Download Concept Review

Concept Review
Dynamics of Population Growth













All the members of a species living in an area at the same time form a
population.
Unrestricted increase in population size is exponential growth.
A graph of exponential population growth appears as a J curve.
Biotic potential refers to population growth if there are no interfering
factors.
The Rule of 70 is used to determine the approximate doubling time of a
population.
Carrying capacity is the maximum number of individuals an ecosystem
can support.
Populations may experience oscillating cycles of population growth and
decline.
Some species regulate population growth according to the supply of
resources.
A logistic growth curve, which appears as an S, or sigmoid, illustrates
population size limited by resource availability.
Organisms with a high rate of reproduction followed by a high mortality
rate are described as r-adapted species.
Organisms with exponential growth patterns are generalists, depending
upon quantity of numbers to ensure survival of some.
Organisms that reproduce more slowly as the population approaches
carrying capacity are K-adapted species.
Organisms that are K-adapted produce fewer offspring, are larger in size,
and live longer.
Factors That Increase or Decrease Populations










Successful reproduction is dependent upon nutrition, climate, soil, and
water conditions.
Fecundity is the physical ability to reproduce.
Fertility is a measure of the number of offspring produced.
Natality is the production of new individuals.
Mortality is the death rate of a population.
Major factors in mortality include predation, disease, accidents, and
environmental influences.
Life expectancy is a measure of the number of years an individual can be
expected to live.
The longest period of time an organism reaches is its life span.
The maximum life span for humans is 120 years.
Life span can be divided into three stages—dependency, reproductive,
and postreproductive

Population size may be reduced through emigration—a dispersal
mechanism.
Factors That Regulate Population Growth





Abiotic factors affect population growth independent of the population’s
density.
Natural disasters, weather, and climatic change over a period of time are
density-independent factors.
Biotic factors affect population growth in a manner that is dependent upon
the density of the population.
Predator-prey relationships and territoriality are biotic factors that are
density-dependent.
Stress and crowding affect the rate of reproduction in dense populations.
Conservation Biology





The minimum viable population size is the number of individuals needed
for long-term survival of a population.
Islands that are closer to the mainland will have larger populations and
greater diversity than islands farther away.
If there are only a few individuals in a population, genetic diversity will be
limited—the founder effect.
As individuals from a population migrate to new areas, the genetic
makeup of the population changes—genetic drift.
Populations that are geographically isolated from each other but have
intermittent gene flow between them form metapopulations.