U3 AOS1 - environmental

Biodiversity

The variability among living organisms from all sources, including terrestrial and aquatic ecosystems and the ecological complexes of which they are part. This includes diversity within species, between species and of ecosystems.

3 levels of biodiversity

Genetic diversity, species diversity, ecosystem diversity.

Importance of biodiversity

Provides food, medicine and materials

Species diversity

The different number of species in an area, as well as their abundance and distribution within that ecosystem.

Species richness

The number of species in an area. It is a numerical characteristic of an ecosystem.

Species abundance

The number of individuals of each species in a given area or ecosystem. It is a numerical characteristic.

Ecosystem diversity

The different biotic and abiotic components of an ecosystem and how they operate. The more complex and interconnected an ecosystem is, the better it can perform critical processes and functions.

Genetic diversity

The variation of genetic information within living organisms. Large and well-connected populations retain high genetic diversity, while small isolated populations can lose genetic diversity.

Impacts of high genetic diversity

Higher adaptive capacity

Impacts of low genetic diversity

Lower adaptive capacity

Factors that affect genetic diversity in populations

Genetic drift

Extinction

The complete disappearance of a species or local population.

Species diversification

The rate of speciation, or evolution of new species, over time.

Mass extinction

Any circumstance that results in the loss of a significant portion of Earth's living species across a wide geographic area within a relatively short period of time.

Biological extinction

A species is considered extinct when no members of the species remain alive anywhere in the world.

Local extinction

When a species is no longer found in an area that it once inhabited but is still found elsewhere in the wild.

Ecological extinction

When there are so few individuals remaining in a population that they can no longer fulfil their ecological role.

Extinct in the wild

When individuals of a species remain alive only in captivity or other human-controlled situations.

Techniques used to date fossils

Relative dating

Radiometric dating

Relative dating

The principle that within a sequence of layers of sedimentary rock, the oldest layer is at the base and the layers are progressively younger. By excavating sites and separating artefacts from each layer, changes over time can be identified.

Radiometric dating

Determines the approximate age of fossils in years based on radioactive decay and the relative proportions of isotopes in different minerals. It is used to divide Earth's history into geological eras, periods and epochs.

Endemism

A term used to describe animals and plants that are native to one specific geographical location.

Biodiversity hotspot

A region particularly rich in biodiversity with a high number of endemic species, but which is under significant threat from habitat loss or other human activities.

Short-term environmental changes

Environmental changes where affected areas can regenerate in years to up to a decade.

Examples of short-term environmental changes

Fire

Medium-term environmental changes

Environmental changes that occur over a period of time where animals have an opportunity to move.

Examples of medium-term environmental changes

El Niño causing droughts, high temperatures and heat waves

Long-term environmental changes

Environmental changes that occur over millions of years.

Example of long-term environmental change

Movement of tectonic plates, including continental drift and the formation of new land.

Random sampling

Selecting sample units from a population so that each unit has an equal chance of being chosen, helping ensure unbiased data collection and analysis.

Systematic sampling

Selecting sample units at regular intervals or according to a predetermined pattern, ensuring an even distribution of samples across a study area.

Sampling edge effects

When an animal or plant is at the edge of a quadrat and a decision must be made about whether it is counted. This can affect measurements of biodiversity.

Line transect

A straight line across an area where organisms touching the line are identified and recorded.

Belt transect

Quadrats are placed at regular sample points and the abundance of organisms within each quadrat is recorded.

Which is quicker: line or belt transect?

Line transect.

Which gives a better indication of vegetation height: line or belt transect?

Belt transect.

Which gives a better indication of species and biodiversity: line or belt transect?

Belt transect.

Which gives a better percentage cover: line or belt transect?

Belt transect.

Four techniques for sampling mammals

Indirect signs

spotlighting

directo observations

live trapping

Indirect signs

Evidence of animals such as droppings, tracks, burrows, food remains and remains of bodies.

Spotlighting

Walking along tracks at night and listening for movement, then viewing animals using a powerful torch or spotlight. Animals' eyes can reflect the light at night, and some animals are only active at night.

Direct observation

Observing animals directly during the day. Photos can be used to identify species, and motion-sensor camera traps can also be used.

Live trapping

Capturing animals using traps to obtain additional data. It requires a permit and can interfere with animals. Capture-mark-recapture can be used to estimate population size.

Capture-mark-recapture formula

N = (M × n) ÷ m.

Capture-mark-recapture N

The estimated population size.

Capture-mark-recapture M

The number of individuals initially captured and marked.

Capture-mark-recapture m

The number of individuals in the second sample that were already marked.

Capture-mark-recapture n

The total size of the second sample.

