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Lecture

ecology

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Department
Biology
Course
BIO330H5
Professor
Dolderman
Semester
Fall

Description
Chapter 52: Ecology and the Distribution of Life 52.1: What is Ecology?  Ecology: scientific study of the rich and varied interactions between organisms and their environment.  Communities: embracing all the organisms living together in the same area  Ecosystems: embracing all organisms in an area plus their physical environment  Biosphere: system that embraces all regions of the planet where organisms live  Environment: encompasses both abiotic and biotic factors 52.2: How are Climates Distributed on Earth?  Climate of a region is the average of the atmospheric conditions found over a long term.  Weather is the short-term state of those conditions.  Climates vary greatly because different places receive different amounts of solar energy. Solar energy drives global climates  Every place on Earth receives the same total number of hours of sunlight but not the same amount of solar energy; this depends primarily on the angle of sunlight.  Higher latitudes experience greater variation in both day length and the angle or arriving solar energy over the course of a year = greater seasonal variation in temperature.  Air temperature decreases with elevation: when air rises, it expands, its pressure and temperature drop, and it releases moisture; when a parcel of air descends, it is compressed, its pressure rises, its temperature increases, and it takes up moisture.  Global air circulation patterns result from the global variation in solar energy input and from the spinning of Earth on its axis.  Air rises when it is heated by the sun and is replaced by air that flows in toward the equator from the north and south  produces the intertropical convergence zone.  Cool air cannot hold as much moisture as warm air, so heavy rains fall in the intertropical convergence zone.  Air that moves into the intertropical convergence zone to replace the rising air is replaced by air i (E ’ A i )  A i i i i .  At the poles, air descends.  Spinning of Earth on its axis influences surface winds. As air mass moves toward equator, it encounters an increasingly faster spin, and its rotational movement is slower than that of the Earth beneath it. As an air mass moves poleward, it confronts an increasingly slower spin, and speeds up relative to the Earth beneath it.  Air masses moving latitudinally are deflected to the right in the N. Hemisphere and to the left in the S. Hemisphere.  Air masses moving toward the equator from the north and south veer to become northeast and southeast trade winds.  Air masses moving away from the equator veer and become westerly winds that prevail at mid- latitudes.  When prevailing winds bring air masses into contact with a mountain range, the air rises to pass over the mountains, cooling as it does. Clouds form on the windward side and release moisture as rain or snow. On the leeward side, dry air descends, warms and picks up moisture resulting in a rain shadow on the leeward side. Global oceanic circulation is driven by wind patterns  Global air circulation drives the circulation patterns of surface ocean waters, currents.  Trade winds converge at the equator and move westward until it encounters a continental land mass; then the water splits along the continental shores. This movement of water which has been heated at the tropics transfer large amounts of heat to the high latitudes.  As currents move towards poles, the water, driven by the winds, veers right in the N. Hemisphere and left in the S. Hemisphere.  Water flowing towards poles turn eastward, encounters another continent and is deflected laterally along its shores.  In both hemispheres, water flows toward the equator along the western sides of continents until it meets at the equator and flows westward again. Organisms must adapt to changes in their environment  Few individuals die exactly where they were born; most move or are moved to a new place  dispersal.  If repeated seasonal changes alter an environment in predictable ways, organisms may evolve life cycles that appear to anticipate those changes  migration and hibernation. 52.3 What is a Biome?  Biome is a terrestrial environment defined by the growth forms of its plants.  Species richness – the number of species present in its communities. TUNDRA o Found in Arctic at high elevations in mountains at all latitudes o Vegetation consists of low-growing perennial plants underlain by permafrost o Little precipitation, lowland Arctic tundra is very wet (no drain source). o Plants grow for only a few months each year o Most Arctic tundra animals either migrate or remain dormant for most of the year. o Tropical alpine tundra is not underlain by permafrost. BOREAL FOREST AND TEMPERATE EVERGREEN FOREST o Found toward the equator Arctic tundra and at lower elevation
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