Topic 11 - Population Growth Flashcards
Population
All of the individuals of a given species that live
and reproduce in a particular place
Population size
number of individuals
alive at a particular time in a particular place
What is population size influenced by
births deaths immigration and emigration (we ignore migration)
When does the exponential model of population growth occur
under ideal conditions - assuming unlimited resources
explain the exponential model of population growth
Under ideal conditions
1. per capita growth rate (r) will be at a maximum
2. rmax is always constant and positive
3. rmax varies by species
what is r max
the intrinsic rate of increase
In the exponential growth model, when will the population reach a maximum?
exponential growth curve never reaches a maxima
What factors limit population growth
Temperature, precipitation, predators, disease, food availability, etc
What is carrying capacity (K)
most environments can only support a certain population size
factors that limit population growth combine to determine K
How close the population size is to the carrying capacity can change
as N goes to K, the growth rate will decreases (less resouces/individual available)
In logistic population growth, what is the predicted effect of N on r
As N (population size) increases, r (per capita population growth) decreases
In the logistic model, how does population size change over time
as populations grow, death rates increase, birth rates decrease
r decreases as N increases towards k
What density-dependent factors is population growth influenced by?
Biotic factors - food availability, shelter, mates, predation, disease
What effect do density-dependent factors have on population growth
they have an increasing affect as N becomes large
