Unit 5 - Factors that Affect Pop Growth Flashcards
two common growth factors
exponential and logistic
Exponential Growth
this occurs when there r unlimited resources and no competition so the pop skyrockets
Logistic Growth
this starts with exponential growth, but then growth slows as pop increases, resources bc limited and finally the carrying capacity of an ecosystem is reached
carrying capacity (K)
is the maximum pop size that can be sustained in an environment for a long time
Limiting Factor
is a property of a pop environment - living or nonliving controls the process of pop growth
two major limiting factors
1) density-dependent factor
2) density-independent factors
Density Dependent factor
a factor that is influenced by pop density having a greater impact as the pop density increase
Biotic Factors
slow a pop growth as pop nears its carrying capacity. These biotic factors often lead to
- sinusoidal growth patterns where the pop size fluctuates around K
examples of density-dependent factors (4)
1) competition
2) predation
3) disease
4) space limitations
magnitude of these factors is directly proportional to the size of the pop
competition
an interaction in which both competing pop lose access to some resources
two types of competition
1) intraspecific competition
2) interspecific competition
Intraspecific Competition
- within a species
when the pop size is large membranes of the same species compete w each other for:
food
breeding sites
shelter
water
sunlight
soil
nutrients
Interspecific Competition
- between different species
when two diff species share a similar habitat, they can compete for resources. This indicates that the species have similar niches
competitive exclusion principle
leads to the competitive exclusion principle which states that species with the same niche cannot co-exist; one will always exclude the other through evolution. this often leads to a change in the species
Predation
the interaction between predator and prey
lack of prediation
cause problems for the prey pop
without predation
the prey pop can increase rapidly which can lead to a depletion of resources and can increase the risk of disease
Disease in pop
also increases with the density of the pop
- high pop density increases spread of disease
- can have catastrophic effects on a pop, as well as on interacting pop within an ecosystem
density-dependent; crowding (4)
- only occurs in hight-density pop with limited space
- affects growth, size, and survival of individuals in a pop
- grow slowly + small, weak and less likely to live
- increase disease spread
not crowded enough ; allee effect
a density-dependent phenomenon that occurs when a pop cannot survive or fails to reproduce enough to offset mortality once the pop density is too low
minimum viable pop size
is the least number of individuals that ensures the continued existence or a pop for a determined period of time, regardless of environmental change or disaster
drops below minimum
viable pop size, the chance of extinction increases dramatically (size is only a prediction)
density-independent factor
a factor that influences pop regulation, regardless of pop density
density-independent or Abiotic factors…
cause a pop to stop growing or crash long bf the carrying capacity is reached. These factors usually produce sudden dramatic declines in a pop
examples of density-independent or abiotic factors
heat waves, fires, earthquakes, floods, droughts, tornados, ice storms, mudslides
ie.environemtal factores
