Flash Cards

Ecology of Populations

Term Definition
? Population Group of individuals of the same species occupying a common geographical area
• Population Ecology The study of how populations interact with their environment
• Population Group of individuals of the same species occupying a common geographical area
• Habitat Where a species normally lives
Characteristics of populations Each population has certain characteristics such as population size, population density, population distribution, age structure.
• Population size Number of individuals making up its gene pool
• Population density Number of individuals per unit of area or volume, e.g.persons/square mile
• Population distribution The general pattern in which the population members are dispersed through its habitat, may be: Clumped (most common), Uniformly dispersed (rare), or Randomly dispersed
• Age structure Defines the relative proportions of individuals of each age: Pre-reproductive, Reproductive, and Post-reproductive
• Zero population growth A near balance of births and deaths
• biotic potential The maximum rate of increase under ideal conditions. Few populations live under ideal conditions because a number of factors limit their growth
• Limiting factor Any resource that is in short supply, e.g. food, minerals, light, living space, refuge from predators, etc.
• Carrying capacity Maximum number of individuals of a species or population a given environment can sustain. Each habitat or area can only support so many individuals
• Cohort A group of individuals born at the same time, e.g. baby boomers are a large group of individuals born just after World War II
Life Table An age-specific death schedule
Survivorship schedule For each age interval there is an predicted life expectancy or survivorship
• r-selected organisms Put most of their energy into rapid growth and reproduction–Unpredictable environments (weeds)
• K-selected organisms Put most of their energy into growth–stable environments–(Redwood trees)
Population growth mathematical equation G=rN (G = population growth per unit time, r = rate of increase and N= the number of individuals)
Logistic Growth S shaped curve–(Early on populations will exhibit very rapid growth but as they near the carrying capacity they will level off)
Density dependent The growth of a population is affected by the density of individuals (26 reindeer in 1910–by 1940 2000 reindeer, no food 8 reindeer in 1950)
Density-independent factors Population size and growth may also be controlled by adverse weather, floods, droughts, cold temperatures etc.


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