What is the definition of an endemic species?
An endemic species is one found naturally in a particular geographic area and nowhere else. It differs from a merely native species, which occurs in an area but may also live elsewhere. Endemism is defined by range, not rarity, and verifying it requires range evidence, not single records.
The clearest way to define an endemic species is by its geographic range. A species is endemic to a place when that place is the only area where it occurs naturally. The defining condition is exclusivity. If the same species also lives somewhere else, it is not endemic to the first place, however common or characteristic it is there. In practice the place can be an island, a country or some other defined region.
[1]Endemic versus native
This is where most confusion arises. A native species simply originates in or naturally inhabits an area, without saying anything about whether it lives elsewhere. An endemic species is a subset of that: native to one area and absent everywhere else. A PLoS One study of Tasmanian eucalypts makes the distinction concrete. Tasmania has 29 native eucalypt species, but only 17 of them are endemic to the island. The remaining 12 are native to Tasmania and also occur on the Australian mainland, which makes them native but not endemic.
[1]- Native to Tasmania and endemic: found on the island and nowhere else.
- Native to Tasmania but not endemic: found there and also on the Australian mainland.
- Endemic therefore always implies native, but native does not always imply endemic.
How endemism comes about
The same research describes a mechanism. Species ranges have been shifting since the Pleistocene, and fragmentation and isolation can reduce gene flow between populations. The study notes that this can result in the local adaptation of novel genotypes and the repeated evolution of endemic species. Tasmania fits the pattern: the study counts 17 endemic eucalypts on the island. The paper also observes that endemic species are often the ones most at risk, which gives the label practical conservation weight rather than just novelty.
[1]A worked comparison
Suppose a wildlife guide lists two eucalypts for Tasmania. The first, Eucalyptus morrisbyi, appears in the endemic group in the study, so it occurs naturally on Tasmania and nowhere else. The second, Eucalyptus viminalis, appears in the non-endemic group: it grows in Tasmania and on the mainland. Both are Tasmanian natives. Only the first is Tasmanian endemic. The label depends entirely on where else the species has been recorded, not on how noticeable or abundant it is locally.
[1]Why occurrence records need care
Occurrence-record databases, including the ones this site uses, can support statements like animals recorded only in Australia, but a record total is not a range assessment. As the site itself cautions, a large number of records reflects recording effort, digitised collections and contributing data feeds, not abundance or a complete habitat map. Equally, no held observation is not proof that a species is absent. So a country page showing a species only in one country is evidence worth checking, not a settled endemism claim.
[2]- Confirm the scientific name matches the species you are assessing.
- Check whether records exist from other countries or territories, not just the one you started from.
- Read coordinate precision, sampling coverage and source limits on the record page.
- Treat a single historical or one-off record cautiously before concluding a species lives, or does not live, somewhere.
One caution: the cited references define endemism by range, but they do not establish a universal threshold for how restricted a range must be before the label applies in every context. Definitions in legislation or conservation assessments can carry specific criteria of their own, so check the relevant authority for the jurisdiction you care about. For everyday purposes, the range-based definition above is the standard one.
[1]As a next step, pick a species you are curious about, compare its recorded countries, and ask one question: does it appear anywhere outside the area you are calling it endemic to? If yes, it is native there but not endemic.
[2]Sources and dates
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4207777/ · accessed 2026-10-18
- https://whatanimalliveswhere.com/ · accessed 2026-10-18