Ecosystem Dynamics and Population Dynamics

A set of 50 flashcards based on lecture notes covering ecosystem dynamics, population sampling, biotic interactions, and geological evidence of past ecosystems.

What is the definition of an ecosystem?

A combination of all organisms (biotic) living in a community and all nonliving (abiotic) factors with which they interact.

What are selection pressures?

Factors that affect the survival and reproduction of an individual within a population.

How are aquatic ecosystems categorized?

They are categorized as fresh water (lakes and rivers) or marine (saltwater, such as coral reefs).

What is viscosity in the context of abiotic factors?

The thickness of a medium and its ability to resist internal movement, such as water or air.

How is buoyancy defined?

The force giving an upward thrust, which is determined by the density of the medium.

What are the two types of ion supply needed for survival?

Macronutrients and micronutrients.

What is a specific plant adaptation for aquatic environments to maximize sunlight?

Being located at the surface for maximum sunlight.

How do terrestrial plants in arid climates reduce transpiration?

By closing their stomates.

What skeletal adaptation allows aquatic animals to move through water efficiently?

Having light or no skeletal systems to allow water to provide support and stream-lined bodies to move through viscous water.

What is predation?

A type of feeding relationship where one organism (predator) kills and consumes another organism (prey).

Describe the population cycle relationship between predators and prey.

As prey numbers increase, predator numbers increase, which then decreases prey numbers, subsequently leading to a decrease in predator numbers.

What is the difference between intraspecific and interspecific competition?

Intraspecific competition occurs between members of the same species, while interspecific competition occurs between members of different species.

What is allelopathy?

The production of specific biochemicals by a plant that can be beneficial or detrimental to another plant by inhibiting or promoting growth.

Provide an example of allelopathy mentioned in the notes.

The release of chemicals by a walnut plant that inhibit the respiration of nearby plants.

What is symbiosis?

The interaction between two dissimilar organisms living in close physical association.

How is mutualism defined?

A relationship where both species benefit from the association.

Give an example of commensalism.

A barnacle benefiting from transport, safety, and food access while the host is unaffected.

What is the difference between ectoparasites and endoparasites?

Ectoparasites live on the surface of the host (e.g., mosquitoes, ticks), while endoparasites live internally in the host (e.g., tapeworms).

What is an ecological niche?

The part of the ecosystem occupied by an organism, including all resources used (both abiotic and biotic).

State the Competitive Exclusion Principle.

Two organisms may occupy the same habitat, but they cannot occupy the same niche.

What is resource partitioning?

A process where similar species (like birds) divide up resources, such as feeding in different parts of the same habitat, to minimize competition.

What is the long-term consequence of competition between two species?

One competitor will usually be more successful and drive out or significantly reduce the numbers of the other.

How does symbiosis contribute to ecosystem resilience?

By increasing biodiversity and creating new opportunities to exploit resources through the integration of genetic material.

What is Devil Facial Tumor Disease (DFTD)?

A highly contagious cluster of cancer cells that is fatal to Tasmanian devils within 6 months of transmission.

How is DFTD transmitted between animals?

Through wounds caused by devils biting each other's faces during conflict.

List four biotic factors in an ecosystem.

Availability of food, number of competitors, number of mates, and number of predators.

What is the purpose of sampling in ecology?

To estimate population numbers when total counts cannot be made.

What is a line transect used to measure?

The distribution of plants and slow-moving animals.

What is the difference between continuous and interval sampling in a line transect?

Continuous sampling records species touching the line along the whole length, while interval sampling records species at specific numbered intervals (e.g., $0.5\,m$).

When is quadrat sampling most appropriate?

When measuring the abundance of plants and slow-moving or non-moving animals.

How is the Capture-Mark-Recapture method performed?

Animals are captured and tagged, released, then a second sample is captured later to count how many individuals were previously tagged.

What is the formula for estimating abundance using Capture-Mark-Recapture?

$$\text{Abundance} = \frac{\text{number captured} \times \text{number recaptured}}{\text{number marked in recapture}}$$

State one assumption of the Capture-Mark-Recapture method.

No population change through migration, births, or deaths occurs between sampling periods.

What is a disadvantage of Line Transects?

They cannot be used to measure abundance.

What two factors are cited as causes for the extinction of Australian Megafauna?

Climate change and Human impact.

How did the climate shift in Australia at the end of the ice age?

It shifted from cold-dry to warm-dry.

What evidence do Aboriginal rock paintings provide to scientists?

Primary evidence of past flora and fauna, changes in abundance, and human observations of the environment dating back $40,000$ years.

How old are the Wandijna paintings?

$50,000$ to $60,000$ years old.

What animals were depicted in the Bradshaw paintings?

Humans, Thylacoleo, and Thylacine.

What biological discovery allows scientists to date the Bradshaw paintings?

The relationship between chemical pigments and the symbiotic fungi and bacteria that have colonized the pigment.

What is micropaleontology?

The study of microfossils, which are microscopic remains of organisms less than a millimeter in size.

What are stromatolites?

Layers of cyanobacteria (autotrophic prokaryotes) that are some of the earliest forms of life, dating back $3.5$ billion years.

What are Banded Iron Formations?

Geological formations consisting of alternating iron-rich and iron-poor sediments.

When did Earth’s atmosphere shift from anoxic to oxic?

Around $2.5$ billion years ago.

How did cyanobacteria cause the formation of iron-rich sediments?

They increased oxygen concentration in the ocean, leading to the precipitation of soluble iron oxide ($Fe_2O_3$).

What is the 'Great Oxidation Event'?

A process that took almost $2$ billion years, resulting in a decrease in anaerobic organisms and an increase in aerobic organisms.

What was a major selection pressure in the pre-oxygen atmosphere?

High levels of UV radiation, which caused cell death or mutations.

How do stromatolites grow in water?

Photosynthetic cyanobacteria colonies trap layers of calcium carbonate ($CaCO_3$) and grow upwards.

What conditions are ideal for stromatolite growth?

Shallow water (to increase light intensity) and warm water (to increase enzyme activity).

What was the major consequence of higher oxygen levels for the complexity of life?

It allowed for the development of larger and more complex multicellular organisms that could undergo respiration.