IB ESS

environmental pressures

the factors (abiotic or biotic) in an ecosystem which put pressure on an organism's survival and increase competition (whether inter-species or intra-species)

biodiversity

a combination of the species diversity, genetic diversity and habitat diversity of an ecosystem

variation

the differences, either physical or genetic, between individuals of a species

simpson's diversity index

a measure of diversity between similar ecosystems

species diversity

the number of species (richness) and their relative proportions (evenness) in a community

genetic diversity

the range of genetic material present in a gene pool or population of a species

random genetic mutations

the small differences which may occur in an organism as a result of reproduction - these small changes may add up to create variation

hotspots

an area of high biodiversity (which is under threat from human activities)

endemic species

the species which only occur in one specific area

speciation

the gradual change in populations of a species over time - often caused by geographical isolations, resulting in new species

evolution

the process by which a species may adapt to environmental pressures through natural selection of favourable variation - caused by random genetic mutations - over thousands of generations

natural selection

survival of the fittest - only the best suited organisms will be able to compete (due to environmental pressures) and so survive long enough to reproduce - their favourable traits are then passed on to new generations

geographical isolation

the separation of populations of a single species - often leads to speciation if populations cannot interbreed for a very long time

physical barriers

e.g. a mountain, ocean or separation of lakes

land bridges

a connection between land masses - often as a result of lowering sea levels e.g. the Bering Straits

continental drift

the movement of the tectonic plates by around 1cm a year causing the change in shape and location of continents

lithosphere

the Earth's crust - the rocky part of Earth

Gondwana

the land mass made up of Africa, New Zealand, Australia and South America, India, Arabia and Antarctica millions of years ago - separated millions of years ago

background extinction rate

the natural rate of extinction of species - around 1 species per million species per year

extinction

the complete loss of a species from Earth - no more individuals of that species exist

mass extinctions

an extinction rate far greater than background extinction rate

Holocene extinction event

the 6th mass extinction occurring for the last 10,000 years, however, much faster in the last 100 years - generally agreed to be as a result of human activity

weedy species

the species (generally plant or animal) which are able to survive the environments we create e.g. urban rats, domesticated animals

Living Planet Report

a report produced by the Worldwide Fund for Nature (WWF) creates on the state of the world's ecosystems

conservation

the act of preserving nature - attempting to save habitats, species and biodiversity in general

2/3

the proportion of living species which are found in tropical rainforests

current extinction rates

approx. 100 species per million species per year

ecosystem complexity

creates stability and resilience to change in an ecosystem - there are many pathways for energy flow

limiting factors

environmental conditions that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem - when there are few of these, biodiversity is likely to be high (and vice versa)

inertia

the ability of an ecosystem to resist change (maintain equilibrium) when subjected to a disruptive force

natural hazards

naturally occurring events which may have a negative impact on the environment e.g. eruption of Mount St Helens in 1980, the 2004 SEA earthquake and subsequent tsunami

habitat loss

the major cause of loss of biodiversity

habitat fragmentation

when a large area of habitat is broken into many smaller areas, often physically divided by roads, towns, factories, power lines etc - leads to the loss of biodiversity

overexploitation

the overuse of a resource to the point that is has a negative impact on the ecosystem e.g. deforestation

introduction of non-native species

when a species which is not naturally occurring in an ecosystem is introduced and may out-compete the native species - this may lead to a loss of biodiversity e.g. rabbits, cane toads, red foxes, camels in Australia

lungs of the Earth

rainforests - they are called this because they are thought to produce around 40% of the oxygen that animals breath

narrow geographical range

a small area that a species inhabits - makes a species prone to extinction

low genetic diversity

caused by small populations or declining diversity - makes a species prone to extinction as they may not be able to adapt to change

low population density

some species need a large area to hunt - if there are only a few organisms over a large territory this may make them prone to extinction, especially if habitats become fragmented

large body

due to the 10% rule, it is much more difficult for big organisms to find enough food - this makes them prone to extinction e.g. wolves, tigers

