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. |