exam unit 3 aos1

categories of biodiversity

• genetic

• species

• ecosystem

genetic diversity

is the total genetic information contained in the genes of all species on earth

species diversity

the variety of different species in a particular area or on earth as a whole

ecosystem diversity

the variation in the processes, habitats, and systems in an ecosystem.

species

is a group of organisms which can reproduce to create fertile (able to reproduce themselves) and viable (capable of surviving and reproducing) offspring.

genetic diversity is of particular interest and is very important why

• A larger amount of genetic material means that it is more likely that in the event of a sudden change, advantageous traits are present. This leads to one part of ‘natural selection’, where the specific populations with the advantageous traits live and hence reproduce, building up the advantageous traits.

• This is to say that genetically diverse species are often more resilient to environmental changes and hence can bounce back better.

why does species diversity rely on both species abundance and species number

• The number of species does not tell the full relationship within the ecosystem

• A dominant, rampant species may take up all the places in the ecosystem, despite a large number of much smaller species, which diminishes the diversity as there is less in comparison

• Hence, it is important to think about both relative abundance and the number of species.

species resilience

In order for a species to withstand environmental changes, they must be both resilient and resistant.

• Resilience is defined as the ability for a species to ‘bounce back’ and recover following an environmental change.

species resistance

Resistance is defined as how well a species can withstand an environmental change.

species resilience and resistance

Typically, a genetically diverse species is more resilient and more resistant. This is because

• Those with advantageous traits have a higher chance of survival and hence develop resistance against those previous changes.

• Advantageous traits which benefit recovery may also develop as a result of genetic diversity.

ecosystems as a source of renewable services that impact on human health and well-being:

• provisioning services: potable water; food; fuel; fibre; and pharmaceuticals

• regulating services: control of climate and disease; pollination; and water purification

• supporting services that maintain conditions for life on Earth: cycling of nutrients; soil formation; and photosynthesis

• cultural services: aesthetic values; recreational benefits; and sense of place

regulating services

that which balances ecosystems and mainains the flow of an ecosystem

• e.g purification,pollination, decomposition,errorision,flood control regulation of carbon dioxide

supporting services

the foundation of an ecosystem that which an ecosystem cannot exist/hold without

• E.g. nutrient cycling, soil formation, water cycle, photosynthesis

provisioning services

the materials and resources we can collect from ecosystems

• E.g. raw materials, fresh water, food, medicine

cultural services

the social and cultural benefits or recreational benefits which we gain from ecosystems.

• E.g. sense of place, recreation, aesthetic value, travel, connection to land

How life on Earth has changed since the beginning of life can be measured using the scientific method of

dating

dating

the process of using scientific techniques to determine the age of something

two types of dating

• Relative dating, which compares ‘strata’ (layers) to tell the relative ages between different things

• Numerical/radiometric dating, using radioactive isotopes to determine the age of a sample (using the half life)

relative dating

is an approximate method and is often used on things with layers (strata), such as sedimentary rock, buried fossils or other organic buried matter. It is considered large-scale and not as accurate as radiometric dating.

radiometric dating

is an accurate method, and is used on things which do not have apparent layers, such as metamorphic and igneous rocks, to find the exact age of a fossil, or specific things like eras and periods.

relative and radiometric dating are not exclusive, that is, they can be used

together, to form a larger picture

For example, relative dating may be used to establish the relationship between different layers, and to find an estimate. Radiometric dating would then be used to find an exact and accurate age. Radiometric dating is often more expensive, requiring either sophisticated equipment or infrastructure.

backgroynd rate of extinction

Background rate of extinction is the natural rate at which species go extinct without human factors. It is generally one species per one million species per year (for example, if there is 3 million species, 3 species will become extinct a year)

5 common ways in which mass extinctions happen

• Comets and asteroids

• Volcanic eruptions

• Change in atmospheric gases

• Sea level changes

• Climate change

speciation can be either be

• divergent

• convergent

divergent

speciation is when different populations of the same species go to different environments and adapt in regards to their environment, eventually reaching a point where they cannot interbreed and hence are considered different species.

convergent

speciation is where different species gain similar traits due to a shared environment.

speciation is caused by

mass extinctions since, following an extinction, surviving species use remaining resources and habitat to recover, spreading out over time and hence undergoing speciation. This also leads to an increase in the amount of species, and also can be considered diversifying the ecosystem.

endemic

only found in one specific area or region, restricted to this area

endemic species

need special consideration, care and maintenance.

• This is because all of the species are concentrated in one area, so a devastating change has the potential to wipe out the entirety of the species.

medium term changes enso ( El nino southern osciliation) cycle

El Nino Southern Oscillation cycle is a periodic change in surface water temperatures in the Pacific Ocean. As waters near the Americas get warmer, air evaporates and tradewinds travel towards the Americas. This is an El Nino event in Australia.

