It is known that the animals introduced to the island undergo a unique evolutionary process, to the extent that the island is called an "evolutionary laboratory." This is called "islandization."A typical example is the law of evolution in which large animals become smaller and smaller animals become larger on islands.
It has been pointed out that such special evolution makes it more susceptible to extinction due to human influence, but until now, the relationship between the magnitude of changes in body size and the susceptibility to extinction has not been clarified.
Therefore, an international joint research group including Lecturer Mugino Kubo of the University of Tokyo constructed a large-scale database of 1,231 extant and 350 extinct species of mammals inhabiting the island, and analyzed the rate of change in body size and extinction. Extensive investigation of risks.As a result, it became clear that there is a positive correlation between the rate of change in body size and the susceptibility to extinction, and that extremely large or small species are more likely to become extinct.
Furthermore, as a result of investigating changes in the extinction rate of mammals living on the island over time, it was found that the extinction rate on the island increased sharply at the time when modern humans (Homo sapiens) appeared.It can be said that the migration of modern humans to the islands has almost completely wiped out mammals that have become extremely large or small. It can be seen that it was serious.
The results of this study suggest that morphological evolution due to islandification may have been a predisposing factor for extinction. It points out that it is necessary to take appropriate conservation measures.In the future, it is expected that further analysis of changes other than body size associated with island formation will reveal the biological background that increased vulnerability to extinction.
Paper information:[Science] Dwarfism and gigantism drive human-mediated extinctions on islands
