Chapter 36 Population Ecology Flashcards
(29 cards)
What is a population?
Group of individuals that belong to a single species that occupies the same geographical area where they can interact
What factors decide whether a group of individuals is a population or not?
- Individuals must consist of the same species
- They must live in an area where they can interact
- Mate with one another
- Affected by the same biotic and abiotic factors
- Rely on the same resources such as food sources
What is the study of population ecology?
Study how populations grow, shrink and respond to environment factors over time
How do populations grow?
Birth and immigration (moving in)
How do populations shrink?
Deaths and emigration (moving out)
What are the two important aspects of a population structure?
- Population density
2. Dispersion pattern
What is population density?
Number of individuals living in a unit area or unit volule
What are some examples of population density?
- Number of oak trees per square kilometer
2. Number of earth worms living in a square meter of soil
How is population density measured?
Sampling the population and estimating the density
What is population dispersion pattern?
The way the individual organisms of a population are spaced out in the area they live in
What are the dispersion patterns?
- Clumping
- Uniform dispersion pattern
- Random dispersion pattern
What is clumped dispersion pattern?
Individuals are grouped in patches
What usually drives clumping in populations?
Unequal resource availability in the environment of the population. Organisms clump closer to the places where resources are available and plentiful
Give an example for clumped dispersion patterns?
Sea stars crowd places where food is plentiful
People crowd cities where employment is plentiful
What is Uniform dispersion pattern?
Organisms in a population are dispersed evenly within the environment
What drives uniform dispersion pattern?
Interaction between individuals
Give some examples for uniform dispersion patterns?
- Some trees secrete toxic chemicals to prevent other trees of the same species from taking root closer to it so that other trees would not compete for the same resources
- Territorial behavior of animals. E.g. Lions
What is random dispersion pattern?
Organisms are dispersed in an unpredictable way
Why is random dispersion rare?
Organisms always react to environment conditions to spread across their environment
Give an example for random dispersion pattern?
Dandelions spreading by wind
What can you say about the human population growth?
It has been growing exponentially from 1500 to today
What is the current estimated human population?
7 billion
Why would a population grow?
Birth rate is higher than death rate (or immigration and birth rate is higher than emigration and death rate)
Why would a population shrink?
Birth rate
