populations in ecosystems Flashcards
Define habitat
The place where an organism lives
Define population
All the organisms of one species in a habitat
Define community
Populations of different species in a habitat
Define ecosystem
A community, plus all the abiotic conditions in the area in which it lives
Define abiotic conditions
The non-living features of the ecosystem
Define biotic conditions
The living features of the ecosystem
Define niche
The role of a species within its habitat
Define adaptation
A feature that members of a species have that increases their chance of survival and reproduction
What does a niche include?
- Biotic interactions e.g. the organism it eats or is eaten by
- Abiotic interactions e.g. the oxygen an organism breathes in, and the carbon dioxide it breaths out
How many species are in a niche
One
What are niches separated by
- Time
- Location
- Behaviour
Why are niches important?
To avoid inter-species competition
Why are ecosystems described as being dynamic?
- Populations constantly rise and fall
- Any small change can have a large effect
- Biotic and abiotic factors may alter the conditions of the ecosystem
What are the 3 different types of adaptations?
- Physiological
- Behavioural
- Anatomical
Describe how adaptations become more common in the population
- Organisms with better adaptations are more likely to survive, reproduce and pass on alleles for their adaptation
- So the adaptation becomes more common in a population
Define population size
The total number of organisms of one species in a habitat
Define the carrying capacity
The maximum stable population size of a species that an ecosystem can support
List abiotic factors which may affect population size
- Amount of light, water and space available
- Temperature
- Chemical composition of their surroundings
What resources might organisms compete for?
- Food
- Water
- Shelter
- Minerals
- Light
- Mates
Describe what happens to a population in their ideal abiotic conditions
- Individuals grow and reproduce
- Population size increases
Describe what happens to a population in their non-ideal abiotic conditions
- Can’t grow fast and reproduce
- Population size decreases
Define infraspecific competition
Infraspecific competition is when organisms of the same species compete with each other for the same resources
Define interspecific competition
Interspecific competition is when organisms of different species compete with each other for the same resources
What are the limiting factors for population size?
The amount of food available limits the population of any species
Define predation
It is where an organism (the predator) kills and eats another organism (the prey)
Describe and explain the relationship between the prey population and the predator population
- As the prey population increases, there’s more food for predators so the predator population grows
- As the predator population increases, more pray are eaten so the prey population begins o fall
- So there’s less food for the predators, so their population decreases
How should you pick out a sample to investigate a population?
- Chose an area to sample, it should be random to avoid bias, e.g. random number generator for co-ordinates
- Repeat the sampling method to take many samples to reduce the likelihood the results are due to chance
How do you estimate the number of individuals in the whole area via a sample?
Mean of data collected in the sample x size of whole area
Define non-motile
Organisms that don’t move
What are the 2 ways of investigating non-motile organisms?
- Quadrats
2. Transects
Define species frequency
How often a species is found or the number of individuals of each species is recorded in each quadrat
How do you measure the percentage covered?
Measured by counting how much of the quadrat is covered by the species
What do transects find out
Can find out how many species are distributed in an area
Describe belt transects
Quadrats are placed next to each other along the transect to work out species frequency and percentage cover along the transect
Describe interrupted belt transects
Quadrats are placed along lines at intervals to cover a long distance
What does mark-release-recapture measure
Measures abundance of motile species
Describe a method where you conduct a mark-release-recapture investigation
- Capture a sample of a motile species
- Mark them in a harmless way
- Release back into the habitat
- Wait a measured amount of time, and take 2nd sample from the same population
- Count how many of the 2nd samples are marked
What is the equation for mark-release-recapture
(total number of individuals in first sample x total number of individuals in the second sample) / number of marked individuals recaptured
How can you mark a species harmlessly during a mark-release-recapture investigation?
- Place a spot of paint on them
2. Remove a tuft of fur
How do you estimate the total population size from your data from a mark-release-recapture investigation?
(number caught in 1st sample x number caught in 2nd sample) / number marked in 2nd sample
What assumptions do you make when estimating the total population size from your data from a mark-release-recapture investigation?
- Marked sample has had enough time and opportunity to mix back into the population and be distributed evenly
- Marking hasn’t affected the organism’s chances of survival
- There are no changes to the population size due to: births, death and migration during the study
Define succession
Succession is the process by which an ecosystem changes over time, the biotic and abiotic conditions change
What is meant by primary succession?
Where an area previously devoid of life is colonised by a community of organisms, there is no soil or organic material to start with
Summarise the process of primary succession
- Abiotic conditions are hostile, pioneer species can survive harsh abiotic conditions because they are specially adapted to and colonise the area
- They change abiotic factors of their environment, they die and microorganisms decompose the dead organic material to form soil
- Conditions become less hostile, so new organisms with different adaptations can move in and grow
- Over time this allows more complex organisms to survive
What is climax community and how is it reached
- The final stage of succession where the ecosystem is balanced and stable
- When the soil is rich enough to support large trees or shrubs and the environment is no longer changing
Define conservation
The protection and management of species and habitats, in order to maintain biodiversity
How might succession be managed in order to aid conservation?
Succession needs to be prevented in order to preserve an ecosystem at a certain point
List various methods of conservation
- Plants can be conserved using seedbanks which tore lots of seeds from different plant species, if the plant becomes extinct in the wild the stored seeds can be used to grow new ones
- Fishing quotas are limited to the number of certain fish species fishermen are allowed to catch, reducing the numbers of fish that are caught and killed
- Protected areas like national parks and nature reserves protect habitats by restricting urban development, industrial development and farming
- Endangered species can be bred in captivity to increase their numbers and then returned to the wild
