Ecology-defintions and species relationships

Predator-prey relationship

a biological interaction where one organism (predator) consumes another organism (prey). This is all fundamental and examples are: lion and zebra, wolf and deer and ladybugs and aphids

Interspecific competition relationship

The interaction between individuals of different species that compete for the same resource in an ecosystem such as with coral reefs (coral + algae), savanna (trees + grasses) and deserts (rodents + insects)

Parasitism relationship

a symbiotic relationship between 2 organisms in which one organism, the parasite, benefits at the expense of the other organism, the host. The Parasite derives nutrients or other resources from the host (echo and Endo). Some examples include: ticks and mammals, mistletoe and trees and tapeworms and humans

Endosymbiosis relationship

one lives inside the cells or body of another organism. Often mutually beneficial with types of algae (zooxanthellae) and coral polyps. Algae lives within the coral’s tissues and provide the coral with photosynthetic products while the coral protects algae and provides it with sunlight

Commensalism relationship

Where one species benefits from the interaction but it has no benefit to the other i.e birds feed on insects disturbed by large grazing herd animals

Mutualism relationship

both organisms of different species benefit from the relationship i.e with cleaner fish and larger marine species and in nitrogen fixation

Coevolution relationship

Mutualistic relationship becomes so narrowed that the organisms are evolutionary dependent i.e honey badger and guide bird

species definition

A group of organisms sharing common characteristics that interbreed and produce fertile offspring

habitat definition

the environment in which a species normally lives

niche definition

describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds

fundamental niche definition

describes the full range of conditions and resources in which a species could survive and reproduce

realized niche definition

describes the actual conditions and resources in which a species exists due to biotic interactions

what are abiotic factors

the non-living, physical factors that influence the organisms and ecosystem, eg temperature, sunlight, pH, salinity and precipitation

what are abiotic factors

the interactions between the organisms, eg predation, herbivory, parasitism, mutualism, disease and competition

population definition

a group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding

what are S and J population curves

describe a generalised response of populations to a particular set of conditions (abiotic and biotic factors)

what are limiting factors

factors that slow population growth as it approaches the carrying capacity of the system

what is an ecosystem

made up of the organisms and physical environment and the interactions between the living and non-living components within them

what is population density

the average number of individuals in a stated area, influenced by: natality (birth rate), mortality, migration

what is carrying capacity

the maximum number of a species or “load” that can be sustainably supported by a given area

what is competition

All the organisms in any ecosystem have some effect on every other organism in that ecosystem. Also any resource in any ecosystem exists only in a limited supply. When these two conditions apply jointly, competition takes place.

what is intraspecific competition

between members of the same species. When the numbers of a population are small, there is little real competition between individuals for resources. Provided the numbers are not too small for individuals to find mates, population growth will be high

what is interspecific competition

Individuals of different species could be competing for the same resource. Interspecific competition may result in a balance, in which both species share the resource.

what is competitive exclusion (the other outcome other than interspecific competition)

The other outcome is that one species may totally out-compete the other

community definition

a group of populations living and interacting with each other in a common habitat.

respiration definition

the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy. Aerobic respiration can simply be described as:

glucose + oxygen → carbon dioxide + water

what do primary producers do in most ecosystems

in the majority of ecosystems convert light energy into chemical energy in the process of photosynthesis.

what is the equation of photosynthesis

carbon dioxide + water → glucose + oxygen

what is photosynthesis

process that produces the raw material for producing biomass.

what is a trophic level?

position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.

what are producers/ autotrophs

typically plants or algae and produce their own food using photosynthesis and form the first trophic level in a food chain. Exceptions include chemosynthetic organisms which produce food without sunlight.

what are ecological pyramids

pyramids of numbers, biomass and productivity and are quantitative models and are usually measured for a given area and time.

what is bioaccumulation

the build-up of persistent/ non-biodegradable pollutants within an organism or trophic level because they cannot be broken down.

what is biomagnification

the increase in concentration of persistent or non-biodegradable pollutants along a food chain.

what do toxins such as DDT and mercury do?

accumulate along food chains due to the decrease of biomass and energy.

what are pyramids of numbers

display different patterns, for example, when individuals at lower trophic levels are relatively large (inverted pyramids)

what are pyramids of biomass

represents the standing stock/storage of each trophic level measured in units such as grams of biomass per square metre (g m-2) or Joules per square metre (J m-2) (units of biomass or energy).

what are pyramids of productivity

refer to the flow of energy through a trophic level, indicating the rate at which that stock/storage is being generated.

what is the compensation point

When all carbon dioxide that plants produce in respiration is used up in photosynthesis, the rates of the two processes are equal and there is no net release of either oxygen or carbon dioxide. This usually occurs at dawn and dusk when light intensity is not too high. it is neither adding biomass nor using it up to stay alive at this point. It is just maintaining itself.

what is a food chain

the flow of energy from one organism to the next. A food chain shows the feeding relationships between species in an ecosystem. Arrows connect the species, usually pointing towards the species that consumes the other: so in the direction of transfer of biomass (and energy)

what are the the trophs?

