Zusammenfassung der Ressource
Variation in population size
- Population size - number of individuals in a population
- Population density - the
number of individuals
per unit area
- Population growth - a
change in the number of
individuals
- Population growth rate - the
change in number of
individuals per unit time
- S-shaped population growth curves
- the population growth curve
of a population colonizing a
new habitat in which
conditions are intially ideal
has an s shape
- Phase 1; Slow growth
- Phase 2; exponential growth
- Phase 3; decelerating growth
- Phase 4; population stabilizers
- Enviromental factors that limit popualtion size
- Density dependant factors - as the
popualtion density increases,
density-dependant factors affect a
larger proportion of the population.
they are usually biotic and include
intraspecific competition for space
and other resources, availability of
food, disease, and preditation
- Density-independant factors - these
facotrs affect the same proportion of the
population no matter how great its
density. they are usually abiotic. the most
important are weather and climate