Topic 7C: Populations in Ecosystems Flashcards
Habitat =
The place where an organism lives
Population =
All the organisms of one species in a habitat
Community =
population of different species in a habitat
Ecosystem =
A community + all non living conditions in the area
Abiotic conditions=
non living features of the ecosystem (temperature, availability of water)
Biotic conditions =
The living features of the ecosystem
Niche =
The role of a species w/in its habitat (what it eats, where and when it feeds)
Adaptations =
A feature that members of a species have that increases their chance of survival + reproduction
The niche a species occupies w/in its habitat include
Its biotic interactions - organisms it eats or eaten by
Abiotic interactions - oxygen an organism breathes in + the carbon dioxide it breathes out
Why do every species have a different niche
if the same there will be competition until only one species left
How do species avoid competition due to niches
every species niche is unique/ slightly different
Example of very similar niches
Common pipistrelle bat + soprano pipistrelle bat both catch insects but are differences
farmland vs woodland
hedges + urban land vs lakes + rivers
different frequencies
Different forms of adaptations
- physiological (processes inside their body)
- behavioural (the way an organism acts)
- anatomical (structural features of their body)
Natural selection =
organisms with the better adaptations being more likely to survive, reproduce + pass on the alleles for that adaptation
Otters adaptations to abiotic conditions
webbed paws - they can both walk on land + swim effectively- increases chance of survival
Seals adaptations to abiotic conditions
thick layer of blubber (fat) helps keep them warm in the coldest seas - can live in places where food is plentiful
Hedgehogs adaptations to abiotic conditions
hibernate- lower their rate of metabolism over winter- increases chance of survival because they can conserve energy
Sea otters adaptations to biotic conditions
use rocks to smash open shellfish + clams- provides another source of food
Male frogs adaptations to biotic conditions
produce mating calls to attract females- increases chance of reproduction
Bacteria adaptations to biotic conditions
produce antibiotics to kill other species of bacteria in the same area- less competition
Carrying capacity =
The maximum stable population size of a species that an ecosystem can support
Examples of abiotic factors
light, water, space available, temperature, chemical composition of the surroundings
Advantages of a mammals surrounding being the optimum temperature
metabolic reactions can take place without using as much energy maintaining the body temperature- more energy used for growth + reproduction so increased population
Interspecific competition
when organism of different species compete with each other for the same resources e.g. red and grey squirrels
Impact of interspecific competition
resources available to both populations are reduced e.g. if food they’ll have less energy for growth + reproduction so population size decreases
Intraspecific competition
when organisms of the same species compete with each other for the same resources
Correlation between population and amount of resources
- population increases when resources increases
- eventually resources become limiting so population begins to decline
- Smaller population- less competition = better for growth + reproduction- population grows again
Predation =
where organism kills and eats another organism
Population sizes of predator and prey are
interlinked- as population of one changes it causes the other to change
Correlation between predator and prey population
-As prey increases there’s more food for predators so population also increases
-predator population increases so more prey eaten so prey population decreases
-less food for predators so population decrease
(Cycle)
How to produce a random sample
- choose an area to sample
- samples should be random to avoid bias
- use appropriate technique
- repeat process as many times as possible to reduce likelihood that results are due to chance
- number of individuals for the whole area can be estimated by taking the mean of the data collected in each sample + multiplying it by the size of the whole area
Quadrats and transects are used to investigate
non mobile organisms or very slow moving organisms (like limpets)
Quadrats =
a square frame usually divided into a grid of 100 smaller squares by strings attached across the frame
How to use quadrats
-placed on a ground at different points - the species frequency (how often a species is found) is recorded in each quadrant
Using quadrats to work out percentage cover
counting how much of the quadrat is covered by the species- counting if more than half a square is covered
-quick way to investigate populations + you don’t have to count all the individual organisms
Transects =
lines to help find out how different plants are distributed across an area e.g. when organism near a hedge or water
Belt transects =
quadrats placed next to each other along the transect to work out species frequency + percentage cover
Interrupted belt transect + why its used
quadrats placed at intervals along the line with spaces in between to cover larger distances
Mark- release- recapture method used to investigate
more motile species
How to perform the mark- release- recapture method
- capture a sample of a species using a appropriate technique + count
- mark in a harmless way
- release back into their habitat
- wait a week then take a second sample from the same population
- count how many of the second sample are marked- use the equation to estimate the total population size
Equation for calculating population size in the mark- release- recapture method
no. caught in 1st sample x no. caught in 2nd sample /no. marked in 2nd sample
Three main assumptions you have to make when doing the mark- release recapture method
- the marked sample has had enough time + opportunity to mix back into the population
- The marking hasn’t affected the individuals chances of survival + marking still visible - not rubbed off
- no changes in population size due to births, deaths + migration in this period of study
How would you investigate the effect of soil pH on marram grass in a coastal ecosystem
- place a tape measure in a straight line from the shore heading inland= your transect
- take 1m^2 quadrat + divide into 100 squares
- starting from shore place the quadrat next to the tape measure
- count the squares containing marram grass + record the results in a table as percentage cover
- At each sample point measure the pH
- Repeat observations every 10 m along the transect
Coastal ecosystem investigation:
How to measure pH
Can use a digital pH probe or take samples of soil back to skl in a test tube for testing using a sieve to remove debris + barium sulphate, distilled water and a pH indicator- shake thoroughly and leave to settle + check colour
Coastal ecosystem investigation: Why does pH decreases as you move inland
near the shore the sand/ soil contains lots of shell fragments made of calcium carbonate= an alkali compound
further inland = rotting vegetation adds organic matter to the soil = more acidic
Coastal ecosystem investigation: Safety issues + how to avoid them
- use tide timetables so you know when low tide is= best time to work
- wear suitable clothing + footwear for weather + terrain
Coastal ecosystem investigation: Ethical issues
All fieldwork affects the environment where its carried e.g. ppl walking on soil causing erosion or killing plants
investigations should be planned to have the smallest impact possible on the area
Succession =
the process by which an ecosystem changes over time
2 types of succession=
- Primary succession
2. Secondary succession
Primary succession=
happens on land that’s been newly formed or exposed e.g. where volcano has erupted to form a new rock surface or where sea levels has dropped- exposing new area
-No soil or organic material to start with- just bare rock
Secondary succession =
happens on land that’s been cleared of all plants but where soil remains e.g. after forest fire or forest cut down by humans
Primary succession starts when
species colonise a new land surface
seed and spores are blown in by the wind and begin to grow
Pioneer species = + why they’re important
the first species to colonise the area
specially adapted to cope with the harsh conditions of the new area
Abiotic conditions of a new land surface
hostile e.g. no soil to retain water
How the pioneer species change the abiotic conditions
they die + microorganisms decompose the dead organic material to form a basic soil
Impact of the decomposing pioneer species forming a basic soil
conditions are less hostile so new organisms w/ different adaptation can move in and grow - they die + decompose too making soil deeper and richer in minerals - for more new organisms
Impact of the constant introduction of new species on new land surfaces
new species make changes to the environment that might not be suitable for the previous species
How does secondary succession happen
happens in the same way as primary succession but there’s already a soil layer so starts at a later stage - with already larger plants
Dominant species in a ecosystem =
the species better adapted to the improved conditions and out competes the previous species already there on the land
As succession increases ___ also increases
biodiversity- new species move in alongside existing species
Climax community =
final stage of succession - the ecosystem is supporting the largest and most complex community of plants and animals that it can- wont change much more- its in a steady state
Climate climax =
climax community
