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

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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)

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

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

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

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

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

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

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

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What is a

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

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

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Case study Betholdia trigona (tiger moth) emits a particularly dense series of ultrasonic clicks Eptesicus fuscus (big brown bat) eats tiger moths. Finds using sonar. From Corcoran et al. Science 2009 You know:

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

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

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

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Results Stopped attack on normal moths, but didnt avoid moths in future Bats caught silenced moths From Corcoran et al. Science 2009 How can you interpret????

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

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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

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Observation Argentine ants are successful invaders of native California ant habitats Jeanna Bryner

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Hypothesis Argentine ants dont 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 Alternative hypothesis If predators prefer native species but dont eat Argentine ants, native species will suffer reduced populations relative to Argentine ants

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

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

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

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

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

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

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Variation Biological variability: differences in individuals Mean The average. But its also important how much the data vary around the mean 55555 71539 average 5 5 0 10 variance

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CONTROL GROUPEXPERIMENTAL GROUP normalThe altered group No special conditionsabnormal Reference point With special condition youre interested in Plants in field Plants with added nitrogen Number of seeds per plant Grow plants with other plants and count seeds

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Independent 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 Dependent variable 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

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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

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Independent variable Dependent variable Positive correlation

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Independent variable Dependent variable Negative correlation

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Independent variable Dependent variable No correlation

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Scatter plot

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Scatter plot with error bars

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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. Add N Control Add NControl Add NControl Add N

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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??? Independent variable? Amount of Nitrogen added Dependent variable? Measure of plant growth

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

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Visual representations DiscreteContinuous Histogram, Frequency distribution Bar graph Scatter plot

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Histogram

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Challenge statement Correlation implies causation

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

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Case study Read the article: Want a Higher G.P.A.? Go to a Private College by C. Rampell, printed in the NY Times 1.What are the variables being compared (look at the title of the article) 2.Which is the dependent variable? The independent variable? 3.Does the headline indicate correlation or causation between the two variables? 4.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 1950s 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.

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

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

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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

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

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Sudden Oak Death Because of testing of alternatives, we now know that its Phytophthora ramorum, in genus of Oomycetes (water molds), like a fungus Hypothesis: beetles were transmitting the pathogen causing SODS Many trees had large weeping cankers, swarms of beetles and green to black fruiting bodies of Hypoxylon fungus This fungus is believed to be in the tree when it is healthy, and to break out and grow in areas of sapwood that die

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What is a Scientific theory?

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What is a theory? THEORY Offers a tested mechanism for this phenomena A phenomena based on a group of observations Close to a scientific law Derived from work of multiple scientists

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Ecology is hierarchical Different levels of organization (scale): Landscape Ecosystem Community Population Individual Scale

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Hierarchies in ecology 1.How do individuals affect and are affected by the environment? 2.How are individuals adapted to the environment? 3.How does an individual make a living? 4.What are the limiting factors for an individuals reproduction and growth? Individual

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Hierarchies in ecology 1.What causes the presence or absence of a particular species? 2.What do we know about the species abundance or rarity? 3.Are there trends and fluctuations in their numbers? 4.What are their characteristics? Life histories Genetics Competition among each other Population

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Hierarchies in ecology 1.What structures communities? 2.What can we say about interactions among species? Predation Competition Parasitism Mutualism Community

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Hierarchies in ecology 1. How does energy and nutrients move through ecosystems? 2.How does this flux influence species? Ecosystem

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Hierarchies in ecology 1.How does energy and nutrients flow between ecosystems? 2.How are ecosystems connected? 3.What determines the presence and absence of species on a large scale? Landscape

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Kinds of ecological studies Observational Comparative Theoretical Experimental Observe natural phenomena No experiments or manipulations Manipulate a microcosm Isolate a portion, limit factors, manipulate conditions May be based on data (or not) e.g. mathematical models that describe ecosystem interactions From literature and / or previously collected data Meta-analysis

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Reading literature 1.What is the problem? 2.What is the hypothesis of the researchers? 3.What are the alternative hypotheses? 4.How did they gather evidence? 5.Does the evidence support the hypothesis? 6.How does this fit in with the larger issues in ecology?