OCR A Level Biology Biodiversity

Biodiversity

The variety of living organisms present in an area.

The importance of biodiversity

All species are interconnected, in regions of reduced biodiversity, connections aren't all present (harming all species).

Which regions have the highest biodiversity

Those closest to the equator

Why measure biodiversity

Informs scientists of the species present in an area, providing a biodiversity baseline.

Levels of biodiversity

Habitat, Species, and genetic

Habitat biodiversity

The number of different habitats found within an area

Species biodiversity

Includes species richness and species evenness

Species richness

The number of different species living in a particular area

Species evenness

A comparison of the numbers of individuals of each species living in a community

Community

All the populations of living organisms in a particular habitat

Genetic Biodiversity

The variety of genes which make up a species.

Why is genetic biodiversity important

• Genetic variation increases the chance that some individuals in a population carry advantageous alleles.

• If the environment changes (e.g. climate, disease), these individuals are more likely to survive and reproduce.

• Ensures natural selection can occur, supporting evolutio

Sampling

To take measurements of a limited number of organisms in a particular area.

Abundance

Number of individuals of a species present

Why is sampling useful

- allows us to estimate the number of organisms in an area without needing to count them.

- we can see how human activities are affecting biodiversity.

Two catagories of sampling

Random and non-random

Random sampling

Each individual in the population has an equal chance of being selected.

Non-random sampling techniques

Opportunistic, Stratified, Systematic.

Oppertunistic sampling

Weakest form of sampling, using organisms which are conveniently available

Stratisfied sampling

Dividing the population into different sub-groups (strata) and then performing a proportional random sample.

(E.g. splitting the sample into males and females, and performing a random sample on both groups).

Systematic sampling

Different areas are identified and sampled seperately, often carried out using a line or a belt transect

Line transect

A line is marked along the ground and samples are taken at specified points.

Belt Transect

Two parallel lines are marked along the ground and samples are taken of the area at specified points.

Issues with sampling reliability

Sampling bias and chance (serendipity)

How to increase sampling reliability

Sampling bias - Use random sampling

Chance - Larger sample size

Animal Sampling Techniques

Pooter, sweep nets, pitfall traps, tree beating and kick sampling

Pooter

- Used to catch small insects

- Insects drawn into the holding chamber via the inlet tube

Sweep Netting

Collecting insects and other organisms by sweeping a net through vegetation

Pitfall traps

- Used to catch small invertebrates. Hole dug deep enough so that the insects cant crawl out into ground which insect falls into. Covered so it doesnt fill up with rainwater

Tree beating

Used to sample invertebrates living in a tree or bush, samples fall on cloth held under tree/bush.

Kick sampling

Used to sample river organisms, riverbed is kicked - organisms flow into net held downstream.

How are plants sampled

Quadrats

Types of quadrat

Point and frame

Point quadrat

Frame with a horizontal bar, samples are taken by pushing pins through the bar.

Frame quadrat

Square frame divided into a grid, samples are inside the squares on the grid.

What can you calculate using a quadrat (species eveness)

Density, Frequency, and Percentage cover

Density

If individuals can be seen clearly, count the number within a 1m by 1m quadrat (giving density/m squared)

Frequency

Used when individuals are hard to count, calculate % of species in each quadrat

Percentage Cover

An estimate of the amount of the percentage ground in a quadrat covered by each species

How are most animal populations estimated

Capture, mark, release, recapture (Counting number of marked individuals in a random recapture of individuals.)

Abiotic factors

Non-living factors affecting biodiversity

How are wind speed, light intensity, relative humidity, pH, temperature, and oxygen content measured?

anemometer, light meter, humidity sensor, pH probe, Temperature probe, Dissolved oxygen probe.

Why is it useful to use a sensor

Allows one to detect rapid changes

Human error is reduced

More precision is achieved

Data can be tracked on a computer

Formula for Simpson's index of biodiversity

Divide all species by total number then add all the results together. Then minus one.

Capital N in Simpson's Index

Total number of organisms of all species

Lowercase n in Simpson's Index

Total number of particular species

What would 0 and 1 represent in the Simpson's Index

0 - no biodiversity

1 - infinite biodiversity

What conditions are expected of an area with high biodiversity

- Large number of successful species

- Not a stressful environment

- Many species with few specific adaptations

- Complex food webs

- Change has no major effect

What conditions are expected of an area with low biodiversity

- Low number of successful species

- Stressful environment

- Few species with many specific adaptations

- Simple food webs

- Change has a major effect

Where does genetic diversity come from?

Different members of the same species have different alleles, but the same genes. Different alleles among members of the same species creates genetic diversity, with more alleles creating more diversity.

Why is genetic diversity important

Species with greater genetic diversity are more able to adapt to changes in their environment (through a greater likelihood of advantageous alleles being present)

Factors increasing genetic diversity

DNA mutations

Interbreeding transferring alleles populations (gene flow).

Factors decreasing genetic diversity

Selective breeding

Captive Breeding Programmes

Rare Breeds

Artificial Cloning

Natural Selection (only those with advantageous alleles live)

Genetic Bottlenecks (where only some survive an extinction)

Founder effect: low number of individuals in an isolated colony

Genetic Drift (some alleles are not passed on randomly)

Polymorphic Genes

Genes with more than one allele

Why are monotrophic genes useful

Basic structure of individuals remains consistent.

