What is the goal of science? : Pattern
Scientists seek to document patterns, understand processes and construct theories that explain the relationships between pattern and process.
How to scientists go about this? What is the goal of science? Scientific Method : Scientific Method Design experiment(s) to test validity of predicted results Results do not support hypothesis Results support hypothesis (predictions confirmed) Predict results assuming hypothesis to be correct Re-evaluate observations and theory More predictions, further experiments, further development of theory (from Gurevitch, Scheiner and Fox 2002) How does the scientific method work? : How does the scientific method work? invasive weed (Asia)
decreases forage availability Knapweed (Centaurea maculosa) introduced cabbage looper moth (Trichoplusa ni) as biocontrol agents predicted decrease in weed biomass, increase in natives
weed biomass decreased, natives did NOT increase
WHY????????? Their alternate hypotheses : Their alternate hypotheses Beth Newingham and Bob Callaway (U. Montana):
Insects feeding on natives also?
Other interactions between knapweed and natives? Experiments : Experiments Labeled native grass with carbon isotopes
What did they find?
Enables “draining” of carbohydrates from native plants Slide 6: Fact:
Theory: Scientific Definitions “It’s just a theory?” : “It’s just a theory?” THEORY GUESS or HYPOTHESIS
Are scientists arguing about evolution?
Why isn’t evolution a law? Scientific Method : Scientific Method Design experiment(s) to test validity of predicted results Results do not support hypothesis Results support hypothesis (predictions confirmed) Predict results assuming hypothesis to be correct Re-evaluate observations and theory More predictions, further experiments, further development of theory (from Gurevitch, Scheiner and Fox 2002) Types of experiments : Types of experiments Manipulative or controlled experiments
Observational experiments Manipulative experiments : Manipulative experiments Experimental Design : Experimental Design What experiment will eliminate alternative hypotheses?
Replication= Natural Experiments : Natural Experiments Modern catastrophes and disturbances
Mt St. Helens eruption in 1980
Yellowstone fires of 1988
Tsunami in Indian Ocean in 2004 Observational Experiments : Observational Experiments How does species diversity change over some gradient? How often have fires occurred in a particular forest? Measurement and Uncertainty : Measurement and Uncertainty Can scientists have 100% certainty in their conclusions? Why or why not?
What is “experimental error”?
What does “experimental error” come from? Ex: Carbon stored in vegetation : Ex: Carbon stored in vegetation Can we use carbon sequestration (growing trees to store carbon) to solve global warming?
How much carbon is stored? Accuracy and Precision : Accuracy and Precision What is the difference between accuracy and precision? 1 2 3 Importance of models in science : Importance of models in science What are models?
What are some examples?
How do scientists use models? Science is a process : Science is a process New ideas are always being suggested.
Scientific understanding is a work in progress
What are some examples?
With time, we get better and better at approximating how the natural world works
Sometimes changes and advances in knowledge are small, sometimes advances happen in a major revolution of ideas.
What were some revolutionary ideas in science? Misunderstandings about the scientific method : Misunderstandings about the scientific method Subjectivity and creativity are a big part of science, especially ecology.
What question to ask, where to look for answers, how best to set up the experiment.
We can never prove hypotheses correct
This fails to recognize knowledge accumulation
Most often in ecology we ask about the relative importance of different processes Today’s assignment : Today’s assignment Come up with a question about environmental science
Outline how you would use the scientific method to answer the question
Describe an experiment that you could use to test your hypothesis
Remember to incorporate treatments and replication
Draw a rough graph assuming that your results agree with your hypothesis