Ecology Flashcards
What is a population?
A group of living things that are the same species that live in the same environment/habitat.
What 4 things characterize a population?
- Size (#/group of species)
- Growth over time
- Density
- Distribution
What’s distribution?
Ask yourself this question: are they all packed together in one spot? Or are they all over the place?
What’s population size?
The total number of individuals in a population.
What 3 things can a population do?
Increase, decrease, or remain the same.
What 4 factors affect the population size?
- Natality (birth)
- Mortality (death)
- Immigration (arrival)=In->I
- Emigration (departure)=Exit->E
What will increase population growth?
Immigration and natality
What will decrease population growth?
Mortality and Emigration
What will make the population remain the same?
If the 4 factors, (immigration, emigration, etc) are all equal.
Why does a population size change over time?
Whenever there’s more predators, theres less prey because the predators are eating the prey. But then theres no more food so the predators start to die from hunger. So now theres less predators and more prey.
What’s the ratio between prey and predator?
10%->Predator & 90%->Prey
What’s carrying capacity?
If there’s a higher carrying capacity that means there are scarce/limited resources in an area so there’s less for a population.
What’s the carrying capacity of an area?
It’s the maximum number of individuals that can be supported.
Name 4 characteristics of biological cycles.
- Frequency of reproduction
- Age of mortality
- Reproductive maturity
- Number of offspring
How can the characteristics of biological cycles vary?
They’ll vary by species
What’s the difference between larger organisms and smaller organisms in terms of offspring?
Larger organisms usually don’t make as many babies as smaller organisms.
What does biotic factors mean?
Living factors
What does abiotic factors mean?
Non-living factors
What are limiting factors?
They are factors that limit the growth and size of a population.
Name the 3 things that aid in estimating the size of a population.
- Count all the individuals
- Sample areas/plots
- Mark and recapture
How do you sample an area?
- Divide an area of land into sections and count the number of individuals in each plot
- Calculate the total number of individuals in the plots
- Calculate the average of the area
What’s the formula you use to calculate a sampled area?
Average # of individuals/(area) per plot = total individuals/total area
When do scientists use mark-recapture sampling?
When the species move around a lot.
What are the 3 steps for mark and recapturing?
- Gently catch an animal
- Mark them with a tag, gps or paint
- Recapture and count all the ones that were marked
What’s population density?
Population density= number of individuals/space occupied(m2, ml, etc)
What’s population distribution?
It means how individuals are spread out on a land.
What 3 ways can a population be distributed?
- Clumped, (most common)
- Uniform
- Random
POPULATION DISTRIBUTION: What does clumped mean?
Individuals form groups that improve chances for survival.
POPULATION DISTRIBUTION: What does uniform mean?
Individuals that always keep an equal ish distance from each other.
POPULATION DISTRIBUTION: What does uniform indicate?
It indicates a strong competition for space and resources.
POPULATION DISTRIBUTION: What does random mean?
When the individuals are “placed” randomly amongst a land.
Is it more likely for animals or plant species to be distributed randomly?
Plants because of the wind and the way they grow.
