2. Population:
A population is a summation of all
the organisms of the same group or species,
which live in the same geographical area, and
have the capability of interbreeding.
In sociology, population refers to a collection
of humans.
Demography is a social science which entails
the statistical study of human populations.
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4. Population ecology
Population ecology: is the study of these and
other questions about what factors affect
population and how and why a population
changes over time. Population ecology has its
deepest historic roots, and its richest
development, in the study of population growth,
regulation, and dynamics, or demography.
Human population growth serves as an
important model for population ecologists, and
is one of the most important environmental
issues of the twenty-first century.
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5. Factors affecting population size
The only factors that can alter population sizes are:
births
Deaths
Immigration
Emigration
Births and immigration add individuals to a population
whereas deaths and emigration remove individuals
from a population. When more individuals are being
added to a population than are being removed, the
population increases in size.
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7. Factors affecting population growth rates
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Population growth rates are affected by interactions with
both the abiotic and biotic environment.
Climactic factors such as precipitation and temperature can
have profound direct and indirect effects on population
sizes. Temporal fluctuations in abiotic conditions can be
important causes of variation in population sizes.
Biotic factors such as competition and predation can directly
and indirectly affect population sizes. Population dynamics
can be influenced by interactions with members of their
own species (e.g., intraspecific competition) and members
of different species (e.g., interspecific
competition,predation, and mutualism).
