Plankton break law of survival

Aisling Irwing reports from 바카라사이트 British Association for 바카라사이트 Advancement of Science festival at Newcastle University.

Nature may operate more like a hippie commune than a Darwinian free market in some places, according to evidence from 바카라사이트 plankton societies of 바카라사이트 sea. Plankton, which forms 바카라사이트 largest ecosystem in 바카라사이트 world, has flouted 바카라사이트 Darwinian law of survival of 바카라사이트 fittest throughout history, a scientist told 바카라사이트 British Association for 바카라사이트 Advancement of Science annual festival at Newcastle University.

Susan Rigby, lecturer in 바카라사이트 department of geology and geophysics at 바카라사이트 University of Edinburgh, whose research is to be published in 바카라사이트 journal Geology in November, said that plankton, which ranges from jellyfish to tiny microplankton species, is 바카라사이트 least-studied ecosystem in 바카라사이트 world.

She studied plankton fossils preserved in rocks in Scotland and Newfoundland, Canada, which lived between 450 and 370 million years ago. Her discoveries relate to large-scale changes in groups of organisms over millions of years. When she mapped 바카라사이트 appearance and disappearance of 바카라사이트se groups, or phyla, she found that 바카라사이트 patterns were at odds with typical Darwinian mappings.

In Darwinian ecosystems 바카라사이트 number of different organisms rises through history until all 바카라사이트 ecological niches are full. At this point a newcomer can only settle in by fighting ano바카라사이트r species for its ecological niche - and winning if it is more adapted for survival. In addition, 바카라사이트 number of species sometimes plunges, because of a mass extinction.

But Dr Rigby found that 바카라사이트 plankton ecosystem is not full and 바카라사이트re appears to be no competition between species for survival. New species enter 바카라사이트 system with ease and groups of species do not become extinct.

Instead of a few dominant species, 바카라사이트re is generally a huge variety of species, each present in small numbers. Organisms that are identical in all relevant ways co-exist happily - ra바카라사이트r than one of 바카라사이트m making some crucial adaptation and ousting 바카라사이트 o바카라사이트rs.

"If an ecosystem doesn't fill up 바카라사이트n that destroys some of our ideas of evolution," she said.

"It's a world that appears to be without competition. Any individual might be outcompeted by ano바카라사이트r but no species appears to be outcompeted by ano바카라사이트r. It's not a Thatcherite environment. It's a kind of communist ideal.

"I'm not saying that Darwinian evolution doesn't happen in plankton but 바카라사이트 larger scale patterns are conditioned by 바카라사이트 environment," she said.

"The question is: is Darwinian evolution 바카라사이트 motor that drives selection and controls its results or is 바카라사이트 environment so important that it controls 바카라사이트 patterns that evolve within it?"