Key Concepts in Ecology

The British Ecological Society is committed to bringing greater understanding of ecology, and its importance, to a wider audience.

Now, more than ever, ecology is taking a prominent role in modern life; therefore, it is important that the BES promotes better appreciation of the ecological jargon and concepts employed in common usage.

The following is not an exhaustive list, more a healthy start to encouraging greater comprehension.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Biodiversity:

An accepted shortening of the phrase ‘biological diversity’. The biological variation found in a defined spatial area: can refer to variation at the level of genome, phenotype, species, community or ecosystem. Most commonly used to describe species richness or diversity, but this common usage should not restrict its correct wider definition.

Climate Change:

Long-term changes in the climatic variables experienced in a defined spatial area (which could vary from local weather to global climate). Recent usage refers to recent and future climate change, which is expected to impose stresses on human standard of living and on the integrity of natural systems.

Community:

All species in a defined spatial area or ecosystem, which interact via trophic, competitive, commensal, amensal or mutualistic interactions. Members of a community may interact directly, or indirectly (e.g. apparent competition) if they share interaction links to other species in the community. There is some debate regarding the true scale at which a ‘community’ can be defined as an independent unit of organisation, with no interaction links outside its boundaries. A common obfuscation is to define a ‘sub-community’ (an arbitrarily chosen set of species that are part of a wider community) as a ‘community’ associated with a key species (e.g. the herbivore ‘community’ associated with a certain plant species).

Competition:

The process via which multiple organisms gain a greater or lesser share of a limited resource. During exploitation competition, strategies concentrate on the gathering of the resource. During interference competition, organisms engage in strategies that protect their share of the resource for future use, or prevent competitors from exploiting that resource.

Ecological niche:

The sum total of all the resources used by, and the biotic and abiotic conditions suffered by, a species. Each resource (e.g. food, shelter) and condition (e.g. temperature, exposure) forms an axis of a multi-dimensional ‘hypervolume’ that describes the ecological requirements and constraints that allow a species to maintain long-term average population growth. An important distinction exists between a species’ fundamental niche (where it could persist) and its realised niche (where it does persist).

Ecology:

The scientific study of the distribution, abundance and dynamics of organisms, their interactions with other organisms and with their physical environment.

Ecosystem:

All organisms and the abiotic environment found in a defined spatial area. For an ecosystem to be a useful unit of biological organisation, it is generally assumed to be the collective description of a community and its physical environment.

Ecosystem Services:

Ecosystems have measurable emergent properties, such as productivity, diversity, stability. A subset of these properties can be considered ‘useful’ in some way to human standard of living. This subset has been terms ‘ecosystem services’. The phrase is commonly used to help quantify the economic benefits of conserving biodiversity.

Evolution:

Change in the relative frequencies of heritable genetic information across generations of organisms. This change can be driven by the deterministic process of natural selection, which acts on genetic variation caused by stochastic mutation processes. Or, evolutionary change can occur via stochastic genetic drift in small populations: drift favours some alleles numerically even though they offer no fitness advantage to their carriers. There exists an important distinction between microevolution, which is change in heritable characteristics within species over short evolutionary timescales, and macroevolution, which is the larger-scale formation of new species during adaptive radiations.

Global Warming:

A significant, long-term increase in mean global temperatures (air or ocean) during the 20th century, and projected to continue into the future. Commonly used synonymously with climate change, but actually only a subset of the climatic parameters that are predicted to change. It should also be noted that an increase in global mean temperature does not mean that any specific part of the globe can expect to be warmer in the future.

Invasive Species:

As a broad definition, any species that has recently expanded its realised niche to colonise a new biogeographical area. Can be used synonymously with ‘non-native’. The negative connotations of the word ‘invasive’ makes ‘invasive species’ commonly synonymous with ‘exotic pest’ or ‘exotic weed’, i.e. a species from ‘elsewhere’ that causes harm to human economy or standard of living. In conservation biology, also commonly defined as a non-native species that harms native biodiversity. Note that only a fraction of non-native species that colonise a new area become established, and that only a fraction of these established invaders cause harm to humans or to biodiversity. An important challenge is to predict invasiveness and therefore prevent introduction of harmful invasive organisms.

Restoration Ecology:

The deliberate management of communities and/or ecosystems, in an attempt to regenerate or recreate historical levels of native biodiversity.

Species Interaction:

Species can interact with each other in various ways:

Amensal

An interaction in which one organism suffers a reduction in resources, or an increase in costs imposed by conditions, due to the presence of another organism. The latter species gains no benefit or cost from its interaction with the harmed organism. It is this lack of benefit or cost to one interactor that distinguishes amensalism from competition, predation or parasitism.

Commensalism

An interaction in which one organism gains resources (or shelter from conditions) from the presence of the other species. The latter species gains no benefit or cost from its interaction with the commensal.

Mutualism

A biotic interaction in which two organisms gain an increase in resources, or a reduction in stressful conditions, from the presence of the other organism. Some mutualisms are obligate, such that neither species can exist without the other, while many are facultative, such that the mutualists can still persist (but with less numerical success) in each other’s absence.

Parasitism

A trophic interaction in which individuals of one species (the parasite) feeds upon the tissues of living individuals of another species (the host). Strictly, parasite-host interactions should not cause death of the host individual. If death occurs (for example in deadly diseases), the parasite produces multiple generations of offspring per host individual (hence death of the host cannot be attributed directly to the actions of any single parasite individual).

Predation

A trophic interaction in which individuals of one species (the predator) kills and eats individuals of another species (the prey).