5.1 How Populations Grow Flashcards
4 things that describe populations
- Geographic range
- density and distrubution
- growth rate
- age structure
Geographical range is
the area inhabited by a population
can be very small of huge
Population distribution is
how individuals in a pop. are spaced out across the range of the pop.
types of population distribution
randomly, uniform, clumped
Growth rate:
determines whether the size of a pop. increases, decreases or stays the same
Factors that affect population size:
birthrate, deathrate, rate at which individuals lave or enter the pop (immigration and emigration)
In terms of birth and death rate, what leads to a pop growing, falling or staying the same?
Grow: birthrate higher than death
Fall: deathrate higher than birth
Same: equal birth and death
In exponential growth, the larger
a pop gets the faster it grows
Under what will a pop grow exponentially
ideal conditions witah unlimited resources
What kinds of animal populations can expirence exponential growth
both rapidly reproducing animals (bacteria) and slowly reproducing animals (elephants) with ideal conditions
Sometimes when an organism is moved to a new environemnt, its population:
grows exponentially for a time
Phases of growth
- exponential growth- resources are unlimtied, few die
- growth slows down
- growth stops- population growth at 0 sometimes stays this size forever
shape of curve on graph for exponential and logistic growth
j shaped for exponential, s shaped for logistic
once a population reaches carrying capacity factors act to:
stablilize it at that size
Population dynamics:
populations are not static, they are ever changing
Mr. Murano’s slides
Population of species described in what 3 ways
- density (ex: number of fish per gallon of aquarium water)
- spacial distribution (the pattern of spacing of a pop within a given area
- Growth rate (significant role in dynamics of a population of a given species- ex elephants, deer, mosquitos)
Mr Murano’s slides
Spacial distribution of differnet animals
- American black bear: uniform dispersion (1 male per km2, females have smaller territories that overlap w/ male territories)
- American bison: clumped groups called herds
- White tailed deer: dispersped randomly thoughout their habitats (density 10 deer per sq km, higher can result in transmission of communicable disease (EHD-Blue Tongue)
Mr Murano’s slides
No populations, not even humans:
Population Range:
occupy all habitats of the biosphere
* some species like L’iiwee bird have very limited pop range (is endemic to the specific geographical area)
* US peregren falcon on all continents execept antartica
