Community Ecology PDF

Community Ecology © Amy Brown Science Community Interactions Community: A community is all of the living organisms found in a particular area. When organisms live in communities, they _______ interact constantly and have a powerful effect on the _________. ecosystem Different types of community inte...

Community Ecology © Amy Brown Science Community Interactions Community: A community is all of the living organisms found in a particular area. When organisms live in communities, they _______ interact constantly and have a powerful effect on the _________. ecosystem Different types of community interactions include: 1. 2. 3. 4. 5. 6. Competition Predation Symbiosis Mutualism Commensalism Parasitism Competition occurs when organisms of the same or different species: attempt to use the same ecological resource in the same place at the same time. © Amy Brown Science What is a resource? A resource refers to anything that is required for life. Resources might include: food, water, light, nesting sites, or room to grow. © Amy Brown Science When organisms are competing for the same resource, there is often a ________________. winner and a loser This is called the: “competitive exclusion principle.” The winner thrives and the loser fails to survive. Competitive Exclusion Principle: No two species can occupy the same niche in the same habitat at the same time. In competitive exclusion one species is _________ eliminated from a community because of __________ competition for the same ______________. limited resource Usually one species uses the resource more _________, efficiently and the other species is __________. eliminated Occasionally, when two species are ________________, intense competitors one or both species may evolve: niche differences or anatomical differences that lessen the intensity of the competition. This phenomenon is called character displacement. Example of character displacement: Finches have different size beaks _____ depending on the type of ____ seed they eat. Two species of finches that are very similar to one another live in the various islands making up the Galapagos Islands. When these two species live on ______________ separate islands and have no __________ beak size competition with each other, they have the same ________. But on an island where both birds are found, their beak sizes are ________. different They have evolved a ____________________ character displacement that enables them to feed on __________________. different-sized seeds Competition is reduced between the two species. Competition is most intense between: closely related species that require the same resources. When similar species coexist, each species uses: only part of the available resources. This pattern of resource use is called resource partitioning. Example of resource partitioning: There are five different species of warblers that live in spruce and fir trees. They all feed on: the same type of insects. Each kind of warbler hunts for insects only in: a particular section of the tree. As a result, competition among the three species is reduced. When can two similar species coexist successfully in the same community? Answer: Only when there is enough difference in their niches. What are two possible outcomes of competition between species having identical niches? Answer: Either the less competitive species will be driven to local extinction, or one of the species may evolve enough through natural selection to use a different set of resources. Land Iguana Marine Iguana Predation Predation is an 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 organism. Predation is a powerful force in the community. Predation determines relationships in _________ food webs and is a very effective regulator of _____________. population size Natural selection favors adaptations that make organisms…. …. better suited for their environment. Predators have become more efficient over time by developing _____ tools (through natural selection) that make them ______________. better predators Examples: Snakes have heat sensitive pits to help them locate prey. Predators may have acute senses, fangs, claws, poison, stingers, and sharp teeth. Spiders have webs to catch their prey. Vietnamese Mossy Frog Just as the predator must be highly adapted to catch the food, the prey must have: adaptations that help them avoid being captured and eaten. a) The prey may have the ability to run very fast to escape the predator. b) The prey may be camouflaged to avoid detection. c) The prey may have poisons that are advertised by bright warning colors. Mimicry Coral snake Mimicry is a form of deception used by the prey as a means of defense against being eaten. In mimicry, a harmless species resembles a poisonous or distasteful species. The king snake is a mimic of the very poisonous coral snake. King snake Viceroy Monarch The viceroy butterfly mimics the monarch butterfly. Birds avoid eating the monarchs due to their very bitter taste. The viceroy does not have a bad taste, but since it resembles the monarch, birds are reluctant to eat it. Herbivores are: animals that eat plants. This makes the herbivore a: predator on plants. Through natural selection, plants have developed adaptations that: protect them from being eaten by animals. Plants and Herbivores Plants may have: sharp spines, thorns, sticky hairs, and tough leaves. Plants may also produce: chemical compounds that are poisonous, or bad tasting. Can you give an example of each of the predatorprey combinations listed in the table below? Predator Prey Example Animal Animal A lion kills and eats a zebra. Animal Plant The zebra grazes on grasses. Fungus Animal Athlete’s foot or ringworm. Bacteria Animal A strep infection. Fungus Plant Blights and mildews. Corn Smut Symbiotic Relationships between Organisms Symbiosis is a close and permanent relationship between organisms of different species. There are three types of symbiotic relationships: Mutualism Commensalism Parasitism Mutualism Parasitism (ticks) Commensalism In mutualism: both species benefit from the relationship. These birds eat the ticks on the back of the hippos. Flowers and insects have a mutualistic relationship. The flower provides the insect with ______, nectar and the insect helps the flower to reproduce by spreading ______. pollen Termites have a particular bacterium that lives in their gut. The bacteria help to digest the wood eaten by the termite, and the termite provides the bacteria with: