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Ecology week 2 Slide 2 Community Interactions Ecosystems are influenced by a combination of biological and physical factors. Biological influences are called biotic factors Physical, or nonliving, factors that shape ecosystems are called abiotic factors Slide 3 If an organisms habitat is its address, its niche is its occupation. Competition ~ competition occurs when organisms of the same or different species attempt to use an ecological resource in the same place at the same time. Predation ~ an interaction in which one organism captures and feeds on another organisms Community Interactions Slide 4 Symbiosis ~ Any relationship in which two species live closely together. Mutualism both species benefit Commensalism one benefits, the other is neither helped nor harmed Parasitism one organism lives on or inside another organism and harms it Community Interactions Slide 5 Ecological Succession Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community Slide 6 Primary succession ~ On land, succession that occurs on surfaces where no soil exists Pioneer species the 1 st to populate the area Secondary succession ~ When a disturbance of some kind changes an existing community without removing the soil. Ecological Succession Slide 7 The Major Biomes Ecologist recognize at least 10 different biomes. Tropical rain forest Tropical dry forest Tropical savanna Desert Temperate grassland Temperate woodland & shrubland Temperate forest Northwestern coniferous forest Boreal forest Tundra Slide 8 BIOMES Each of these biomes is defined by a unique set of abiotic factors particularly climate and a characteristic assembladge of plants and animals South Florida is considered by some scientists to be tropical others, consider it to be more temperate. It is commonly referred to as sub-tropical Slide 9 Slide 10 Slide 11 Slide 12 Slide 13 Slide 14 Slide 15 Slide 16 Slide 17 Slide 18 Slide 19 Slide 20 Aquatic Ecosystems Nearly 3/4 th of the planet is covered by water, so it is not surprising that many organisms make their homes in aquatic habitats Freshwater ecosystems Flowing-water Standing-water wetlands Slide 21 Estuaries ~ estuaries are wetlands formed where rivers meet the sea. Example: Florida Bay Aquatic Ecosystems Slide 22 Marine ecosystems Depending on how much sun-light penetrates the water, is how salt-water environments are classified Photic zone: The area from the surface to about 200 meters light is able to reach therefore, photosynthesis can occur Aphotic zone: below 200 meters, light has difficulty penetrating. Only chemosynthetic autotrophs are the only producers able to survive. Aquatic Ecosystems Slide 23