1. Wrap-up Natural Selection + Evolution… then… Energy Flow in the Global Ecosystem, PART I ES 100: October 6 th, 2006

2. Does Natural Selection  Evolution?

3. Defining ‘evolution’ Scientific Definitions: All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today –Neil Campbell The origination of species of animals and plants… –O.E.D. Common Usage: A process of continuous change from a lower, simpler, or worse to a higher, more complex, or better state –Merriam-Webster’s Dictionary From a scientific point of view, evolution is just how new species come about

4. Theory of Evolution: Criticisms Microevolution is generally accepted, but macroevolution is hotly debated –How does evolution add information to a genome to create progressively more complicated organisms? –How is evolution able to bring about drastic changes so quickly? –How could the first living cell arise spontaneously to get evolution started? BasilosaurusAmbulocetusPakicetus Humpback

5. Today: Energy Flow in Earth Ecosystem Solar energy input imbalance  Climate Global climate  Biomes Biomes  Plant/Animal Adaptations

6. Reflected by clouds and atmosphere Reflected by surface albedo Solar Energy Budget Absorbed as heat Absorbed in photosynthesis 100 23 8 20 Absorbed by atmosphere and clouds 57 47 2  chemical energy drives climate 

7. Weather vs. Climate Weather describes short term variability Difficult to predict Butterfly effect Lorenz Climate describes typical conditions for a region More predictable Global Climate: Hadley Cells Tilt + Orbit = Seasons Frontal Systems  Biomes Local Climate: mountains oceans and lakes latitude elevation Micro-Climates

8. Uneven Heating of Earth LATITUDE: More Heat Energy at Equator than at Poles sun’s rays hit more directly less atmosphere to penetrate

9. Uneven Heating of Earth LATITUDE: More Heat Energy at Equator than at Poles sun’s rays hit more directly less atmosphere to penetrate

10. Hadley Cells: Heat Moves Air

11. What’s missing? Biome: A large geographical region where plants have similar physiological adaptations to the climate.

12. Another Energy Imbalance: Orbit + Tilt = Seasons

13. Hadley Cells + Frontal Systems +Seasons = Biomes

14. What’s missing? Biome: A large geographical region where plants have similar physiological adaptations to the climate.

15. Biomes can be classified by precipitation and temperature. Boundaries are fuzzy (ecotones) !

17. Arctic Tundra:  Short, intense growing season  Intense cold  Strong winds  Permafrost  Low primary productivity  Slow decomposition  Lots of C held in soil

19. Boreal Forest Cold, long, snowy winters Warm summer Why the cone-shaped trees?

21. Evergreen and deciduous  Intermediate temperature  Adequate moisture  Few constraints on growth High primary productivity

23. Temperate Grasslands:  Continental regions - hot summer, low rainfall  Fires  Windy

25. Tropical Savanna Grassland  Similar to Temperate Grasslands  hot summer  moderate rainfall  Fires

27. Deserts:  North and south of tropics  Dry  Hot or cold Natural selection: Convergent Evolution

28. Plant adaptation to hot environments: Physical Structure

29. Plant adaptations: Physiology Stomata must be open to take in CO 2 Open stomata = water loss How can a plant minimize water loss? Keep stomata closed as much as possible Open only at night = CAM plants Cactus, some epiphytes, succulents Open only a little bit = C 4 plants Some grasses

31. Tropical rainforests:  Near the equator  Hot  Moist conditions  Fast Decomposition  High primary productivity  Tight cycling of nutrients- soils are actually quite poor

32. Where is Santa Barbara?

34. Chaparral or Mediterranean-type Strong seasonality Hot, dry summers Mild, wet winters  high productivity Fires feed on large fuel supply

35. Most Rapidly Expanding Biome?

36. Summary: Solar energy input imbalance  Climate Global climate  Biomes Biomes  Plant/Animal Adaptations NEXT: Local climate and micro-climates effect smaller scale vegetation patterns Ecosystems governed by: feedbacks, climate, biology