Ap Biology Ecology

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ecology

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interactions among organisms

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the study of interactions between living things and their environment, both physical and biotic

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biotic factors

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interactions between organisms and their nonliving, physical environment

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population density

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the number of individuals of a species per unit of habitat area or volume at a given time

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random dispersion

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individuals in a population are spaced throughout an area in a manner unrelated to the presence of others

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pattern of spacing in which individuals in a population are spaced unpredictably

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uniform dispersion

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individuals are more evenly spaced than would be expected form a random occupation of a given habitat

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aggregated dispersion

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individuals are concentrated in specific parts of the habitat

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natality

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birth rate

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rate at which organisms produce offspring

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mortality

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death rate

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intrinsic rate of increase

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maximum rate at which a population could increase under ideal conditions when resources are abundant and its population density is low

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exponential population growth

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the accelerating population growth rate that occurs when optimal conditions allow a constant per capita growth rate

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growth that occurs at a constant rate of increase over a period of time

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examples of density-dependent factors

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preditation, disease, competition

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interference competition

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(contest competition) dominant individuals obtain an adequate supply of the limited resource at the expense of other individuals in the population

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exploitation

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(scramble competition) individuals in the population share the limited resource more or less equally

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density independent factor

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random weather events that reduce population size

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any factor, such as climate, that does not depend on the density of populations

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zero population growth

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point at which the birth rate equals the death rate

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carrying capacity

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the maximum number of organisms that an environment can support

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replacement-level fertility

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number of offspring a couple must produce in order to replace themselves

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emigration

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the movement of individuals out of a population

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intrinsic rate of increase

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maximum rate of increase of a species that occurs when all environmental conditions are optimal

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doubling time

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the amount of time it takes for a population to double in size, assuming that its current rate of increase does not change

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population crash

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abrupt decline in a population from high to very low population density

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population

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group of organisms of the same species that live in the same geographical area at the same time

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community

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an association of populations of different species living and interacting in the same place at the same time

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ecosystem

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a biological community and its abiotic environment together

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three main types of interaction in a community

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competition, predation and symbiosis

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niche

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totality of adaptations by a species to its environment, use of resources, and lifestyle to which it's suited

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fundamental niche

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potential ecological niche of a species

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realized niche

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lifestyle that a species actually pursues and the resources it actually uses

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limiting resource

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any environmental resource that tends to restrict the ecological niche or a species

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intraspecific competition

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competition among individuals within a population

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competitive exclusion principle

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two species cannot indefinitely occupy the same niche in the same community

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resource partitioning

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reduction in competition for environmental resources among coexisting species as a result of each species niche differing from the others in one or more ways

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character displacement

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the divergence in traits in two similar species living in the same geographic area

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three forms of symbiosis

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mutualism, commensalism, parasitism

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ecosystem

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individual community and its abiotic components

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biosphere

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all of earths communities combined

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food web

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complex of interconnected food chains in an ecosystem

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pyramid of numbers

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illustrates how many organisms there are in each trophic level

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pyramid of biomass

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quantitative estimate of the amount of living material at each level

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pyramid of energy

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can never be inverted

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gross primary productivity

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rate at which energy is captured during photosynthesis

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net primary productivity

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energy that remains in plant tissues after cellular respiration

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biological magnification

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increase in concentration as a toxin passes through successive levels of the food web

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five steps of nitrogen cycle

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nitrogen fixation, nitrification, assimilation, ammonification, denitrification

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two abiotic factors that most affect organisms

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water and temperature

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rain shadows

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dry lands on the sides of mountains away from the prevailing wind

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greenhouse effect

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warming of the earth resulting from the retention of atmospheric heat caused by the build up of certain gases, especially carbon dioxide

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threatened species

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species whose population is low enough for it to be at risk of becoming extinct

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biological diversity

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the number and variety of living organisms

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extinction

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the disappearance of a species from a given habitat

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greenhouse gases

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carbon dioxide, methane, nitrous oxide, CFCs, and ozone

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artificial insemination

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a method of controlled breeding in zoos

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in situ conservation

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efforts to preserve biological diversity in the wild

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subsistence agriculture

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production of enough food to feed oneself and ones family

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endangered species

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species whose numbers are so severely reduced that it is an iminent danger of becoming extinct

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ozone

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the layer in the upper atmosphere that helps shield the earth from damaging ultraviolet radiation

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symbiosis

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intimate relationship between two or more organisms of different species

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mutualism

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symbiotic relationship in which both partners benefit from the association

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commensalism

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symbiosis in which one organism benefits and the other is neither harmed nor helped

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parasitism

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symbiotic relationship in which one member (parasite) benefits and the other (host) is adversely affected

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oceanic province

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the part of open ocean that overlies an ocean bottom deeper than 200m

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neritic province

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ocean water that extends from the shoreline to where the bottom reaches the depth of 200m

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stratospheric ozone

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absorbs 99% of incoming ultraviolet radiation, shielding earths surface