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Lecture 2

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Biological Sciences
Marc Cadotte

Lecture 2: Ecology as science Science ▯ - Science is a series of steps, it gives us a method to answer questions, to obtain knowledge, not just believe ▯ - belief and knowledge are separate things but are both important in science ▯ - Modern science is grounded in reasearch ▯ - You first make an educated decision, then you attempt to test it, carry out an experiment, then you analyze ▯ the data, and then you come to a conclusion ▯ - When ecologist observe things, they design methods to test it (experiments, observations, models) ▯ Answering Ecological Questions ▯ - Concept: ecologists evaluate competing hypotheses about natural systems with experiments, observations, ▯ and models ▯ - Because of the complexity of testing hypotheses, ecologists design various way of testing these hypotheses ▯ - Ecologists use several methods to answer questions about the natural world: ▯ ▯ 1) Observational studies in the field: what we can observe ▯ ▯ ▯ - can be done over time ▯ ▯ ▯ - you need to have very clear structure: like location, time, how, etc ▯ ▯ ▯ - using the appropriate method can make this form of study powerful ▯ ▯ 2) Experiments in the field ▯ ▯ 3) Controlled lab experiments: ▯ ▯ ▯ - growing plants in a lab ▯ ▯ ▯ - in these conditions the experimenter can control all the variables ▯ ▯ 4) Quantitative models: ▯ ▯ ▯ - its challenging to observe ecological processes through capacity ▯ ▯ ▯ - eg. Population growth ▯ ▯ - Ecological methods are not always on a large scale since it is sometimes challenging to understant ▯ ▯ such large system. So they operate on a scale that can help fit mathematical models also ▯ - Experimental Design: ▯ ▯ 1. Replicate: perform each treatment more than once ▯ ▯ 2. Assign treatments at random ▯ ▯ 3. Statistical analysis is used to determine significant effects ▯ - Two key Rs: Replicate and Randomize ▯ ▯ - You have a body of soil. You have plants that you put pesticide on and ones you donʼt. You can ▯ ▯ expect the plants with pesticide to be bigger since there are no pests. However, you notice the plant ▯ ▯ with no pesticide was smaller. You must then randomize in order to see legit results ▯ - Critical C: it is also important to have control ▯ ▯ - Growth of plants with fertilizer: Some plants grow less with fertlizer. You will see this behaviour in ▯ ▯ nature a lot. There are many reasons for the declide in growth with more fertilizer. Eg. fertilizer ▯ ▯ become toxic when added too much. You must then have a control: growth without fertilizer ▯ ▯ - Eg. Injecting fish with hormone. We need control for handling the fish and injecting the fish. Inject ▯ ▯ with something that isnʼt the hormone, and the other could be handle the fish but donʼt stab it. Effect of ▯ ▯ the stabbing with syringe and actual hormone - Experimental controls are used to
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