Geoscience Reference
In-Depth Information
the cyanobacterium likely gained shelter within the eukaryote. Over
evolutionary time, the eukaryote took control of the cyanobacterium,
which subsequently lost much of its own metabolic machinery. The
cyanobacterium slowly lost its identity as a separate organism and be-
came the chloroplast of the ancestral eukaryotic algae. This fascinating
idea was first developed by the Russian botanist Konstantin Sergeevich
Merezhkovsky in 1905. The idea was largely lost, to be rediscovered and
made famous by Lynn Margulis many decades later. It has since been
proven correct with modern molecular biological techniques that clearly
and cleverly showed that the chloroplast contains cyanobacterial DNA.
We owe much to our little oxygen-producing friends. They have given
us oxygen to breathe, and they make sure there is plenty of nitrate in the
oceans to support the great food webs of the seas. They engaged in part-
nerships with early eukaryotes to give us algae and eventually plants,
and they can be found today populating countless different environ-
ments with fascinating adaptations to each of them. For me, it's hard
to think about life on Earth without winking at the cyanobacteria and
thanking them for making so much of it possible.
