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

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

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

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) fitness adaptation

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.

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

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

evolution.berkeley.edu

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

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

Rainforest Ecology Light competition Lots of rain –Promotes fungal growth High biodiversity Adaptations include –Epiphytes, vines, leaf morphologies

Desert Ecology Water limited Temperature extremes Adaptations include –CAM, annual life cycle, water storage

Stomata 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 Trade-off between staying open and obtaining CO 2, and staying closed to reduce water loss

weblogs.com/ //20 04/01/22.html uk.org.uk/micropolitan/botany/fra me1e.html Ma/Leaf.html Stomata density varies across plant species and habitats

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 cm 2.

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

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

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

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.

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

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

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

Wet Habitat Plant Fitness Dry Prediction

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

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: 1)Using class data, do you think your prediction was right? Why? 2)What is one flaw of this study? 3)Could a study like this one conclusively show stomata densities are the result of a local adaptation? Explain. 4)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.