversity of a community • Is the variety of different kinds of organisms that make up the community

2. Species richness • Is the total number of different species in the community • Relative abundance (evenness)

3. Two different communities • Can have the same species richness, but a different relative abundance

4. Simpson diversity index • Can be used to measure and compare the species diversity of a community/ecosystem • Is a measure that takes into account both richness and evenness

5. Biogeographic factors affect community diversity • Two key factors correlated with a community’s species diversity

6. Species richness generally declines along an equatorial-polar gradient (moving latitudinally from equator towards the poles)

7. Climate • Is likely the primary cause of the latitudinal gradient in biodiversity

8. The two main climatic factors correlated with biodiversity

9. Area Effects • All other factors being equal, the larger the geographic area of a community, the greater the number of species

10. A species-area curve of North American breeding birds • Supports this idea

11. Island Equilibrium Model • Species richness on islands • Depends on island size, distance from the mainland, immigration, and extinction

12. Studies of species richness on the Galápagos Islands

13. Reasons for conservation of biodiversity • Aesthetics - ensure that future generations can experience the beauty of ecosystems such as rainforests • Potential source of new biopharmaceuticals, medicines, genes for genetic engineering, phytochemicals

14. Reasons for conservation of biodiversity • Economic reasons • Farming on clear-cut rainforests has not been successful • Potential sources of chemicals, genes used to improve crops • Ecological reasons • Protect against invading organisms (competition) • More CO2 in atmosphere leading to global warming • Soil erosion, flooding

15. Reasons for conservation of biodiversity • Ethical reasons • Affects local populations most • Ensure future generations can enjoy • Aesthetics

16. Arguments against conservation • May slow down economic development of some countries

17. Introduction of alien species • Disrupts communities • Many nonnative species provide us with food, medicine, and other benefits but a few can wipe out native species, disrupt ecosystems, and cause large economic losses.

18. INVASIVE SPECIES • Kudzu:deliberate release of an alien species Kudzu vine was introduced in the southeastern U.S. to control erosion. It has taken over native species habitats.

19. Zebra mussels:accidental release of an alien species • May have been introduced by European cargo ships which contained mussels in ballast water

20. Prickly pear: an alien species under control • Introduced to Australia in mid 1800’s • Spread rapidly • Moth quickly destroyed prickly pear, and exists in a balance today - an example of biological control

21. Impact of alien species on ecosystems • Interspecific competition - may out-compete native species, resulting in a loss in biodiversity • Red squirrel/grey squirrel • Predation - may feed on other species • Lampreys • Species extinction - out-compete native species leading to their extinction

22. INVASIVE SPECIES • Many invasive species have been introduced intentionally.

23. INVASIVE SPECIES • Many invasive species have been introduced unintentionally.

24. INVASIVE SPECIES • The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. • Most probably from ships. • No natural predators.

25. INVASIVE SPECIES • Prevention is the best way to reduce threats from invasive species, because once they arrive it is almost impossible to slow their spread.

26. Biological control • Using a natural predator to control an unwanted or invasive species • Carries great risk of unexpected consequences • Gallerucella beetles have been released to attempt to control Purple Loosestrife

27. Biomagnification • Process by which chemical substances become more concentrated at each trophic level • DDT caused eggs of predatory birds to have thin shells which cracked when mother birds sat on them - caused a decline in number of predator birds

28. Pollution • Each year pesticides: • Kill about 1/5th of the U.S. honeybee colonies. • 67 million birds. • 6 -14 million fish. • Threaten 1/5th of the U.S.’s endangered and threatened species. Example of biomagnification of DDT in an aquatic food chain.

29. Effects of ultraviolet radiation • Non-lethal skin cancer • Lethal skin cancers • DNA mutations • Sunburn • Cataracts • Reduced biological productivity

30. OZONE DEPLETION IN THE STRATOSPHERE • Less ozone in the stratosphere allows for more harmful UV radiation to reach the earth’s surface. • The ozone layer keeps about 95% of the sun’s harmful UV radiation from reaching the earth’s surface. • Chlorofluorocarbon (CFCs) have lowered the average concentrations of ozone in the stratosphere.

