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BISC 1112- Week 7 Notes

by: Nikita Shah

BISC 1112- Week 7 Notes BISC1112

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Nikita Shah

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Doebel Week 7 Notes
ntroBio-Bio of Organisms (BISC 1112)
Class Notes
Bio, BISC 1112
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This 5 page Class Notes was uploaded by Nikita Shah on Saturday March 26, 2016. The Class Notes belongs to BISC1112 at George Washington University taught by Doebel in Spring 2016. Since its upload, it has received 11 views. For similar materials see ntroBio-Bio of Organisms (BISC 1112) in Biology at George Washington University.


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Date Created: 03/26/16
Chapter 54 54.1 Interspecific Interactions: Interactions that include competition, predation, herbivory, symbiosis (including parasitism, mutualism, and commensalism), and facilitation.) Interspecific Competition: is a -/- interaction that occurs when individuals of different species compete for a resource that limits their growth and survival. Competitive Exclusion: A slight reproductive advantage will eventually lead to local elimination if the inferior competitor Ecological Niche: The sum of a species’ use of the biotic and abiotic resources in its environment Resource Partitioning: The differentiation of niches that enables similar species to coexist in a community  Fundamental Niche- the niche potentially occupied by a species  Realized Niche - the portion of its fundamental niche that it actually occupies Character Displacement: The tendency for characteristics to diverge more in sympatric than in allopatric populations of two species Predation: This refers to a +/- interaction between species in which one species, the predator, kills and eats the other, the prey. Adaptations Aposematic Coloration: warning coloration Cryptic Coloration: Camouflage Batesian Mimicry: A palatable or harmless species mimics an unpalatable or harmful one Mullerian Mimicry: When two or more unpalatable species, such as the cuckoo bee and yellow jacket, resemble each other. Herbivory: Refers to a +/- interaction in which an organism eats parts of a plant or alga  Because a plant can not run away, it uses defense mechanisms such as it’s chemical toxins (how some plants create cinnamon or peppermint – toxic to some herbivores but not to humans) or structures such as spines and thorns Symbiosis: When individuals of two or more species live in direct and ultimate contact with one another Parasitism: Refers to a +/- symbiotic interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process  Endoparasites: parasites that live within the body of their host o Ex. Tapeworms  Ectoparasites: parasites that feed on the external surface of a host o Ex. ticks and lice Mutualism: Is an interspecific interaction that benefits both species (+/ +).  Obligate Mutualism – when at least one species has lost the ability to survive on its own o Ex. Termites and the microorganisms in their digestive system  Facultative Mutualism – both species can survive alone o Ex. Acacia-ant species Commensalism: An interaction between species that benefits one of the species but neither harms nor helps the other (+/0)  Ex. “hitchhiking” species such as barnacles that attach to whales Facilitation: Species that can have positive effects (+/+ or 0/+) on the survival and reproduction of other species without necessarily living in the direct and intimate contact of a symbiosis  Particularly common in plant ecology 54.2 Species Diversity: the variety of different kinds of organisms that make up the community 1. Species Richness: the number of different species in the community 2. Relative Abundance: the proportion each species represents of all individuals in the community Shannon Diversity (H): Widely used index to calculate indexes of diversity based on species richness and relative abundance: H=-(p ln A pA+ p lB p + B ln pC+ …) Chere A, B, C…are species in the community, p is the relative abundance of each species, and ln is the natural log Biomass: The total mass of all organisms in a habitat Invasive Species: Organisms that become established outside their native range Trophic Structure: The feeding relationships between organisms Food chain: The transfer of food energy up the trophic levels from its source in plants and other autotrophs (primary producers) through herbivores (primary consumers) to carnivores (secondary, tertiary, and quaternary consumers) and eventually to decomposers Energetic Hypothesis: This suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain – only about 10% of the energy stored in the organic matter of each trophic level is converted to organic matter at the next level Dominant Species: The species that are the most abundant or that collectively have the highest biomass Keystone Species: Species that are not usually abundant in a community Ecosystem Engineers: Species that dramatically alter their environment  Ex. Beavers Bottom-up Model: Postulates a unidirectional influence from lower to higher trophic levels VH (an increase in vegetation will increase the numbers of biomass of herbivores) Top-down Model: Postulates that predation mainly controls community organization because predators limit herbivores, herbivores limit plants, and plants limit nutrient levels through nutrient uptake, also called trophic cascade model. Biomanipulation: an approach to prevent algal blooms and eutrophication by altering the density of higher-level consumers instead of using chemical treatments. 54.3 Disturbance: An event, such as a storm, fire, flood, drought, or human activity, that changes a community by removing organisms from it or altering resource availability Nonequilibrium Model: Describes most communities as constantly changing after disturbance Intermediate Disturbance Hypothesis: States that moderate levels of disturbance foster greater species diversity than do high or low levels of disturbance Ecological Succession: When a disturbed area may be colonized by a variety of species, which are in turn replaced by another species, which are then replaced by another Primary Succession: When ecological succession occurs in an area where soil has not been formed yet, such as on a new volcanic island or on the rubble left by a retreating glacier Secondary Succession: This occurs when an existing community has been cleared by some disturbance that leaves the soil intact 54.4 Latitudinal Gradients of Species Richness 1. Evolutionary history 2. Climate  Evapotranspiration: the evaporation of water from soil and plants o Potential Evapotranspiration: the measure of potential water loss that assumes that water is readily available – determined by the amount of solar radiation and temperature and is highest in regions where both are plentiful The Species Area Curve: All other factors being equal, the larger the geographical area of a community, the more species it has, in part because larger areas offer a greater diversity of habitats and microhabitats S=cA z Where S=the number of species found in a habitat C is a constant Z is how many species should be found in a habitat as its area increases 54.5 Pathogens: Disease-causing microorganism, viruses, viroids, or prions Zoonotic Pathogens: Pathogens that are transferred to humans from other animals, either through direct contact with an infected animal or by means of intermediate species known as vector (ticks, lice, mosquitos) 52.4 Dispersal: The movement of individuals or gametes away from their area of origin or from centers of high population density  Ecologists want to know not only where species occur but also why those species occur where they do


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