Biodiversity on oceanic islands:a palaeoecological assessment

Summary Islands are bounded ecosystems and serve as excellent laboratories for assessing changes in Biodiversity. Some oceanic islands, such as Madagascar, Bermuda and notably the islands in the Pacific (e.g. Hawaii), are home to unique forms of endemic plants and animals that have evolved in isolation over millions of years. The palaeoecological record indicates that such islands are characterized by waves of extinctions concomitant with colonization by humans. By way of contrast, the biota of the islands of the north Atlantic (Greenland, Iceland and Faroe) do not follow the expected pattern and the few extinctions recorded are very localized. This is not a result of the scale of human impact, which is as great as on other islands, but relates to the virtual lack of endemics. The dearth of endemic forms and the disharmonic nature of these island communities indicates a youthful biota and the operation of severe filters and sweepstakes during colonisation over the last 10,000 years. This paper draws upon an extensive invertebrate fossil record to contrast and examine these spatial and temporal patterns in island Biodiversity.