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What influences evolutionary winners and losers?

15 Ebrill 2011

Extinct planktonic foraminifer species from the Eocene (330 million years old) of Tanzania; All are smaller than a pinhead. Credit: Professor Paul Pearson.Extinct planktonic foraminifer species from the Eocene (55.5 - 33.7 million years old) of Tanzania; All are smaller than a pinhead. Credit: Professor Paul Pearson.

Scientists have examined 65 million years of evidence to discover what factors influence evolution.

Researchers from Cardiff University and Imperial College London examined marine plankton, called foraminifera, providing them with an unparalleled fossil record showing 65 million years of evolution.

Tracy Aze, of Cardiff University’s School of Earth and Ocean Sciences explains: "Importantly this fossil record has recorded what happens to the foraminifera in terms of diversity and abundance across an extensive period of time when environmental conditions in the oceans were very different to our modern oceans."

The research co-authored by Tracy Aze and Professor Paul Pearson at Cardiff University and Dr Thomas Ezard and Professor Andy Purvis, Imperial College London is published in the journal Science (April 14). The research disputes a well established theory that the probability of extinction in groups of organisms is constant and not dependent on age. Instead the researchers found that species are more likely to become extinct if they are "older". They also found that the emergence of new species is more likely to occur early on in the lifetime of pre-existing ancestor species.

A live Globigerinella siphonifera - Credit: Dr Thomas Ezard.A live Globigerinella siphonifera collected during the Glow research cruise to the Indian Ocean in February 2009. Credit: Dr Thomas Ezard.

The research, funded by the Natural Environment Research Council (NERC), addressed evolutionary questions dating from both Darwin and his contemporary Wallace. It looked at how competition between species that were alive at the same time and environment change influenced the extinction and emergence of new species. Darwin thought that environment played a more important role in natural selection whilst Wallace thought that interactions between species were more dominant.

By incorporating detailed information about species ecologies the study empirically demonstrated that both sets of factors are important in shaping the evolution of a group.

Tracy Aze at Cardiff University said: "If we are to attempt to conserve global biodiversity and maintain global ocean ecosystems we need to understand how organisms respond to environmental change

"Our research has shown that extinction is more strongly influenced by changes in the environment, while the emergence of new species – known as speciation – is more strongly influenced by the interactions between species."

Related links

School of Earth and Ocean Sciences