Module 4 - Ecosystem Dynamics

Population Dynamics

Inquiry Question: What effect can one species have on the other species in a community?

• Organisation within ecosystems

  1. Biosphere contains all the living thighs on Earth

• Environments can positively or negatively impact an organism - An organism living and non-living surrounds its ecosystem

• Impact of Abiotic Factors

  1. Abiotic factors are not easily disturbed

• Own unique way of thriving within the limits of the abiotic environment

• Water is a very effective filter of sunlight

• Rapid drop in temperature

• Oxygen levels

• Impact Of Biotic Factors

  1. Living organisms can affect each other by predation and symbiosis but also have an equally profound effect on resources

• Food sources, mates, light, nutrients, water

• Predation

• Predator obtains its food by killing and eating another animals

• Found in aquatic or terrestrial ecosystems

• Spider capturing bugs in its web and eating it

• Competition

Competition is usually for a resource in the environment that is limited supply but valuable for survival

• All competition involves risk to the competitors and the rewards must outweigh the inherent risk

• Intraspecific → Within a species

• Interspecific → Between species

• Symbiotic

• Interactions in which two organisms live together in a close relationship that is beneficial to at least one of them

• Obligate relationship → species depend on each other to live

• Mutualism

• Both organism benefit

• Clownfish and sea anemone → Clown fish is protected by the sea anemone whilst the fish cleans the plant

• Commensalism

• One species is benefited whilst the other is not harmed or helped

• Birds that live in hollow holes in trees

• Parasitism

• One species benefits whilst the other is harmed

• Parasite obtains shelter from the host organism while feeding upon the tissue and fluids

• Ecological Niches occupied by Species

  1. The part of an ecosystem that the organism occupies is called a niche

• Refers to all the resources that a species uses, including biotic and abiotic

• The process of having unique living strategies

• Fundamental niche → The perfect conditions and resources for an organism to live and reproduce

• Realised Niche → All the aspects of the ecosystem including the interactions of other species

• Consequences in ecosystems

  1. Predation

• Effect the distribution and abundance of prey

• If the prey can reproduce fast enough, rates wont drop

- Prey and predators are in direct proportion

• Competition

• Effects reproduction and survival rates

• More food sources → More abundance of both species

• Different traits will boost a species survival of getting resources

• Symbiosis

• Increased evolutionary diversification

• Development of new species from the integration of genetic material

More resilient ecosystems → Biodiversity

• Disease

• Any process that adversely affects the normal functioning of tissue in a living organism

• Bacteria, virus, Pathogen

• Alter the balance of food webs → Affected species will decline in numbers

• Recent Extinction

• Climate Change

  1. Continent dried out

• Rainforests were contracting – stored moisture and returned moisture to the atmosphere.

• Eucalypt forests replaced these, and water was not as efficiently retained.

• Became hotter and drier, fires broke out due to lightning.

• Plants and animals that survived the drought and fire reproduced, changing the flora and fauna.

• Arrival Of Humans

  1. Aboriginal people arrived successful predators.

• Used ‘fire stick’ farming techniques.

• Introduction of dingoes may have reduced the diversity of carnivore predators.

• Level Of Nutrients

  1. Low level of nutrients in the soil → dry

• Led to smaller animals →F can be sustained on less

• Evidence for this can be seen in the smaller size of mammals in Australia compared to counterparts across the world.

Past Ecosystems

Inquiry Question: How do selection pressures within an ecosystem influence evolutionary change?

• Past Ecosystems

  1. It is unclear when humans first became interested in fossils.

• Philosophers hinted that fossils were evidence of previous life.

• Law of superposition → oldest layer at bottom and newest at top.

• Aboriginal Rock Paintings

  1. Longest unbroken tradition in the world

• Humans are driven by nature to record details of their existence

• West Kimberly’s rock paintings

• Radiometric dating is used to date the paintings

• Uranium/Thorium can be used to underlying calcite formations to show when they were formed

• Types and abundance of animals depicted in paintings changed overtime

• Geological Evidence

  1. Allows reconstruction of timeline of events

• Represents the course of changes in geological and fossil deposits

• Banded iron Formations

• Form of geochemical evidence found in Australia

• Earth's atmosphere has undergone changes, change from anaerobic to aerobic

• Form of iron rich and iron poor sediments

• Prokaryotes lead to an increase in oxygen concentration in the ocean, leading to precipitation of insoluble iron oxide

• Precipitate accumulated at the bottom of the ocean, forming an iron rich layer of sediments

• Great oxygenation event transformed Earth’s atmosphere

• Resulted in much larger and multicellular organism→ Organisms had to adapt to more oxygen

• Palaeontological Evidence

• Fossils offer clues to the selection pressures of living things like the climate and environment at the time

• Found in sedimentary rocks → Preserve evidence rather than destroying it

• Fossilised soils contain large concentrations of carbon that indicate presence of life

• Chemosynthesis is a process where organisms use inorganic compounds available from their environment.

