Biodiversity

Question 1

Different diversities

Answer 1

-Species diversity
-Genetic diversity
-Habitat diversity

Question 2

species diversity

Answer 2

the number of different species and individuals within each species in a community

species richness-the number of different species in a particular area at the particular time

Question 3

genetic diversity

Answer 3

the variety of genes amongst all the individuals in a population of one species

Question 4

habitat diversity

Answer 4

the range of different habitats

Question 5

reduction in genetic diversity

Answer 5

The genetic diversity of a population is reduced by captive breeding, inbreeding, genetic bottlenecks and the founder effect.

• Captive breeding in zoos results in a small number of individuals breeding.

• A genetic bottleneck is when only a small number of a population have survived an event (such as a natural disaster or new disease). The gene pool is decreased and only the alleles in the remaining population can be passed on to future offspring.

• The founder effect is similar in outcome (a reduced gene pool, but has a different cause. The founder effect is when a small number of individuals from a population decide to colonise a new, isolated area.

Question 6

genetic diversity

Answer 6

• Calculated by examining polymorphic genes within isolated populations, such as zoos (captive breeding), rare breeds and pedigree animals where selective breeding has been used.

• A polymorphic gene is one that has more than one allele. Most genes within the population only have one allele and are therefore monomorphic. To calculate genetic diversity, you can measure polymorphism using this formula:

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

-The higher the proportion of polymorphic gene loci, the larger the genetic diversity within the population.

Question 7

index of diversity

Answer 7

Formula: D=N(N-1)/SUM OF n(n-1)

N = the total number of organisms of all species
n = total number of organisms of a particular species
D = Simpson’s diversity index
1 is the lowest value for D. The larger the value for D, the greater the species diversity. It is typically between 1-10.

Question 8

sampling

Answer 8

When measuring the biodiversity of a habitat, sampling is used.
To ensure your sample is representative of the population, you must:

• Take a large sample - you can calculate a mean and statistical test to see if any differences or correlations you see are significant.

-Randomly sample-to avoid bias

Question 9

random sampling

Answer 9

• Lay out two tape measures at right angles to each other to create a gridded area.

• Use a random number generator (such as on a calculator) to generate two numbers to serve as coordinates on the grid.

-Place your quadrat at the coordinates and record the data

Question 10

Non-random sampling

Answer 10

There are three non-random sampling techniques: opportunistic, stratified and systematic.

Opportunistic
• This method is unlikely to result in a sample that accurately represents the population. This method involves sampling organisms which are conveniently available and therefore involves bias.

Stratified
• Some populations or habitats can be separated into groups to sample from, or strata. For example, when sampling a pond you may split the pond into three regions: surface, shallow and deep-water regions. You would then take random samples within each group (strata).

Systematic
• This method involves identifying different areas within a habitat to sample.
It is used when there is a change in the distribution of species within the habitat and you want to investigate the impact of the change on biodiversity. Often involves a belt transect. This is when you would place a single tape measure along the sample area and at a regular set distance along the tape measure you would place your quadrat and record the data.

Question 11

quadrats

Answer 11

• Used to sample plants and slow-moving organisms.

• A point quadrat is a horizontal bar with holes along it at set intervals that long pins can be placed through. The pin is pushed through to touch the ground and any species touching the pin are recorded.

• A frame quadrat is a frame of a known size, typically 0.5m x 0.5m.

Question 12

using a quadrat

Answer 12

When you place your quadrat, there are three different methods used to record the species present.

• Density: This is when you count the individuals present. For example, counting how many daisy plants are present.

• Frequency: This is a very quick method and requires a gridded frame quadrat with 100 squares. You would then count how many squares out of the 100 the species you are investigating is present in. If the plant species was present in 25 squares, your frequency would be 25%.

• Percentage cover: Estimate the percentage of the entire quadrat covered with the species that is being investigated. This method is quick, but subjective and therefore results in lower accuracy. The method can be improved by standardising how the percentage is estimated. For example, using a quadrat with 100 squares and counting 1% for every small square that is at least half covered with the plant.

Question 13

sampling techniques for animals

Answer 13

Sweeping nets
• These are nets that can be used to capture insects with long grass.

Pitfall traps
• A hole is dug in the ground and a pot is placed within it. Small invertebrates may crawl into the trap and will be unable to crawl out. A roof-like structure is placed on top to prevent the trap from filling with rainwater and investigators will return daily to collect results and release the animals.

Pooters
• These are used to capture very small insects. Two tubes are connected to a closed pot. The investigator sucks on one tube and places the other tube over the insect. This creates suction and draws the insect into the pot.

