What is science?

1. What is science? Science is our effort to understand the world around us, using observable physical evidence. Science is done through observation and experimentation

2. What is ecology? Simple answer: the study of how organisms interact with each other and their environment Long answer: “Ecology is the scientific study of the processes regulating the distribution and abundance of organisms and the interactions among them, and the study of how these organisms in turn mediate the transport and transformation of energy and matter in the biosphere (i.e., the study of the design of ecosystem structure and function).” (Krebs 1972)

3. What is ecology? Behavior Evolution Geology Ecology is by nature multi-disciplinary Physiology Physics Chemistry Hydrology Genetics

4. You notice: moss grows on north side of trees Why?????

5. moss grows on north side of trees Pattern Process microclimate is cooler on north side and more favorable to moss

6. You notice: deer live in groups Why?????

7. deer live in groups Pattern Process reduces susceptibility to predation OR… groups to more easily find mate Alternative hypothesis

8. Science is detecting interesting patterns and asking WHY????? Pattern Non-random outcome or event that begs an explanation Process Mechanism causing a natural pattern

9. This method of scientific inquiry called hypothetico-deductive reasoning • Or the Popperian method (after Karl Popper) • There is an ongoing debate though, on how science should be done • Philosophy of science

10. hypothesis? What is a

11. Reasonable explanation Testable statement HYPOTHESIS Asks how? or why? Usually an if / then statement

12. Challenge statement: You can prove a hypothesis true. Agree or disagree? Why?

13. Case study You know: Eptesicusfuscus (big brown bat) – eats tiger moths. Finds using sonar. Betholdiatrigona (tiger moth) – emits a particularly dense series of ultrasonic clicks Why? From Corcoran et al. Science 2009

14. Hypothesis 1: are blocking the sonar of Hypothesis 2 (or alternative hypothesis): have a warning effect on (telling them they taste bad) How can you test this??????? From Corcoran et al. Science 2009

15. As an if / then statement: Hypothesis 1: If moths are blocking sonar, naïve bats should startle and stop attack. Won’t affect subsequent attack. Hypothesis 2 (or alternative hypothesis): If moths have a warning effect (say they taste bad), then naïve bats should complete attack but not attack again Now it’s testable From Corcoran et al. Science 2009

16. Experiment Silence some moths Tether moths and watch how bats react when attack Leave some alone From Corcoran et al. Science 2009

17. Results Bats caught silenced moths Stopped attack on normal moths, but didn’t avoid moths in future How can you interpret???? From Corcoran et al. Science 2009

18. Interpretation Moths are obstructing the bats sonar, allowing them to escape being eaten Alternative hypothesis of being distasteful and giving a warning is disproven From Corcoran et al. Science 2009

19. Back to hypothetico-deductive approach Formulates a hypothesis from observation – then tries to nullify alternatives • Never really proves the hypothesis, just disproves the alternatives • Eliminates alternatives within a certain degree of error

20. Observation Argentine ants are successful invaders of native California ant habitats JeannaBryner

21. Hypothesis • Argentine ants don’t fight amongst themselves, but do fight with other species (observation) Hypothesis: if / then If Argentine ants are more genetically similar, they will fight more with native species than with their own If predators prefer native species but don’t eat Argentine ants, native species will suffer reduced populations relative to Argentine ants Alternative hypothesis

22. Experiment Hypothesis: Check genetic similarity between native species and Argentine ants and among themselves Alternative hypothesis Feeding experiments – which species do predators prefer BUT, even if predators prefer the natives, does that affect their population numbers?

23. Results Hypothesis: Argentine ants are very similar genetically to other Argentine ant nests – the same is not true of native ants Alternative hypothesis Predators prefer native ants, but predation is probably less important in structuring community than competition

24. Interpretation Argentine ants represent a “supercolony” – individuals from nearby nests recognize each other as siblings rather than intraspecific competitors.

25. Tools Statistics are a tool scientists use to see patterns and test hypotheses.

26. There is considerable variation in traits among individuals of the same species All individuals Average trait

28. Correlation between spot length and wing length of Anopheles darlingi from the Amazon (open circles) and MatoGrosso (closed circles) Wing length (mm) What does each point represent? From Charlwood 1996

29. Variation Biological variability: differences in individuals The average. But it’s also important how much the data vary around the mean Mean average 5 0 10 average 5 variance

31. Independent variable Dependent variable Difference between control and experimental groups Factor being tested Can be different levels (e.g. different time points, different amount of nutrients Sometimes call treatment Cause Factor assume will be affected Factor being measured Factor that depends on the treatment e.g. Plant growth, seed production, number of offspring, growth rate Effect

32. Scatter plot The scatter plot shows the hours of study and test scores of 20 students As the number of hours of study increases, the marks scored tend to increase So, the scatter plot describes a positive trend

33. Dependent variable Independent variable Positive correlation

34. Dependent variable Independent variable Negative correlation

35. Dependent variable Independent variable No correlation

36. Scatter plot

37. Scatter plot with error bars

38. Controls Experiments that are testing a treatment should also have a control with the exact same conditions as the treatments, without the treatment. Hypothesis:If nitrogen is a limiting nutrient for a certain plant community, then adding nitrogen will lead to increased growth of the plants in the community.

39. Hypothesis:If nitrogen is a limiting nutrient for a certain plant community, then adding nitrogen will lead to increased growth of the plants in the community. What would the results graph look like??? Dependent variable? Measure of plant growth Independent variable? Amount of Nitrogen added

40. Kinds of data Continuous Discrete • Usually a measurement • Usually numeric data • e.g. the number of seeds per plant or dry weight of a plant • Also called categorical • Data have clear beginning and end • e.g. Food in a diet (seed, plant, animal)

41. Visual representations Discrete Continuous Histogram, Frequency distribution Bar graph Scatter plot

42. Histogram

43. Challenge statement Correlation implies causation

45. Correlation and Causation Pattern Correlation Describes the relationship between two variables Process Describes cause and effect Causation

46. Read the article: Want a Higher G.P.A.? Go to a Private College by C. Rampell, printed in the NY Times Case study • What are the variables being compared (look at the title of the article) • Which is the dependent variable? The independent variable? • Does the headline indicate correlation or causation between the two variables? • Study claims following causal relationships: • Students at private schools started receiving significantly higher grades than equally qualified students (based on SAT scores) in public schools around the 1950’s • All schools inflate grades, but private schools inflate more • Admissions officers at top medical, business and law schools and some PhD. programs are fooled by private school students’ inflated grades • Lower grades in the sciences discourage American students from studying such disciplines • Which, if any, claim is supported by the study? Explain.

47. Correlation and Causation Sudden Oak Death (SODS) On a slope near Mt. Tamalpais, facing SF Bay, where cool, moist fog bathes the hillsides First observed in the mid-1990’s in Marin County

48. Correlation and Causation Tan oak (Lithocarpusdensiflorus), not a true oak, but a close relative Hikers noticed several clusters of tan oaks had turned brown and died Arborists also reported dying tan oaks elsewhere with unusually large swarms of three common bark beetles on he trunks, attracted to cankers

49. Sudden Oak Death All trees that were sick or died had a beetle infestation These beetles were known to burrow and tunnel in trunks of dead trees to nest and reproduce

50. Sudden Oak Death Fungus transmitted by elm bark beetle Pathogen in Dutch elm epidemic was transmitted by insects, so assumed that they played the same role in this disease