4.11 - Biodiversity

Question 1

Biodiversity

Answer 1

the variety of living organisms present in an area

Question 2

habitat biodiversity

Answer 2

The number of different habitats found within an area
- each habitat can support a number of different species so in general, the greater the habitat biodiversity, the greater the species biodiversity

Question 3

Components of species biodiversity

Answer 3

species richness = the number of different species living in an area

species evenness = a comparison of the numbers of individuals in each species living in a community

Question 4

Genetic biodiversity

Answer 4

• the variety of genes that make up a species
• different alleles existing results in genetic biodiversity within a species, leading to different characteristics being exhibited, leading to better adaptation to a changing environment

Question 5

Sampling

Answer 5

• taking measurements of a limited number of individual organisms present in a particular area
• can be used to estimate the number of organisms in an area (abundance) or a particular characteristic of an organism

Question 6

Random sampling

Answer 6

• selecting individuals by chance, each individual in the population has an equal likelihood of selection
• random number tables or computers used

Question 7

Non-random sampling

Answer 7

• the sample is not chosen at random
• opportunistic (weakest as may not be representative), uses organisms that are conveniently available
• stratified, random sample taken from strata proportional to its size
• systematic, sampling different areas within an overall habitat, often using a line or belt transect

Question 8

Line transect vs belt transect

Answer 8

• line transect = marking a line along the ground between two poles and taking samples at specific points
• belt transect = two parallel lines are marked and samples are taken in the area between the two lines, provides more information

Question 9

sampling bias and chance

Answer 9

• selection process may be biased, bias can be reduced using random sampling so human involvement in choosing the samples is removed
• organisms selected may by chance be not representative of the population. Chance can never being completely removed, but its effect can be minimised by using a large sample

Question 10

Techniques for sampling animals

Answer 10

• pooter, insects drawn into the holding chamber by sucking on a mouthpiece
• sweep nets, used to catch insects in areas of long grass
• pitfall traps, hole dug in ground covered by roof structure to catch crawling invertebrates
• tree beating, shaken t0o dislodge invertebrates ;living in a tree or bush
• kick sampling, river bank is kicked and there is a net downstream

Question 11

Sampling plants

Answer 11

Using a quadrat:
- point quadrat, a frame containing a horizontal bar. Long pins are pushed through the bar at set intervals and plants that touch the pin are recorded
- frame quadrat, a square frame divided into a grid of equal sections. The type and number of species within each section is recorded. Can measure density, frequency and percentage cover

Question 12

Simpson’s index of biodiversity

Answer 12

• allows us to calculate biodiversity, taking both species richness and species evenness into account
• 0 = no biodiversity, only 1 species present in a habitat
• 1 = highest biodiversity, exactly the same population of each species

Question 13

Estimating animal population size

Answer 13

• capture-mark-release-recapture
• involves capturing as many individuals of a species in an area as possible and then marking and releasing them
• time is allowed for the organisms to redistribute themselves
• another sample of animals are collected
• by comparing the number of marked and unmarked individuals in the sample, scientists can estimate population size

Question 14

measuring abiotic factors

Answer 14

• wind speed = anemometer
• light intensity = light meter
• relative humidity = humidity sensor
• pH = pH probe
• temperature = temperature probe
• oxygen dissolved in water = dissolved oxygen probe

Question 15

Why are electronic sensors advantageous for measuring abiotic factors

Answer 15

• rapid changes can be detected
• human error in taking a reading is reduced
• a high degree of precision can often be achieved
• data can be stored and tracked on a computer

Question 16

Typical habitat features for environments with low biodiversity

Answer 16

• relatively few successful species
• stressful and/or extreme environment with relatively few ecological niches
• the few species that live in the habitat often have very specific adaptations for the habitat
• relatively simple food web
• a change to the environment would have major effects on the ecosystem as a whole

Question 17

Typical habitat features for environments with high biodiversity

Answer 17

• a large number of successful species
• not a stressful environment with more ecological niches
• many species live in the habitat, with few specific adaptations to the environment
• complex food web
• a change to the environment would have a relatively small effect on the ecosystem as a whole

