BIO 311D 1st Edition Lecture 36Outline of Last Lecture I. Life history traits are products of natural selectionII. Evolution and Life History DiversityIII. “Trade-offs” and Life HistoriesIV. Overview: Discovering EcologyV. The Scope of Ecological ResearchVI. Global EcologyVII. Landscape EcologyVIII. Ecosystem EcologyIX. Earth’s climate varies by latitude and season and is changing rapidlyOutline of Current Lecture I. HerbivoryII. SymbiosisIII. ParasitismIV. MutualismV. CommensalismVI. FacilitationVII. Community EcologyVIII. Organismal EcologyIX. Global Air CirculationX. Latitudinal Variation in Sunlight IntensityCurrent LectureHerbivory• Herbivory (+/– interaction) refers to an interaction in which an herbivore eats parts of a plant or alga• It has led to evolution of plant mechanical and chemical defenses and adaptations by herbivoresSymbiosis• Symbiosis is a relationship where two or more species live in direct and intimate contact with one anotherParasitism• In parasitism (+/– interaction), one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process• Parasites that live within the body of their host are called endoparasites• Parasites that live on the external surface of a host are ectoparasites• Many parasites have a complex life cycle involving a number of hosts• Some parasites change the behavior of the host in a way that increases the parasites’ fitnessMutualism• Mutualistic symbiosis, or mutualism (+/+ interaction), is an interspecific interaction that benefits both species• A mutualism can be– Obligate, where one species cannot survive without the other– Facultative, where both species can survive aloneCommensalism• In commensalism (+/0 interaction), one species benefits and the other is neither harmed nor helped• Commensal interactions are hard to document in nature because any close association likely affects both speciesFacilitation• Facilitation (+/+ or 0/+) is an interaction in which one species has positive effects on another species without direct and intimate contact– For example, the black rush makes the soil more hospitable for other plant speciesThe Scope of Ecological Research• Ecologists work at levels ranging from individual organisms to the planetGlobal Ecology• The biosphere is the global ecosystem, the sum of all the planet’s ecosystems• Global ecology examines the influence of energy and materials on organisms across the biosphere• Landscape Ecology• A landscape or seascape is a mosaic of connected ecosystems• Landscape ecology focuses on the exchanges of energy, materials, and organisms across multiple ecosystemsEcosystem EcologyAn ecosystem is the community of organisms in an area and the physical factors with which they interactEcosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic componentsCommunity Ecology• A community is a group of populations of different species in an area• Community ecology deals with the whole array of interacting species in a communityPopulation Ecology• A population is a group of individuals of the same species living in an area• Population ecology focuses on factors affecting population size over timeOrganismal Ecology• Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges• Organismal ecology includes physiological, evolutionary, and behavioral ecologyEarth’s climate varies by latitude and season and is changing rapidly• The long-term prevailing weather conditions in an area constitute its climate• Four major abiotic components of climate are temperature, precipitation, sunlight, and wind• Macroclimate consists of patterns on the global, regional, and landscape level• Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log Global Climate Patterns• Global climate patterns are determined largely by solar energy and the planet’s movement in space• The warming effect of the sun causes temperature variations, which drive evaporation and the circulation of air and water• This causes latitudinal variations in climateLatitudinal Variation in Sunlight Intensity• The angle at which sunlight hits Earth affects its intensity, the amount of heat and light per unit of surface area• The intensity of sunlight is strongest in the tropics (between 23.5° north latitude and 23.5° south latitude)Global Air Circulation and Precipitation Patterns• Global air circulation and precipitation patterns play major roles in determining climate patterns• Water evaporates in the tropics, and warm, wet air masses flow from the tropics toward the poles• Rising air masses release water and cause high precipitation, especially in the tropics• Dry, descending air masses create arid climates, especially near 30° north and south• Air flowing close to Earth’s surface creates predictable global wind patterns• Cooling trade winds blow from east to west in the tropics; prevailing westerlies blow from west to east in the temperate zonesRegional and Local Effects on Climate• Climate is affected by seasonality, large bodies of water, and mountainsSeasonality• Seasonal variations of light and temperature increase steadily toward the poles• Seasonality at high latitudes is caused by the tilt of Earth’s axis of rotation and its annual passage around the sun• Belts of wet and dry air straddling the equator shift throughout the year with the changing angle of the sun• Changing wind patterns affect ocean
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