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| One individual is harmed, the other is unaffected. |
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| Neither organism is harmed or benefits from interaction. |
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| Both organisms are harmed. |
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| One organism benefits, the other is harmed. |
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| One organism benefits, the other is unaffected. |
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| Coined the word niche; an organism’s habitat. |
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| Redefined niche; an organism’s role in the environment. |
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| Redefined niche; all physical and biological variables that affect organisms. Coined the term hypervolume. |
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| Conditions under which an organism can theoretically survive. |
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| Conditions where an organism actually does live. |
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| Exploitative; siblicide in raptors and egrets. |
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| Interference; territoriality in songbirds. |
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| Intraspecific Competition |
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| Between individuals of the same species (males vs. females, adults vs. young, etc.). |
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| Influence increases with increasing population density (disease). |
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| One individual loses more than the other (most common in interspecific competition). |
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| Natural selection favors changes that lessen competition. |
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| Methods of Reducing Intraspecific Competition |
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| Territoriality (birds), prolonged breeding season (frogs), dispersal of male or female offspring (cheetahs, African wild dogs). |
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| Unchecked growth (humans, theoretical growth without environmental restrictions). |
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| Exponential growth limited by carrying capacity (most organisms). Also known as sygmoidal growth. |
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| Number of individuals capable of being supported by the environment. |
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| Interspecific Competition |
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| Between individuals of different species. |
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| If resource requirements between individuals are similar, extinction or range shift occurs. |
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| Using different resources, in different areas, or at different times. |
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| One species takes over entire ecosystem. |
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| Competing species are removed from an area, eliminating competition. |
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| Kill and eat another organism. |
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| Lay eggs on/in host, offspring consume host (Hymenoptera, Diptera). Sex of eggs can be controlled by parent. |
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| Predators that take nutrients from another organism. Usually live in several hosts throughout life, shouldn’t kill host. |
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| Consume (but usually do not kill) vegetation. |
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| Predator-Prey Relationships |
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| Late 1800’s – focus on pest control, continued later as theoretical interest. |
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| Search, pursuit, handling times. |
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| Fur trading company that recorded lynx/hare populations around Hudson’s Bay. Discovered population cycles (oscillations). |
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| Studied effect of refuges, immigration, and emigration on predator prey relationships in microorganisms. |
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| Studied effect of environmental complexity on predator-prey oscillations using mites and oranges. |
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| Lotka and Volterra (1929) |
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| Created equations to explain predator-prey oscillations. |
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| Type I Functional Response |
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| Proportion of prey consumed remains constant with increase in prey population. |
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| Type II Functional Response |
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| Proportion of prey consumed drops with increase in prey population. |
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| Type III Functional Response |
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| Proportion of prey consumed increases with increase in prey population, until a limit is reached and the proportion of prey consumed decreases. |
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| Ability to locate prey easily after a few trials. |
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| Eating at different prey densities. |
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| Breeding at different prey densities. |
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| Feeding as efficiently as possible given other constraints (what to eat and where to eat). |
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| Long search time, lots of calories. |
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| Short search time, less calories. |
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| Predator decides what to eat. |
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| Predator decides where to eat. |
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| Minimizes time used to find food (hummingbird). |
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| Consumes as many calories as possible with no time constraints. |
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