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Lecture 1: "Introduction To Ecology"

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Biology 2483A
Hugh Henry

Ecology Lecture No. 1: Introduction To Ecology th Tuesday September 11 , 2012 Ecology: -The scientific study of interactions between organisms and their environment; the scientific study of interactions that determine the distribution (geographic location) and abundance of organisms. General Misconceptions In Ecology: -The notion that there is a balance of nature and return to an original preferred state after disturbance is a common misconception as many random factors contribute to complete changes in ecosystems that are not necessarily reversible. -The notion that each species has a role to play in maintaining the balance of a given ecosystem is a common misconception as ecological communities exhibit a lot of redundancy in the sense that many different species carry extremely similar ecological roles and the environment will continue regardless of the fact that a particular species has gone extinct. There are however, a handful of keystone species that the ecosystem relies upon to stay abundant. Ecological Maxims: -I) Organisms interact and are interconnected – though the connectedness may sometimes be vague, it is nevertheless present. -II) Everything goes somewhere – despite the negative consequences faced by an ecosystem, life continues and organisms are immediately influenced. -III) No population can increase in size forever – as in human populations and bacteria in a beaker, there are certain limits that imposed upon population growth in every ecosystem. -IV) Finite energy and resources result in trade-offs – organisms always develop vulnerabilities to their ecosystem despite their numerous strengths. -V) Organisms evolve – the abiotic and biotic factors of a given ecosystem will allow organisms selected against the opportunity to evolve. -VI) Communities and ecosystems change over time – ecological spaces housing numerous organisms are never static; they are the products of change. -VII) Spatial scale matters – There are important distinctions surrounding an organism, a population, a community, an ecosystem, and the biosphere. The Ecological Hierarchy: -Organism – any contiguous biological system; part of a population. -Population - Group of individuals of a species that are living and interacting in a particular area. -Community - Association of populations of different species in the same area. -Ecological studies often include both the biotic (living components), and abiotic (physical components) of natural systems. An ecosystem is a community of organisms plus the physical environment (abiotic). -Landscapes - Areas with substantial differences, typically including multiple ecosystems. -Biosphere - All living organisms on Earth plus the environments in which they live; all the world’s ecosystems. Connections In Nature: -Adaptation - A 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. E.g. antibiotic-resistant bacteria. Ecosystem Processes: -Producers - Capture energy from an external source (e.g. the sun) and use it to produce food. -Net Primary Productivity (NPP) - Energy captured by producers, minus the amount lost as heat in cellular respiration; the actual energy available for consumers. -Consumers - get energy by eating other organisms or their remains. How Ecosystems Work: -Energy moves through ecosystems in a single direction only—it cannot be recycled. But nutrients are continuously recycled from the physical environment to organisms and back again—this is the nutrient cycle. Energy is eventually lost as heat
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