Topic 7C: Populations in Ecosystems Flashcards
What is a niche?
- The role of a species within its habitat
How are niches occupied?
- Can only be occupies by one species
- If occupied by 2 - one outcompetes the other and is more successful
What does a niche include?
- Biotic interactions - what it eats and is eaten by
- Abiotic interactions - O2 in and CO2 out
What is an adaptation?
- Features that increase an organism’s chance for survival
- More likely to reproduce and pass on allele for adaptation
What are three types of adaptation?
- Physiological - processes inside a body
- Behavioural - the way an organism acts
- Anatomical - structural features on the body
What are three examples of adaptations to abiotic conditions?
- Otters - webbed paws - can live in water and on land
- Seals - blubber - stay warm and survive
- Hedgehogs - hibernate - conserve energy to survive by reducing metabolic rate
What are three examples of adaptations to biotic conditions?
- Otters - use rocks to smash open seafood - access to other food sources
- Frogs - mating calls - attract same species - reproduce successfully
- Bacteria - can produce antibiotics - kills others to reduce competition
What is carrying capacity?
- Maximum stable population size of a species that an ecosystem can support
How can abiotic factors cause variation in population size?
- When ideal –> organisms can grow and reproduce well - ideal temp (less energy needed to maintain temp) etc
- When not ideal –> cannot grow and reproduce well
What is interspecific competition and how does it cause populations to vary?
- Different species, same resources
- If one is better adapted, it will outcompete the other
Define intraspecific competition and how it causes population size variation
- Same species, same resources
- Cyclical –> plentiful resources, pop inc, resources become limited, pop reduces, resources become more plentiful again
How does predation affect population sizes?
- Prey population increases - more food for predator
- Predator population increases - eats more
- Prey population decreases - less food available
- Predator population decreases again
How do you take a random sample in an area?
- Choose a small sample area and split it into a grid
- Randomly generate coordinates - repeat lots
- Can multiply mean up to the whole area
What are quadrats and what are they used for?
- Square frame divided by strings into 100 small squares
- Investigate non motile (plants) & slow moving (limpets)
- Measure species frequency or number of individuals
- Measure % cover - count all squares over 1/2 covered
How are transects used?
- Finding distribution across an area
- Belt –> quadrats placed next to each other - find frequency and % cover
- Interrupted belt –> placed at intervals to cover larger distance
What is mark - release - recapture for?
- Measures the abundance of motile species
Describe the process of mark - release - recapture
- Capture a sample - use pitfall trap
- Mark harmlessly - paint
- Release and wait a week
- Take a second sample and count those with marks
What is the equation for finding total population size from mark - release - recapture?
total pop size = (no/ in 1st sample x no/ in 2nd sample) / number marked in 2nd sample
What assumptions are made during mark - release - recapture?
- Organisms have enough time to mix back into the population
- Marking doesn’t change their chances of survival
- The marking is still visible
- There were no changes to population size during the experiment
How would you investigate an environmental factor with species distribution?
- Along a transect - measure something else e.g. pH
- Can plot % cover and pH together - same graph
- Can compare
In investigations, what ethical considerations must be made?
- Needs to have the smallest possible impact on the environment
- Restrict where people can walk and avoid treading on plants
What safety measures need to be taken during these investigation?
- Sea - do at low tide
- Wear suitable clothes
- Wash hands after
What is succession?
- How an ecosystem changes over time
How does primary succession work?
- On newly formed / exposed land
- Pioneer species - specially adapted
- Changes the abiotic conditions - produces soil by decomposing - makes environment less hostile
- New organisms with different adaptations arise - increased biodiversity
- New species can change the environment so it is no longer suitable for the pioneer species
Describe secondary succession
- An area of cleared plants but soil remains
- Succession starts at a later stage
- Pioneer species is larger plants
- At each stage new and better adapted organisms for the improved conditions outcompete old - dominant species
- Ecosystem = more complex - new species move in alongside - increases biodiversity
What is a climax community?
- The largest and most complex community if plants and animals the ecosystem can support
- Lives in a steady state
How are climax communities different in different climates?
- Temperate climate –> water available, mild temp, minimal changes - large tress, deep soils
- Polar climate –> minimal water, low temp, large seasonal changes - no large trees, just shrubs
What is conservation?
- Protection and management of species and habitats in a sustainable way
What is a plagioclimax?
- Humans prevent succession to stop a true climax community from forming
- Mowing a lawn prevents other plants from growing
Describe conservation by preventing succession
- Maintains habitats for native species and prevents eradication
- Allow animals to graze - keeps plants low + from taking over
- Managed fires - stimulates secondary succession - pioneer species are the one being conserved
How do humans and conservation conflict?
Use grassland as an example
- People want to raise cattle for income
- These can destroy the land for wildlife
- Conservationists help them to make money from conservation and to farm sustainably
- Meets current economic needs and sustains life
What are 4 other conservation methods?
- Seedbanks
- Fishing quotas
- Protected areas
- Breeding endangered species in captivity
