Module 4 - Ecosystem Dynamics
Inquiry Question: What effect can one species have on the other species in a community?
Organisation within ecosystems
- 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
- 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
Impact Of Biotic Factors
- 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
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 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
- 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
Both organism benefit
- Clownfish and sea anemone → Clown fish is protected by the sea anemone whilst the fish cleans the plant
One species is benefited whilst the other is not harmed or helped
Birds that live in hollow holes in trees
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
- 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
Effect the distribution and abundance of prey
If the prey can reproduce fast enough, rates wont drop
- Prey and predators are in direct proportion
Effects reproduction and survival rates
More food sources → More abundance of both species
Different traits will boost a species survival of getting resources
Increased evolutionary diversification
Development of new species from the integration of genetic material
More resilient ecosystems → Biodiversity
- 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
- 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
- Aboriginal people arrived successful predators.
Used ‘fire stick’ farming techniques.
- Introduction of dingoes may have reduced the diversity of carnivore predators.
Level Of Nutrients
- 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.
Inquiry Question: How do selection pressures within an ecosystem influence evolutionary change?
- 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
- 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
- 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
- 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
- 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.
- 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.
- 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
- Australia’s change in climate due to the split of Gondwana
Arrival of indigenous
- Introduction of non native plant + animals → invasive species → Destroys or affects the natural food web
Inquiry Question: How can human activity impact an ecosystem?
Human Induced Species
- 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
- 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.
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
- 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
- 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
- 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
Increase of concentration of greenhouse gases
More energy being absorbed in oceans and land
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
- 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
- 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
- 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