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T9
Island Evolution: a ‘front-line’ biotic response to sea-level change
Victoria Herridge 1 , David Richards 2 , Jean-Luc Schwenninger 3 , Ed Rhodes 4 , Kirsty
Penkman 5 and Adrian Lister 1 .
1 Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD
2 School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS
3 Research Laboratory of Archaeology and the History of Art, University of Oxford, South Parks Road,
Oxford, OX1 3QY
4 Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567, USA
5 Department of Chemistry, University of York, York, YO10 5DD
Island biodiversity is closely related to island area and distance from the mainland two
characters unquestionably linked with eustatic sea level. Additionally, island populations
typically have high evolutionary rates and are characterized by endemic and often unusual
flora and fauna that are vulnerable to extinction. Thus we might expect island faunas to be
affected to a greater extent, and at a faster rate, than those of the mainland – forming the
‘front-line’ of biotic response to global sea-level change. Quaternary island systems show
great potential for quantifying the evolutionary response of faunas to climatically driven
environmental and associated sea-level changes characteristic of that period (Siddall et al
2003). A widespread evolutionary response of insular Quaternary large mammals is
extreme body size reduction (e.g. 100 kg elephant Palaeoloxodon falconeri on Sicily and
Malta descended from 10,000 kg mainland species, P. antiquus). This phenomenon is
usually ‘explained’ by the ‘Island Rule’, whereby small mammals become large and large
mammals dwarf on islands. A paucity of geochronological information has hampered the
consideration of insular body-size change within the context of the climatic fluctuations of
the Quaternary, despite the fact that island conditions are significantly affected by climate
and sea-level changes. Using new evidence, we make a preliminary assessment of the
role that sea-level change may have played in driving the evolution of Mediterranean
dwarf elephant and dwarf deer.