Announcements

1. Announcements • Next week: THANKSGIVING, NO CLASS! • Work on Group Project Presentation (p170—checklist p 171-172) • In 2 weeks, Functional Response Lab

2. Today’s Objectives • Examine examples of adaptation & convergent evolution in the greenhouse • Explore the relationship between stomata density and climate—a study of adaptation? • Consider how adaptations are studied and the link between ecology and evolution

3. Adaptation Heritable characteristic that improves organism’s fitness (survival & reproduction) Schemske et al.

4. fitness adaptation Why do organisms ‘match’ their environment? • the ‘match’ is genetic • the ‘match’ is induced by environment Natural selection: differential survival and reproduction of individuals based on genetic differences in some trait(s)

5. Adaptation • Any heritable characteristic of an organism that improves its ability to survive and reproduce in its environment. • Also used to describe the process of genetic change within a population, as influenced by natural selection.

6. Adaptation ≠ Acclimation • Acclimation • individual changes over short period of time to survive better in environment • Ex: shed winter fur in summer • Adaptation • a population evolves to be better suited to its environment via natural selection & genetic change over multiple generations • Ex: evolution of cryptic coloring to avoid predation flickr

7. Natural Selection • Selection acts on phenotypes • If brown beetles are less visible to predators than green beetles • Then brown beetles will be more likely to survive & reproduce • Evidence is seen in populations over generations

8. evolution.berkeley.edu

9. Natural selection – key points differential survival and reproduction of individuals based on genetic differences in some trait(s) • For adaptations to evolve: • - differences in the trait must cause differences in • fitness • - differences in the trait must be heritable • Fitness depends on the environment. • local adaptation

10. Ecology & Evolution are interconnected • Ecology • study of interactions between organisms and their environments • Adaptation • An evolved characteristic of an organism that improves its fitness in its environment • Thus, adaptations are both ecological & evolutionary

11. RainforestEcology • Light competition • Lots of rain • Promotes fungal growth • High biodiversity • Adaptations include • Epiphytes, vines, leaf morphologies

12. DesertEcology • Water limited • Temperature extremes • Adaptations include • CAM, annual life cycle, water storage

13. Stomata • Trade-off between staying open and obtaining CO2, and staying closed to reduce water loss • Structures on the outer layer of plants • “Mouth” in Greek • Allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out

14. Stomata density varies across plant species and habitats http://www.scienceclarified.com/Io-Ma/Leaf.html http://radio-weblogs.com/0105910//2004/01/22.html http://www.microscopy-uk.org.uk/micropolitan/botany/frame1e.html

15. Stomata study • 1. Choose a plant in the greenhouse or outside. Apply an even, thin layer of clear nail polish on to the underside of the leaf surface. • 2. Wait till the polish dries completely. • 3. Gently lift the sides to peel off the nail polish without tearing it. • 4. Place the peeled layer onto a slide (without any creases). • 5. Observe under a 10 or 40x lens and count the number of stomata. If the number of stomata is too numerous to count, just count a portion of the field of view and multiply the results accordingly. • 6. Calculate stomatal densities per cm2.

16. Slide tips and greenhouse use • Stay on path and be respectful of plants • Use plant tips, or herbivore-attacked leaves • AVOID—small plants, healthy, centrally-located leaves, and Wellwichia • Do not choose fuzzy or moist leaves—nail polish does not come off

17. At Greenhouse • IN PAIRS: Use worksheet (pg 140) to tour greenhouse & identify different adaptations • Find examples of 10 adaptations on sheet • INDIVIDUALLY: Make a stomata slide from a species you can identify. Your group must have at least one rep from desert, temperate, and rainforest habitats TAKE: p 140, a pencil, nailpolish

18. Find stomata densities • Count all you see in a field at either 10x or 40x • Divide your stomata number by the approximate area of your field (for either 10x or 40x) • Look up average temperature, rainfall, humidity?, etc. of your plant’s habitat • Put all information on the board

19. While you wait • Answer the questions on the handout. • For question 2, read up on an adaptation you think is interesting (but not that we have discussed) using the web. Consider using You-Tube.

20. How do we know if a trait gradient is caused by a local adaptation? • Trait variation across the gradient is greater than variation within the gradient • Observed trait variation has a genetic basis • Trait variation must have evolved in that location, and not be from an already different founder population • Variation must have an effect on survival in that habitat

21. Dry Wet habitat: Testing for local adaptation Observation: differences in stomata density is correlated with humidity and temperature morph: How can we test whether the difference in stomatal density is an adaptation? What other explanations are possible?

22. Testing for adaptation: reciprocal transplant experiment Dry Habitat Wet Habitat effective predators

23. Prediction Plant Fitness Wet Dry Habitat

24. If we see this pattern…. • Stomata density is likely to be an adaptive trait. • Plants with LOW stomatal density have high fitness at DRY habitat • Plants with HIGH stomatal density have high fitness at WET habitat

25. Wrap-up the study • IN PAIRS Use the info on the board. On a new sheet of paper, make either 1 bar graph of the mean stomata densities and standard errors from each climate AND 1 bar graph of the % closed in each climate OR make line graphs comparing the 3 climate variables to stomata densities. • Answer these questions on your separate sheet: • Using class data, do you think your prediction was right? Why? • What is one flaw of this study? • Could a study like this one conclusively show stomata densities are the result of a local adaptation? Explain. • Do you think plants grown in a greenhouse would have different #s of stomata than the same species in nature? If yes, does this support or refute the idea that s. densities are adaptive? Explain.