(19) Populations in ecosystems Flashcards
define ecology
the study of the inter-relationships between organisms and their environment. Includes abiotic and biotic factors
define habitat
the place where an organism lives normally
define population
all the organisms of one species in a habitat
define community
populations of different species in a habitat
define ecosystem
a community plus all the non living (abiotic) conditions in the area in which it lives - can be small or large eg a pond or an ocean
define abiotic conditions
the non living features of an ecosystem eg temp and availability of water
define biotic conditions
the living features of the ecosystem eg predators / food
define niche
the role of a species within its habitat eg what it eats, where and when it feeds
some species may appear similar but their nesting habits or other aspects of their behaviour will be different- only one species can occupy a particular niche
define adaptation
a feature that members of a species have that increases their chance of survival and reproduction
what does the niche a species occupies within its habitat include
1) its biotic interactions eg the organisms it eats and those its eaten by
2) its abiotic interactions eg oxygen it breathes in and carbon dioxide it breathes out
what is the competitive exclusion principle
the fact that no two species can occupy the same niche and where 2 species are competing for limited resources the one that uses them most effectively will eliminate the other
what are microhabitats
smaller units within habitats that have their own microclimate
what are the 3 different types of adaptations
physiological- processes inside their body
behavioural- the way an organism acts
anatomical- structural features of their body
what is carrying capacity
the maximum stable population size of a species that an ecosystem can support
what is interspecific competition
when organisms of different species compete for the same resources- resources and therefore populations will be limited
what is intraspecific competition
when organisms of the same species compete for the same resources
describe how to take samples to investigate populations
1) choose an area to sample and then a smaller area within to investigate
2) should be random to avoid bias (divide field into grid and use random number generator to select coordinates
3) take as many samples as possible to reduce likelihood of results being down to chance
4) multiply by size to estimate population for whole area
what is mark release recapture used for
to measure the abundance of more motile species
how to carry out mark release recapture
1) capture a sample of species using an appropriate technique
2) mark them in a harmless way
3) release them back into their habitat
4) wait a week and take a second sample from same population
5) count how many are marked and use the equation : total population = ( number caught 1st x number caught 2nd) / number marked in 2nd
what are 3 assumptions made in mark, release, recapture
1) marked sample has enough time and opportunity to mix back in with the population
2) the marking hasn’t affected the individuals chance of survival and the marking is still visible
3) no changes in population size due to birth, death, migration during period of study
define succession
the process by which an ecosystem changes over tim. the biotic conditions change as the abiotic conditions change
what is primary succession
happens on land that has been newly formed or exposed eg where a volcano has erupted to form a new rock suface
what is secondary succession
happens on land that has been cleared of all the plants but just the soil remains eg after a forest fire or when a forest has been cut down by humans
what are pioneer species
species that colonise an inhospitable environment in the first stage of succession
