The continental islands are the largest, are connected to the continental shelf and may have detached from the continent due to erosion, lowering of the land, rising water levels, strong earthquakes, volcanic eruptions, etc.
or simply because the continental shelf is lower, in some places, than the water level. A particular type of continental islands are those that have detached from the continent due to continental drift such as the island of Madagascar detached from the African continent.
Another particular type are the islands formed by the accumulation of the eroded sand from the neighboring continent. Another type of volcanic island is one formed by a tectonic plate that flows under another. This flow creates a chain of volcanoes which, as they emerge, form a chain of islands.
These islands can also sink again after a long period of frequent earthquakes and eruptions, such as the Aeolian Islands. The last type of volcanic island is formed by a spot over which a tectonic plate flows. Examples are the Hawaiian Islands.
The diversity of mammals on islands worldwide has multiple factors
On the islands across the planet there is a great variety of mammals, which are often very different from each other due to multiple factors. The study: Area, isolation and climate explain the diversity of mammals on islands worldwide, published on the Proceedings.
Biological sciences, told: "Insular biodiversity is expected to be regulated differently than continental biota, but their determinants remain to be quantified at a global scale. We evaluated the importance of physical, environmental and historical factors on mammal richness and endemism across 5592 islands worldwide.
We fitted generalized linear and mixed models to accommodate variation among biogeographic realms and performed analyzes separately for bats and non-volants. Richness on islands ranged from one to 234 species, with up to 177 single island endemics.
Diversity patterns were most consistently influenced by the islands' physical characteristics . Area positively affected mammal diversity, in particular the number of non-volant endemics. Island isolation, both current and past, was associated with lower richness but greater endemism.
Flight capacity modified the relative importance of past versus current isolation, with bats responding more strongly to current and non-volant mammals to past isolation. Bi odiversity relationships with environmental factors were idiosyncratic, with a tendency for greater effects sizes with endemism than richness.
The historical climatic change was positively associated with endemism. In line with theory, we found that area and isolation were among the strongest drivers of mammalian biodiversity. Our results support the importance of past conditions on current patterns, particularly of non-volant species."