7.4: Populations in ecosystems (ecology) Flashcards
(53 cards)
Define population
all of the individuals of the same species in a habitat at the same time
Define community
all of the individuals of all species in a habitat at the same time
Define ecosystem
the relationship between the community and the abiotic environment
What is meant by the term ‘biotic factor’ and describe two examples
The living component - interactions between individuals within the community e.g. predation, competition, mutualism
What is meant by the term ‘abiotic factor’ and state two examples found in each of aquatic and terrestrial environments
non-living component
aquatic: pH and temperature of water
terrestrial: light intensity, water availability
Name the 2 types of competition and describe the difference between them
Intraspecific - between individuals of the same species
Interspecific - between individuals of different species
Using examples, explain the difference between primary and secondary succession
Primary = colonisation of bare rock e.g. on a lava flow
Secondary = recolonisation of an area e.g. following a forest fire
Compare and contrast the pioneer and climax communities
pioneer - harsh abiotic factors, few plant species (highly specialised), less stable (will change)
climax - less harsh abiotic factors, more plant species (less specialised), more stable (doesn’t change)
Explain why animal biodiversity is greater in a climax community
there are more plant species providing a greater variety of food sources and so there are more niches available and so there are more animal species
How can you link the Nitrogen cycle to a wet habitat
waterlogged soils, less O2, anaerobic conditions, decrease in nitrates, increase in nitrifying bacteria, increase in N2 gas
Fully describe how you could estimate the size of a population of sundews in a small marsh
1- Create a grid using two tape measures
2- Use a random number generator to produce coordinates
3- Place a quadrat at the coordinate and count the number of sundews it contains
4- Repeat at 10 different coordinates on the grid
5- Repeat steps 1-4 in a different area of the marsh
6- Add up the total number of sundews and divide by the number of quadrats used to calculate the mean number of sundews per quadrat
7- Multiply the mean number of sundews per quadrat by the total area of the marsh
Suggest two precautions needed when marking organisms when using the mark-release-recapture method to make sure the estimate of the number of organisms is valid
1- Mark isn’t visible to predators, so they are not more likely to be eaten
2- Mark isn’t toxic, so it doesn’t kill them
What is a parasitic relationship
Where one member gains, and the other is harmed
What is a mutualistic relationship
Where both members gain
What is a commensalistic relationship
Where one member gains, and the other neither gains nor is harmed
What is a niche
The role an organism plays in its environment
What is the difference between the realised niche and the fundamental niche
realised = no species is better than them in this area
fundamental = competition with other species
Define succession
The change in structure of a community and an ecosystem over time
What is the difference in time between secondary and primary succession and explain why
Secondary is quicker than primary as there are phosphates, nitrates, DOM, seeds, soil etc
How does the standard deviation suggest if the mean of something is significantly greater than the mean of something else
if the standard deviations of the mean masses do not overlap
The standard deviations of the mean masses of two samples do not overlap. What does this mean?
That the mean mass of one sample is significantly greater than the mean mass of the other sample
HYPOTHESIS TESTING
p =< 0.05 therefore…..
the result is significant as the result is not due to chance therefore the null hypothesis is rejected
In terms of ecology stats tests,
if measurements are taken and you are looking for a correlation between 2 different measurements, what test would you use?
Spearman’s Rank test
In terms of ecology stats tests,
if measurements are taken and you are not looking for a correlation between 2 different measurements, but are comparing means from 2 sets of data, what test would you use?
Student’s T-test
