3.7.2 Populations Flashcards
What does the Hardy- Weinburg principle state?
proportion of dominant and recessive alleles in a population stays the same from one generation to the next
What are the 5 conditions that must be met for Hardy-Weinburg?
- no mutations
- isolated populations
- no selection (alleles equally likely to be passed on)
- Large population
- Random mating within population
What are the 2 Hardy Weinberg equations?
- p + q = 1
- p^2 + 2pq + q^2 = 1
- where p is dominat allele and q is recessive allele
What is a population?
- total number of organisms of one species
- in an ecosystem /habitat/area
- at a given time
What is a gene pool?
All the alleles in a population
What is an ecosystem?
The interactions of all the organisms with the physical environment and the biotic and abiotic factors which affect them
What is a community?
All the living organisms of all the populations of all species in an area
What is an ecological niche?
An organisms role in the ecosystem
What assumptions are made for mark-release-recapture?
- no migration
- no reproduction
- marked individuals are fully mixed with unmarked individuals
- marking doesn’t make individuals more likely to be eaten by predators
- sample large enough
What is the mark-release-recapture equation?
Population size =
(No. in 1st sample X no. in 2nd sample) / no. of marked individuals recaptured
How would you perform mark-release-recapture?
- capture, mark and release
- method of marking does not harm organism or make it more visible to predators
- leave sufficient time for organisms to randomly distribute before collecting 2nd sample
- population = (No. in 1st sample X no. in 2nd sample) / no. of marked individuals recaptured
What is succession?
Changes in the species of a particular area over time
What is a pioneer species?
- initiates succession
- 1st to colonise a hostile environment
- will cause a change in biotic/abiotic conditions
What are the series of succession?
- colonisation by pioneer species
- which change the environment (eg abiotic factors like forms soil, nutrients)
- so it becomes less hostile for new species
- and more suitable for new species which outcompete the previous species
- so pioneer species decreases
- over time increase in biodiversity
- until there is a climax community
What are 3 features of a climax community?
- stable community of the same species present over a long time
- constant abiotic factors
- population becomes stable