Autotrophs- make their own food from carbon dioxide and water using energy from sunlight

Chemotrophs- which make their own food from other simple compounds eg ammonia, hydrogen sulphide or methane, do not require sunlight and are often bacteria found in deep oceans.

Heterotrophs- which feed on autotrophs or other heterotrophs to obtain energy (herbivores, carnivores, omnivores, detritivores and decomposers).

the carbon and nitrogen cycles contain…

storages (sometimes referred to as sinks) and flows which move matter between storages

what are the storages in the carbon cycle

include organisms and forests (both organic), or the atmosphere, soil, fossil fuels and oceans (all inorganic)

what are the flows in the carbon cycle

include consumption (feeding), death and decomposition, photosynthesis, respiration, dissolving and fossilisation

what are the storages in the nitrogen cycle

include organisms (organic), soil, fossil fuels, atmosphere and water bodies (all inorganic).

what are the flows in the nitrogen cycle

include nitrogen fixation by bacteria and lightning, absorption, assimilation, consumption (feeding), excretion, death and decomposition, and denitrification by bacteria in waterlogged soils.

what is productivity

the conversion of energy into biomass over a given period of time. It is the rate of growth or biomass increase in plants and animals. It is measured per unit area per unit time, eg per metre? per year. (m-? yr ")

what is gross productivity

is the total gain in energy or biomass per unit area per unit time. It is the biomass that could be gained by an organism before any deductions.

what is net productivity

is the gain in energy or biomass per unit area per unit time that remains after deductions due to respiration.

what is the gross primary productivity

is the total gain in energy or biomass per unit area per unit time by green plants. It is the energy fixed [or converted from light to chemical energy) by green plants by photosynthesis.

what is net primary productivity

the total gain in energy or biomass per unit area per unit time by green plants after allowing for losses to respiration. This is the increase in biomass of the plant - how much it grows - and is the biomass that is potentially available to consumers (animals) that eat the plant.

what is nitrogen fixation

when atmospheric nitrogen (N,) is made available to plants through the fixation of atmospheric nitrogen. This conversion from gaseous nitrogen to ammonium ions can be carried out in one of five ways

what are the five ways in which nitrogen fixation can be carried out

1. By nitrogen-fixing bacteria free-living in the soil (Azotobacter).

2. By nitrogen-fixing bacteria living symbiotically in root nodules of leguminous plants (Rhizobium). The plant provides the bacteria with sugars from photosynthesis, the bacteria provide the plant with nitrates.

3. By cyanobacteria (sometimes called blue-green algae) that live in soil or water. Cyanobacteria are the cause of the high productivity of Asian rice fields, many of which have been productive for hundreds or even thousands of years without nitrogen-containing fertilizers.

4. By lightning also causing the oxidation of nitrogen gas to nitrate which is washed into the soil.

5. The industrial Haber process is a nitrogen-fixing process used to make fertilizers. Nitrogen and hydrogen gases are combined under pressure in the presence of iron as a catalyst (speeds up the reaction) to form ammonia.

what is nitrification

some bacteria in the soil are called nitrifying bacteria and are able to convert ammonium to nitrites (Nitrosomonas) while other convert the nitrites (NO,~) to nitrates (Nitrobacter) which are then available to be absorbed by plant roots.

what is denitrification

denitrifying bacteria (Pseudomonas denitrificans), in waterlogged and anaerobic (low oxygen level) conditions, reverse this process by converting ammonium, nitrate and nitrite ions to nitrogen gas which escapes to the atmosphere.

how is decomposition apart of the nitrogen cycle

Decomposition of dead organisms supplies the soil with much more nitrogen than nitrogen fixation processes. Important organisms in decomposition are animals (insects, worms among others), fungi and bacteria. They break down proteins, producing different ions: ammonium ions, nitrite ions and finally nitrate ions. These ions can be taken up by plants which recycle the nitrogen.

assimilation in the nitrogen cycle:

Once living organisms have taken in nitrogen, they assimilate it or build it into more complex molecules. Protein synthesis in cells turns inorganic nitrogen compounds into more complex amino acids and then these join to form proteins. Nucleotides are the building blocks of DNA and these too contain nitrogen.

how do legumes influence the nitrogen cycle

leguminous crops with root nodules containing nitrogen-fixing bacteria. These plants enrich the soil with nitrogen when they decompose.

how does soil affect the cycle

The soil condition also affects the nitrogen cycle. If it becomes waterlogged near the surface, most bacteria are unable to break down detritus because of lack of oxygen but certain bacteria can. Unfortunately they release the nitrogen as gas back into the air. This is called denitrification. Excessive flow of rainwater through a porous soil, such as sandy soil, will wash away the nitrates into rivers, lakes and then the sea. This is called leaching and can lead to eutrophication.

