lecture 13 Flashcards
what does the assumption no I or E mean?
the population is closed, changes in population depend only on local births
what does the constant b and d assumption mean?
if a population is going to grow with constant birth and death rates an unlimited supply of space food and other resources is required
what does the assumption all individuals are the same mean?
no genetic structure, or if there is, the genetic structure must be the same through time
what does the assunmption no age or size or sex structure mean?
no differences in b and d among individuals due to their age or body size or sex
what does the assumption continuous growth with no time lags mean?
individuals are being born and dying continuously and the rate of increase change instantly as a function of the current population size
what is density dependent growth?
the per capita brith abd death rates are dependent on the density of the population
what happens if the population density is equal to k?
birth and death rates are the same, population won’t change
what will happen if the population density is above k?
population will shift backwards, death rate increases, population decreases
what will happen if the population density is below k?
population will shift forwards towards k, birth rate increases, population increases
why does density dependence occur?
at high density:
- intraspecific competition (resource limitation, competition for space, food, resources)
- predation or pathogens
where is the per capita growth rate the highest?
at r max
what are the assumptions of logistic growth?
- contant carrying capacity
- linear density dependence
- no immigration or emmigration
- individuals are identical
- changes in density effects per capita rates instantaneously
what is the allee affect?
at low densities the per capita growth rate can increase as a function of density
what causes the allee affect?
- mate limitation
- limits cooperation
- plants not attracting enough pollinators