31. Depletion of Atmospheric Ozone • Life on Earth is protected from the damaging effects of UV radiation

32. Satellite studies of the atmosphere • Suggest that the ozone layer has been gradually thinning since 1975

33. The destruction of atmospheric ozone • Probably results from chlorine-releasing pollutants produced by human activity

34. Scientists first described an “ozone hole” • Over Antarctica in 1985; it has increased in size as ozone depletion has increased

35. OZONE DEPLETION IN THE STRATOSPHERE • Ozone thinning: caused by CFCs and other ozone depleting chemicals (ODCs). • Increased UV radiation reaching the earth’s surface from ozone depletion in the stratosphere is harmful to human health, crops, forests, animals, and materials such as plastic and paints.

36. The average area covered by the Antarctic ozone hole this year (2012) was the second smallest in the last 20 years, according to data from NASA and National Oceanic and Atmospheric Administration (NOAA) satellites. The average size of the 2012 ozone hole was 6.9 million square miles. The Sept. 6, 2000 ozone hole was the largest on record at 11.5 million square miles

37. Conservation of Biodiversity • Indicator species are those that are very sensitive to environmental change

38. Lichens are a common indicator species because they are very sensitive to pollution, they can also show the presence of metals such as lead and mercury in the air • Macroinvertebrates (insect larvae) are an indicator species that can be used to determine the quality of water • Very sensitive organisms like mayfly and caddisfly larvae require high levels of oxygen and low levels of organic matter

39. Biotic index • As measurement that determines the quality of water in an environment • Measures the number of different types of organisms in each group multiplied by a sensitivity factor • Sensitive X 3 • Somewhat sensitive X 2 • Tolerant X 1

40. The Passenger Pigeon - Gone Forever • Once the most numerous bird on earth. • In 1858, Passenger Pigeon hunting became a big business. • By 1900 they became extinct from over-harvest and habitat loss.

41. The Passenger Pigeon, once probably the most numerous bird on the planet. Their flocks, a mile wide and up to 300 miles long, were so dense that they darkened the sky for hours and days as the flock passed overhead. Total populations may have reached 5 billion individuals and comprised up to 40% of the total number of birds in North America.

42. Carolina parakeet • Became extinct in wild around 1900 • Settlers cleared trees destroying habitat • Release of honeybees displaced parakeets from nesting in trees • Hunted for feathers which were used to make women’s hats

43. SPECIES EXTINCTION • Species can become extinct: • Locally: A species is no longer found in an area it once inhabited but is still found elsewhere in the world. • Ecologically: Occurs when so few members of a species are left they no longer play its ecological role. • Globally (biologically): Species is no longer found on the earth.

44. Global Extinction • Some animals have become prematurely extinct because of human activities.

45. Endangered and Threatened Species • Endangered species: so few individual survivors that it could soon become extinct. • Threatened species: still abundant in its natural range but is likely to become endangered in the near future.

46. SPECIES EXTINCTION • Some species have characteristics that make them vulnerable to ecological and biological extinction.

47. SPECIES EXTINCTION • Scientists use measurements and models to estimate extinction rates. • The International Union for the Conservation of Nature and Natural Resources (IUCN) publishes an annual Red List, listing the world’s threatened species. • The 2004 Red List contains 15,589 species at risk for extinction.

48. SPECIES EXTINCTION • Percentage of various species types threatened with premature extinction from human activities.

49. IMPORTANCE OF WILD SPECIES • We should not cause the premature extinction of species because of the economic and ecological services they provide. • Some believe that each wild species has an inherent right to exist.

50. HABITAT LOSS, DEGRADATION, AND FRAGMENTATION • Conservation biologists summarize the most important causes of premature extinction as “HIPPO”: • Habitat destruction, degradation, and fragmentation • Invasive species • Population growth • Pollution • Overharvest