limitation to population growth
TRANSCRIPT
LIMITATION TO POPULATION
GROWTH Presented by: JOHN FLORENTINO E. ECHON
MAEd-GenSci
Bataan Peninsula State University Main CampusBALANGA CITY, PHILIPPINES
ECHON, JOHN FLORENTINO E.Environmental Science
ECHON, JOHN FLORENTINO E.Environmental Science
Limiting FactorIn the context of populations, a limiting factor is a factor that causes population growth to decrease.
ECHON, JOHN FLORENTINO E.Environmental Science
Density-dependent and
Density-independent
Population density describes the number of individuals in a given
area.
Two types of limiting factors
ECHON, JOHN FLORENTINO E.Environmental Science
A limiting factor that depends on population size is called a density-dependent limiting factor.
Density-Dependent Factors
ECHON, JOHN FLORENTINO E.Environmental Science
Density-dependent limiting factors include:• competition• predation• parasitism• disease
ECHON, JOHN FLORENTINO E.Environmental Science
When populations become crowded, organisms compete for food, water space, sunlight and other essentials.
Competition among members of the same species is a density-dependent limiting factor.
Competition
ECHON, JOHN FLORENTINO E.Environmental Science
Populations in nature are often controlled by predation.The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control.
Predation
ECHON, JOHN FLORENTINO E.Environmental Science
Parasites can limit the growth of a population.A parasite lives in or on another organism (the host) and consequently harms it.
Parasitism and Disease
ECHON, JOHN FLORENTINO E.Environmental Science
Density-dependent factors operate only when the population density reaches a certain level. These factors operate most strongly when a population is large and dense.They do not affect small, scattered populations as greatly.
Remember
ECHON, JOHN FLORENTINO E.Environmental Science
Density-independent limiting factors affect all populations in similar ways, regardless of the population size.
Density Independent Factor
ECHON, JOHN FLORENTINO E.Environmental Science
Examples of density-independent limiting factors include:• unusual weather• natural disasters• seasonal cycles• certain human activities—such as damming rivers and clear-cutting forests
ECHON, JOHN FLORENTINO E.Environmental Science
Density-dependent limiting factors
Density-independent limiting factors
Are usually biological in nature (competition, disease, predation).
Are usually physical in nature (hard winters, failure of rainy season).
Are more important for large organisms (which are buffered from physical environment).
2. Are more important for small organisms, because small organisms are not as well buffered against physical environment.
Are more important in physically benign and constant environments.
Are more important in extreme or highly seasonal environments than in mild, stable environments.
Can interrupt exponential growth or cause declines, and CAN regulate a population near a stable population size.
Can interrupt exponential growth or cause declines, but cannot regulate a population at a stable population size.
Let’s Compare
ECHON, JOHN FLORENTINO E.Environmental Science
Thank You for Listening
References: • highered.mheducation.com/sites/dl/free/.../
ch17_Concept_Review.doc
• http://study.com/academy/lesson/the-limiting-factors-of-population-growth.html
http://www.nhptv.org/natureworks/nwep12a.htm