Announcements Seminar: How development has influenced morphologic evolution in mammals: Evidence from the lab and fossi

1. Announcements Seminar: How development has influenced morphologic evolution in mammals: Evidence from the lab and fossil record Karen Sears, University of Colorado B102 CLSL

2. Basic Scientific Principles Scientific method. Form and test hypotheses. Approaches to studying behavior. Limitations of science.

3. Scientific Thinking Science —A process used to solve problems or develop an understanding of nature that involves testing possible answers. Scientific Method —Gaining information about the world by forming possible solutions to questions, followed by rigorous testing to determine if the proposed solutions are valid.

4. Scientific Method Presumptions Specific causes for observed events. Causes can be identified. General rules can describe observations. Repeated events have same cause. Perceptions are not individualistic. Fundamental rules of nature are universal.

5. Scientific Method Hypothesis— Logical statement that potentially explains an event, or answers a question. A good hypothesis will: take into account all known facts be as simple as possible be testable and falsifiable

6. Scientific Method Test Hypothesis Theoretical approach Comparative approach Experimental approach

7. Scientific Method Test Hypothesis Theoretical approach Comparative approach Experimental approach Use models and simulations to make predictions. Input should come from best available data.

8. Scientific Method Test Hypothesis Theoretical approach Comparative approach Experimental approach Gather information from different groups (individuals, species, sites) that vary in as few factors as possible. For example, juveniles vs adults in a population.

9. Scientific Method Test Hypothesis Theoretical approach Comparative approach Experimental approach For comparisons among species, need to control for independent evolutionary events (the comparative method).

10. Speciation event Sp. B Sp. A present past ancestor

12. Phylogeny’s allow for comparisons among species while controlling for evolutionary independent events (comparative method of independent contrasts)

13. Trap-jaw ant (Odontomachus bauri) Photo - Alex Wild

15. Scientific Method Test Hypothesis Theoretical approach Comparative approach Experimental approach Devise a manipulative experiment. Predict the outcome of the experiment if the hypothesis is correct.

16. Scientific Method Manipulative experiment — experimental factors are varied to test hypothesis. Important features of manipulative experiments: Control–Separate variables and divide experiment into experimental and control groups. There should be only one difference between the experimental and control groups. Replication— Experiment is repeated to eliminate unconscious bias or a spurious correlation.

17. R. Wehner How do they find their way back to the nest?

18. Wittlinger, Wehner and Wolf. 2006. Science

19. Scientific Method Conclusion— statement if the hypothesis has been supported or not by the results of the test. If results match predictions, then hypothesis supported. If results to not match predictions, then hypothesis not supported. Hypotheses are never “proven” true!!

20. Statistics A branch of applied mathematics concerned with the collection and interpretation of quantitative data. Probability How likely are your results true?

21. Our ability to accept or reject a hypothesis will be based on the accuracy and precision of our measurements. Accuracy - an estimate of nearness to the truth or the true value Precision - the repeatability of reproducibility of a measurement

22. Quantitative vs. Qualitative data Quantitative data: Based on numerical data - can be precise. (descriptive of size, magnitude or degree) example - the number of species in a community Qualitative data:A general description of properties that often cannot be written in numbers and may be subjective. (descriptive of kind, type or direction) example - aggressiveness Much of what we measure in Animal Behavior is qualitative - often poses problem for statistical analysis.

23. = Minors = Majors The ethogram, a graph of the time course or switch points in a sequence of behaviors, became a way of categorizing species-typical behaviors. Pogonomyrmex badius

24. http://labworks.hms.harvard.edu/fruit_fly/index.html

25. Behavioral scientists often convert qualitative data into quantitative data. Place behaviors into discrete categories. Assign relative values to different behaviors (e.g. scales of aggression or attraction)

26. Example: Measuring intraspecific aggression in ants. After two individuals come in contact, many behaviors can occur. 1. Place these behaviors into discrete categories. 2. Record the amount of time spent doing each behavior. Touch - contacts that include antennation, grooming and trophallaxis. Avoid - contacts that resulted in one or both of the ants retreating in opposite directions. Aggression - head biting, leg biting, leg pulling, or charging. Fighting - prolonged aggression, often consisted of ants locking mandibles, grappling, or death.

