Unit 6 - Population and Sustainability Flashcards
Stages on population graph
Slow growth
Rapid growth - resources plentiful, reproductive rate > mortality rate
Stable state (no growth) - mortality = reproduction
Cannot support a larger pop. due to carrying capacity, small fluctuations
Populations can
Remain stable
Rise or fall suddenly
Oscillate up and down w. the reg. pattern
Types of limiting factors
Density dependent
Density independent
Density dependent
Factors that affect pop. the more they increase in size e.g resources, predators, intra and inter spp comp.
These limiting factors place the carrying capacity on population size
Density independent
Factors that affect the the same proportion of the population regardless of size
Types of strategists
k and r
K selection
Offspring have a high prob of survival Heavy parental care and nurturing Larger organisms Much lower reproductive rate Young are altricial, longer lifespans and have overlapping generations
Altricial
Born in an undeveloped state and requiring care and feeding by the parents
R selection
Produce many low effort organisms
Species grow rapidly
Found in less competitive and low quality environments
Young are precocial
High of mortality so start reproducing earlier
Non overlapping generations, shorter lifespans
Boom and bust (cyclical)
Precocial
Born in an advanced state and able to feed itself almost immediately
Predator prey interactions
When predator pop increases, more prey eaten
Prey pop decreases, less food available for predator s
W/ less food, fewer predators survive so their pop. decreases
W/ fewer predators, fewer prey are eaten so their pop. increases
More prey = more food, predator pop. increases
Two populations are in eqm and stable due to -ve feedback
When does competition occur
When there are not enough resources to satisfy all of the organisms that depend on them
How does intraspp comp affect population
Population drops –> comp. reduces –> pop. increases –> pop. drops (oscillates)
Examples of interspp comp. affecting population
Red and grey squirrels - Invasive species
May leads to extinction of one species
Greater specialisation to avoid competition
Change in distribution of the species
Where does invasive species have a largest effect
Islands
Competitive exclusion principle
2 competitive species cannot coexist at the same population level esp if ones staring population is higher than the other
Preservation
Keeping habitats/species as they are now (assuming they are currently undisturbed)
Focuses on eliminating any human effects on ecosystems
Conservation
Active management of ecosystems by humans to maintain biodiversity
Involves management of ecosystem so that natural resources can be used sustainably and reclamation
Reclamation
Restoring ecosystems that have been damaged/destroyed
Threats to biodiversity
Over-exploitation of ecosystems by humans
Habitat disruption and fragmentation
Intro of invasive species by humans that outcompete native species to extinction
Potential management strategies
Raise carrying capacity by increasing nutrients Move individuals to enlarge pop Encourage natural dispersion using dispersion corridors between fragmented habitats Fencing Controlling predators and poachers Vaccinate individuals Prevent pollution/disruption Intervene to restrict succession