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LITE3_study_guide - Study Guide Chapter 3 Ecosystems What...

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Study Guide – Chapter 3 - Ecosystems: What Are They and How do They Work? The case study on tropical rainforests is a central problem for conservation if the world’s biodiversity. Look at the pictures in Figure 3-1; this is not an uncommon sight in tropical regions around the globe. We will discuss many important organisms this semester, both eukaryotic organisms (e.g., plants and animals), and prokaryotic organisms (e.g., bacteria), the latter of which are extremely important in the nutrient cycling processes that fuel ecosystems. Individuals within a species can mate and produce fertile offspring. We know about 1.8 million of them, but there may be 10 times that number yet to be described - can we afford to destroy habitats before we discover these species, what they do, why they are important in nature, and how they might be important to us? A population is a group of individuals within a species that live together and exchange genetic material; it is different from a species. For example, cottontail rabbits in Australia may be the same species as cottontail rabbits in the U.S., but they are very different populations. Individuals within populations vary because of genetic diversity and the constant recombination of genes as each successive generation mates. All populations live in a habita t, which provides resources such as food, water, proper environmental conditions, and cover from predators. A community is a group of populations living in a particular habitat. They may be similar populations (e.g., birds in a forest), but the community will also include very dissimilar organisms (insects, fungi, mammals that also live in the forest). An ecosystem is a community and its environment (biotic and abiotic); they can be small or large, and many are not distinct, they grade into each other to produce habitats known as ecotones . Note the Science Focus on page 54. We often ignore insects, even more often try and destroy them as pests, yet they are an incredibly important part of ecosystem function. Earth’s life-support systems consist of the biosphere (where life is found), the atmosphere (the troposphere with its greenhouse gasses and the stratosphere with its ozone layer are the most important to us), the hydrosphere (water as ice, liquid, or vapor), and the geosphere , the Earth’s core, mantle, and crust. Terrestrial ecosystems are divided into biomes , large land areas with distinctive climate and resident biotic communities. These can be visualized in Figure 3-7, which shows several biomes that differ primarily in temperature and rainfall. Aquatic ecosystems are divided into aquatic life zones , which are analogous to biomes, and differ in characteristics such as depth, salinity, and water velocity.
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