low reproductive potential

reproducing slowly and/or infrequently - this makes a species prone to extinction as it may take a long time for a population to recover its numbers

seasonal migration

the movement between different areas at different seasons - this makes a species prone to extinction as they rely on more than one habitat - if one is destroyed, they will not survive

poor dispersers

a species which cannot move easily to new habitats - this makes them prone to extinction - for example plants which rely on a slow dispersal of seeds, flightless birds of New Zealand

specialised feeders

a species which requires a specific food and cannot eat others e.g. giant pandas eat bamboo shoots, koalas eat eucalyptus leaves - this makes them prone to extinction if their food source becomes scarse

minimum viable population size

the lowest number of individuals of a species needed for a population to be able to recover - if a population is lower than this number, they may become extinct

IUCN

The International Union for the Conservation of Nature and Natural resources - often known as the World Conservation Union

made up of government agencies, states, non-governmental organisations (NGOs) and scientists and experts - their goal is to conserve nature and increase sustainability of resource use

IUCN Red List

the conservation status of species based on: population size, degree of specialisation, distribution, reproductive potential, geographic distribution and fragmentation, habitat quality, trophic level and therefore, the probability of extinction

extinct (EX)

IUCN Red List Status - no reasonable doubt that the last of a species has died

extinct in the wild (EW)

IUCN Red List Status - a species is known only to survive in cultivation, captivity or outside of its past range

critically endangered (CR)

IUCN Red List Status - at extreme risk of extinction in the wild

endangered (EN)

IUCN Red List Status - facing a very high risk of extinction in the wild

vulnerable (VU)

IUCN Red List Status - facing a high risk of extinction in the wild

near threatened (NT)

IUCN Red List Status - likely to qualify as vulnerable or endangered in the near future (but does not yet)

least concern (LC)

IUCN Red List Status - widespread and abundant

data deficient (DD)

IUCN Red List Status - when there is insufficient data to determine a species' status

not evaluated (NE)

IUCN Red List Status - when a species has not been evaluated against the criteria

UN

United Nations

UNEP

United Nations Environmental Program

CITES

Convention on International Trade in Endangered Species

UNDP

United Nations Development Program

WWF

Worldwide Fund for Nature

WRI

World Resource Institute

species

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

population

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

habitat

the environment in which a species normally lives

abiotic factors

non-living, physical factors that influence the organisms and ecosystem, e.g. temperature, sunlight, pH, salinity, pollutants.

biotic factors

the living components of an ecosystem - organisms, their interactions or their waste - that directly or indirectly affect another organism

niche

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

fundamental niche

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

realised niche

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

limiting factors

factors which slow down growth of a population as it reaches its carrying capacity

carrying capacity

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

population dynamics

the study of the factors that cause changes to population sizes

competition

when two or more individual organisms try to exploit a resource that is in limited supply

intraspecific competition

competition between members of the same species

interspecific competition

competition between individuals of different species

competitive exclusion

when interspecific competition results in one species being driven out by the other

predation

when one animal eats another animal

herbivory

when an animal eats a plant

parasitism

A symbiotic relationship where one organism (the parasite) lives in or on another (the host) feeding on or from it. One suffers, the other is harmed.

mutualism

a symbiotic relationship where both species benefit.

S and J population curves

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

community

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

ecosystem

a community and the physical environment it interacts with.

respiration

the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy.

photosynthesis

the process by which green plants make their own food from water and carbon dioxide using energy from sunlight

food chain

the flow of energy from one organism to the next. It shows the feeding relationships between species in an ecosystem

trophic level

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

producers (autotrophs)

an organism which produces its own food

photoautotrophs (green plants, algae, etc)

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

chemoautotrophs

make their own food from simple compounds such as ammonia, hydrogen sulphide or methane, not requiring sunlight

consumers (heterotrophs)

obtain their food by eating other organisms

food web

a complex network of interrelated food chains

ecological pyramids

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

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.

biomass

the living mass of an organism or organisms. Measured by obtaining the dry mass and usually calculated per unit area.

biome

a collection of ecosystems sharing similar climatic conditions

biosphere

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