ESS Individuals, populations, communities, and ecosystems

Biosphere

an ecological system composed of individuals, populations, communities, and ecosystems.

individual organism

member of a species

Species

group of organism with common characteristics that can interbreed to produce fertile offspring.

Classifications

organisation of organisms into different taxa or groups.

Binomial system

The two-worded scientific name of an organism, where the first word is the genus and the second word is the species; it should be written in italics or underlined.

Clade

evolutionary relationships between members of a taxon, showing that each came from a common ancestor.

Population

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

Habitat

The place/environment in which a community, species, population or organism lives.

Ecosystem

A community of interdependent populations and the physical environment with which they interact.

Fundamental niche

full range of biotic and abiotic conditions and resources in which a species or population could theoretically survive and reproduce.

Realised niche

The actual conditions and resources in which a species or population exists in due to biotic interactions.

selective pressure

process that affects biological diversity in an ecosystem, where species with helpful characteristics for survival in the local conditions will thrive and others without these characteristics may die.

Predation

One organism acts as the predator and feeds on another organism, called the prey.

Herbivory

interaction between species where organisms, usually animals, feed on plants.

Parasitism

an interaction between two species in which one organism, the parasite, gets the resources it needs from another organism, the host, but may harm the host in the process.

Mutualism

an interaction where both species benefit and neither suffers.

Disease

departure from the normal state of functioning of any living organism and is marked by symptoms of illness.

Competition

organisms compete for a resource that is in limited supply

Intraspecific competition

Where members of the same species compete for a limited resource.

Interspecific competition

members of different species compete for a resource that they both need.

Amensalism

an interaction where a species harms another without any cost or benefit to itself

Neutralism

Both species are unaffected by each other’s presence.

Carrying capacity

average size of a population determined by competition for limited resources and can be sustainably supported by a given environment.

Limiting factor

A resource in the environment that can significantly affect a population's size if it becomes limited.

Density-independent factors

These are limiting factors that do not depend on the size of a population and affect every population in the ecosystem; they tend to be abiotic.

Density-dependent factors

Limiting factors that limit population growth and emerge due to population density, is usually a biotic factor.

R-strategists

Species that tend to spread their reproductive investment among a large number of offspring so that they are well adapted to colonise new habitats rapidly and make opportunistic use of short-lived resources.

K-strategists

Species that usually concentrate their reproductive investment in a small number of offspring, thus increasing their survival rate and adapting them for living in long-term climax communities.

Community

collection of interacting populations within an ecosystem at the same time

Keystone species

A single species in an ecosystem that maintains its structure and function.

Biosphere integrity

encompasses species and genetic diversity, as well as ecosystem function.

Niche

specific role of an organism within its ecosystem, compromising of a particular set of abiotic and biotic conditions and resources on which an organism or a population depends.

Ecological niche

smallest unit of the habitat that refers to where an organism lives, what it does and how it fits into the ecosystem. It describes how the organism survives and reproduces.

Sample

a subset of individuals from a population, making generalisations or estimates about the population as a whole.