Population Regulation

carrying capacity, limited resources, predation, disease, environmental disturbances

carrying capacity, limited resources, predation, disease, environmental disturbances

what controls populations?

yes

does abundance vary from place to place?

limited resources

So what prevents unlimited increase in the high and low density populations?

births and deaths

what is equal at carrying capacity?

if both birth and death rates are density independent

when is there no carrying capacity and equilibrium point?

Kreb’s 1st principle of population regulation

at least one of birth and death rate must be density dependent for there to be closed population to stop growing

Kreb’s 2nd principle of population regulation

Differences between two populations in equilibrium density can be caused by
variation in either density-dependent or density-independent per capita birth and death rates

limiting factor

change in the factor changes equilibrium density

potential regulating factor

percentage mortality increases with population density (or reproduction decreases)

compensation

Change in one factor produces the opposite change of identical magnitude in another factor

unchanged

With the combined effects of compensation, the population remains __________

intrinsic factors

internal to a population; affect population by interactions between individuals in it

extrinsic factors

affect a population by the action of other species, outside factors such as climate, nutrients, etc.

environment, disease

what factors may promote instability ina population?

stochastic domination

negative events that may occur and often decrease the population size

Allee Effect

a population crashes when it is very low

there is no longer the highest growth at lowest populations, makes highest growth int he middle

how does an Allee effect contrast normal density-dependent growth

compensatory mortality

Because of this, predation may not affect pop growth rate at all, up to a point

rare plants that require cross pollination, passenger pigeons

example of allee effect

metapopulation

group of small local subpopulations linked together by dispersal over the landscape

yes

can subpopulations within a metapopulation have different lambda values?

stable over whole landscape but unstable on single islands

where is the CA butterfly population stable vs unstable?

distance and suitability of habitat

what variables play a role in the island colonization of CA butterflies?

sink population

b < d
• net loss of individuals

source population

b > d
• net production of individuals