Question 18

Factors that affect genetic biodiversity

Answer 18

Increase:
- mutations creating new alleles
- interbreeding between different populations, alleles are transferred between the two populations (gene flow)

Decrease:
- selective breeding/artificial selection
- captive breeding programs in zoos
- rare breeds
- artificial cloning (asexual reproduction)
- natural selection
- genetic bottlenecks (very few members of the population survive an event or change)
- the founder effect - a small number of individuals created a new colony geographically isolated from the rest
- genetic drift (some alleles are lost due to the random nature of inheritance)

Question 19

Measuring genetic biodiversity

Answer 19

Measure the proportion of genes that are polymorphic (more than 1 allele)

proportion of polymorphic gene loci = number of polymorphic gene loci / total number of loci

Question 20

Human influence on biodiversity

Answer 20

• deforestation, directly reduces the number of trees present, reduces habitat diversity if one tree type is felled, animals forced to migrate
• agriculture, monoculture, deforestation, removal of hedgerows, pesticides and herbicides
• climate change, extinction of species living in arctic regions, saltwater encroaching on freshwater habitats from sea level rise, loss of non-drought resistant plants, loss of insects or spread of tropical diseases from insect migration

Question 21

Aesthetic reasons for maintaining biodiversity

Answer 21

• inspiration for artists
• natural environment reduces stress

Question 22

Economic reasons for maintaining biodiversity

Answer 22

• soil erosion and desertification as a result of deforestation may reduce abilities to grow crops, leading to resource and economic dependence on other countries
• conservation of ‘useful’ organisms used to make things
• species with economic potential may become extinct before discovered (chemically or medically useful)
• continuous monoculture results in soil depletion, weakening crops, farmers become more reliable on expensive pesticides and fertilisers
• high biodiversity provides protection against abiotic stresses
• high biodiverse areas attract tourism
• wild varieties of plants are needed for genetic engineering to make crops more viable

Question 23

ecological reasons for maintaining biodiversity

Answer 23

• removal of one species may have a significant effect on others, as species within ecosystems are interdependent on each other

Question 24

Keystone species

Answer 24

An organism that has a major influence on the way its ecosystem works.
There are three types:
- predators
help control the populations of prey species, which in turn affects the quantity of plants and animals further along the food web
- ecosystem engineers
an organism that creates, changes, or destroys a habitat e.g. beavers
- mutualists
two or more species in an ecosystem interact for each other’s benefit, such as bees and flowering plants

Question 25

Conservation

Answer 25

the preservation and careful management of the environment and natural resources
- in situ conservation within the natural habitat
- ex situ conservation out of the natural habitat

Question 26

Sustainable development

Answer 26

economic development that meet the needs of people today without limiting the ability of future generations to meet their needs

Question 27

Active management techniques on wildlife reserves

Answer 27

• controlled grazing
• restricting human access
• controlling poaching
• feeding animals
• reintroduction of species
• culling or removal or invasive species
• halting succession

Question 28

Examples of ex situ conservation

Answer 28

• botanic gardens
• seed banks, dried and stored at low temperatures to maintain viability (doesn’t work for tropical rainforest trees) store of genetic material. e.g. Svalbard ‘Doomsday Vault’
• captive breeding programs, produce offspring of species in a human-controlled environment to create a stable, healthy population and gradually reintroduce species

Question 29

Why are some organisms born in captivity not suitable for release into the wild

Answer 29

• loss of resistance to local diseases, or new diseases in the wild
• behaviour, domesticated animals may not learn learned behaviour like searching for food
• genetic makeup of captive animals can become so different they cannot breed with wild animals
• habitat may have to be restored first

Question 30

Conservation agreements

Answer 30

• International Union for Conservation of Nature (IUCN) publishes red list of endangered species so countries can work together to conserve species, also involved in treaty regulating international trade in wild animals
• The Rio Convention 1992
  The Earth Summit, resulted in conventions contributing to maintaining biodiversity such as the Convention on Biological Diversity, requiring countries to make strategies for sustainable development
• Countryside stewardship scheme
  Offers governmental payments to farmers and land managers to
• sustain beauty and diversity of landscape
• improve, extend and create wildlife habitats
• restoring neglected land and conserve historical and archaeological features
• improve opportunities for countryside enjoyment