Ecology: Interactions and Dynamics in Ecosystems

Ecology

Scientific study between organisms and their environment

Ecological Organisation

Individual (Organism) →Population →Community→Ecosystem →Biome →Biosphere

Ecosystem

Environment containing living (biotic) organisms interacting with each other, and with the non living (abiotic) parts of that environment.

Abiotic Factors

Physical and chemical factors such as temperature, rainfall, type of soil and salinity of water.

Biotic Factors

All living organisms, how many types there are, their numbers, distribution and interaction.

Temperature Variation

A way abiotic factors can affect a species in a terrestrial environment.

Availability of Water

A way abiotic factors can affect a species in a terrestrial environment.

Pressure Variation

A way abiotic factors can affect a species in a terrestrial environment.

Thermometer

Measure temperature (°C).

Hygrometer

Measure humidity (%).

Light Meter

Measure light intensity (LUX).

Kestrel/Wind Meter

Measure wind speed and direction.

Predation

Type of feeding relationship where the predator obtains its food by killing and eating another organism.

Competition

When two or more organisms use one or more resources in common such as food, shelter and mates.

Intraspecific Competition

Competition between members of the same species.

Interspecific Competition

Competition between members of different species.

Allelopathy

Typically plants release chemicals which can harm/benefit other plants.

Mutualism

An interspecific interaction in which both species benefit from the association.

Commensalism

A situation where one species benefits and the other is neither harmed nor helped.

Parasitism

A relationship in which one species benefits (parasites) and the other is harmed.

Ectoparasites

Parasites that live on the outside of a host's body, such as fleas, ticks, and lice.

Endoparasites

Parasites that live inside the host's body, such as tapeworms, liver flukes, and malaria-causing Plasmodium.

Ecological Niches

Describes the functional role and position of an organism, within its environment.

Ideal Niche

Where an organism could live.

Realised Niche

Where an organism does live.

Symbiosis

A close and long-term interaction between two different species.

Radiometric Dating

The process whereby scientists determine the age in years of a fossil, rock or mineral.

Half Life of Carbon-14

5730 years.

Decay of Radioactive Isotopes

The process used to establish absolute dates for geological events.

Age Equation

The rate of the decay process is calculated by comparing the abundance of the naturally occurring isotope in the rock vs the abundance of the decay product.

Gas and Isotope Analysis

Use the data in ice cores to reconstruct atmospheric concentrations of certain gases (carbon dioxide and oxygen).

Selection Pressure

All the Abiotic and Biotic factors in an organism's environment that affects the individual's behaviour, survival and reproduction.

Point Sampling

Individual points are chosen on a map and the organisms at those points are counted.

Transect Sampling

Lines are drawn across a map. Organisms occurring along the line are sampled.

Belt Transect

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

Quadrat Sampling

Sampling squares (quadrats) are placed in a grid pattern on the sample area and the occurrence of organisms in each quadrat is noted.

Mark Release Recapture

Population Size (N) = N1 (number of individuals captured) + N2 (Number of individuals recaptured) + M2 (Number of individuals marked in recapture).

Palaeontology

The study of fossils, providing insights into how life evolved and how ecosystems have changed over time.

Geology

The study of Earth's rocks, minerals, and landforms, helping reconstruct past climates, landscapes, and environmental conditions.

Megafauna

Large animals that lived in Australia during the Pleistocene epoch (Period of Ice Age).

Extinction Period of Megafauna

Around 46,000 years ago.

Evidence of Humans and Megafauna Coexisting

Fossil records with cut marks on bones indicate human interaction.

Burnt Eggshells of Genyornis

Suggest human consumption.

Aboriginal Oral Histories

References encounters with large animals.

Tools and Megafauna Remains

Found together at archaeological sites.

Diprotodon

largest marsupial

Thylacoleo

lion

Procoptodon

kangaroo

Megalania

lizard

Genyornis

flightless bird

Eastern Barred Bandicoot

Common name: Eastern Barred Bandicoot; Scientific name: Permeles Gunni; Fossil evidence for evolution: Evolved from ancient marsupial ancestors in Australia; Fossils date back to Miocene epoch (23-5 mya); Long term adaptations.

Time period of fossil evidence for Eastern Barred Bandicoot

Late 19th century, significant discoveries in 20th and 21st century.

Major Changes in the Eastern Barred Bandicoot species

Anatomical: Ancestral bandicoots were larger, different dental structures. Modern bandicoots have developed strong forelimbs and claws for burrowing; Physiological: Adapted to high reproductive rate to counteract predation pressures; Behavioural: Used to be active both day and night→ now modern bandicoots are mainly nocturnal to avoid predators.

Environmental changes contributing to evolution of Eastern Barred Bandicoot

Biotic: Introduction of predators and competition from introduced species such as rabbits; Abiotic: Changes in climate, habitat destruction.

River red gum

Common name: River red gum; Scientific name: Eucalyptus Camaldulensis; Fossil evidence for evolution: 50 mya to the Eocene epoch, when Australia was apart of supercontinent Gondwana.

Major Changes in the River red gum species

Anatomical: Ancient trees were smaller and less fire resistant. Modern→ thick fire resistant bark, leaves evolved to reduce water loss; Physiological: Developed lignotubers (woody swelling of the root); Behavioural: Evolved allelopathy (produces biochemicals that influence the growth, survival, development, and reproduction of other organisms).

Time period of fossil evidence for River red gum

Early 20th century.

Environmental changes contributing to evolution of River red gum

Biotic: evolution of fire adapted ecosystems in Australia led to natural selection for fire resistant traits; Abiotic: Gradual drying of Australia over millions of years favoured availability and nutrient poor soils. Increased bushfire contributed to fire resistant traits.

Aboriginal rock paintings

Ancient artworks created by Indigenous Australians on rock surfaces, some dating back over 40,000 years, providing insights into past ecosystems, cultural beliefs, and human interaction with the environment.

Banded Iron Formation (BIF)

Distinctive layered sedimentary rocks composed of alternating layers of iron-rich minerals and silica-rich minerals, primarily formed 2.5 to 1.8 billion years ago during the Precambrian era.

How Did BIFs Form?

1. Early Earth's Atmosphere: The early Earth had little to no oxygen in the atmosphere; Oceans were rich in dissolved iron due to volcanic activity and hydrothermal vents. 2. Photosynthesis & Oxygen Production: Cyanobacteria, through photosynthesis, started releasing oxygen into the oceans; This oxygen reacted with dissolved iron, forming iron oxides (rust-like precipitates). 3. Layer Formation: The iron oxides settled on the ocean floor, forming iron-rich layers; Periods of low oxygen levels led to the deposition of silica-rich layers; This cycle continued for millions of years, forming alternating Bands.

Ice Core Drilling

A method of extracting long cylinders of ice from glaciers and ice sheets, where each layer in an ice core represents a different period in Earth's climate history.

Depth of Ice Cores

3 km deep into ice = 1 million years into the past.

How Ice Cores Provide Evidence

Trapped air bubbles - Provide data on past atmospheric composition; Dust & pollen - Indicate past volcanic activity or plant life; Stable isotopes - Help reconstruct past temperatures.