20.1- Flashcards
formula for population density
D= NA (n= #organisms a= area)
3 patterns for distribution
1) Uniform
2)Random
3)Clumped
Uniform=
even distribution
eg- agriculture
Random distribution occurs where…
resources are abundant and there’s little competition
Clumped=
organisms grouped together in certain areas
4 factors affecting population growth
Birth, death, immigration, emigration
birth rate is AKA
Natality
Death rate is aka
mortality
formula for calculating population growth
^N= (b+i) - (d+e)
growth rate formula is
gr= ^N/^t
Growth rate=
change in population over time
population explosion=
rapid increase in population that happens too fast to be contained
population crash=
rapid decrease in population
per Capita GR (cgr) takes into account…
initial population size
per Capita cgr=
^N/N= Nf-Ni/N
Biotic potential (r)=
The highest possible per Capita GR
Biotic potential is AKA ___
exponential growth
Different species have ____ exponential growth
different
Factors affecteing biotic potential (5)
1) # of offspring per reproductive cycle
2)# of offspring to reach reproductive age
3) Age of reproductive maturity
4) # of times and individual reproduces
5) Life span of individuals
lag phase=
low population growth due to few organisms able to reproduce
exponential growth phase=
rapid increase in population due to an increase in birth rates compared to death rates
why cant exponential growth continue forever
competition and limiting factors slow growth
stationary phase=
birth and death rates are equal
Logistical GR results in ____
an S shaped graph
Carrying capacity (k)=
theoretical maximum for a stable population
Density dependent factors=
biotic factors that limit carrying capacity
eg- predators, parasites, disease
Density independent factors=
abiotic factors that limit carrying capacity as well as growth regardless of population size
eg. floods, drought, fires
environmental resistance=
total effect of all limiting factors preventing a population from growing at its biotic potential
characteristics of r- selected (5)
short life span
small in size
early reproduction age
many offsrpring
affected by density- dependant factors
characteristics of k- selected
Larger animals, slow reproduction rates, longer life span, fewer offspring, affected by density- dependant factor
open populations _____ but closed populations have _____
allow immigration
no immigration
