Why do we see high levels of endemism on remote islands?

We see high levels of endemism on remote islands due to their isolation, unique environments, and limited gene flow.

Endemism, the ecological state of a species being unique to a defined geographic location, is often high on remote islands. This is primarily due to the isolation of these islands. When species arrive on an island, either by flying, floating, or being carried there, they become isolated from their original population. Over time, these isolated populations can evolve into new species that are distinct from their ancestors, a process known as speciation. This is particularly likely to occur on remote islands, where the chances of new individuals arriving and mixing their genes with the existing population (gene flow) are low.

The unique environments found on islands also contribute to high levels of endemism. Islands often have unique climates, soil types, and vegetation, which can all exert selective pressures on the species living there. These pressures can lead to the evolution of unique adaptations and, ultimately, the formation of new species. For example, the unique conditions on the Galapagos Islands led to the evolution of distinct species of finches, each adapted to a specific type of food source.

Furthermore, the limited gene flow on islands can also lead to high levels of endemism. Gene flow is the transfer of genetic variation from one population to another. If a population is isolated, such as on an island, there is less chance for gene flow to occur. This means that the genetic makeup of the population can become very different from that of other populations, leading to the formation of new species.

In conclusion, the isolation, unique environments, and limited gene flow found on remote islands all contribute to high levels of endemism. These factors can lead to the evolution of unique species that are found nowhere else in the world, making islands hotspots of biodiversity.