As waters near Australia get warmer, tradewinds travel towards Australia and the warm water evaporates, causing an unusually large amount of rain and cooler temperatures. THis is La Nina.

long term changes

• continental drifts

• evolution

continetal drifts

convection currents move tectonic plates shifting landmasses

• Over time, populations of the same species are separated due to continental drift

• Populations are isolated, they fill their unique ecological niches and over long periods of time, speciation occurs

• New species are formed which are often considered endemic to the regions.

evolution

process where over generations, traits change in response to the environment and randomly.

• Natural selection, those who are more likely to survive and reproduce pass down their genetic material to their children. Over time, eventually leads to speciation, which is the process where one species splits into two or more species with different characteristics.

practical techniques used for assessing species diversity

• sampling with grids

• transects

• different shaped quadrats

including consideration of edge effects and mark recapture

quadrats

a closed frame typically a square but also can be a circle triangle etc

transects

a line/path put through an area

spotlighting

walk along trakc sat night and listen for rustling/movement

direct oberservation

look at the species (during the day or with a camera)

indirect signs

things like scat, tracks, burrows, scratches, nests, food remains can be used to identify some species

mark recapture

capture a number of individuals from a species, then later recapture and count how many marked animals are in there, then calculate.

for quadrats

• random sampling

• systematic sampling

random sampling

split up area into a grid, assign each gridbox a pair of Cartesian coordinates, use a random number generator, to generate pairs of numbers. Put quadrats on the generated spaces.

systematic sampling

use a transect and place quadrats along the line in regularly spaced intervals. Not necessarily just for plants, also for (typically slow-moving) animals BUT also can be used for mammals.

advantages and disadvantages for quadrants

Advantages

• Cheap and effective for their cost

• Simple

Disadvantages

• Only covers a small region; may not be representative of the whole habitat

• Not as suitable for larger, more mobile species

transects

• Systematic sampling, as before

Walk along the transect, look for any changes in foliage, sights of animals, change in tree cover etc.

Uses for each:

• Quadrats are usually used in large regions of land to see changes in a site over a region.

• Transects are better to monitor changes across a line, along a gradient.

-Good for looking at zonation patterns (zonation = gradual change of species across an environmental gradient)

E.g. For a field, quadrats would be suitable, but if you were measuring along the coast from deep to shallow waters, transects would be preferred.

edge effects considerations

• Edge effects, the consistent inaccuracy in measurement because of the researchers consideration of whether to include the species across the border of a quadrat.

E.g., if you were to count every species that touched the edge of the quadrat, you’d likely get a higher proportion of species than expected.

• Bias, need to use specific methods to ensure that identification is correct.

mark recapture formula

n/m = N/M

mark recapture formula letters stand for

Mark-recapture formula: , where

𝑚

𝑀

• N is the population which needs to be estimated

• n is the number of individuals in the first, marked sample

• M is the size of the second sample

• m is the amount of individuals in the second sample which were marked

(That is, the proportion of the marked individuals which are caught is equal to the proportion of the total population in each sample)

mark recapture

E.g. estimate the number of individuals in a population using mark-recapture. 55 individuals were marked and released, then later, 58 were recaptured, with 23 marked in that sample.

simpsons index

where n is the number of individuals in a particular species and N is the total amount of species sampled.

• Measure from [0,1] where D=0 means no species diversity and D=1 means very high species diversity.

Simpson’s Index takes into account both species richness and species abundance (relative abundance).

• Species richness = the number of different species in an area

• Species abundance = the relative number of individuals within each species.

simpsons index disadvantages

• SID does not directly consider the effects of weeds on the species diversity

• Does not directly consider the effects of endemic species

• May be less reliable if the sample size is low.

extinct

no reasonable doubt the last individual dead

extinct in the wild

surviving in captivity cultivation

critically endagered

immediate future high risk

endangered

near future high risk 1

vulnerable

not endangered but high risk in meidum term future

near threatened

close to meeting the threateneded thresholds

least concern

low risk of extinxtion

data deficient

not enough data

not evaluated

not yet assessed

qualitative assessment of conservation

• changes in availability of suitable habitat

• geographic distribution

• population size

changes in availability of suitable habitat

• Consider whether the habitat is shrinking, fragmented or damaged

• Competition, fewer resources, human effects etc.

geographic distribution

• How widespread or restricted are the species

• More restricted, and endemic species are more vulnerable to disease, human activity, threats etc.

population size

Smaller populations are more susceptible to inbreeding, extinction, disease.

6 main threats HIPPCO

• habitat destruction

• invasive species

• population growth

• pollution

• climate change

• overexploitation

habitat destruction

the modification and destruction of habitats for reasons