Museum palaeontologists are leading a project to study the effect of dramatic environmental changes over the last 800,000 years on the evolution and survival of dwarf elephants and dwarf deer. Such work may help us understand how mammals might respond to climate change today.
Dwarf elephants and dwarf deer are now extinct, but between 800,000 and 3,000 years ago they lived on islands throughout the Mediterranean, Indonesia and off the coasts of Siberia and California.
They are remarkable examples of rapid evolutionary change. For example, some dwarf elephants, like those that lived on Sicily and Cyprus, were only about 1m tall as adults, the size of a new-born African elephant. However, their ancestor on the mainland was larger than the adult African elephant today.
We also know that dwarf deer on Jersey took less than 6,000 years to halve their body size. In evolutionary time this is very fast indeed.
When dwarf elephants and dwarf deer lived in the Mediterranean, the climate fluctuated between ice ages and warm stages every 100,000 years.
Global sea levels dropped during ice ages as water froze to form ice sheets, and then rose again in warmer stages as the ice melted. This altered the size of the islands and their distance from the mainland. A land bridge may even have formed at times.
We know from present-day islands that the bigger the island and the closer it is to the mainland, the more species inhabit it. The number of species able to live on the island will be affected if either of these factors changes.
Island species are often unique or endemic to a particular island, so they are vulnerable to extinction. They also evolve more quickly. We therefore expect island species to be affected by climate change to a greater extent and at a faster rate than those on the mainland. They are the front line of response to climate change.
Previously, no one had considered the evolution of Mediterranean dwarf elephants and deer in the context of climate change. This is because uncertainty over the age of most of the fossils meant the corresponding climatic conditions could not be precisely determined. We are using the latest state-of-the-art techniques to get accurate and reliable dates for when dwarf elephants and deer lived on Mediterranean islands.
The research is being carried out by a team of scientists from the UK, the USA and Mediterranean countries. It is supported by a Natural Environment Research Council (NERC) grant, 2009-2012.