4.1.2 Biodiversity Flashcards
What is biodiversity?
variety of living organisms in an area i.e plants, animals, fungi etc
Why is biodiversity important?
-maintains a balanced ecosystem which minimises impact if an individual is affected
-species can be interdependent
-humans rely on high biodiversity for medicine, food, clothes etc
What is a community?
the populations of living organisms in a habitat
How does maintaining biodiversity impact conservation?
-informs scientists of the species present in a habitat to provide baseline for biodiversity
-effect of any changes in the environment
Habitat biodiversity
-the number of different habitats found within an area
-can support a wide variety of species, so leads to higher species biodiversity
-abiotic factors= soil, temp range
-biotic factors= availability of food, presence of predators
Species biodiversity
-group of similar organisms able to reproduce to give fertile offspring
-i.e woodland= relatively large number of each species with no species dominating
-i.e farmland= large population of a small no. of species
Species richness
-the number of different species present in a particular area
-measured by taking random samples of a habitat and counting the number of different species
Species evenness
-comparison of the abundance of each species living in a community
-measured by taking random samples of a habitat and counting the number of individuals of each species
What is Simpson’s Index of Diversity and how is it calcuated?
-used to measure species diversity
- n= total number of organisms in one species
- N= total number of all organisms
- ∑ = Sum of
-always a value between 0 and 1 (closer to 1= higher species richness & evenness, so more diverse and can adapt to environmental changes)
Genetic biodiversity
-refers to the variety of genes/alleles that make up a species
-code for wide variation in characteristics seen between species–> better adaptation to a changing environment + more likely to result in resistance to pathogens
3 ways that genetic biodiversity can be assessed
-the proportion of polymorphic gene loci
-the proportion of the population that is heterozygous for any specific gene loci
-allele richness(number of different alleles that exist for specific genes)
What is the difference between polymorphic and monomorphic genes?
-polymorphic genes have two or more alleles whereas monomorphic have one allele for each gene–} most genes are monomorphic
-M leads to lower genetic biodiversity as there is a smaller number of alleles present + no new alleles introduced
How to calculate genetic biodiversity
proportion of polymorphic gene loci= number of polymorphic gene loci/total number of loci
Why is genetic biodiversity important?
-high genetic biodiversity(wide range of alleles present in the population) are more likely to adapt to environmental changes + less likely to be extinct
-due to having an advantageous allele which enables them to survive in altered conditions
Factors that increase genetic biodiversity: mutations
-random + spontaneous mutations in the DNA of an organism, creating a new allele
BUT mutations don’t have an impact because they are degenerate or introns that are spliced
Factors that increase genetic biodiversity:
interbreeding between different populations
-when an individual migrates from one population and breeds with a member of another population, alleles are transferred–} gene flow
Factors that decrease genetic biodiversity:
selective breeding
-only a few individuals within a population are selected for their advantageous characteristic and bred i.e pedigree animals/food crops
-less desired alleles disappear from population
Factors that decrease genetic biodiversity:
captive breeding programmes
-small number of captive individuals of a species are available for breeding
-i.e zoos, conservation centres (normally for endangered/extinct species)
-re-population within limited population reduces the gene pool
Factors that decrease genetic biodiversity:
rare breeds
-normally the result of selective breeding
-small gene pool causes problems when trying to restore numbers but maintain certain characteristics
Factors that decrease genetic biodiversity:
artificial cloning
-asexual reproduction
-using cuttings from a a plant to clone a farmed plant
Factors that decrease genetic biodiversity:
natural selection
-individuals with advantageous alleles are more likely to survive + reproduce to pass them on–} less advantageous alleles become less common
Factors that decrease genetic biodiversity:
genetic bottlenecks
-an event that severely reduces the gene pool because few individuals survive and can pass on alleles i.e forest fires
Factors that decrease genetic biodiversity:
the founder effect
-small number of individuals create a new colony that is geographically isolated from the original
-small gene pool
Factors that decrease genetic biodiversity:
genetic drift
-random nature of alleles being passed on from parents to their offspring–} allele frequency will vary and sometimes disappear
-normally in populations with a low genetic biodiversity
Features of a habitat with LOW biodiversity
-relatively few successful species
-stressful/extreme environment with relatively few ecological niches
-species have very specific adaptations for the environment
-simpler food webs
-change to environment has a major effect on the ecosystem
features of a habitat with HIGH biodiversity
-large number of successful species
-less stressful with more ecological niches
-many species in the habitat with fewer specific adaptations
-complex food webs
-change to environment has a relatively small effect
What is sampling and why is it used?
