AP Bio Unit 8

Ecology

Population ecology

Organisms of the same species in a given area

Size of population depends on

availability of reousrces

When energy availability changes

Adaptations may aid survival

• examples

• deciduous trees shed leaves when daylight period decreases

• migration

• fat storage

Effect of Density on populations

• Population growth is influenced by two types of factors

  • Density-dependent factors

  • Density-independent factors

Density-dependent factors

• territoriality

• resource abailability

• predation

• disease

Density-independent factors

• natural disasters

  • fires

  • floods

  • volcanic activity

  • pollution

Population Dispersal

• Uniform

• Clumped

• Random

Mark- Recapture Assumptions

• method of estimating population size

• marked individuals are just as likely to survive as unmarked individuals

• births and deaths do not occur in significant numbers between time of release and recapture

• marked individuals mix randomly with unmarked individuals

• immigration/emigration

• marked individuals are neither easier or harder to catch the second time

• marks dont come off

Species Richness/Species Evenness (aka Relative Abundance)

Simpson’s Diversity Index

• D = Diversity

• N = total number of individuals

• n = numbers of each different species (relative abundance of each species)

• Diveresity indenx = 1 - sigma (n/N)²

• D = 1, the most diversity possible

• D = 0, complete uniformity

Biodiversity tends to be high in

• old growth forests

• rainforests