Characteristics of Population Flashcards
U5L1 (13 cards)
What is population size?
Population size is generally an estimation of the total number of organisms within a habitat.
What is population density?
It is the number of individuals of one species per unit area.
What are the two methods for measuring P-size and density?
1) Quadrats (good for inanimate species)
2) Mark-Recapture (good for mobile species)
How do Quadrats work?
Quadrats are good for small sample areas.
The population of a species is physically counted in each section of the Quadrat.
The average of these counts and the area of the quadrat is used to make an estimation of the population
What is the formula for Quadrats?
D = Average density
N = total number in Quadrats
A= total area
D = N/A
If you are trying to find the total population number, just rearrange it so it is N = D(A)
Why is mark-recapture sampling used?
In mobile populations (herds), it is very difficult to contain them in things like Quadrats. Because of this, we take a group of the population, mark them, let them loose and recapture some animals from that population after a few weeks.
We find the number of those who we sampled the first time in that pack and with some math we can determine the population.
What is the formula for Mark-Recapture sampling?
M/N = m/n
M = total marked
N = Total population
m = # of recaptures
n = size of second sample
More often then not, you will be looking for N, hence you use this modified version of the formula.
N = Mn/m
What are some ethics to be concerned about with this method?
You gotta make sure that whatever you are using to mark the samples does NOT hinder with their ability to live.
What are the three types of population dispersion?
Clumped, Random and Uniform
What is Clumped Dispersion?
Basically, it is when a group of organisms are clumped together in an area.
It could be the result of a clumped dispersion of resources.
It could also be social behaviour such as travelling in herds for safety or hunting in packs.
What are examples of groups that do Clumped dispersion?
Penguins, Wolf packs and Herds of sheep
What is uniform dispersion?
It is when individuals are evenly distributed throughout the habitat.
Oftentimes, uniform dispersion results from individuals being in competition with eachother for food, nesting or breeding. These species typically set up territories.
Examples include Birds of prey.
What is Random Dispersion?
Random Dispersion is the dispersion of individuals within the habitat. There is no pattern.
Individuals that exhibit random dispersion is usually caused when they are minimally influences by interactions with other individuals.
