TOPIC 7 - populations in ecosystems Flashcards
(22 cards)
define community.
all the different species that live in one area and interact with each other
define ecosystem.
living and non living aspects of the environment found in one area
describe biotic and abiotic factors.
biotic - living features of an ecosystem eg. predators, disease
abiotic - non-living features of an ecosystem eg. light, temperature
define habitat.
the place where an organism lives within an ecosystem
define niche.
The role of species within its habitat, consisting of both biotic interactions and abiotic interactions
what is meant by carrying capacity?
the max size of population an ecosystem can support
4 abioitic factors that may affect population growth?
pH
temperature
light intensity
humidity/water
what is meant by intraspecific and interspecific competition?
Intraspecific = competition between organisms of the same species
Interspecific = competition between organisms of different species
what resources might organisms compete for?
food, water, shelter, minerals, lights, mates
describe the pattern of a typical predator prey relationship in terms of population change?
- prey is eaten by predator, resulting in predator population increasing and prey population decreasing
- fewer prey means increased competition for food, so predator population decreases
- fewer predators mean more prey survives, and the cycle begins again
how are quadrats used for estimating population size?
- placed at grid coordinates
- placed at intervals along a line transect
- for slow moving or non mobile organisms
how is mark-release-recapture used for estimating population size?
- sample of species is captured, marked and released back into the same area they were caught from
- after certain period of time = another sample is captured and number of marked organisms are counted
equation for mark-release-recapture?
total no of individuals in first sample x total number of individuals in second sample / number of marked individuals recaptured
what assumptions does the mark-release-recapture method make?
- marked individuals distribute evenly
- no migration in or out of the population
-few births or deaths
-method of marking doesn’t affect survival - mark does not come off
why are ecosystems described as being dynamic?
- populations constantly rise and fall
-any small change can have a large effect - biotic + abiotic factors may alter the conditions of the system
what is meant by primary succession?
area previously devoid of life is colonised by a community of organisms
summarise the process of primary succession?
- pioneer species can survive harsh conditions and colonise the area
- they change abiotic factors of their environment
- overtime, this allows more complex organisms to survive
what is the climax community and how is it reached?
final stage of succession where ecosystem is balanced and stable = soil is rich enough to support large shrubs or trees + environment is no longer changing
how might species alter the environment that develops during succession?
may alter it to make it more suitable for other species or worsen environment making it less suitable for other species
what is secondary succession?
- starts from land where vegetations has been cleared
eg human deforestation - less harsh abiotic conditions
- faster
- pioneer species can be larger
define conservation.
protection of species and habitats in order to maintain biodiversity
how might succession be managed in order to aid conservation?
sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point.
