Adaptation, migration, extinction of biota as response to climate change
|Category||Paleontology and Stratigraphy|
|Location||International Geological Congress,oslo 2008|
|Holding Date||27 September 2008|
A long tradition of palaeobotanical and palaeontological research has gathered a considerable amount of data on how plants and animals have responded to climate changes during the Quaternary. However, new questions and prospects continue to emerge, showing that this field of research is still very active and may significantly contribute to a better understanding of global changes processes, evolutionary dynamics and environmental management and conservation.
One main issue concerns the localization, extension and duration of "refuge areas" for plants and animals during the glacial stages, in view also of predictive models for future climate changes. While it is clear that during the glacial periods climate conditions have caused the retreat of plant and animal populations in more or less reduced areas, or even their extinction, there is still much debate on how far to the north temperate species could survive. For example, it has been shown that Fagus populations survived the last glacial period in several refuge areas, and persisted there over multiple glacial-interglacial cycles (Magri et al., 2006). Unexpectedly, the Mediterranean refuges for Fagus did not contribute to the colonization of central and northern Europe, which were colonized from refuge areas north of 45°N.
Another emerging research line combines the results of palaeobotanical/palaeontological analyses with modern/ancient genetic data. This combination helps disentangling migrations and adaptations of plant and animal populations in response to climate changes and/or to the isolation in refuge areas during the glacials. One of the most intriguing questions is the assessment of the time and causes of genetic diversification and distribution of plants, interpreted in the light of fossil record, past climate changes and tectonic processes. Published investigations have shown that Quaternary climate changes, producing successive retreats, isolations and re-expansions of plant populations, may induce genetic differentiations among populations. However, recent surveys have also shown that some species may maintain their genetic characters over times longer than the Quaternary. For example, genetic and palaeobotanical data show that cork-oak (Quercus suber), a tree living in the main islands of the western Mediterranean, persisted in the same territories since the Miocene with an amazing genetic stability, reflecting the tectonic dynamics of the western Mediterranean Basin during the last 25 Ma, and stimulating new extensive and multidisciplinary studies of fossil records stretching from the present down to at least the Pliocene.