Populations Flashcards
Habitat
Place where an organism lives
Population
All the organisms of one species in a habitat
Community
Populations of different species in a habitat make up a community
Ecosystem
All the organisms living in a particular area and all the abiotic conditions (eg. Lake)
Abiotic conditions
Non-living features of an ecosystem (eg. Temperature)
Biotic conditions
Living features of an ecosystem (eg. Predators)
Niche
Role of a species within a habitat (eg. Its diet)
Adaptation
A feature that members of a species have that increases their chance of survival and reproduction
How are organisms adapted to abiotic and biotic conditions?
Physiologically, behaviourally and anatomically.
What do better adaptations mean for a species?
They are more likely to survive, reproduce and pass on alleles, meaning adaptions become more common in the population - natural selection.
Every species is adapted to use an ecosystem in a way that no other species can.
Abundance
Number of individuals of one species in a particular area.
Distribution
Where a particular species is within the area investigated.
Equation of Mark-Release-Recapture
(Number caught in first sample x number caught in second sample) all over the number marked in the second sample.
Three assumptions of Mark-Release-Recapture:
I - marked sample has had enough time and opportunity to mix back in with the population.
II - marking hasn’t affected its chance of survival and is still visible.
III - changes of population size is small during the study period, ie. birth, death, migration.
Which biotic factors cause variation in population size?
Interspecific competition, intraspecific competition and predation.
Birth rate
Number of live births each year for every 1000 in the population.
Death rate
Number of deaths each year for every 1000 in the population.
Population growth rate
Birth rate - death rate x 100
What do population growth curves show?
Change in population size - the gradient is how fast the population is changing.
What so survival curves show?
Survival rates and life expectancy
Survival rate
The percentage of all the individuals that were born in a population that are still alive at a given age.
Life expectancy
The average age that people die at, ie. the age that a person born into a population is expected to live to.
