Ecosystem Dynamics

ecological niche

The specific region that an organism takes within an ecosystem in response to influences from abiotic and biotic factors.

eg. Extremophiles are organisms adapted to and thriving in areas of environmental extremes

predation

when one organism benefits and the other is killed

eg. lion + wildebeest

competition

when two or more organisms compete for the same limited resource

intraspecific competition

when two or more organisms from the same species compete for the same limited resource

has a larger effect on population than interspecific. this is because the abiotic and biotic requirements are the same

interspecific competition

when two or more organisms from different species compete for the same limited resource

less influential than intraspecific on population. this is because whilst some abiotic and biotic requirements are the same, there are some differences.

eg. zebra + wildebeest both needing water

symbiotic relationship

when two or more organisms from different species live in close proximity and at least one of them benefits

mutualism

symbiotic relationship where both species benefit.

effect on population: both increase until carrying capacity

e.g. zebra + oxpecker. oxpecker removes parasites from zebra and gets food.

commensalism

symbiotic relationship where one party benefits and the other is unaffected

effect on population: unaffected stays the same. beneficial increases until carrying capacity

e.g. cattle and egret. cattle digs up soil and egrets eat insects dug up

parasitism

symbiotic relationship where one party benefits and the other is harmed but not immediately killed.

effect on population: beneficial increases until carrying capacity and harmed slowly decreases

e.g. mosquito and human.

law of conservation of energy

Energy cannot be created or destroyed but can be rearranged. as food moves along a food chain, more and more energy is removed at each step.

carrying capacity

The maximum, equilibrium number of individuals of a species that can be supported indefinitely in a given environment.

abundance

population of a species in a specific area

distribution

the spread of a population in a specific area

sampling techniques

calculation the abundance or distribution of a population when direct counts are not possible
reasons:
- organism is highly mobile
- environment is isolated/dangerous
- the organism is nocturnal
- there are too many
- habitat is too large

random quadrats

using a 1×1m square randomly placed to calculate abundance in an area. random to eliminate bias. used for plants or immobile organisms. ASSUMES EVEN DISTRIBUTION OF POPULATION

line transects

Used to measure distribution of plants or immobile animals. A random straight line is drawn through the study area, and the presence of any species along the transect is recorded at set intervals along the line.

belt transects

Used to measure BOTH distribution and abundance of plants or immobile animals. In addition to recording the presence of any species along the transect at set intervals, the numbers are also counted either side of the line for a set distance.

capture-re-capture

Used for highly mobile and/or difficult to observe animals. Procedure:

1. Capture a number of individuals and ‘mark’ them (S1)
2. Returning them the wild population
3. Recapture a second sample of the population (S2)
4. Record the number of individuals in S2 that are ‘marked’ (M2)
5. Use the following equation to determine an estimate of the total population: S1 x S2 M2

e.g. used for fish population before fishing season

extinction

the reduction in a population to 0.
e.g. Kangaroo Island emu • Red-crowned parakeet • Gastric-brooding frog

mass extinction/extinction event

involves the reduction to zero in a large number of species.

endemic

a species found only in one country or region?

disease

a condition that adversely affects the normal functioning of an organism

infectious disease

a condition that adversely affects the normal function of an organism caused by pathogens and can be transferred between individuals

e.g. influenza

non-infectious disease

a condition that adversely affects the normal functioning of an organism that is environmental, genetic or nutritional and can not be transferred between individuals.

e.g. type 1 diabetes

law of superposition

in any undisturbed sequence of rocks, each layer is younger than the one beneath and older than the one above it

iron banding

distinct layers of sedimentary rocks containing iron oxide

ice core drilling

cylinders of ice are drilled out of the Arctic and Antarctic ice sheets to observe gas concentration and dust concentration of atmospheres.

dust concentration

used to measure atmospheric circulation

radiometric dating

technique used to determine the age of an object or substance by measuring the amounts of specifric radioisotopes and its decay products.

gas analysis

analysis of gas mixtures using spectroscopy, chromatography or SHRIMP. analyses to determine qualitative and quantitative gas composition.

radioisotopes

elemental molecules made unstable by a not normal amount of neutrons. have radioactive activity. lose energy/radioactivity over time. they can measure the age of an object/substance.

half-life

the time it takes for a radioisotope to decay to half its original value

radiometric dating

measuring the percentage of a radioisotope that remains.

number of half lives x half life years = age