Chapter 14 - Ecology Of Populations And Communities

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ecology of populations and communities

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the study of how groups of organisms are distributed in a particular area at a particular time and how they interact with other species coexisting in the same locale

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zero population growth

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in a population, the number of individuals gained is exactly equal to the number lost

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survivorship curve

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a plot of the data representing the proportion of a population that survives to a certain age

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late-loss survivorship curve

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a plot of survivorship data indicating that an organism’s life expectancy decreases with each passing year

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early-loss survivorship curve

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a plot of survivorship data indicating that most individuals in a population die young

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life expectancy

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the maximum probably age an individual will reach

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fertility curve

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generally, a graph that plots reproduction rate versus the age of female population members

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biotic potential

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an organism’s capacity for reproduction under ideal conditions of growth and survival

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J-shaped curve

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a plot of population growth with an upsweeping curve that represents exponential growth

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exponential growth

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growth of a population without any constraints; hence, the population will grow at an ever-increasing rate

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S-shaped curve

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a plot of population growth with a flat section, a steeply rising section, and then a leveled off section that represents logistic growth

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logistic growth

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growth of a population under environmental constraints that set a maximum population size

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carrying capacity

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the density at which growth of a population ceases due to the limitation imposed by resources

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life history strategy

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the way an organism allocates energy to growth, survival, or reproduction

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Agricultural Revolution

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the transition of a group of people from an often nomadic hunter-gatherer way of life to a usually more settled life dependent on raising crops, such as wheat or corn, and on livestock; it was under way in the Middle East by 8000 years ago

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Industrial Revolution

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the replacement of hand tools with power-driven machines (like the steam engine) and the concentration of industry in factories beginning in England in the late 18th century

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demographic transition

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a changing pattern from a high birth rate and high death rate to a low birth rate and low death rate

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age structure

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the number of individuals in each group of a given population

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habitat

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the physical place within a species’ range where an organism actually lives

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niche

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the role, function, or position of an organism in a biological community

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fundamental niche

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the potential range of all environmental conditions under which an organism can thrive

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realized niche

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the part of the fundamental niche that a species actually occupies in nature

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interspecific competition

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competition for resources—e.g., food or space—between individuals of different species

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competitive exclusion

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a situation in which one species eliminates another through competition

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predator

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an organism, usually an animal, that obtains its food by eating other living organisms

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prey

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living organisms that are food for other organisms

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predation

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the act of procurement and consumption of prey by predators

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camouflage

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body shapes, colors, or patterns that enable an organism to blend in with its environment and remain concealed from danger

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chemical warfare

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a defense strategy of prey species in which these organisms produce distasteful oils or other toxic substances that kill or harm predators

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mimicry

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the evolution of similar appearance in two or more species, which often gives one or all protection; for example, a nonpoisonous species may evolve protection from predators by its similarity to a poisonous model

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parasite

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a type of predator that obtains benefits at the expense of another organism, its host; a parasite is usually smaller than its host, lives in close physical association with it, and generally saps its host’s strength rather than killing it outright

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commensalism

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a relationship between two species in which one species benefits and the other suffers no apparent harm

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mutualism

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a symbiotic relationship between two species in which both species benefit

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succession

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the process through which a regular progression of communities will regrow at a particular site

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pioneer community

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the species that are first to colonize a habitat after a disturbance such as fire, plowing, or logging

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transition community

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a community of organisms that establish themselves at a particular site based upon conditions produced by the activities of the pioneer community

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climax community

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the most stable community in a habitat and one that tends to persist in the absence of a disturbance

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species richness

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the total number of species in a community