Three methods to assess biodiversity

Degree of endemism

Degree of endemism to assess biodiversity

Examine the degree of endemism of species present. A species is endemic if it is restricted to that area. The level of endemism can be expressed as a percentage.

Measuring vegetation structure to assess biodiversity

The biodiversity of flora can be assessed based on the physical structure of vegetation as well as the number of species.

Factors determining vegetation structure

Type of vegetation

Two characteristics used to classify vegetation structure

Height of the tallest vegetation present

Simpson's Index of Diversity

A measure of diversity that considers both the number of species present and the relative abundance of each species. More weight is given to common species. As species richness and evenness increase, diversity also increases.

Simpson's Index of Diversity formula

SID = 1 − [Σni(ni − 1) ÷ N(N − 1)].

Simpson's Index of Diversity N

The total number of organisms.

Simpson's Index of Diversity ni

The number of individuals in each species.

P-value

The probability of obtaining the observed result, or something more extreme, if the null hypothesis is true. If the p-value is less than 0.05, reject the null hypothesis because there is sufficient evidence of a statistically significant difference.

Null hypothesis

The hypothesis that there is no difference between the two conditions.

Alternative hypothesis

The hypothesis that there is a difference between the two conditions.

Minimum viable population

The smallest population that has a reasonable probability of surviving for some time into the future.

Three components that contribute to rarity of a species

Population size

Population size as a component of rarity

The density or number of individuals within a local area.

Geographic range as a component of rarity

The spatial distribution of a species and where it lives.

Habitat specificity as a component of rarity

The variety of ecological conditions within which a species can survive.

9 species classifications

Extinct

extinct in the wild

critically endangered

endangered

vulnerable

near threatened

least concern

data deficient

not evaluated

Extinct

There is no reasonable doubt that the last individual has died.

Extinct in the wild

The species is known to survive in cultivation or captivity, but surveys have failed to record any individuals in the wild.

Critically endangered

The species is facing an extremely high risk of extinction in the wild in the immediate future.

Endangered

The species is facing a very high risk of extinction in the wild in the near future.

Vulnerable

The species is facing a high risk of extinction in the wild in the medium-term future.

Near threatened

The species is close to meeting the threatened categories or would be threatened without ongoing species-specific conservation programs.

Least concern

The species has been evaluated to have a low risk of extinction.

Data deficient

There is inadequate information to make a direct or indirect assessment of extinction risk.

Not evaluated

The species has not yet been assessed against the relevant criteria.

4 levels to consider biodiversity

Genetic

population

species

ecosystem

Threats to biodiversity

Creation and isolation of small populations

Bioaccumulation

The build-up of persistent, non-biodegradable pollutants within an organism over time.

Biomagnification

The increase in concentration of a pollutant along a food chain through different trophic levels.

Creation and isolation of small populations leads to

Habitat loss through habitat modification, habitat degradation, habitat fragmentation and habitat edge effects.

Habitat modification

A change in environmental conditions where native habitat is changed from its original conditions.

Habitat degradation

A reduction in the quality of a habitat where natural habitat is altered so dramatically that it can no longer support native species.

Habitat fragmentation

The creation of isolated areas of suitable habitat.

Habitat edge effect

The effects experienced at habitat edges, which are most susceptible to impacts from surrounding areas.

Remnant vegetation

Patches of native trees, shrubs and grasses that remain after habitat loss.

Metapopulation

A group of spatially separated populations of the same species that interact at some level.

Translocation

The managed movement of living plants or animals from one location to another.

Reintroduction

The translocation of a species to an area that used to be part of its range but where no individuals of the species remain.

Captive breeding

The process of breeding animals outside their natural environment in zoos or other closed facilities.

Gene bank

A type of biorepository that preserves genetic information by storing genetic material from species that are endangered or close to extinction.

Seed bank

A gene bank used for the conservation of plants.

Strategies that maintain or build populations also build

Resilience

Best results for biodiversity conservation

Best results are generally achieved when multiple management tools are used together.

Wildlife corridors or zones

Improve connectivity between areas of remnant vegetation, increasing interactions between subpopulations within a metapopulation. Connectivity can enable recolonisation of empty patches and promote gene exchange, reducing inbreeding depression and random demographic effects.

Advantages of wildlife corridors

Allow animals to move between habitat patches

Disadvantages of wildlife corridors

Can aid the spread of disease, pests and weeds

Protected areas or reserve lands

Protected areas of land or water that are managed for nature conservation.

6 management strategies for protecting biodiversity

Retaining remnant vegetation

3 approaches to renewing or regenerating degraded ecosystems

Restoration of habitat