New Study Reveals Island Species with Extreme Body Size Changes are More at Risk of Extinction
A recent study published in Science by the German Center of Integrative Biodiversity Research (iDiv) and Martin Luther University Halle-Wittenberg (MLU) has revealed a previously unknown result: species on islands that have evolved to more extreme body sizes than their mainland relatives are more likely to become endangered or go extinct.
Islands are hotspots for biodiversity, taking up less than 7 percent of the Earth's surface but accounting for up to 20 percent of all terrestrial species. Unfortunately, they are also hotspots for species extinction, as 50 percent of today's IUCN threatened species are native to islands. Researchers from the German Centre for Integrative Biodiversity Research (iDiv), Martin Luther University Halle-Wittenberg, the University of Nebraska–Lincoln, and elsewhere looked into how the extreme body size changes, or gigantism or dwarfism, of island-dwelling creatures can affect their risk of extinction.
The research team used data on over 1,500 island mammals from 182 islands, both existing and extinct, to examine the relationship between body size and extinction risk. They discovered that species that experienced more extreme body-size shifts, either larger or smaller, were more likely to become endangered or to go extinct on islands.
The researchers suggest that a large difference in body mass between an island species and its mainland counterpart is a better predictor of extinction risk than body mass alone. This is because comparative differences between island and mainland body mass is a more accurate indicator of how “weird” an animal is, or in biological terms, how ecologically naive it is. Changes to an island’s environment or invasion from mainland species can put these unusual creatures in jeopardy.
The findings of this research suggest that species on islands are more likely to become endangered or go extinct if their body sizes suffer more dramatic changes, whether larger or smaller. This highlights the importance of understanding the unique characteristics of island environments and their effects on the evolution of species to better protect and conserve them.
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