Community Interactions
Organisms not only live together in ecological communities, but they also constantly interact with one another. These interactions, which include predation and competition, help shape the ecosystem in which they live. 1. Based on your own experiences, define predation. Give one example of predation. 2. Based on your own experiences, define competition. Give one example of competition.
Living and Non-living Factors Living things ECOSYSTEM Non-living things
Biotic and Abiotic Factors Living things = BIOTIC FACTORS ECOSYSTEM Non-living things = ABIOTIC FACTORS
Biotic and Abiotic Factors The living (biotic) and nonliving (abiotic) parts of an ecosystem are always interacting. The biotic and abiotic factors of an ecosystem shape that ecosystem. http://www2.for.nau.edu/courses/hart/for479/images/alpine01.jpg
Community Interactions Not only do the biotic and abiotic parts of an ecosystem always interact, the living things are always interacting with each other. When organisms live together in an ecological community, they constantly interact. A community is a collection of different populations that live together in a certain area.
Community interactions can powerfully affect an ecosystem. Three main types of interactions between the living (biotic) things in an ecosystem: Competition Predation Symbiosis
Competition Competition occurs when organisms try to use the same resources in the same place at the same time. A resource is any necessity of life, such as water, nutrients, light, food, or space.
Competition In a forest, for example, trees with large leaves may compete for sunlight by growing tall, spreading out their leaves, and blocking the sunlight from shorter trees. Direct competition in nature often results in a winner and a loser. The loser then fails to survive and dies. www.rr.ualberta.ca/ Index.asp?page=News&news=633
Competitive Exclusion Principle Two species cannot occupy the same niche in the same habitat at the same time. Habitat – the place where an organism lives that provides all of its needs Niche – the job of a living thing in its community
Competitive Exclusion Principle Figure 4-5 Three Species of Warblers and Their Niches Competitive Exclusion Principle Section 4-2 Cape May Warbler Feeds at the tips of branches near the top of the tree Bay-Breasted Warbler Feeds in the middle part of the tree Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches Spruce tree Each of these warblers has a different niche in its spruce tree habitat. By feeding in different areas of the tree, the birds avoid competing with one another for food. Go to Section:
Predation Predation is a community interaction in which one organism captures and feeds on another organism. The predator is the organism that does the killing and eating The prey is the food necsi.org/.../ co-evolution_predator.html
Symbiosis Symbiosis is a relationship between two species that live close together. Three classes of symbiosis in nature 1. Mutualism 2. Commensalism 3. Parasitism www.unibas.ch
Mutualism In mutualism, the relationship benefits both species. http://wc.pima.edu/~bfiero/tucsonecol109/animals/Images/inter01.jpg
Commensalism In commensalism, one organism benefits from the relationship and the other is neither helped nor harmed. http://www.cbu.edu/~seisen/ExamplesOfCommensalism_files/image002.jpg
Parasitism In parasitism, one organism lives on or inside another organism and harms it. http://userwww.sfsu.edu/~biol240/labs/lab_03symbiosis/media/viscumalbum.jpg