6:3:2 Populations and Sustainability Flashcards
What is carrying capacity
The maximum stable population size of a species that an ecosystem can support
What are limiting factors
Abiotic and biotic factors that prevent further increase of a population by preventing individuals from reaching adulthood and reproducing.
What is environmental resistance
The combined effects of limiting factors
What are abiotic factors affecting population size
- Non-living parts of ecosystems
- Light availability
- Water supply
- Water mineral content
- Temperature
- Space available
- Soil pH
- Breeding sites
- Oxygen availability
How does temperature affect population size
Mammals have to use more energy to maintain optimum body temperature, and there will be less energy to grow and reproduce, limiting population growth
What are biotic factors that affect population size
- Living parts of ecosystems
- Food availability
- Interspecific competition
- Intraspecific competition
- Predation
- Parasitism
- Mutualism
What is interspecific competition
- Competition for the same resources between different species
- Species can outcompete each other if better adapted (e.g. grey and red squirrel)
- Population increases = competition increases
What is intraspecific competition
- Competition for the same resources between individuals in the same species
- Can affect population size and distribution
- Population increases = competition increases
What is predation
- The interaction where one organism (predator) kills and eats other organisms (prey)
- Numbers of predators and prey rise and fall in cycles
What are the effects of competition
- Competition exclusion
- Character displacement
- Resource partitioning
What is competitive exclusion
- 2 species occupy similar niches
- Species that is better adapted to compete leaves the weaker species to starve
- Weaker species move and find a different niche to adapt to
What is resource partitioning
- Resources (e.g. fruit tree) divided up to satisfy needs of different feeders
- Species aren’t competing directly but instead coexisting
What is character displacement
- Closely related species occupying similar niches differentiate to minimise niche overlap and avoid competitive exclusion
- E.g. Galapagos finches changing beak sizes, and those which survive better are favoured in natural selection
What factors affect population size
- Natality
- Immigration
- Mortality
- Emigration
What causes lag phase
- Few individuals
- Acclimatising to habitat
- Rate of reproduction is low
- Growth is slow
What causes log phase
- Plenty of resources and good climatic conditions
- Rate of reproduction is high
- Reproduction rate exceeds mortality rate
- Rapid population increase
What causes stationary phase
- Population has reached carry capacity
- Mortality rate = natality rate
- Determined by limiting factors
What is the equation to estimate population size
- Lincoln Index
- Total population = (N. animals first marked and released x N. animals captured in second sample) / N. marked animals in second sample
What is conservation
- Maintaining biodiversity and sustainability
- Allowing change to the profile of organisms in ecosystems
- Allowing human activity alongside other species
- Maintaining ecosystems after change has occurred
What is preservation
- Maintaining habitats and populations exactly as they are now
- No allowance for usage by humans
- Prior to changes in biodiversity
What are the reasons for conservation
- Economic: timber, agriculture, tourism, pharmaceuticals
- Social: aesthetic, inspirational, recreational
- Ethical: right to life, cultural significance
- Environmental: CO2 emissions, breakdown of organic waste, water cycle, producers
- Ecological: biodiversity
What are the causes for biodiversity loss
- Overhunting/harvesting
- Changes to agricultural practices
- Introduction of alien species or pathogens
- Climate change
What are consequences to biodiversity loss
- Species can’t adapt to changes
- Loss of genetic diversity
- Reduced gene pool
- Genetic erosion (extinction)
What is in situ conservation
Conservation where populations stay where they are (e.g. nature reserves/national parks)
What are the advantages of in situ conservation
- Species remain adapted to their habitat
- Animals maintain natural behaviour patterns
- Natural interactions are maintained
What are threats to in situ conservation
- Poaching
- Climate change
- Natural dictators
- Invasive species
What are the ways to manage nature conserves
- Continuous monitoring
- Habitat conservation
- Maintained boundaries
- Measures of successful completion of life cycles
- Restocking/reintroducing common species
- Active conservation management: reversing human activity effects (e.g. controlling poachers, removing invasive species)
What is ex situ conservation
Conservation that involves the removal of species from the natural habitat (e.g. botanic gardens, seed banks, captive breeding programmes)