Tullgren funnel
• This is used to extract small organisms from within soil samples. The soil sample is dried using a heat lamp, and this causes the animals to move in the opposite direction, downwards, where a collecting dish is placed.

Kick sampling
• This is used to sample organisms within river beds. One investigator will gently kick to the river bed to disturb the earth and the organisms within it. A second investigator stands behind them with a net to capture any organisms that are released.

Question 14

measuring species richness and evenness

Answer 14

-Species richness - the number of different species present.

• Sampling methods can be used and you would record the number of different species present.

• To measure species evenness, for each species identified, you would also have to record the number of individuals present.

Question 15

factors affecting biodiversity

Answer 15

The increase in the human population, agriculture and climate change all reduce biodiversity.

Human population
• Increasing at an exponential rate.
• Increased need for space for housing, farming and industry. (requiring deforestation).

Agriculture
• Increased agriculture to feed everyone. Clearing land for agriculture results in the destruction of habitats, chemical pesticides or fertilisers may be added to the land and monocultures may be grown. All of this reduces the number of habitats and range of food sources.

Climate change
• The increase in global temperatures is melting polar ice caps, and therefore destroying habitats. It is also resulting in sea levels rising, which is reducing aiso mean some pl fles ding animals he goal to surviver erop otes rainfall
becoming the dominant species is some areas, with these plants outcompeting others as they can survive in harsher abiotic conditions.

Question 16

reasons to maintain biodiversity

Answer 16

• If an ecosystem experiences a loss in biodiversity, it is a cause for concern as this indicates a change is causing the loss of habitats and therefore death and extinction of species often follow.

• A reduction in biodiversity is undesirable for many reasons ranging from ecological, economical and aesthetical.

Question 17

reasons to maintain biodiversity 2

Answer 17

Ecological reasons
• Agriculture reduces biodiversity as it removing natural habitats. All organisms are interdependent on each other, and therefore the loss of one species impacts all others. For example, the removal of a habitat also removes food sources for many animals. It is therefore essential to put in place conservation measures to protect these habitats, but not to an extent that farming is no longer possible, and humans run out of food.

Economic reasons
• Deforestation can result in soil erosion and monocultures can result in soil becoming deficient in particular minerals that the crop absorbs a lot of. Both results in soil depletion and can negatively impact a country’s ability to grow crops. Tourism often relies on people visiting areas of natural beauty and observing animals in their natural habitat. Extinction of habitats, plants and animals could reduce tourism and therefore impact the economy. Also, many medicines have been based on chemicals naturally occurring in plants, so plant species going extinct could have potentially held the molecules needed to cure diseases in humans.

Aesthetic reasons
• Being in nature around animals and plants enriches people’s lives and this is why people may choose to visit different environments like the rainforest and beaches. Nature is also a creative inspiration for art, music and writers. Being amongst nature has been shown to improve people’s mental health.

Question 18

methods of maintaining biodiversity

Answer 18

in situ-within the natural habitat

ex situ-not within the natural habitat

Question 19

in situ

Answer 19

In situ
• As conservation happens with the habitat, genetic diversity is maintainea as individuals are not bred captively. Another advantage is, because all organisms are interdependent, putting measures in place in situ to prevent the extinction of one species will have a positive impact on all other species dependent on it.
Examples include marine conservation zones and wildlife reserves.
• Marine conservation zones are areas designated for wildlife to recover and repopulate, for example, areas where fishing and tourism aren’t allowed. Wildlife reserves are the same concept, but on land. These areas are actively managed to conserve wildlife.

Question 20

ex situ

Answer 20

• Involves removing organisms from their natural habitat to try and protect them, and it is usually used in addition to in situ measures.

• Examples include botanical gardens, seed banks and captive breeding. A wide range of plant species can be grown in botanical gardens, providing them with the optimal conditions for growth.

• Seed banks are like a store of genetic material. Seeds of a variety of plants species are stored in water and temperature-controlled environments to keep them viable for longer. These are stored as a backup for potential plant species that may go extinct.

• Captive breeding programmes involve reproducing animals in zoos and aquariums. The aim is to increase the number of endangered species, and these individuals can then be reintroduced into the wild.

Question 21

international and local conservation agreements

Answer 21

• Convention on International Trade in Endangered Species (CITES)
• The Rio Convention on Biological Diversity (CBD)
• The Countryside Stewardship Scheme (CSS)
• CITES is a treaty that regulates the trade of international animals, plants and their products. This regulation of international trade requires cooperation and agreement between countries.
The CBD began in 1992 when 172 nations met in Rio and came up with three agreements:
• Countries must come up with strategies for sustainable development.
• To stabilise greenhouse gas emissions and concentrations within the atmosphere.
• To prevent the destruction of fertile land into desert and reduce the effects of drought.