shelter, warmth, water, and food. Some mutualistic relationships are so close: that neither species can survive without the other. One such example is the ants that live in the acacia shrubs. The ants nest inside the acacia’s large thorns and receive ____ food from the plant. The ants protect the acacia from: predation by herbivores. Commensalism Commensalism is the relationship between two different species in which: one species benefits from the relationship. The other species is neither harmed nor helped. The large fish seen here is called a triggerfish. The triggerfish is able to move large rocks that create feeding opportunities for the smaller fish. There is no benefit to the triggerfish. Barnacles are mollusks that attach to the skin of whales. The barnacle does not ____ hurt the whale nor does it ____ help the whale. The barnacle is a filter feeder and ________ benefits from the constant flow of water. Parasitism Parasitism is the relationship between: two different species in which one species is helped and the other species is harmed. The parasite obtains its _______ nutrition from the other organism, the ____. host Ectoparasites are….. …..external parasites. They live on their host but __________ do not enter the host’s body. Examples include: Leeches, ticks, fleas, and lice. Endoparasites are….. …..internal parasites. These live _____ inside the host’s body. Examples include: Some bacteria, some protists, and intestinal worms such as tapeworms. This is the number of different species found in the community. Community 1 has greater species diversity. This is the relationship between the number of species in the community to the relative abundance of each species. Species richness varies with _______. latitude Species richness is greatest in the tropical rain forests. As a general rule, the closer a community is to the ______, equator the ___________ more species it will contain. A pattern of species richness is that: larger areas usually contain more species than smaller areas do. This relationship is called the species-area effect. Why does species richness increase with increasing area? Larger areas usually contain a greater diversity of habitats and thus can support more species. There is a very important consequence of the species-area effect. Reducing the: size of a habitat reduces the number of species it can support. _________________ Habitat destruction by an ever-growing human population is occurring at a faster and faster rate each day. Currently, about ____ 2% of the tropical rain forests are destroyed each year. What is the result of habitat destruction? The extinction of species!! Disturbances A disturbance is: an event, such as a storm, fire, flood, drought, overgrazing, or human activity that changes a community by removing organisms from it or altering resource availability. Human activities that cause the greatest disturbance to communities include: Agricultural development Logging and clearing Mining and farming Succession is the gradual, sequential regrowth of an area following a disturbance. There are two types of succession: ü Primary succession ü Secondary succession Primary succession is: the development of a community in an area that has not previously supported life. Primary Succession Examples might include: a bare rock, a sand dune, or an island formed by volcanic eruption. Primary succession often occurs very ______ slowly because: the minerals necessary for plant growth are unavailable. Over time, rocks will begin to break down due to _________. weathering Lichens are usually the first to colonize these barren areas. (A lichen is the mutualistic relationship between an algae and a fungus.) As these plants die, they add more decayed organic matter to the soil and soon a few shrubs will appear. The shrubs are then followed by trees. The combination of ________ minerals from rocks, and the ________________ dead organic matter from the lichens will begin to form a thin layer of ____ soil in which a few_________ grass-like organisms can grow. This is...... the replacement of species that follows a disturbance in an already existing community. Secondary Succession The disruption may occur from: a natural disaster such as a forest fire or a strong storm, or from human activities such as clear-cutting, mining or farming. The disturbance has left: the existing soil intact. Pioneer Species These are the organisms that are generally the first to colonize the area. They appear: early in succession. These organisms tend to be: small, fast growing, and very fast at reproduction. These organisms have: adaptations that make them well suited to invading and occupying a new area. For example, they may be very good at seed dispersal, or have adaptations that allow them to withstand harsh conditions. Climax Communities In succession, the community proceeds through a series of stages until it reaches … Climax community... a stable end point called the climax community. The organisms in each stage of succession alter the ___________________ physical environment in ways that make it ____ less favorable for themselves but _____ more favorable for the organisms that follow. The climax community remains constant for a long period of time. Succession in a Marine Ecosystem (Whale-Fall Community) The deep dark ocean floor is a: barren, inhospitable environment. Succession can take place in this environment even when a __________ disturbance occurs. The disturbance begins when: a large whale dies and sinks to the barren ocean floor. The whale carcass attracts: many scavengers and decomposers that begin to feast on the decaying carcass. Within a year, most of the whale’s ______ tissues will have been _____ eaten and only a much smaller community of organisms: can be supported. The ____________ decomposition of the carcass has enriched the surrounding sediments, attracting: a new population of sediment dwellers such as marine worms. When only the skeleton remains….. …..a third community moves in. Heterotrophic bacteria begin to...... decompose oils inside the whale bones. This releases chemical compounds that can be used by...... chemosynthetic bacteria. The chemosynthetic bacteria can support a diverse community of: mussels, snails, worms, crabs, and clams. Clipart Credits Created by Amy Brown Copyright © Amy Brown Science All rights reserved by author. This document is for your classroom use only. This document may not be electronically distributed or posted to a public, nonpassword protected web site.