A species (pl.: species) is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can...

An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction...

introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a...

In zoological nomenclature, a type species (species typica) is the species name with which the name of a genus or subgenus is considered to be permanently...

An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological...

On the Origin of Species (or, more completely, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle...

An IUCN Red List Critically Endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature...

Speciesism (/ˈspiːʃiːˌzɪzəm, -siːˌzɪz-/) is a term used in philosophy regarding the treatment of individuals of different species. The term has several...

last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult...

precise meanings are cryptic species for two or more species hidden under one species name, sibling species for two (or more) species that are each other's closest...