Relative Density
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What is relative density?
The representation of some relatively constant but unknown relationship to the total population size.
Provide an example of what you could use to find relative density.
• roadside counts • fecal pellates • pelt records • vocalization frequency
What are the four parameters of relative density?
• natality • mortality • immegration • emmigration
Define natality
The production of new individuals by birth, hatching, germination, or fission.
Define fecundity
An organism’s physiological potential reproductive capacity.
Provide an example of potential fecundity.
One female salamander may lay several hundred eggs per year.
Define fertility
The ecological potential, number of viable young produced during a period of time.
Provide an example of realized fertility.
The same female salamander (hundreds of eggs laid) may sire 30 young during a two year period.
Define mortality
Deaths, why organisms die and how others avoid it (survive).
Define longevity
Age of death of individuals within a population.
Define potential longevity
The maximum lifespan as set by physiology (old age, usually obs. in lab)
Define realized longevity
Lifespan following disease, predation, or other natural hazard, usually in field.
Provide an example of potential vs realized longesvity.
• Great Horned Owls live 30-40 years in captivity, but only 7-10 in the wild. -lifespan of females compared to Rome vs today
Define immigration and emigration
movement into and out of populations
Why is dispersal important?
• prevents inbreeding. • limits geographical distribution. • affects community composition. • some areas are sources, others sinks. • data collected with radio transmitters. • more difficult if small animal moves long distance.
If you cannot control dispersal, then what do you do?
Measure it.