investigating populations and succession Flashcards
succession
Change in community over time due to change in abiotic factors and species present
climax community
stable community where there is no further succession
define abiotic factors x2
Describe and explain how two abiotic factors cause differences in species growing between two different sites. .
Definition: the non-living part of an ecosystem
factors + explanation:
More Air movement – more evaporation or damage
Less humidity – more evaporation or damage
Temperature – link to reactions (photosynthesis/respiration), evaporation or enzymes appropriately.
pH – link to proteins/enzymes appropriately.
Describe interspecific competition
Competition between different species
eg for named food source, habitats,
anything within the same niche.
Describe intraspecific competition
. Competition between individuals in the same species.
eg for named food source, habitats,
mating partner
Explain how the mark-release-recapture method can be used to estimate the size of a [named species]
Collect samples, mark and release.
Ensure marking does not harm [named species].
Allow time to re-integrate and randomly distribute within the rest of the population before collecting second sample and count number
Mark-release recapture and “how science work questions” (feel free to use more than one flash card)
Describe ways to standardise this sampling method.
Describe conditions for results to be valid with this sampling method.
Describe why results may be unreliable when sampling an area to represent a very large area
Same size of area sampled
Same size net/mesh
Same sampling time
marking is not removed and does not affect survival/ does not increase vulnerability to predation
No immigration or emigration
Sufficient time for marked individuals to re-integrate and randomly distribute within population.
No births or deaths
Sampling method is the same
Less chance of recapturing fish
Harder to capture marked animals as they congregate
Describe how you would you use a transect to investigate whether the distribution of [named non motile] across a distance
Lay tape measure from one side of …… to other side of ……
Place quadrat at regular intervals along the tape measure.
Count numbers/ percentage cover of [name species]
Use several transects
Describe how could estimate the size of a population of [name species] in an area.
Use a grid
Use a random number generator to obtain random coordinates.
Place quadrat at coordinates and count number of [named species] present
Large sample and calculate mean number per quadrat
by dividing total number of plants by number of quadrats (# per quadrat)
Describe how could estimate the % cover of a population of [name species] in an area.
Use a grid
Use a random number generator to obtain random coordinates.
Place quadrat at coordinates and determine % cover [named species] present
Large sample and calculate mean % cover per quadrat
by dividing total % cover by number of quadrats (% per quadrat)
change ‘quadrat’ to ‘area of quadrat’ and scale to get % cover per m2
Quadrats and “how science work questions”
Why did a scientist use % cover rather than frequency to record abundance of [named plant]?
Why do scientists sample randomly?
Why do scientists take a large number of samples at each site?
difficult to determine numbers as there are too many to count
grows in clumps/ Individual organisms not identifiable/ too small to count/
Avoids bias so data is representative
Allows use of statistical tests
produces a more reliable mean as anomalies can identified.
Describe and explain how succession occurs
Area colonised by [named] pioneer species which increases in numbers.
[named] Pioneer species changes abiotic factors
Making area less hostile for new [named] species
[named] Pioneer species out competed by new [named species].
Increase in species diversity [shown by data]
To climax community [represented by named species]
Give features of a climax community
Same species present over long period of time
Abiotic factors constant over time
Population stable at carrying capacity
primary succession
first introduction of species in a habitat
secondary succession
reintroduction of species in a habitat that had been damaged eg forest fire of clearance of land
