Dynamics of Population Growth Flashcards
define a population
a group of individuals belonging to one species and living in the same geographical area
What are the 2 types of possible growth for a population?
- unlimited environment
2. actual environment
describe an unlimited environment
one which the inherent power of increase would be realized
describe an actual environment
on which the limited resources prevent the inherent power to be realized
define models
the basic working tools for population ecologists
define population growth models
mathematical models that describe the growth of populations according to certain questions
What are the two types of population growth models?
- exponential growth model
2. logistic growth model
describe exponential growth
the population size increases by a multiplicative factor
the exponential growth model consists of what 2 phases?
lag and acceleration phase
lag phase occurs during
early growth
lag phase results from
the fact that organisms need to adjust to their new environment
What is unlimited and limited in the acceleration phase?
unlimited: environmental resources
limited: organisms physiological capacity to survive and reproduce
the logistic growth model is a modification of
the exponential growth model
K is the
carrying capacity
What are the 4 phases to the logistic growth curve?
- lag phase
- acceleration phase
- deceleration phase
- equilibrium phase
describe the deceleration phase
- decreased growth rate
- decrease birth rate
- increased death rate
the equilibrium phase is reached when..
the environment becomes saturated with individuals
describe the equilibrium phase
birth rate declines and becomes equal to the death rate
What can NOT be predicted by exponential/ logistic models?
fluctuations, oscillations, and crashes
growth of a natural population of organisms is a result of
that organism’s biotic potential
biotic potential is a consequence of?
reproductive factors
6 examples of reproductive factors
- sexual maturity
- # of offspring produced
- # of matings
- gestational period
- nurturing period
- years of fertility
examples of density-DEPENDENT factors
- prey/predator ratio
- food supply
examples of density-INDEPENDENT factors include…
- climate changes
- available cover
what is environmental resistance?
density dependent factors + density independent factors added together
What year will the population reach 8 million?
2022
define growth rate
the # of people born - the # of people that die
define zero population growth
equilibrium between the people that are born and the people that are dying
What factors contributed to the world’s population growth?
advances in medicine, sanitation, and nutrition
What will happen when population exceed the Earth’s carrying capacity?
loss of drinkable water, starvation
Why does a population not level off during the same year that it reaches zero population growth?
b/c of long lives and increased health