• The fossils formed from stromalites provide valuable informationof early orgaims and the environment in which they lived

• Ice Core Drilling

  1. Accumulation of ice layers in places such as antarctica leaves an annual record of gas and dust in that atmosphere of that time

• Scientists can drill into the ice, extract gases and reconstruct the climate record

• Increases understanding of past environments

• Radiometric Dating

  1. Process where scientists determine the age in years of a fossil, rock or mineral

• Based off the content of radioactive isotopes

• Unstable isotopes change to form stable isotopes → Undergoes radioactive decay which scientists can compare to examine the life of the rock

• More half lives → Older

• Rate of decay is calculated using the age​ equation that compares the abundance of the naturally occurring isotope with the abundance of the decay product.

• Gas Analysis

  1. Scientists can use data in ice cores to reconstruct atmospheric concentrations of certain gases, particularly CO~2~​ and O~​~ 2.​

• CO~2~​ is a normal part of Earth’s atmosphere along with nitrogen, oxygen, argon and other trace gases

• But CO~2~​ is also considered a ‘greenhouse gas’ that traps solar radiation keeping the Earth warm enough to sustain life

• However, increasing CO~2~​ in atmosphere is likely to increase Earth’s atmospheric temperature, known as the ’enhanced greenhouse effect’ or ‘global warming’

• Scientists use ancient CO~2~​ levels~​~ to infer past climates - warming or cooling would have a direct effect on the types of plants and animals that are suited to survive in such a climate

• Oxygen has three naturally occurring isotopes: ^16^​ ^​^O, ^17^​ ^​^O and ^18^​ ^​^O which are incorporated into water molecules. The ratio of ^18^​ O/^​^​^16^ ^​^O in analysed ice core samples indicates ancient water temperatures which scientists can use to reconstruct water temperatures on Earth.

• Small Mammals

  1. We Can use fossil of past animals to show similarities and differences to present day animals and therefore propose evolutionary relationships between them.

• When comparing the modern platypus to fossils, body shape became smaller + more simplified.

• We can infer a change in diet as dentition is different

• Habitat reduced in size → May have become vulnerable.

• Reasons for Change

  1. Australia’s change in climate due to the split of Gondwana

• Climate change

• Arrival of indigenous

• Introduction of non native plant + animals → invasive species → Destroys or affects the natural food web

Future Ecosystems

Inquiry Question: How can human activity impact an ecosystem?

• Human Induced Species

  1. Increasing Population

• Selective breeding, use of fertilisers, pesticides and herbicides

• Medical breakthroughs with antibiotics, better hygiene and vaccinations

• Increasing populations of humans lead to an increase of the demand of resources from ecosystems

• Selective breeding limits the biodiversity of species, hence making them more susceptible to being majorly effected by disease or change

• Agriculture

• Removal of trees leaves the soil vulnerable to erosion → Loss of valuable minerals for an ecosystem

• Pollutions harms the water and atmosphere

• Irrigation was developed alongside the domestication of plants

• Selective breeding of crops and livestock radically altered their features to favour large yields

• Introduced Species

• Many invasive species out compete native species for light, water, habitats and nutrients

• Change the environments to alter the microclimate of the areas to favour their own development

• Completely alter the food web system which has detrimental effects on the rest of the ecosystem

• Land Clearing

• Refers to the removal of native vegetation for urban and agricultural development

• Removes nesting and habitats of native animals → Cannot reestablish anywhere else.

• Extinction

• Habitat loss is the leading cause of extinction

• Most historic extinctions have occurred on islands because a small habitat loss has devastating effects

• Extinction opened niches for surviving organism to expand into → Rapid development of species

• Past To Inform the Future

  1. Can estimate rates of extinction by studying recorded extinction events, examining fossil record and by analysing modern trends in habitat loss

• Over exploitation of resources → Harvesting an amount that is not sustainable over time

• Introduced species → New species effect relationships due to competition, predation and disease

• Disruption of ecological relationships → loss of available niches alter the distribution and abundance of species

• Biodiversity

  1. Genetic diversity → Intraspecies diversity in traits that makes a population resilient to environmental changes

• Species Diversity → Variety of species in an ecosystem

• Ecosystem diversity → Variety of ecosystems available in a broader area such a continents or globally

• Climate Change

  1. Greenhouse Effect

• Solar radiation reaches and penetrates earths atmosphere

• Some energy is trapped and absorbed into the land and ocean

• Keeps earth warm and sustainable

• Enhanced Greenhouse

• Increase of concentration of greenhouse gases

• More energy being absorbed in oceans and land

• Warmer climate

• External factors → Solar input from the sun, Earths variety in orbit

• Internal factors → Active release of CO2 from volcanoes, diffusion of CO2 from ocean, less reflection of light from ice (Melting ice is bad)

• Human Factors → burning fossil fuels, agriculture, land clearing

• Models Predicting Biodiversity

  1. Resources increase slow

• Humans grow quick

• Humans will outgrow their ability to feed themselves

• Greater fertility will lead to starvation

• Keep numbers and population in check

• Mining Sites

  1. Required to follow laws and strict guidelines, which include submitting information on how they intended to ensure minimal harm to environment

• All mining companies must complete an environmental impact statement as a part of their license application

• Land Degradation and Agriculture

  1. Marked improvement in the management of Australiansoils and waterways

• Farm owners can have their land inspected by scientists

• Management of salinity and erosion are high priorities

• Biological controls are being used to maintain pests

Now for the HSC course