Populatipns And Ecosystems Flashcards
What is a population?
All the organisms of one species in a habitat
What is a community?
Populations of different species in a habitat that make up a community
What is an ecosystem?
All the organisms living in a particular area and all the abiotic conditions
What is meant by abiotic conditions?
The non-living features of an ecosystem e.g. Temperature
What is meant by biotic conditions?
The living features of an ecosystem e.g. Predators
What is a niche?
The role of a species within its habitat
What is an adaptation?
A feature that members of a species have that increase their chance of survival and reproduction
What happens if two species try to occupy the same niche?
They compete with each other, as a niche can only be occupied by one species
What is meant by abundance?
The number of individuals of a species in a given area
What type of sampling do quadrats involve?
Random sampling
What time of sampling do transects involve?
Systematic sampling
What is meant by frequency in sampling?
The number of samples a species is recorded in
What is percentage cover and what is it used for?
How much of the investigated area is covered by a species, and is used for plants only
What are the main steps when conducting a sample?
## choose an area ## make sample random e.g. Random number generator to avoid bias ## use appropriate technique(quadrats,transects) ##repeat samples for a more reliable estimate for the whole area ##carry out necessary calculations (e.g. % cover, mean abundance)
What 3 factors need to be considered when using quadrats?
Size , position and number of sample quadrats to use
What are the 3 types of transects and what do they involve?
- Belt - Quadrats placed next to each other along transect to work frequencies and % cover
- Line - Tape measure placed along transect and species that touch it are recorded
- Interrupted - Take measurements at intervals
What are the steps of mark-release-recapture?
## Capture sample of species using an appropriate technique ## Give each organism a harmless marking ## Released them back into their habitat ## Allow enough time before taking a second sample from the same population ## Count number of marked organisms in second sample ## calculate estimated population size
What assumptions do the mark-release-recapture technique rely on?
- Marked sample has had enough time to mix back with population
- Marking hasn’t affected individuals chances of survival and is still visible
- Number of births,deaths and migrations are small during sampling period
How is the estimated population size calculated?
(No. Caught in 1st sample X No. Caught in 2nd sample)
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No. Marked in 2nd sample
How does population size vary?
Because of abiotic and biotic factors
How do abiotic factors affect population size?
When ideal for a species, they can grow fast and reproduce successfully e.g. Optimum temperature for metabolic reactions , which increases size of population
However when they aren’t ideal, they can’t grow or reproduce as well, causing size of population to decrease
What 3 biotic factors affect population size?
Inter specific competition, Intraspecific competition and predation
What is interspecfic competition and how does it affect population size?
Competition between members of different species e.g. For food or space , if two species are competing but one is better adapted than the other, less adapted species is out competed and won’t be able to exist along size the other well adapted species
What is Intraspecific competition and how does it affect population size?
Competition between members of the same species, when they compete for the same resources as the size of the population’s needs cannot be meet by availability, population declines. A smaller population means that there is less competition for resources and so population starts to increase again