what is maximum sustainable yield

is the largest crop or catch that can be taken from the stock of a species (eg a forest, a shoal of fish) without depleting the stock. Taken away is the increase in production of the stock while leaving the stock to reproduce again. It is often used in managing fisheries.

what are biomes

collections of ecosystems sharing similar climatic conditions which can be grouped into five major classes - aquatic, forest, grassland, desert and tundra. Each of these classes will have characteristic limiting factors, productivity and biodiversity.

what does the tricellular model of atmosphere circulation explain

the distribution of precipitation and temperature influencing structure and relative productivity of different terrestrial biomes.

what is donation

refers to changes in community along an environmental gradient due to factors such as changes in altitude, latitude, tidal level or distance from shore

what is succession

the process of change over time in an ecosystem involving pioneer, intermediate and climax communities.

how do r and K-strategist species have…

reproductive strategies that are better adapted to pioneer and climax communities respectively.

what is the biosphere

is that part of the Earth inhabited by organisms. It extends from the upper part of the atmosphere down to the deepest parts of the oceans which support life.

what are the 9 different biomes?

tropical forest

savanna

polar and high-mountain ice savanna

chaparral

desert

temperate grassland

temperate deciduous forest

coniferous forest

tundra

how do latitude and altitude influence climate and biomes

Latitude (distance north or south from the equator) and altitude (height above sea level) both influence climate and biomes. It generally gets colder as you increase latitude or increase altitude. So there is snow on Mt Kilimanjaro and the Himalayas and Andes and they have alpine or polar biomes even though they are at lower latitudes.

what is primary succession

occurs on a bare inorganic surface. It involves the colonization of newly created land by organisms. It occurs as new land is either created or uncovered such as river deltas, after volcanic eruptions, on sand dunes.

what is the first stage of primary succession

Colonisation- First species to colonize an area are called pioneers adapted to extreme conditions. Pioneers are typically r-selected species showing small size, short life cycles, rapid growth and production of many offspring or seeds. Simple soil starts from windblown dust and mineral particles.

what is the second stage of primary succession

Establishment- Species diversity increases. Invertebrate species begin to visit and live in the soil increasing humus (organic material) content and water-holding capacity. Weathering enriches soil with nutrients.

what is the third stage of primary succession

Competition- Microclimate continues to change as new species colonize. Larger plants increase cover and provide shelter, enabling K-selected species to become established. Temperatures, sun and wind are less extreme. Earlier pioneer r-species are unable to compete with K-species for space, nutrients or light and are lost from the community.

what is the fourth stage of primary succession

Stabilisation- Fewer new species colonize as late colonizers become established shading out early colonizers. Complex food webs develop. K-selected species are specialists with narrower niches. They are generally larger and less productive (slower growing) with longer life cycles and delayed reproduction.

what is the last stage of primary succession

The final stage or climax community is stable and self-perpetuating. It exists in a steady-state dynamic equilibrium. The climax represents the maximum possible development that a community can reach under the prevailing environmental conditions of temperature, light and rainfall.

what is secondary succession?

Where an already established community is suddenly destroyed, such as following fire or flood or even human activity (plowing) an abridged version of succession occurs. This secondary succession occurs on soils that are already developed and ready to accept seeds carried in by the wind. Also there are often dormant seeds left in the soil from the previous community. This shortens the number of stages the community goes through.

what changes during secondary succession?

• The size of organisms increases with trees creating a more hospitable environment.

• Energy flow becomes more complex as simple food chains become complex food webs.

• Soil depth, humus, water-holding capacity, mineral content and cycling all increase.

• Biodiversity increases because more niches (lifestyle opportunities)

• appear and then falls as the climax community is reached.

• NPP and GPP rise and then fall.

• Productivity: respiration ratio falls.

what is a sub-climax community

a stage or community in an ecological succession immediately preceding a climax

what causes a sub-climax community

Succession may be stopped or 'arrested' at a stage by an abiotic factor, eg soil conditions such as waterlogging, or a biotic factor such as heavy grazing. This results in an arrested or sub-climax community which will only continue its development if the limiting factor is removed.

what is a plagioclimax community

A Plagioclimax community is an area or habitat in which the influences of the humans have prevented the ecosystem from developing further.

what causes plagioclimax and what is the result of it

Under other circumstances a climax community may be affected by either a natural event, eg fire or landslide, or human activity such as agriculture, regular use of fire or habitat destruction. This will lead to a deflected or plagioclimax community such as pasture, arable farmland or plantations with reduced biodiversity.

what happens if the human activity that created the plagioclima community ceases

Again if the human activity ceases the plagioclimax community will develop into the climatic climax community.

what increases during succession

biodiversity

what decreases during succession

mineral cycling