-taking measurements of a select number of individual organisms in a particular area
-can estimate the total number of organisms
-can measure a particular characteristic of an organism i.e crop height
Random sampling
-selecting individuals by chance–} an equal likelihood of selection
-i.e divide the field into a grid using 2 measuring tapes laid at right angles, use random numbers to determine coordinates and take a sample at each of the coordinate pairs generated
-can use species identification key
-count number of organisms and record this
-if species is over 50% outside, it is not counted
Non-random sampling
-sample is not chosen at random–} useful when there’s lots of variety in the distribution of species in the habitat
Opportunistic sampling
-samples are chosen by investigator (normally when organisms are not readily available)
less representative of the population + data will be biased
Stratified sampling
-populations are divided into subgroups(strata) before sampling
-based on a particular characteristic i.e males + females
-random sample is then taken from each strata proportional to its size
more representative
Systematic sampling
-samples are taken at fixed intervals across different areas in a habitat
-line transect= marking a line on the ground between 2 poles and taking samples at specified points(can measure organisms that touch the line/distances of samples from the line)
-belt transect= 2 parallel lines across the habitat–} samples are taken of the area between the two lines
What is sampling bias + chance?
-sampling bias= process of selecting a sample may be bias, reduced using random sampling due to no human involvement in choosing
-chance= organisms selected may not be representative of the whole population, reduced by using a larger sample size–} lower probability that chance will impact results
Sampling animals: Pooter
-device used to catch small insects by sucking on a mouth piece to draw them into a holding chamber
-filter before the mouth piece prevents them from being ingested
Sampling animals: Sweep nets
-used to catch insects in areas of long grass
-stand still and sweep the net left to right through the grass and quickly sweep up the net and pour contents into collecting tray to count
Sampling animals: Pitfall traps
-used to catch small, crawling animals
-hole where they fall into, covered with a roof structure so it doesn’t fill with water, stone to raise lid
Sampling animals: Tullgreen funnel
-for small organisms that live in soil/leaf litter
-sample of this is put on a mesh filter at the top of a funnel and a light shone down onto it
-light acts a heat source and dries out the soil/leaf litter, so organisms moves away from it and fall into the beaker
-mesh holds the soil/leaf litter in place but lets the small organisms pass through
Sampling animals: Kick sampling
-used to study the organisms living in a river
-river bed is ‘kicked’ for a period of time to disturb the substrate
-net is held just downstream for a set period of time in order to capture any organisms released into the flowing water
Sampling plants: point quadrat
-frame containing a horizontal bar
-at set intervals, long pins can be pushed through the bar and each species of plant the pin touched is recorded
Sampling animals: Frame quadrat
-type and number of species within each section of the quadrat is recorded
-used with random sampling to collect a representative sample
counted by:
- density= count individual large plants
Human population growth
-grown at a dramatic rate in the past centuries and is continuing to grow
-linked to improvements in medicine, hygiene, housing + infrastructure–} increase life expectancy
Impacts of human population growth: deforestation
-provides wood for building and fuel(logging) and more space for infrastructure, housing and agriculture (land clearing)
-decreases habitat diversity–} impacts species diversity due to habitat loss
-may increase biodiversity of neighbouring areas as animals are forced to migrate
Impacts of human population growth:
Urbanisation
Cities and major road developments mean that species can become isolated and populations cannot interbreed–} lower species diversity
Impacts of human population growth:
Over-exploitation
-greater demand for resources i.e food, water, energy, so resources are being used up faster than replenished–} destroy habitats + directly affect species
-i.e industrial fishing can deplete certain fish species, reducing genetic diversity
Impacts of human population growth:
Pollution
-human population is producing more waste and higher pollution rates–} kill species + decrease biodiversity
i.e acid rain= lowers pH for aquatic organisms
Impacts of agriculture: land clearing
-increase the land available for growing crops/rearing animals
-i.e removal of hedgerows= allows farmers to use large machinery for harvesting crops + more land for growing crops–} reduces plant species diversity and destroys the habitat of many animals
Impacts of agriculture: use of pesticides and herbicides
-reduces species diversity of naturally occurring plants + animals seen as pests/weeds* and may destroy food source of other organisms
*weeds compete with the cultivated plants for lights, minerals, and water
Impacts of agriculture: monoculture
-many farms specialise in producing a single variety of one crop i.e palm oil plantations in Africa
-no wild crop varieties due to less economic benefit–} reduces species diversity AND genetic diversity(crop cannot adapt to any environmental changes + evolve due to no new alleles introduced)
-increase vulnerability to pathogens and increase dependence on expensive pest/herbicides + fertilisers
Climate change
-significant long-term change in an area’s climate
-naturally occurring but worsened by increasing CO2 levels in the atmosphere
Impacts of climate change: Polar ice caps melting
-could lead to extinction of species in those regions