What are the advantages of ex situ conservation
- Species actively managed with necessary resources
- Furthers genetic diversity and biodiversity
- Offspring produced in human controlled environment
- Cryogenic embryo storage
What are the disadvantages of ex situ conservation (captive breeding programmes)
- Species wouldn’t be adapted to common diseases
- Reduces sex-specific behaviour
- No uptake of innate behaviour (e.g. migration)
- Genetic drift: Animal put back in natural habitat aren’t easily reintroduced, may cause habitat destruction by interrupting carrying capacity
What are examples of conservation programmes
- The Rio Convention
- International Union for the Conservation of Nature
What is sustainability
The ability of an ecosystem to maintain its biodiversity whilst simultaneously providing humans with resources they need over a long period of time
How are commercial fishing schemes managed
- Leave enough fish in the ocean, protect marine habitats, maintain human livelihoods
- Fishing quotas
- Banned/permitted areas
- Inspecting catch
- Banning harmful practises
- Promote practises which reduce bycatch
How is timber production managed
- Felling and clearings added to increase biodiversity in areas of timer production
- Genomic research to find faster growing trees to shorten breeding process
- Coppicing and pollarding on rotation to sustainably manage slow growing trees
- Replacing felled trees
- Protecting lands of indigenous people
What is mass extinction
- Where a large number of species have become extinct at one time
- Rate of extinction is very high
- Due to major/sudden shifts in the environment
What are the causes of extinction
- Climate change
- Competition
- Introduction of non-native species
- Hunting by humans
- Mass agriculture
- Degradation/loss of habitats
How can climate change cause extinction
- Burning of fossil fuels causes increased levels of CO2 in atmosphere
- This causes greenhouse effect which increases global temperature
- Ice caps melt, sea levels rise
- Causes flooding and salination of soil
- Rising temperature and acidity of water changes habitats for species
How can competition cause climate change
- Limited supply of resources causes competition
- Competition reduces population size, and weaker species can become extinct
- Competition for resources with humans can cause extinction as well
How can introduction of non-native species cause extinction
- Species have no natural competitors or pathogens to control population growth
- Population size increases
- Take resources etc from native species
- e.g. Red and grey squirrels
How can hunting by humans cause extinction
- Livestock and food processing industry means humans don’t need to hunt
- However hunting for sport is popular
- More vulnerable species are usually targets
How can degradation/loss of habitats cause extinction
- Main cause of species extinction
- Humans have destroyed habitats (deforestation, pollutants, etc)
- Species survival adaptations don’t work
- Necessary resources not available
- Causing species to search for new resources of compete with other species
Describe the Snowdonia National Park case study
- National park in wales
- Rich diversity of animals (deer, buzzards, cormorants)
- Rich diversity of plants (oak, snowdonia lily)
- Non-native species (pink flower) introduced and became a pest species
- It caused trees to die, soil acidity, competition
- Authorities are trying to eradicate it
Describe the Maasai Mara National Reserve case study
- Reserve in Kenya with high diversity of species
- Maasai people raise livestock and poison predators (lions) which can damage (overgrazing) the land causing conflict with conservationists
- Working with Maasai people a balance is reached, both needs are met
- Employing locals to work on conservation and ecotourism
- Employing locals to monitor lions
- Legal hunting to cull unnecessary animals
Describe the Terai Region case study
- Grassland and forest region in Nepal
- Diverse animal and plant species including endangered bengal tiger, Asian elephant and one-horned rhinoceros
- Densely populated with people relying on land for resources
- Agriculture and migration into cleared areas conflicts with wildlife
- Conservationists work with locals
- Protect against poachers
- Protect endangered species
- Promote sustainable agriculture and forestry
Describe the peat bogs case study
- Peat bogs are regions of waterlogged land within which the process of decomposition is incomplete (no O2 to decompose)
- Under anaerobic conditions the partially decomposed plant matter forms peat
- Peat builds up and forms carbon stores where the carbon remains locked up and isn’t released into the atmosphere
- Unique plant species (mosses, bog cotton, heathers) which support many animals habitats
- Humans burn peats for fuel, 90% in the UK have been lost to human exploitation
- Conversation organisations fill in drainage ditches, control grazing, removal of tree seedlings
