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ENVIRONMENTAL STUDY
CHAPTER 7 - POPULATIONS: CHARACTERISTICS AND ISSUES *
| Question | Answer |
|---|---|
| population | a group of individuals of the same species occupying a given area |
| natality | the number of individuals added to the population through reproduction |
| birthrate | the number of individuals born per thousand individuals in the population per year |
| mortality | the number of deaths per year |
| death rate | the number of deaths per thousand individuals in the population declining |
| survivorship curve | a graph that shows the proportion of individuals likely to survive to each age |
| population growth rate | the rate at which additional individuals are added to the population; the birthrate minus the death rate |
| sex ratio | comparison between the number of males and females in a population |
| age distribution | the comparative percentages of different age groups within a population |
| population density | a measure of how close organisms are to one another, generally expressed as the number of organisms per unit area |
| dispersal | migration of organisms from a concentrated population into areas with lower population densities |
| emigration | movement out of an area that was once one’s place of residence |
| immigration | movement into an area where one has not previously resided |
| biotic potential | living portions of the environment |
| lag phase | the initial stage of population growth during which growth occurs very slowly |
| exponential growth phase (log phase) | the period during population growth when the population increases at an ever-increasing rate |
| deceleration phase | a part of the population growth curve in which the rate of population increase begins to decline |
| stable equilibrium phase | the phase in a population growth curve in which the death rate and birthrate become equal |
| limiting factors | the primary condition of the environment that determines the population size for an organism |
| environmental resistance | the combination of all environmental influences that tend to keep populations stable |
| extrinsic limiting factors | factors that limit population size and that come from outside the population |
| intrinsic limiting factors | factors that limit population size that come from within the population |
| density-dependent limiting factors | those limiting factors that become more severe as the size of the population increases |
| density dependent limiting factors | those limiting factors that are not affected by population size |
| death phase | the portion of the population growth curve of some organisms that shows the population declining |
| carrying capacity | the optimum number of individuals of a species that can be supported in an area over an extended period of time |
| k-strategies | large organisms that have relatively long lives, produce few offspring, provide care for their offspring, and typically have populations that stabilize at the carrying capacity |
| r-strategists | typically, a small organism that has a short life span, produce a large number of offspring, and does not reach a carrying capacity |
Created by:
Jessica C
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