Adaptive Leaf Size Adaptive Leaf Size Week Two (analysis)

Hypotheses : H 1 : Plants in wet soil do not have to conserve water, so they will be as warm as possible to maximize photosynthesis. H 2 : Plants in dry soil must conserve water, so they will be as cool as possible. Predictions :

Predictions: Sunny Shady WetDry In the sun, the air temp is the coolest the leaf can be, so this leaf should be small to reach air temp and conserve water: get cool In the sun, a leaf can be warmed above the air temp by the sun, so this leaf should be large to increase photosyn.: stay hot Decrease water loss Increase photosynthesis In the shade, the air temp is as warm as the leaf can be, so this leaf should be the air temp to increase photosyn.: get hot In the shade, the leaf can get below air temp (due to evaporative cooling), so this leaf should be large to conserve water: stay cool

Assumptions : o  Temperature :  Photosynthesis (to a point) o  Temperature :  Water loss

Fun with Statistics! o We will do 4 t-tests o Don’t forget where you predicted the larger vs. smaller leaf!

t-test… t = t-test value X = group mean s = st. dev. n = sample size

Food for thought… o According to the model, what environmental factors determine leaf size? o What other environment factors could influence leaf size? o Why is the model applied to vine-like plants? o What assumptions did you make to test the model? o Do you think they were valid? o Which lab measurements were: o Qualitative? o Quantitative?

Sunny Shady WetDry What is important in the wet habitat? What is important in the dry habitat?

Will this leaf be large or small? WHY? Sunny Shady WetDry Decrease water lossIncrease photosynthesis

Will this leaf be large or small? WHY? Sunny Shady WetDry Decrease water loss Increase photosynthesis

Sunny Shady WetDry Decrease water loss Increase photosynthesis

Sunny Shady WetDry Decrease water loss Increase photosynthesis

Sunny Shady WetDry Decrease water loss Increase photosynthesis

Sunny Shady WetDry In the sun, the air temp is the coolest the leaf can be, so this leaf should be small to reach air temp and conserve water: get cool In the sun, a leaf can be warmed above the air temp by the sun, so this leaf should be large to increase photosyn.: stay hot Decrease water loss Increase photosynthesis In the shade, the air temp is as warm as the leaf can be, so this leaf should be the air temp to increase photosyn.: get hot In the shade, the leaf can get below air temp (due to evaporative cooling), so this leaf should be large to conserve water: stay cool