Biodiversity✅ Flashcards
define biodiversity
the variety in life in an area, which can be measured in terms of genetic species or habitat diversity
what is measured in genetic diversity
an estimate of gene variants (alleles) in a species
what is measured in species diversity
two components are measured:
species richness (number of species in an area)
species evenness ( number of individuals of each species)
what is measured in habitat/ecosystem diversity
number of different habitats (or ecosystems) in an area. Hardest measure to calculate in biodiversity because boundaries of ecosystems are often difficult to determine with accuracy
describe the difference between a population and a community (2 marks)
population: a group of organisms of the same species
Community: a set of populations within an ecosystem
suggest and explain which measure of biodiversity is most significant when assessing the health of one ecosystem (3 marks)
species biodiversity
because the variety and abundance of species within the ecosystem indicates the stability and health of food chains
explain how a habitat can contain many specie but its biodiversity is considered low (3 marks)
species richness might be high
but a few species might dominate/many species have low numbers
biodiversity based on both species richness and species evenness
what principles should you bear in mind when designating a sample method
larger sample size- more representative of whole ecosystem
avoiding bias-when choosing where to take samples will increase validity of results
sampling can only be claimed to be a representative estimate of an ecosystem biodiversity
what is random sampling, how do you decide the location of sampling points
random sampling avoids bias, can produce unrepresentative picture of ecosystem
generating random numbers, which are used as grid coordinates
taking samples from these coordinates
what is stratified sampling
study site divided into smaller areas, based on distribution of habitats, this sampling is more representative of the ecosystem and reduces sampling error
what is systematic sampling
a transect is used where environmental gradients exist (eg soil pH). You can investigate whether the distribution of organisms also changes across the habitat
state 3 factors that might limit the sample size in ecological survey (3 marks)
time
money
labour availability
access (to the ecosystem)
equipment
outline how you would estimate the abundance of plant species from a rocky shoreline to the edge of sand dunes 30M inland (4 marks)
Belt transect
line placed along the ecosystem (from shoreline to edge of sand dunes)
quadrats used at intervals
abundance of each species estimated (eg by percentage cover)
what animals and how is pooter and sweep nets technique used for sampling
Pooter: used on insects, insects sucked into a chamber
Sweep nets: used on insects in long grass, net is swept through the habitat
what animals and how is pitfall traps, tree beating and kick sampling techniques used for sampling
pitfall traps: used on small, crawling invertebrates, a hole in the ground traps organisms
tree beating: used on tree-dwelling invertebrates, trees are shaken and organisms fall on a sheet
Kick sampling: used on river-dwelling organisms, a river bed is disrupted and organisms are captured in a net
how are plants sampled, what 2 ways can they be recorded
using quadrats
1. count absolute number of individuals in the quadrat
2. estimate % of a quadrat covered by a species
how can wind speed, light intensity and temperature be measured
wind speed=anemometer, ms^-1
light intensity=photometer, lux
temperature=thermometer, degrees
pitfall traps are covered. suggest why (1 mark)
to prevent rainwater from entering and drowning trapped organisms
suggest why the % coverage of a species rather then its density might be recorded (2 marks)
time limitations
in cases where individuals of a species are difficult to count
what is used to calculate species diversity
Simpsons diversity index (D)
D=1-[sum of (n/N)^2]
n=number of individuals of a particular species
N= total number of all individuals of all species
suggest why an ecosystem with a low value of D is vulnerable to environmental change (3 marks)
few species/ low numbers in many of all species
an environmental change may cause the loss of species from the ecosystem
why can genetic diversity of a population increase
DNA mutation
gene flow from another population (ie breeding between populations of same species)
how can genetic diversity decrease in a population
selective breeding
captive breeding
genetic bottlenecks (ie when a population is reduced to a small size because of disease, habitat destruction, or migration)
how can genetic diversity be measured/ what methods
number of alleles per gene
heterozygosity: the proportion of individuals in a population that have 2 different alleles for a particular gene
the proportion of genes for which more than 1 allele exists. a gene that has 2 or more possible variants/alleles is known as a polymorphic gene, a gene for only 1 variant/allele called a monomorphic gene
what is equation is used to calculate proportion of polymorphic genes
= number of polymorphic genes/total number of gene
describe how genetic diversity can decrease in a natural population (3 marks)
small population
