Researchers at the Christian-Albrechts-Universitat zu Kiel (CAU) showed that biodiversity decreases towards the poles almost everywhere in the world, except along the South American Pacific coast.
Investigating fossil clams and snails Steffen Kiel and Sven Nielsen show that this unusual pattern originated at the end of the last ice age, 20.000 to 100.000 years ago, and retreating glaciers created a mosaic landscape of countless islands, bays and fiords in which new species developed rapidly - geologically speaking.
“Opinions include that southern Chile is a museum of diversity where species survived for millions of years in addition to new arrivals; or that Antarctic species colonized this area from the south,” wrote the researchers.
Their analysis of around 35.000 fossil clams and snails, belonging to about 400 species, allowed the palaeontologists to draw some more precise conclusions: “Our fossils reject both hypotheses. Biodiversity in this area always decreased toward the south in the geologic past, and we didn’t find any intruders from Antarctica”, explained Kiel. In addition, the vast majority of species and genera that lived in that area only 16 million years ago had become extinct.
The most species-rich groups of animals in the southern Chilean fjordlands are those inhabiting rocky shores. This is exactly the habitat that was created when the glacier retreated from their marine termini. The study is published in the current issue of the scientific journal Geology.