1. Announcements • No section this week, but we will have lecture on Friday • Invasive species writing assignment due at beginning of lecture this Wednesday • Problem set will be handed out in lecture this Wednesday • Problem set is due Wednesday, November 24th • we will not have lecture that day • you can turn problem set into your TA’s box in the ES Program office • for on-time turn-in, put it in your TA’s box by 10am at the latest on November 24th

2. Summary from Friday • Metapopulation Theory • subpopulations • maintenance of genetic diversity • source and sink populations • controls on immigration • Invasive Species • definition of terms • why invasive species are successful • problems with invasive species

3. How can they be stopped? • Physical removal • slow and costly • leaves some to recolonize • Chemical eradication • can harm natives • expensive • Biocontrol • may not work • can create a bigger problem than you solve

4. Global Change • What will the world be like in 100 years? • Population growth • Land use/cover change • Climate change

5. With this kind of exponential growth, when will we reach carrying capacity?

6. Human Population Growth • The maximum biological carrying capacity for humans = 50,000,000,000 • this figure assumes that all primary production is consumed by people…is this possible?

7. Human Population Growth • The maximum biological carrying capacity for humans = 50,000,000,000 • this figure assumes that all primary production is consumed by people…is this possible? So, what is a more meaningful estimate of carrying capacity?

8. Human Population Growth • The maximum biological carrying capacity for humans = 50,000,000,000 • this figure assumes that all primary production is consumed by people…is this possible? So, what is a more meaningful estimate of carrying capacity? 8 to 16 billion people

10. Slowing the growth • What is the most effective way? • provide access to birth control • raise standard of living • education

12. Why does population matter? • More people will need space, food, and other materials • land clearing • habitat destruction • increased emissions of greenhouse gasses • CO2 carbon dioxide • CH4 methane • N2O nitrous oxide

13. Land use and land cover change • Deforestation • Desertification

16. Greenhouse gases and global warming • industrialization = higher emissions • gases trap heat in the lower atmosphere CO2

18. Secondary effects of warming • Heat can alter hydrological cycles • melting of ice caps • rise in sea level • evaporation • cooling in certain areas • movement of air: wind • storms

19. Human Population (size and resource use) Industry Agriculture CO2 increase Nitrogen cycle Land use and cover change Global climate change Loss of biological diversity

20. Studying climate change What happens? • Add CO2 • Add heat

21. Announcements • Invasive species writing assignment due now • No section this week, but we will have lecture on Friday • Make sure to get the problem set today • Problem set is due Wednesday, November 24th • we will not have lecture that day • you can turn problem set into your TA’s box in the ES Program office • for on-time turn-in, put it in your TA’s box by 10am at the latest on November 24th

22. Summary from Monday • Global change • Population growth • why it matters • carrying capacity for humans • how to slow the growth • Land use and land cover change • deforestation • desertification • Climate change • increased CO2 emissions by human activity • studying climate change

23. Global change  community change • Different species have different responses • elevated CO2 and C4 vs. C3 plants

24. Global change  community change • Different species have different responses • elevated CO2 and C4 vs. C3 plants • water use and drought-tolerant plants • heat stress

25. potential survival, but stressed potential survival, but stressed Success intolerant intolerant optimum Temperature

26. Global change  community change • Different species have different responses • elevated CO2 and C4 vs. C3 plants • water use and drought-tolerant plants • heat stress

27. Global change  community change • Different species have different responses • elevated CO2 and C4 vs. C3 plants • water use and drought-tolerant plants • heat stress • With a change in community, biodiversity may… • increase • decrease • stay the same

28. What is biodiversity? Biodiversity = variation in living things • Genetic diversity • Species diversity • Species richness: # of species • Species evenness: how #’s are distributed • Growth-form diversity • Community diversity • How is biodiversity measured?

29. Measuring Biodiversity • Count the # of species present • Count the # of families represented • Look for different “functional groups”

30. Biodiversity Hotspots

31. Distribution of Biodiversity • general increase from poles to equator

32. Bird species in North America Diversity increases from pole to equator for many species. Why?

33. Diversity in the Tropics • 50-80% of today’s species live in tropical rainforest • high temp. and rainfall in tropics • many species rely on trees • however, tropical forests in Africa not as diverse as those elsewhere  other drivers of biodiversity aside from climate

34. Distribution of Biodiversity • general increase from poles to equator Must also consider: • history • productivity of the system • habitat structure • specialization of species • survival of specialists

35. History • Most of Earth’s land mass was once tropical • Evolution of flowering plants in tropics increased diversity of: plants insects mammals • When Earth’s climate cooled, some species at high latitudes went extinct

36. Productivity • Tropics are near the equator • Sun’s rays are direct  high productivity • More energy at the bottom of the food chain means more species can be supported With more energy, 16 niches are possible With less energy, only 8 niches exist

37. Habitat Structure • diverse structure  more biodiversity • multi-aged stands of trees • epiphytes • gaps • physical structure provides • feeding surfaces • nesting sites • microclimates

38. Specialization • constant presence of food in tropics • migration not necessary in tropics • certain specialized feeding strategies that are not possible in temperate regions work in the tropics

39. Survival of Specialists • temperate regions have been glaciated several times in the past 2 million years

40. Survival of Specialists • temperate regions have been glaciated several times in the past 2 million years • with every ice age, glaciers scour temperate regions and primary succession must take place • generalists are more successful than specialists in temperate zones

41. Why is biodiversity important? Genetic diversity • Long term survival requires responsiveness to small changes in the environment • Prevent genetic bottleneck Population size Genetic diversity Time

42. Conserving a viable population Goal of conservation: maintain a MVP MVP: minimum viable population • it is difficult to know what this number is With too few mating pairs: • inbreeding depression:lowered fitness of offspring • genetic drift: random loss of alleles from the genetic pool

43. Why is biodiversity important? Species Diversity • Ethical Reasons • some believe in a universal right to exist • aesthetic, spiritual, or other intrinsic value • Practical Reasons • medicines • pest control • ecosystem services

44. Announcements • Pick up the problem set from your TA if you don’t have it already • Problem set is due Wednesday, November 24th by 10am in your TA’s box • No section this week

45. Summary from Wednesday • Global change drives community change • Biodiversity • increases from poles to equator • higher temp. and rainfall in tropics • other drivers: • history • productivity • structure • specialization • survival of specialists • Why is biodiversity important?

46. Ecosystem Services • Primary production for food, forage, fiber

47. Ecosystem Services • Primary production for food, forage, fiber • Control of water dynamics • flood control • water purification

48. Ecosystem Services • Primary production for food, forage, fiber • Control of water dynamics • flood control • water purification • Pollination

49. Ecosystem Services • Primary production for food, forage, fiber • Control of water dynamics • flood control • water purification • Pollination • Regulation of nutrient distribution • CO2 uptake and C sequestration but how does biodiversity matter?

50. Control of ecosystem services Redundancy • more than one species has a similar “job” • if one goes extinct, the others compensate Atta sexdens Atta cephalotes