4.2.1 Biodiversity Flashcards
(26 cards)
How can biodiversity be measured
Habitat
Species
Genetic
What is habitat biodiversity
Number of different habitats within an area
What is species biodiversity
Species richness: number of difference species in a particular area
Species evenness: comparison of number of individuals of each species in a community
What is a community
All the populations of living organisms in a particular habitat
What is genetic biodiversity
Variety of genes that make up a species
- difference in alleles among individuals of a species creates genetic biodiversity within the species or within population of the species
What is random sampling
Selecting individuals by chance
E.g.
- mark out grid using tape measures
- use random numbers to pick coordinates
- take samples at coordinates
Why can a sample not be reliable
Sampling bias: selection process may be biased
- reduced using random sampling
Chance: organisms might not be representative of whole population by chance
- effect minimised by using large sample size, never completely removed
What is non-random sampling
Opportunistic: uses organisms that are conveniently available
- weakest, not representative of population
Stratified: population divided into number of strata based on characteristic
- random sample then taken from each strata proportional to size
Systematic: different areas within habitat sampled separately
- carried out using line or belt transect
- line transect: samples at specified points along a line
- belt transect: 2 parallel lines marked, samples taken of area between lines
How can animals be sampled
Pooter: for small insect, insects drawn into chamber by sucking on mouthpiece
Sweep nets: catch insects in areas of long grass
Pitfall traps: catch small, crawling invertebrates (beetles, spiders, slugs)
- hole in ground, they fall in, covered with roof so it doesn’t fill with rain water, left overnight for nocturnal species
Tree beating: white cloth under tree, tree shaken to dislodge invertebrates, will fall onto cloth
Kick sampling: river bank/bed kicked, net held downstream to capture organisms released into water
How can plants be sampled
Point quadrat: pins put through a horizontal bar at set intervals
- each species pin touches is recorder
Frame quadrat: square frame divided into grid
- type and number of species within each section is recorded
Should be use with random sampling to collect valid and representative sample
Or can use systematically to measure how distribution across an area of land varies
How can frame quadrats be used
Density: count number of individual plants within 1m by 1m square quadrat, density per square metre found
Frequency: count number of squares a species is present in
Percentage cover: estimate by eye of area within a quadrat that a particular plant species covers
Take multiple samples and calculate a mean
Can multiply by area to find total population in area that had been sampled
How to estimate population size for animals
Capture-mark-release-recapture used
- capture as many as possible, mark
- allows for animals to redistribute themselves, number of marked and unmarked in an area is compared, scientists estimate population size
- greater number of marked individuals recaptured, smaller population
How can abiotic factors be measured
Wind speed: anemometer
Light intensity: light meter
Relative humidity: humidity sensor
PH: pH probe
Temperature: temperature probe
Oxygen content in water: dissolved oxygen probe
Advantages to using sensors to measure abiotic factors
Rapid changed detected
Human error in taking reading reduced
High degree of precision achieved
Data stored and tracked on computer
How to calculate biodiversity
Simpsons index of diversity
- takes into account species richness and evenness
What does value of simpsons index of diversity indicate
0-1
0 = no diversity
1 = infinite diversity
Higher value = more diverse
Features of low biodiversity habitat
- few successful species
- stressful/extreme environment, few ecological niches
- species have specific adaptations to the environment
- simple food webs
- change to environment has a major effect on ecosystem
Why is genetic biodiversity beneficial
Species with high genetic biodiversity likely to be able to adapt to changes in environment, less likely to become extinct
- some organisms may carry an advantageous allele, can survive in different conditions (e.g. disease)
- can reproduce, species survives
What factors affect genetic biodiversity
Number of alleles within a population needs to increase
- mutation
- interbreeding between different populations (gene flow)
Can decrease through
- selective breeding/ artificial selection
- captive breeding (zoos and conservation centres)
- rare breeds
- artificial cloning
- natural selection
- genetic bottlenecks (few individuals survive event)
- founder effect (small number of individuals create new colony, geographically isolated)
- genetic drift
How can genetic biodiversity be measured
Measuring polymorphism: genes with more than one allele
Measuring proportion of polymorphic gene loci = number of polymorphic gene loci ÷ total number of loci
How does deforestation impact biodiversity
- reduced number of trees in an area
- reduces species diversity if one type is targeted
- reduces number of animal species present in an area, destroys habitat/food source/home
- animals forced to migrate, biodiversity increases in other areas
How does agriculture impact biodiversity
- species are selected, biodiversity reduced
- deforestation
- removal of hedgerows for machinery, reduces plant/animals
- use of chemicals, herbicides and pesticides, reduces species diversity and destroys food sources
- weeds removed
- monoculture
How does climate change impact biodiversity
- melting of polar ice caps, extinction of species
- rising sea levels floods which destroys habitats
- higher temperatures, less rainfall, plant species fail to survive
- insect life cycles/ populations change as they adapt
Humans influence on biodiversity
Human population growth
- space for housing, industry, and farming to support growing population disrupts ecology of areas
Deforestation, agriculture, climate change
Pollution, littering
