CLASSIFICATION (3.7.4) Flashcards
(20 cards)
What is a community?
All the populations of different species that occupy the same habitat at the same time
What forms an ecosystem?
A community + the non-living components of its environment together can form an ecosystem (an ecosystem can be very small or very large)
What is a niche?
A niche of a species of is the role it plays in the habitat
Species have evolved to occupy a…
Specific niche. Adapted to both biotic and abiotic factors.
What is a biotic factor + examples:
LIVING FACTOR
- bacteria
- predation
- competition
What is a abiotic factor + examples:
NON-LIVING
- light
- temperature
- water
What is carrying capacity?
An ecosystem supports a certain size of population of a species
What alters the population of a carrying capacity?
- abiotic factors
- interactions between organisms (inter + intra specific competition + predation)
How can the size of a population be estimated for non-motile organisms?
Randomly placed quadrats, or quadrats along a belt transect
How can the size of a population be estimated for motile organisms?
Mark- release- recapture method
Assumptions for the mark- release- recapture method:
1) proportions are the same in the sample as the whole population
2) marked individuals distribute well in the population
3) no immigration/ emigration
4) few deaths/ births
5) mark isn’t lost/ doesn’t rub off/ isn’t toxic
Ecosystems are…
Dynamic
What is succession?
Process by which a biological community evolves over time
Primary succession process:
- Colonisation by pioneer species- these species are often hardy + can survive harsh abiotic conditions
- Pioneer species alter the environment- modify abiotic factor such as contributing to organic matter as they die, decompose + form hummus
- Environment becomes LESS hostile- more suitable for other species to survive, increases biodiversity
- Change in species composition- over time, newer species out compete the pioneers + further alter the environment
- Increase in biodiversity + biomass- increase in the number of living habitats + niches leading to greater biodiversity + biomass
- Climax community reached- stable, more complex ecosystem where the species composition remains relatively stable
Conservation of habitats frequently involves…
Management of succession
Two features of a climax community:
- Abiotic factors are more/ less constant
- Populations are stable
What information is suggested by an increase in the index of diversity?
- Increase in the number of species
- Increase in numbers of some species
Describe the features of a succession which would bring about an increase in the index of diversity (4 marks):
- Initial environment hostile
- These organisms change the environment
- More niches/ habitats
- Allowing other organisms to become established
Describe how you would determine the mean percentage cover for beach grass on a sand dune (3 marks):
- Randomly determine position of quadrats (random number generator)
- Repeat a large number (20) times
- Divide total % cover by number of quadrats