27. 1 = touch 2 = avoid 3 = aggression 4 = fighting Average aggression score Average aggression score Correlation of hydrocarbon profiles between nests

29. Example of hypothesis testing: Niko Tinbergen observed that digger wasps could return to their exact nest location after spending considerable time away (ignoring the 100s of other nests at the same location). Observation: Wasps can relocate their inconspicuous nests. Question: How do digger wasps relocate their nests?

30. Question: How do digger wasps relocate their nests? Hypotheses: The wasp returns to any nest. The wasp uses chemical scents to relocate the nest. The wasp uses visual landmarks to relocate the nest.

31. Question: How do digger wasps relocate their nests? Hypotheses: The wasp returns to any nest. The wasp uses chemical scents to relocate the nest. The wasp uses visual landmarks to relocate the nest. Tinbergen further observed that when wasps left the nest, they spent time flying back and forth around the nest entrance.

32. Question: How do digger wasps relocate their nests? Hypotheses: The wasp returns to any nest. The wasp uses chemical scents to relocate the nest. The wasp uses visual landmarks to relocate the nest. Tinbergen further observed the when wasps left the nest, they spent time flying back and forth around the nest entrance. Null hypothesis: visual landmarks are not used to relocate the nests.

33. Tests & Predications: If I modify the visual landmarks around the nest, the wasp will not be able to find it. If I move the landmarks (keeping them intact), the wasp will return to the wrong location. If I give the wasp landmarks (pine cones), she will use them to relocate her nest. Important to only manipulate one thing at a time!!

34. Results: Wasps took much longer to find their nests if landmarks were manipulated. If landmarks were moved to a new location (intact), the wasp searched for her nest in that new location. Experimental manipulation of landmarks allowed us to predict where the wasp would look for her nest.

35. Conclusions: The wasp probably uses visual landmarks to relocate the nest. Why say probably? Was this an example of a proximate or ultimate question?

36. Another example of hypothesis testing: Observation: Adult black-headed gulls remove broken egg shells from their nests. Question: Why do gulls remove broken egg shells? Tinbergen was not interested in the mechanisms of egg shell removal (how they were recognized), but why they were removed (in an evolutionary sense)

37. Question: Why do gulls remove broken eggshells? Hypothesis: Broken egg shells attract predators to the nest. Tests & Predications: The presence of broken egg shells increases the probability of nest predation.

38. Results: The presence of egg shells near the nest increased the probability of predation.

39. Conclusions: Black-headed gulls (or some ancestor) likely evolved the behavior of removing eggs shells to reduce the probability of their nests being located by predators. Why say probably? What are some alternative testable hypotheses?

40. Scientific Method Humans have been using this method in some form for a long time.

41. Blurton-Jones (1976) documented Kalahari bushmen’s (!Kung) knowledge of animal behavior Hunter-gatherer society, similar to most of human’s history. - Discriminated data from theory - Developed hypotheses - Used reasoned skepticism

42. “When asked whether newborn cape buffaloes stayed with their mothers or were kept hidden, one man replied that he had not looked ‘since buffaloes kill you, you don’t go after them.’ However, he then suggested that since buffaloes are like cows, and newborn calves stay with their mothers, the same would be true of buffaloes. Or, that since newborn buffaloes are large and conspicuous, the option of trying to stay hidden wouldn’t work very well.” These are examples of comparative (behavior same as similar species - phylogenetic) and ecological (based on interactions with the environment) hypotheses.

43. Limitations of Science - Restricted to those things that can be logically tested and falsified. - More than one hypothesis can predict the same outcome of a test. - Results can be interpreted in different ways, leading to different conclusions. - Hypotheses constantly being reevaluated and modified as more results and information are gained.

44. Next time: Proximate vs Ultimate causes of behavior.