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Unformatted text preview: 3-1 Laboratory 3Does Biodiversity Vary Between Habitats?The species you will encounter this semester--small and large, simple and complex--are the working cogs of the living machine that is our biosphere and our only home. Each is important to the workings of its ecosystem. Even though we humans have not yet fathomed the ecological roles of most non-human species, we must learn to recognize them as we search for their importance to us and to the biosphere. As you recall from your first semester of biology, the most ancient living organisms, in the Domain Archaea and Domain Bacteria, are sometimes referred to as prokaryotes. Prokaryotic organisms lack membrane bounded organelles, and their DNA consists of a single, circular chromosome of double stranded DNA organized in what is known as the nucleoid regionof the cell. More recently derived, eukaryotes(Domain Eukarya) are believed to share a most recent common ancestor with the Archaea. Eukaryotes may have evolved from ancient prokaryotes that formed symbiotic relationships with one another (The Endosymbiont Model) and/or who underwent inpocketing of their external plasma membranes to form an internal membrane network (The Autogenous Model). It is quite probable that both phenomena were involved in the evolution of eukaryotes. Let’s meet some of the results of these millennia of evolution. I. Inquiry-Based Exercise: Differences in Species Diversity in Two Local EcosystemsA. IntroductionThe responsibility and rush of every day life sometimes distracts us from the natural world around us. The diversity of non-human species is immense, and yet most people rarely stop to consider it. Today, we hope to change that. Located to the west of the Cox Science Building is the Gifford Arboretum Native Biome. Nestled in its center is a small pond, complete with plants, animals, fungi, protists and bacteria of many species. A little bit farther off, towards the center of campus, lies Lake Osceola. What might we have in store for you? Hint: You never know just what you'll find in a bit of pond sludge. All species of living organisms have different tolerance limits for various environmental factors, including temperature, light, humidity, nutrients, etc. Because different ecosystems have different levels of each of these factors, the species in each ecosystem will differ accordingly. The abiotic(non-living) components of any given habitat determine the composition and abundance of the biotic(living) components of that habitat, and the biotic components, in turn, affect each other's abundance and diversity. Consider that a freshwater habitat presents more of an osmotic (water/salt balance) challenge to living cells than a saltwater or brackish environment. Also consider that different habitats not only have natural variables when it comes to abiotic factors, but that in an urban/suburban environment, they also are subjected to differing levels of human disturbance from things like pesticide and fertilizer runoff, physical disturbance, sanitation/clearing efforts, etc. sanitation/clearing efforts, etc....
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- Spring '08