Population in Ecosystems Flashcards
- intraspecific competition
- compete with fertile males to mate
describe how the mark-release-recapture method could be used to determine the population of A.aegypti at the start of the investigation?
- capture, mark and release
- leave time for mosquitoes to disperse before second sampling
- population size = no. caught in 1st sample x no. caught in 2nd sample / number marked in second sample
the release of radiation-sterilised A.aegypti has not been very successful in controlling the transmission of dengue.
suggest why?
radiation affects attractiveness of A.aegypti
suggest why the scientists released more transgenic males every week?
- maintain competition
- as more transgenic males die
the release of transgenic males proved successful in reducing the number of A.aegypti.
describe how the results in the figure support this conclusion?
number lower after 12 weeks
define habitat?
place where an organism lives
define population?
all the organisms of one species in a habitat
define community?
populations of diff species in a habitat
define ecosystem?
a community, plus all the non-living condtions in the area in which it lives.
can be small/large
define abiotic conditions?
non-living features of the ecosystem
e.g. temp, availability of water
define biotic conditions?
living features of ecosystem
e.g. presence of food / predators
define niche?
role of a species within its habitat
e.g. what it eats, where and when it feeds
define adaptation?
a feature that members of a species have that increases their chance of survival and reproduction
the niche a species occupies within its habitat includes what?
- biotic interactions - organism eats, what its eaten by
- abiotic interactions - oxygen breathes in, CO2 breathes out
every species has its own unique…
niche
if 2 species try to occupy the same niche, what happens?
- will compete
- one species more successful than other
- until one species left
define natural selection?
organisms with better adaptations more likely to survive, reproduce and pass on favourable allele
adaptations to abiotic conditions?
- otters have webbed paws - can walk and swim - can live and hunt on land and water
- seals have thick layer blubber - keeps them warm in coldest seas - can live in places where food plentiful
- hedgehogs hibernate - lowers metabolism rate - conserve energy during cold months
adaptations to biotic conditions?
- sea otters use rocks smash open shellfish and clam - gives access to another source of food
- male frogs prod mating calls - attract mate of same species - successful mating more likely
- bacteria prod antibiotics - kill other species of bacteria in same area - less competition
define population size?
total number of organisms of one species in habitat
define carrying capacity?
maximum stable population size of a species that an ecosystem can support
list some abiotic factors?
- light
- water
- space
- temp
- chemical composition
what is interspecific competition?
when organisms of different species compete with each other for same resources
what can interspecific comp lead to ?
- resources available to both species reduced
- pop limited by lower amount of food
- less energy for growth and reproduction
- populations smaller
if 2 species are competing but one is better adapted to its surroundings than other, what happens?
less well adapted OUTCOMPETED
how does the grey squirrel have a better chance of survival?
- larger
- store more fat
- eats wider range of food
what is intraspecific competition?
when organisms of same species compete with each other for same resources
what can intraspecific comp lead to?
- pop inc when resources plentiful
- more organisms competing for same amount of space and food
- resources = limiting
- pop declines
- smaller pop = less comp
- better for growth and reprod
what is predation?
where organism kills and eats another organism
the population sizes of predators and prey are interlinked.
how?
as population of one changes, causes other population to change
describe the predator-prey relationship?
- prey pop inc
- more food for pred, pred pop inc
- more prey eaten, prey pop dec
- less food for pred
- pop dec
what are non-motile organisms?
organisms that dont move about e.g. plants
what are quadrats?
square frame divided into a grid
how are quadrats used?
placed on ground at random diff points in area
define species frequency?
how often species found / number of individuals of each species reacorded in each quadrat
how can percentage cover be found?
counting how much quadrat covered by species
what is percentage cover a quick way of?
investigating pop
to cover larger distances, what can you do?
quadrats places at intervals along line (interrupted belt transects)
mark-release-recapture method?
- capture sample of species
- mark in harmless way
- release back into habitat
- wait week, take 2nd sample
- count how many of 2nd sample marked
TOTAL POP SIZE = NUMBER CAUGHT IN 1ST SAMPLE X NUMBER CAUGHT IN 2ND SAMPLE / NUMBER MARKED IN 2ND SAMPLE
what are the assumptions you have to make in the mark-release-recapture method?
- sample had enough time and opportunity to mix back in with pop
- marking not affected individuals’ chance of survival
- no change in pop size due to births, deaths and migration
investigating the effect of soil pH on marram grass in coastal ecosystem?
- place tape measure in straight line from shore heading inland
- take 1m^2 quadrat divided into 100 squares
- starting from shore, place quadrat next to tape measure
- count squares containing marram grass and record result in table as percentage cover
- at each sample point, measure pH and record
- repeat every 10m along line
how can you measure pH?
- use digital probe
OR
- take sample
- add barium sulfate, distilled water and pH indicator
- shake
- compare colour against pH chart
why does pH inc near shore?
- sand/soil contain shell fragments
- made of calcium carbonate
- alkaline
why does pH dec as you move inland?
rotting veg adds organic matter to soil = acidic
safety issues?
- local tide times
- suitable clothing and footwear
- wash hands before eating
ethical issues?
- people trample on marram grass
- erosion
define succession?
process by which an ecosystem changes over time
primary succession?
- happens on newly formed / exposed land
- no soil / organic material
secondary succession?
- happens on cleared land
- e.g. deforested land
- soil remains
define pioneer species?
first species to colonise an area
process of primary succession?
- pioneer species colonise rocks e.g. lichens grow on & break down rocks –> rel minerals
- lichens die, and decompose = thin soil
- thickens as more organic material formed
- other species e.g. moss can grow
- larger plants need more water - move in as soil deepens
- soil deepen as larger plants die and decompose
- larger plants grow and out-compete smaller plants = dominant species
- biodiversity inc
- soil deep and rich enough in nutrients to support large trees
- climax community formed
process of secondary succession?
- happens in same way as primary
- already soil layer - starts later
- pioneer species = larger plants e.g. shrubs
what is the final stage of succession called?
climax community
define climatic climax?
climax community for a particular climate
define plagioclimax?
when succession stopped artificially
what are the ways to manage succession to conserve the moorland ecosystem?
- animals allowed graze on land
- similar to mowing - animals eat growing points of shrubs and trees –> stops establishing themselves
- keeps veg low
- managed fires lit
- secondary succession occurs after fire
- pioneer species conserved
define conservation?
protection and management of species and habitats in a sustainable way
define sustainable?
enough resources are taken to meet needs of people today, without reducing ability of people in future to meet their own needs
