2.1: Population Flashcards
What is a population?
A population is a group of individuals of the same species living in a specific area at the same time.
Define population density.
Population density is the number of individuals of a species per unit area or volume.
Define population distribution.
Population distribution refers to how individuals in a population are spaced across a given area.
What is clumped distribution?
Clumped distribution is when individuals in a population are grouped together in patches, often around resources.
What is uniform distribution?
Uniform distribution is when individuals are evenly spaced due to interactions like territorial behavior or competition.
What is random distribution?
Random distribution is when individuals are spread unpredictably across an area, often occurring when environmental conditions are consistent and resources are evenly available.
Why might populations exhibit clumped distribution?
Clumped distribution often occurs in environments where resources are unevenly distributed, or social species benefit from being near others.
Why might populations exhibit uniform distribution?
Uniform distribution occurs when individuals compete for resources or space, such as in territorial species where spacing minimizes competition.
Why might populations exhibit random distribution?
Random distribution can occur in habitats with evenly distributed resources and no strong social interactions or competition among individuals.
Calculate population density:
A 50-acre forest contains 200 deer. What is the population density?
Population density = 200 deer ÷ 50 acres = 4 deer per acre.
How do you calculate population size using the quadrat method?
- Divide the area into quadrats.
- Count the number of individuals in several quadrats.
- Calculate the average number of individuals per quadrat.
- Multiply the average by the total number of quadrats.
A researcher samples 10 quadrats, each 1 square meter in size. She counts an average of 3 plants per quadrat. The total area is 100 square meters. Estimate the population size of the plants in the area.
Population size = (Average number per quadrat) × (Total area ÷ Quadrat size)
= 3 plants × (100 ÷ 1)
= 300 plants.
How do you calculate population size using the mark and recapture method?
- Capture and mark a sample of individuals.
- Release them back into the population.
- Recapture another sample.
- Use the formula:
Population size = (Number of marked individuals × Total number in second sample) ÷ Number of recaptured marked individuals.
In a mark and recapture study, 50 fish are captured and marked. Later, 100 fish are recaptured, 10 of which are marked. Estimate the population size.
Population size = (50 × 100) ÷ 10 = 500 fish.
