1. Nothing in Biology Makes Sense Except in the Light of Evolution - Theodosius Dobzhansky

2. What is Science? Nature exists separate from our mind Our perceptions & instruments can perceive features of Nature Natural phenomena have natural causes Natural ‘laws’ operate the same everywhere and for all time (past & future) Valid observations are replicable by independent observers Inferences about observations are provisional, and may change as new observations are made or new models of natural phenomena are proposed Scientists hold values, and make professional decisions based on those values, but observations are to be reported as objectively as humanly possible An observation is to be publicly reported, thoroughly enough that anyone can accurately attempt to replicate it, and evaluate the reasonableness of inferences made based on it – Peer Review is intended to assure this

3. Biology is the Science of Life What characterizes a Life form? Complex, organized structures of (primarily) carbon-based molecules Converts materials and energy from the environment to other forms Actively maintains its complex structures and internal environment Grows Responds to environmental stimuli Reproduces accurate copies of itself Evolves (changes), usually in response to changing environmental conditions

4. Atoms Molecules Organelles Cells Tissues Organs Organ Systems Individuals Populations Species Communities or Higher Taxa Ecosystem or Higher Taxa Biosphere Increasing Complexity Hierarchy of Biological Organization

5. Increasing Complexity

6. Issues in Biology How do we integrate multiple levels of explanation? Hierarchy Reductionism Emergent Properties Scale Proximate Causation: How Questions Ultimate Causation: Why Questions

7. Biological Phenomenon Hypothesis A Prediction 1 Prediction 2 Prediction 3 Hypothesis B Prediction 1 Prediction 2 Prediction 3

8. How Do We Test Theories ? Bad :( Seek supporting evidence for one hypothesis. Good Test multiple working hypotheses. Reject what you can. :)

9. Biological Phenomenon Hypothesis A Prediction 1 Prediction 2 Prediction 3 Hypothesis B Prediction 1 Prediction 2 Prediction 3

10. Methods of Inquiry Observational Data Comparative Data Theoretical Models Experiments

11. Observational Data Helper Number Offspring Number Black-backed jackal

12. Comparative Data Convergence Independently derived similarities, usually Due to living in a similar environment Homology Resemblances due to common evolutionary history

13. Convergence? Homology?

14. Homology

15. Convergence

16. Theoretical Models Graphical Models Computer Simulations Analytical (Math) Models Clarify thinking Identify constraints Make testable predictions (forecast) age size age size

17. Experiments Natural – natural perturbation Manipulative – perturbation purposefully caused by scientist –Press Continuous perturbation –Pulse One – time perturbation

18. What Makes an Experiment Good? Internal Validity - is the experiment well designed? External Validity - does the experiment answer the general question? In Vitro > Cell/Tissue Culture > Animal Model > Human Trial Laboratory > Mesocosm > Field

19. Requirements for a Good Experiment Validate & Calibrate Control Replicate Randomize Intersperse

20. Validate & Calibrate –Show that technique really does provide data you want (e.g. test against another, valid technique) –Show that technique continues to work (nothing that can change has changed)… includes observer accuracy! Control –Eliminate confounding factors by creating uniformity among samples, statistically removing predictable extraneous effects –Provide a comparison that only differs in the factor(s) of interest –Reduce observer bias by ‘blind’ scoring protocols

21. Replicate –Reduce risk that results are due to ‘chance’ variation by doing multiple, independent replications of each treatment type Randomize –To prevent results being due to differences in extraneous factors among subjects (or treatment replicates), make assignment of treatment type as random as possible Intersperse –To prevent results being due to differences in the time or spatial position of treatment-types, intersperse as evenly as possible the preparation and position of replicates of each treatment-type

22. = apply water only = dilute application = recommended application = heavy application Pesticide Toxicology Test A field trial