Native Vs. Non-Native Species
Species have and inevitably do move around the globe raising complex questions about what is native or non-native. Frequently, there is confusion over the origination of wildlife "”both plants and animals.
Categorizing species is a helpful way to clarify exactly what role any animal has in an ecosystem or in its distribution around our planet. Here are six categorizations used to explain species and their presence in a habitat.
Native species
A native species is found in a certain ecosystem due to natural processes such as natural distribution. The koala, for example, is native to Australia. No human intervention brought a native species to the area or influenced its spread to that area. Native species are also sometimes called indigenous species.
While a native species can be helped by new species introduced to an area "” like flowers native to North American helped by European honeybees in the last several centuries "” the native species itself developed on its own in the area and is particularly adapted to its habitat.
The key aspect of a species being native is that it occurs in an area without human influence. In fact, it's that human influence that has helped to create several other species categorizations.
Endemic species
A native species can be indigenous or endemic. When a species is indigenous, it's found in a particular location and surrounding areas. For instance, an indigenous species might be found throughout the Sierra Nevada Mountain range as well as the surrounding areas east of the mountains.
An endemic species, however, is a native species found only in a particular area. A species can be endemic to an entire continent or relatively minuscule area. For instance, an endemic species might be found only in a particular mountain range at a certain elevation zone or only in a certain lake, single river or small island.
Often, endemic species are confined to a certain area because they are highly adapted to a particular niche. They may eat only a certain type of plant that is found nowhere else or a plant might be perfectly adapted to thrive in a particular climate and soil type.
Because of this specialization and inability to move into new habitats, some endemic species are at particular risk when a disease hits, when the quality of its habitat is threatened or if an invasive species enters its region and becomes a predator or competitor.
Introduced or non-native species
Introduced species occur in an area where they are not native but were brought there through human influence "” either purposefully or accidentally.
A common misconception is that introduced and invasive species are interchangeable terms, but these are actually distinct. Introduced species don't necessarily have a negative impact on their new ecosystem and could even be beneficial.
The European honeybee is a great example of a beneficial introduced species, as the honeybee is critical to North America's crops and doesn't have a negative impact on other pollinators. However, an introduced species has the potential of becoming an invasive species.
Invasive species
An invasive species is introduced into an ecosystem and thrives so well that it negatively affects native species.
The USDA defines invasive species as:
1) non-native (or alien) to the ecosystem and 2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.
Invasive species can be plants, animals and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions.
The negative impacts can include out-competing native species in the same ecological niche, reducing biodiversity in their new habitat or altering that habitat in ways that make it difficult for native species to survive.
Cosmopolitan species
While an endemic species is limited to a particular range, a species that's found in a globally broad range in a particular type of habitat all over the world or which rapidly extends its range in opportunistic ways is called cosmopolitan.
The categorization of cosmopolitan is complex. While it typically describes a species with global distribution, it is assumed the polar regions, deserts, high altitudes and other extremes are automatically excluded. The label may also be used to describe species that might be found on most continents or many ocean habitats but not all. The term is mostly used to describe species that are generally widespread but doesn't necessarily mean that the species is found everywhere.
Orcas are one such species. They're found throughout the world's oceans, from the icy waters off North America and Antarctica to the more temperate waters of the Mediterranean. They do not appear everywhere in the oceans, but they have a broad distribution.
Houseflies, rats, domestic cats, humans and many other species also fit under the label of cosmopolitan as they're found globally.
Cryptogenic species
While a native or introduced species is usually easy to categorize, that's not always the case. Sometimes, it is nearly impossible to tell whether a species originated in an area or was brought in long ago. The origins or the cryptogenic species are unknown or cannot be definitively determined. So, a cryptogenic species could either be native or introduced but has settled into its habitat so thoroughly that no one knows for certain.
It isn't necessarily known whether the species were introduced relatively recently, appeared there naturally in recent natural history or have been there for eons.