Ecology Flashcards
Ecology
- Interactions of organisms with either environment
- Biotic
- Abiotic
Population
group of individuals of single species that occupy the same area
Individuals in a pop
- Rely on the same resources
- influenced by the same environmental factors
- likely to interact and breed with one another
Population ecology
- changes in population size
- factors that regulate populations over time
Populations increase/decrease through
- birth/immigration
- death/emigration
Factors affecting population size
- habitat quality
- habitat quantity
- dispersal patterns
- degree of habitat fragmentation
Population growth model
Nt+1 = Nt + B - D + I - E
- Births
- Deaths
- Immigrants
- Emigrants
Population Growth Model if Pop. closed
Nt+1 = Nt + B - D
∆N = G = B - D
b = births/individual•time
d -
Difference between birth and death rates
r=b-d
Exponential Growh Formula
G=rN
Demographic Transition
- Shift from high birth and death rates to low
- Lowered rate of growth in developed countries
Demographic transition in developing nations
- Death rates dropped, birth rates high
- Pop. growing rapidly
Why can’t populateions increase exponentialy w/o bound?
Resources are limited
Logistic growth includes
Carrying capacity
Logistic growth formula
G=rN(K-N)/K
K-carrying capacity
Carrying capacity
Maximum population size a particular environment can sustain
Density dependence
growth rate slows at high density
Logistic growth predicts
That population growth will slow and eventually stop as pop. density increases
density dependent rates result in
- declining births
- increase in deaths
intraspecific competition
- competition between individuals of same species for limited resources
- is a density-dependent factor that limits growth in natural populations
Factors limiting pop. growth
- Food
- nutrients
- retreats for safety
- nesting sites
community
All species that occur at any particular locality
Species interactions
- Competition
- pathogens
- herbivory
- predation
- parasitism
- mutualism
Competition
When individuals use at some of the same resources and resource use by one individual reduces resources available to other individuals
