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Ecology 1.docx

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Western University
Biology 2483A
Mark Moscicki

Ecology-Lecture 1 Sept 12 2013 What is Ecology?  Interaction between organisms and their environment  Study of the distribution/abundance of organisms  How organisms affect-and are affected by other organisms and their environment  Although similar, an ecologist is not necessarily an environmental activist. Compared with ecology, environmental science is focused more specifically on how people affect the environment and how we can address environmental problems Misconceptions  There is no balance to nature. Human impact may prevent returning to the original state and populations are dynamic. A change in one part of an ecological system can alter other parts of that system.  The ecological community doesn't have a species with only one role to play. Many similar species are redundant with similar functions. Different species in an area respond in different ways to changing conditions, a finding at odds with the idea that each species has a distinct function within a larger tightly knit group of species. Guiding Principles of Ecology 1. Organisms interact and are interconnected. All organisms are connected to their environment. Even species that do not interact directly with one another can be connected indirectly by shared features of their environment. 2. Everything goes somewhere! (movement of energy/nutrients) There is no 'away' into which waste materials disappear 3. Populations cannot increase in size forever. There are limits to the growth and resource use of every population, including our own 4. Finite energy/resources result in tradeoffs. If you invest energy into any given strategy you are taking it away from something else. 5. Organisms evolve/change over time. Evolution is an ongoing process because organisms continually face new challenges from changes in both the living and non living components of their environment. 6. Communities/ecosystems change over time. New species replace others over time 7. Spatial scale matters. Abiotic and biotic environmental conditions can change dramatically from one place to another, sometimes across very short distances. This variation matters because organisms are simultaneously influenced by processes acting at multiple spatial scales, from local to regional to global Ecological Hierarchy (organism->population->community->ecosystem- >biosphere)  Population: Single species in a single area  Community: Variety of species in the same area. They are typically grouped based on location. They can cover large or small areas and they can differ greatly in terms of the numbers and types of species found within them  Ecosystem: Community of organisms plus their physical environment  Landscapes: Areas with substantial differences. Typically includes a collection of ecosystems  Biosphere: All of the living organisms on earth plus the environments in which they live (highest level of biological organization) Adaptation & Natural Selection  A universal feature of living systems is that they change over time or evolve. Evolution can be defined as a change in the genetic characteristics of a population over time or as descent with modification, the process by which organisms gradually accumulate differences from their ancestors. The following are 2 key evolutionary terms.  Adaptation: Characteristic that improves survival or reproduction. If the adaptation is heritable, the frequency of the characteristic may increase in a population over time  Natural Selection: Individuals with certain adaptations tend to survive and reproduce at a higher rate than other individuals  Ex: Antibiotic resistance occurs through what is called natural selection and mutation. The simple explanation for this process is that when an antibiotic is administered to combat a certain species of microorganisms it may cause a mutation in the genetic code of some microorganisms of this specific species causing them to survive the course of antibiotic so, some of these microorganisms will die and the mutant microorganism will tend to replicate and spread the mutant gene between them horizontally, and the colony became fully resistant to that type of antibiotic. Ecosystem Processes  Producers: Capture energy from an external source like the sun and use it to produce food (primary producer/autotroph)  Net Primary Productivity (NPP): Energy captured by producers minus the amount lost as heat in cellular respiration. Changes in NPP can have large effects on ecosystem function, and NPP varies greatly from one ecosystem to another.  Consumers: Get energy by eating other organisms or their remains How Ecosystems Work  Each unit of energy captured by producers is eventually lost as heat. Therefore, energy moves through ecosystems in a single direction. It cannot be recycled.  Nutrients are continuously being recycled from the physical environment to organisms and back again. This is known as the nutrient cycle. (nitrogen and phosphorous)  Plants take in the sun's energy. Primary consumers gain energy by eating the plants. When the consumer dies, the energy is lost and the nutrients end up back in the physical environment. This allows plants to take up the nutrients and the cycle begins. Ecological Experiments  Investigator alters one or more features of the environment and observes the effect of that change on natural processes. (control group and one or more experimental groups)  Can be done at different scales. every ecological study addresses events on some scales but
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