Population and Community Ecology
Terms
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- K-selection
- The concept that in certain (K-selected) populations, life history is centered around producing relatively few offspring that have a good chance of survival.
- Integrated hypothesis
- The concept, put forth by F.E Clements, that a community is an assemblage of closely linked species, locked into associated by mandatory biotic interactions that cause the community to function as an integrated unit, a sort of super organism.
- Zero population growth
- A period of stability in population size, when the per capita birth rate and death rate are equal.
- Host
- The larger participant in a symbiotic relationship, serving as home and feeding ground to the symbiont
- Herbivory
- An interaction in which an herbivore eats parts of a plant or alga
- Logisitic population growth
- A model describing population growth that levels off as population size approaches carrying capacity.
- Ectoparasite
- A parasite that feeds on the external surface of a host
- Keystone species
- A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche.
- Semelparity
- A life history in which adults have but e a single reproductive opportunity to produce large numbers of offspring, such as the life history of the Pacific salmon; also known as semelparity.
- Dominant species
- Those species in a community that have the highest abundance or highest biomass. These species exert a powerful control over the occurrence and distribution of other species.
- Population dynamics
- The study of how complex interactions between biotic and abiotic factors influence variations in population size.
- Predation
- An interaction between species in which one species, the predator, eats the other, the prey.
- Intermediate disturbance hypothesis
- The concept that moderate levels of disturbance can foster greater species diversity than low or high levels of disturbance.
- Dynamic stability hypothesis
- The idea that long food chains are less stable than short chains.
- Reproductive table
- An age-specific summary of the reproductive rates in a population.
- Ecological footprint
- A method of using multiple constraints to estimate the human carrying capacity of Earth by calculating the aggregate land and water area in various ecosystem categories appropriated by a nation to produce all the resources it consumes and to absorb all the waste it generates.
- Ecological niche
- The sum total of a species' use of the biotic and abiotic resources in its environment.
- Evapotranspiration
- The evaporation of water from soil plus the transpiration of water from plants.
- Age structure
- the relative number of individuals of each age in a population
- Life expectancy at birth
- The predicted average length of life at birth.
- Emigration
- The movement of individuals out of a population.
- Parasitoidism
- A type of parasitism in which an insect lays eggs on or in a living host; the larvae then feed on the body of the host, eventually killing it
- Life tables
- table of data summarizing mortality in a population.
- Species-area curve
- The biodiversity pattern, first noted by Alexander von Humboldt, that illustrates that the larger the geographic area of a community, the greater the number of species.
- Resource partitioning
- The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species
- Commensalism
- A symbiotic relationship in which one organism benefits but the other is neither helped nor harmed.
- Metapopulation
- A subdivided population of a single species.
- Species diversity
- The number and relative abundance of species in a biological community.
- Mark-recapture method
- A sampling technique used to estimate wildlife populations.
- Mullerian mimicry
- mutual mimicry by two unpalatable species
- Invasive species
- A species that takes hold outside of its native range; usually introduced b y humans.
- Carrying capacity
- The maximum population size that can be supported by the available resources, symbolized as K.
- Interspecific competition
- Competition for resources between plants, between animals, or between decomposers when resources are in short supply
- Parasite
- An organism that benefits by living in or on another organism at the expense of the host
- Density independent
- Referring to any characteristic that is not affected by population density.
- Coevolution
- The mutual evolutionary influence between two different species interacting with each other and reciprocally influencing each other's adaptations.
- Top-down model
- A model of community organization in which predation controls community organization because predators control herbivores, which in turn control plants, which in turn control nutrient levels; also called the trophic cascade model.
- Trophic structure
- The different feeding relationships in an ecosystem, which determine the route of energy flow and the pattern of chemical cycling.
- Exponential population growth
- The geometric increase of a population as it grows in an ideal, unlimited environment.
- Biomass
- The dry weight of organic matter comprising a group of organisms in a particular habitat.
- Facilitators
- A species that has a positive effect of the survival and reproduction of other species in a community and that contributes to community structure.
- Nonequilibrium model
- The model of communities that emphasizes that they are not stable in time but constantly changing after being buffeted by disturbances.
- Community
- All the organisms that inhabit a particular area; an assemblage of populations of different species living close enough together for potential interaction.
- Redundancy model
- The concept, put forth by H.A Gleason and Brian Walker, that most of the species in a community are not tightly coupled with one another (that is, the wbe of life is very loose). According to this model, an increase or decrease in one species in a community has little effect on species in a community has little effect on other species, which operate independently.
- Demography
- The study of statistics relating to births and deaths in populations
- Bottom-up model
- A model of community organization in which mineral nutrients control community organization because nutrients control plant numbers, which in turn control herbivore numbers, which in turn control predator numbers.
- Terriotiality
- The study of statistics relating to births and deaths in populations
- Primary succession
- A type of ecological succession that occurs in a virtually lifeless area, where there were originally no organisms and where soil has not yet formed.
- Batesian mimicry
- A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators
- Pathogen
- A disease-causing agent.
- Individualistic hypothesis
- The concept, put forth by H. A. Gleason, that a plant community is a chance assemblage of species found in the same area simply because they happen to have similar abiotic requirements.
- Aposematic coloration
- The bright coloration of animals with effective physical or chemical defenses that acts as a warning to predators
- Character displacement
- The tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species.
- Energetic hypothesis
- The concept that the length of a food chain is limited by the inefficiency of energy transfer along the chain.
- Ecological succession
- Transition in the species composition of a biological community, often following ecological disturbance of the community; the establishment of a biological community in an area virtually barren of life.
- Secondary succession
- A type of succession that occurs where an existing community has been cleared by some disturbance that leaves the soil intact.
- Cohort
- A group of individuals of the same age, from birth until all are dead.
- R-selection
- The concept that in certain (r-selected) populations, ahigh reproductive rate is the chief determinant of life history.
- Ecological capacity
- The actual resource base of a country
- Competitive exclusion
- The concept that when populations of two similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population
- Species richness
- The number of species in a biological community
- Infant mortality
- The number of infant deaths per thousand life births.
- Demographic transition
- A shift from zero population growth in which birth rates and death rates are high to zero population growth characterized instead by low birth and death rates.
- Iteroparity
- A life history in which adults produce large numbers of offspring over many years; also known as repeated reproduction.
- Rivet model
- The concept, put forth by Paul and Anne Ehrlich, that man or most of the species in a community are associated tightly with other species in a web of life. According to this model, an increase or decrease in one species in a community affects many other species.
- Mutualism
- A symbiotic relationship in which both participants benefit.
- Relative abundance
- Differences in the abundance of different species within a community.
- Density dependent
- Referring to any characteristic that varies according to an increase in population density
- Density
- The number of individuals per unit area or volume.
- Population ecology
- The study of populations in relation to the environment, including environmental influences on population density and distribution, age structure, and variations in population size.
- Endoparasite
- a parasite that lives within a host
- Biomanipulation
- A technique for restoring eutrophic lakes that reduces populations of algae by manipulating the higher-level consumers in the community rather than by changing nutrient levels of adding chemical treatments.
- Immigration
- The study of statistics relating to births and deaths in populations
- Population
- A localized group of individuals that belong to the same biological species (that are capable of interbreeding and producing fertile offspring).
- Surviviorship curve
- A plot of the number of members of a cohort that are still alive at each age; one way to represent age-specific mortality.
- Dispersion
- The pattern of spacing among individuals on both extremes of a phenotypic range over intermediate phenotypes.
- Food webs
- The elaborate, interconnected feeding relationships in an ecosystem.