Crimes Of Evolution: Genes Stolen From Captive Algae
December 3, 2012
Microscopic animals held algae captive and stole their genes for energy production millions of years ago, reveals a new study.
AsianScientist (Dec. 3, 2012) – Microscopic animals held algae captive and stole their genes for energy production millions of years ago, reveals a new study.
The study, published this week in the journal Nature, reveals a ‘missing link’ in evolution, where tiny protozoa frozen in time captured algal genes for photosynthesis – the process of harnessing light to produce energy which is used by all plants and algae on earth.
Until now, the international team led by researchers from Dalhousie University in Canada had suspected that quantum leaps of evolution occurred by one organism cannibalizing another, but had insufficient evidence to prove this hypothesis.
But when they looked at two specific algae – Guillardia theta and Bigelowiella natans – the team realized the evolution was not quite complete. They could see that their cells had two nuclei, which is unusual because plant and animal cells only have one.
“We think that the genes for photosynthesis originally evolved only once about three billion years ago. So all plants, algae, and blue green bacteria can produce their own energy from light because they have acquired these genes for photosynthesis,” said Professor McFadden from the University of Melbourne, a co-author on the study.
Like prisoners in Alcatraz, the captive algae appear to have been nurtured by their enslavers and the precious sugars produced from photosynthesis became a vital part of the protozoan slave keeper’s diet.
The captives lived inside the protozoan cell and, under the right conditions, the pair gradually became unified as a single organism – a process called endosymbiosis, which literally means living inside each other.
“We discovered that the captors were initially able to keep many separate clones of their slaves and occasionally pillage one or two for most of the essential genes. However, at some point in time, the number of captives reduced inside each gaoler to just one individual,” McFadden said.
“So if they broke into the alga’s cell to steal the last essential genes, they would destroy it in the process and would not then be able to use the genes to run photosynthesis. So the two cells, one captive and one captor, had apparently reached an evolutionary stand-off situation where both are dependent on each other to survive,” he said.
The article can be found at: Curtis BA et al. (2012) Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs.
Source: University of Melbourne; Photo: Paul Gilson/U Melbourne.
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