Module 4: Ecosystem Dynamics

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 ageequation 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

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