islandendemic

Island endemism refers to species that occur exclusively on a specific island or island group and nowhere else. Endemics arise when geographic isolation limits gene flow with mainland populations, allowing divergent evolution and speciation to occur over time. Islands, especially those that are remote or volcanically active, often harbor high levels of endemism relative to their area, although overall species richness can be low because of limited space and resources.

Causes and patterns include geographic isolation that prevents immigration, founder effects and genetic drift that fix unique traits, and adaptive radiations that fill available ecological niches. Endemic species may be confined to a single island, to a few islands within an archipelago, or to particular habitats such as mountaintops, caves, or specialized vegetation zones. Well-known examples of island endemism involve the Galápagos finches and other Galápagos reptiles, Hawaiian honeycreepers, and numerous island-restricted plants and invertebrates. In some regions, endemic floras and faunas reflect long-term isolation and unique evolutionary histories shaped by climate, geology, and ecological opportunity.

Conservation considerations are central to island endemics because limited ranges and small population sizes increase vulnerability to extinction. Threats include habitat loss, invasive predators and competitors, diseases, and climate change. Management priorities commonly emphasize invasive species control or eradication, habitat protection, and, where feasible, restoration or ex situ conservation to safeguard irreplaceable island biodiversity.

In studies of biogeography, endemism on islands illustrates how isolation and scale influence patterns of species richness, colonization, and diversification.