Please enable JavaScript.
Coggle requires JavaScript to display documents.
Population (Methods for Quantifying (putting a number to) population size,…
Population
Methods for Quantifying (putting a number to) population size
Total census
when you count every single individual, used for large animals, humans, and trees.
Lincoln method
Mark and recapture method, used for small, mobile organisms
N=nM (num/nm)
N=population size, nM=number of individuals marked and released at first catch. nm=number of individuals caught in second catch that were marked from first catch. num=Number of unmarked individuals at second catch
Quadrant/transect method
Uses a grid pattern to measure small sessile, or territorial organisms populations
growth
exponential (or geometrical) growth curve shows the growth rate in an unlimited environment
as population size increases, rate of population also increases
Not realistic. This would have to be perfect conditions, and this state of growth will not last long.
Circumstances for exponential growth
favorable environments
low population densities in the beginning
Area in recovery or recently disturbed
Lacking much competition
Factors affecting population growth
birth
immigration
death
emigration
Factors that slow population growth
Density-independent factors (abiotic)
Density dependent factors (biotic)
also includes type of competition (Inter or intra)
Logistic population growth shows the growth rate when it slows and eventually stops
When K=N, growth will stop
K=carrying capacity, N=population size
When N=K/2, The poulation growth is the highest
important definitions or ideas that don't really fit anywhere
Deme
a local group of individuals that mate at random, the unit within which evolution occurs
Maximum yield is obtained from populations at less than maximum density
Harvesting less than maximum yields helps to avoid population crashes
Population models are usually too simple. Stochasticity (Random variation) disrupts equilibrium
evolutionary approach
A population is a local group of individuals that mate at random
The boundaries are determined by the barriers to mating and gene flow.
ecological approach
A population is a group of individuals that occupy a defined area
The boundaries are determined only by ecologically relevant change in the environment
Definition
A group of individuals
of a single species
inhabiting a particular
area
Boundaries (Distribution across the landscape
Determined by demographics
The number of individuals
Spatial distribution
reproductive rate
isolation vs. connectivity