due to disease
or habitat destruction
or migration (founder effect)
natural selection
explain the importance of genetic diversity to species survival (2 marks)
idea that high genetic diversity indicates a species that has a wide range of traits on which natural selection can act
idea that when a selection pressure is exerted there is a greater chance that some members of the species will adapt and survive
how has agriculture impacted biodiversity
deforestation to clear land for farming
hedgerow removal (to maximise space available for crops and machinery)
intensive farming uses chemicals eg pesticides and herbicides) to kill plants and animals that considered pests or weeds. EG neonicotinoid insecticides been blamed for reducing population of bee species
monocultures (growing a single crop) reduces number of animals that can use the farmland as a habitat
how has forestry management and deforestation impacted biodiversity
removal of native trees has destroyed habitats, causing animal migration and death
sometimes non-native tress are grown instead to meet demands of timber and fuel industries, but biodiversity lowered because fewer species are grown
what are the indirect impacts of agriculture on biodiversity
fertilisers pass into watercourses, contaminating neighbouring ecosystems (eg eutrophication)
demand for water has resulted in rivers/lakes being drained, decimating aquatic ecosystems
how has fossil fuel combustion directly impacted biodiversity
habitat destruction for access to fossil fuel sources
how has fossil fuel combustion indirectly impacted biodiversity
acid rain production has contributed to habitat destruction
climate change has caused habitat destruction (eg changes in sea temp, melting of ice)
suggest 2 ways in which climate change has damaged ecosystems (2 marks)
desertification
melting frozen habitats
changing sea currents/ temperature
describe how the rising human population has affected biodiversity in aquatic ecosystems (4 marks)
(reduced biodiversity due to) eutrophication
toxic chemicals poisoning aquatic organisms
acid rain production altering pH in aquatic ecosystems
global warming altering sea currents/ temperature
drainage of rivers and lakes
what are the economic reasons for maintaining biodiversity
discovery of useful genes or compounds ( eg medicines or agriculture)
sustainable- removal of resources helps land remain economically viable for longer
high genetic diversity increases chance of species adapting to future environmental change, greater biodiversity increases range of traits available for artificial selection in future
money can be made through tourism in biodiverse areas
why are ecosystems with a low biodiversity unstable and vulnerable to environmental change
species within community interdependent, removal of one species can disrupt food chain
outline 2 economic reasons for maintaining biodiversity (2 marks)
greater chance of future drug/genetic resource discoveries
ecotourism
greater gene pool for artificial selection
suggest 2 long-term benefits of sustainable forestry (2 marks)
reduces chance of soil degradation
land remains visible for longer
biodiversity is maintained
energy/food requirements can be meant for a longer period of time
sea otters eat urchins, which eat kelp. Explain why sea otters are a keystone species in kelp forest habitats (2marks)
otters prevent an overpopulation of urchins
which would severely reduce kelp population
what are some in situ methods for maintaining biodiversity
wildlife reserves- human access restricted, animals are fed, reintroducing species, culling, preventing succession which is a natural process of ecological change that occurs over many years
marine conservation zones- limits placed on hunting and fishing within refuge areas
what are some ex situ methods of maintaining biodiversity
botanic gardens-plants experience optimum conditions
seed banks- seeds from many plant species stored in conditions that enable them to remain viable for centuries
captive breeding programmes-production of offspring in human-controlled environments, reintroduction of species into natural habitats, animals experience optimum nutrition, a lack of predators, and medical attention
what is the conservation agreement
national and international agreements enable conservation targets and rules to be created
Rio convention- targets agreed for sustainability, reducing desertification and greenhouse gas emissions
CITES- regulates trade of species
state the principal outcome of the Rio convention (2 marks)
sustainability targets
targets to reduce desertification/ increase land fertility
targets for greenhouse gas reduction
suggest 3 advantages of using seed banks rather than botanic gardens to conserve plant species (3 marks)
seeds are smaller then plants, therefore easier to transport
and less space is required for storage
lower probability of disease/ damage
long term storage/ viability maintained for many years
evaluate advantages and disadvantages of ex situ conservation in comparison to in situ methods (5 marks)
in situ is usually cheaper
in situ enables interspecies relationships to be maintained
in situ avoids potential problems when reintroducing species
ex situ provides optimum conditions/ veterinary care
ex situ enables controlled breeding programmes
