Causes of Island Fauna Extinctions

The Role of Dwarfism and Gigantism in Human-Mediated Extinctions on Islands


Skeletal replica of the fossil rhino from Taiwan on display at the National Taiwan Museum.

Associate Prof. Cheng-Hsiu Tsai of NTU’s Department of Life Science and researchers from 20 institutions worldwide led by Dr. Roberto Rozzi collaborated on an international paleontology research project to assess island extinctions globally.

Islands have long been recognized as singular evolutionary arenas leading to morphologically distinct species, such as dwarfs and giants. The research team assessed how body size evolution in island mammals may have exacerbated their vulnerability, as well as how the arrival of modern humans has contributed to their past and ongoing extinctions, by integrating data on 1231 extant and 350 extinct species on islands and paleo-islands worldwide spanning the past 23 million years. It was found that the likelihood of extinction and endangerment is the highest in the most extreme island dwarfs and giants. Extinction risk of insular mammals was compounded by the arrival of modern humans, which accelerated extinction rates more than tenfold, resulting in an almost complete demise of these iconic marvels of island evolution.

This study is also an integral part of Associate Prof. Tsai’s long-term research project on Taiwan’s fossil vertebrates to remind people of past diversity and extinction events in Taiwan. By delving into the diversity of the past and ascertaining the causes of the extinctions, we will be more prepared to deal with and ameliorate the ongoing sixth mass extinction.

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journal article in Science.

Associate Prof. Cheng-Hsiu Tsai gave a brief introduction to the research on dwarfism and gigantism on islands.

The effect of body size change on extinction risk of mammals on islands worldwide.

A large Palaeoloxodon skull from Taiwan. On display at the Land Fossil and Mineral Museum, Tainan.