-loss of habitat would lead to forced migration of species to find suitable conditions
Impacts of climate change: Rising sea levels
-result of polar ice caps melting and thermal expansion of oceans
-saltwater would fill up freshwater rivers, reducing habitats of aquatic organisims/species living around it
-flood +destroy coastal habitats
Impacts of climate change: less rainfall
-drought-resistant species would dominate over non-drought resistant–} loss of these plants would lead to loss of animal species that rely on them as food source
-animal species that feed on xerophytes would dominate
Impacts of climate change: life cycles impacted by adaptations
-if the range of insects that are pollinators i.e bees changes, it could cause extinction of the plants that rely on pollination + lower plant species distribution
Reasons for maintaining biodiversity: Aesthetic reasons
-provides pleasant landscapes for leisure use i.e walk in local woodland/visit a rainforest
-nature provides inspiration for musicians + writers
-natural environment reduces stress and helps recover from injuries
Reasons for maintaining biodiversity: economic reasons
-prevent economic dependence on other nations due to soil erosion + desertification
-wide variety of species that can be chemically/medically useful i.e plants with chemical-based defence mechanisms may be potential sources of medicine
-prevents monoculture causing soil depletion(less diversity in soil nutrients)
-protection against abiotic stresses i.e extreme weather/disease
-eco-tourism i.e coral reefs
-can crossbreed with wild plant varieties to increase yield + help adaptations
Reasons for maintaining biodiversity:
Ecological reasons
-maintains interdependence–} i.e decomposers break down dead plant and animal remains + recycle nutrients, plants rely on pollinators(bees) which would pollinate crop and increase yields
-keystone species(key role in maintaining the structure of an ecological community)= disproportionately large effect on their environment relative to their abundance i.e beavers who build dams –} help determine the species richness + evenness in the community
What is conservation?
-maintenance of biodiversity through human action
-increases chancels of survival + reproduction
What is sustainable development?
-economic development that meets the needs of people today, without compromising the needs of future generations
In-situ conservation
-within the natural habitat
-maintains genetic diversity, allows species continue to adapt to changing environment + preserves interdependent relationships between species, both species and habitat are conserved
BUT may be expensive and hard to manage i.e poaching, climate change
Wildlife reserves
-controlled grazing
-restricting human access
-controlling poaching i.e issuing fines
-reintroduction of species i.e to areas that have become locally extinct
-culling of invasive species= not native and has negative effects on economy, environment or health
-halting succession= i.e land developing into woodland–} allows for higher biodiversity + more species richness
Marine conservation zones
-preserve species-rich areas i.e coral reefs
-create areas where populations can build up and repopulate nearby areas
Ex situ conservation
-involves the removal of an organisms from their natural habitat
-can be used to protect individual animals in a controlled environment–} can manage predators + hunters
-competition for resources reduced + breeding can be manipulated i.e IVF + hormones
BUT only a small number of individuals can be cared for, can be difficult and expensive to sustain that environment + may not adapt to their environment/breed successfully
Botanic gardens
-plant species are managed to provide best resources to grow i.e soil nutrients, watering, pesticides
-can conserve wild varieties of crop as a potential source of genes
Seed banks
-often used alongside in situ methods
-seeds are dried and stored at cold temps to maintain viability and slow down loss of ability to germinate–} can be used to grow new plants in the future
Captive breeding programmes
-produce offspring in a human-controlled environment–} gradually reintroduce stable, healthy population back into the wild
-can import suitable breeding partners from other zoos to introduce new alleles
-can maintain genetic diversity by keeping history log of breeding–} prevent inbreeding/reduction of gene pool
What are conservation agreements?
-local + international cooperation to ensure preservation of species/habitats
The Rio convention on Biological Diversity(CBD)
-aims to develop international strategies on the conservation of biodiversity and how to use animal and plant resources sustainably
-international law that conserving biodiversity is a collective responsbility
CITES agreement
-Convention on International trade in Endangered Species
-increases international cooperation in regulating wild animal + plant specimens
-member countries all agreed to make it illegal to trade products made from endangered animals i.e rhino ivory
-raises awareness of threats to biodiversity via education
The Countryside Stewardship Scheme 1991 (UK)
-aims to conserve wildlife and biodiversity + to improve and extend wildlife habitats by promoting specific management techniques to landowners
-landowners offered 10 year pay agreement if they followed the management technique suggested
-i.e regenerate hedgerows
-10,000 agreements by the year 2000–} rebuilt species i.e birds
What is preservation?
-protection of an area by restricting human interference
-aims to protect environmentally sensitive ecosystems i.e -Galapagos islands= dodos became extinct due to introduction of other animals by humans
-Antartica
Fishing quotas
-limits on how much fish can be hunted per year
-fishing net mesh size regulations= larger mesh so smaller fish can pass through and reproduce
-preserved areas where no fishing is allowed
