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Biology Unit 2 - Natural Selection

biomass the total dry mass of all the organisms in a given area
energy pyramid a triangular diagram that shows an ecosystem's loss of energy, as energy passes through an ecosystem's food chain: each row in the pyramid represents a trophic level in an ecosystem and the area of row represents the total energy stored in that level
habitat the place where the organism usually lives
ecological niche all of the physical, chemical and biological factors that a species needs to survive, stay healthy, and reproduce in an ecosystem
competitive exclusion the exclusion of one species by another due to competition
ecological equivalent organisms that share a similar niche but live in different geographical regions
competition ecological relationship in which two organisms attempt to obtain the same resource
predation an interaction between two organisms in which one organism, the predator, kills and feeds on the other organism, the prey
symbiosis a relationship in which two different organisms live in close association with each other
mutualism a relationship between two species in which both species benefit
commensalism a relationship between two species in which one organism benefits and the other is unaffected
parasitism a relationship between two species in which one species, the parasite, benefits from the other species, the host, which is harmed
artificial selection the human practice of breeding animals or plants that have certain desired traits
heritability ability of a trait to be passed from one generation to the next
natural selection the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do; a theory to explain the mechanism of evolution
population a group of organisms of the same species that live in a specific geographical area
fitness a measure of an organism's ability to survive and reproduce offspring relative to members of a population
gene pool the total set of genes, including all the alleles, that are present in a population at any one point in time
allele frequency proportion of one allele, compared with all the alleles for that trait, in the gene pool
normal distribution a distribution of numerical data whose graph forms a bell-shaped curve that is symmetrical about the mean
directional selection a natural selection process in which one genetic variation is selected and that causes a change in the overall genetic composition of a population
stabilizing selection a type of natural selection in which the average form of a trait is favored and becomes more common
disruptive selection a type of natural selection in which two extreme forms of a trait are selected
Created by: lpgullett