Formula for percentage polymorphic gene loci

X result by 100

What does a high polymorphic gene loci mean

Genetically diverse

Human actions which affect biodiversity

Human population growth, Agriculture, Climate Change

How human population growth affects biodiversity

- HABITAT LOSS: Deforestation for grazing/agriculture -> loss of habitat

- OVER-EXPLOITATION:a

How deforestation affects biodiversity

Reduces the number of trees

Reduces tree species diversity (if only one type is felled)

Reduces animal species numbers (habitat loss)

Causes migration (increasing other region's biodiversity)

How agriculture affects biodiversity

Deforestation (to make land) exticntion migration reducing

Remove hedgerows (destroys habitats and plants)

Use of herbicides and pesticides kills plants reducing species diveirsty

Monoculture (only supports one type of species) reduces species diversity

How climate change affects biodiversity

Arctic species extinction

More temperate plants moving north

Rising sea levels flooding land and freshwater

Non arid adapted plants dying from high temp and less rain

Animals praying on non-arid adapted plants die

Insect life cycles and populations change - less pollination

Three main reasons to maintain Biodiversity

Aesthetic, Economic, Ecological

Aesthetic reasons to maintain biodiversity

- Areas rich in biodiversity provide pleasant, attractive landscapes people can enjoy.

- Nature provides artists with inspiration

- Patients recover from stress faster in nature

Economic reasons to maintain biodiversity

- Make medicines

- maintain gene pool

-for fishing/agricutultree

- prevent natural disasters -> cost money

- ecotourism

- increase crop yield due o disease resistance

Ecological reasons to maintain biodiversity

- allows dispersal of seeds by animals

-pollination by insects

- Organisms are interdependent on each other, the removal of one would affect others + disrupt the food chains

Keystone species play an important role in maintaining an ecosystem

Keystone species

Species which have a disproportionately large effect on their environment relative to their abundance, and that drastically alter the habitat when removed.

Agricultural benefits in maintaining biodiversity

- BIodiverse soils helps crop producitivity more source of food

- plant varieties for cross-breeding

-provide natural predators for pests reduce need for pesitcidce

Wild plants have valuable alleles like disease resistant can be used in cross breedinh

How humans can increase biodiversity

Human intervention to create habitats (e.g. maintaining farmland)

Conservation

Preserving and carefully managing natural resources and the environment

Catagories of conservation

In Situ

Ex Situ

In situ conservation

Conservation methods within the natural habitat.

Ex situ conservation

Conservation methods outside of the natural habitat.

Conservation Classification

Extinct (No organisms anywhere in the world)

Extinct In The Wild (Organisms only in captivity)

Endangered (In danger of becoming extinct)

Vulnerable (In danger of becoming endangered)

Non-threatened

Least Concern

Sustainable Development

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Benefits of in situ conservation

- Maintains the genetic diversity of species

- Evolutionary adaptations that enable it to adapt to changing environments e.g. climate or pest populations and natural selection pressure

- Preserves interdependent species in ecosystem

- Generally less expensive

Examples of in situ conservation

Wildlife reserves and marine conservation zones

Wildlife reserves

An area of in situ conservation which requires active management once designated

Active Management Techniques to manage ecosystems

- Controlled grazing: seperating animals in an area to maintain biodiversity by not allowing outcompetition and halting succesion.

- Restricting human access: Not allowing people to visit

- Legislation laws to protect habitats CITES

- Reintroduction of species: Adding species which were gone captive breeding programms

- Seed banks backup if species go instic

.

Marine conservation zones

Preserve species-rich areas (e.g. coral reefs) often require large areas (fish move further).

Examples of ex situ conservation

Botanical gardens, Seed banks, Captive breeding programmes.

Botanical Gardens

Species of plants are actively managed to give them the best resources to grow (e.g. water, soil, no pests).

Seed banks

Known as a gene bank, it acts as a store of genetic material. Seeds are carefully stored at -20 degrees, slowing germination and supplying a back-up against extinction. However, they don't work for all plants - tropical tree seeds die if frozen.

Captive breeding programmes

Produce offspring in a human-controlled environment, aiming to create a stable, healthy population to reintroduce. They provide animals with shelter, food, and veterinary treatment.

Issues with captive breeding programmes

Difficult to maintain genetic diversity, the small numbers of individuals can cause inbreeding. Catalogues and artificial insemination mitigate this.

Reasons why organisms born in captivity may not be suitable for reintroduction

- Diseases (animals lose resistance to disease)

- Behaviours (animals learn behaviours in captivity - cannot be in wild)

- Genetic races (Genetic make-up changes, too different to breed)

- Habitat (Reintroduction may cause stress on ecosystem due to limited territory/food)

Conservation agreements

IUCN, The Rio Convention, Countryside Stewardship Scheme

IUCN

International Union for the Conservation of Nature; a group of nations, makes an annual Red List detailing the conservation status of threatened animals so countries conserve them. Established CITES, a treaty which regulates international trade of wild plants and animals to prevent over-exploitation.

Rio Convention

Meeting of nations which resulted in several new agreements:

- Convention On Biological Diversity

- United Nations Framework Convention on Climate Change

- United Nations Convention to Combat Desertification

Each Convention Is Intrinsically Linked

Convention On Biological Diversity

Countries must develop national strategies for sustainable development to ensure biodiversity

United Nations Framework Convention on Climate Change

Nations take steps to stabilise greenhouse gas emissions

United Nations Convention to Combat Desertification

Prevents fertile land from becoming desert to reduce drought through cooperation

Countryside Stewardship Scheme

Usually local, offers governmental payments to land owners and farmers to enhance and conserve natural landscapes, sought to sustain beauty, wildlife habitats, restoring neglected and potentially historic land, improving countryside enjoyment.