Mito, Chloro, and Nitro – Oh my!
Of major evolutionary leaps
Today is Friday before Pose Ponder’s week off. Normally I would give you an “index” post collecting related previous writing on a topic. I’m going to skip it this time. Y’all should go outside and spend time in the sunshine, fresh air, and blooms of Spring! (Unless you’re in the tropics or southern hemisphere, of course.)
But here is something to think about in terms of major leaps in the evolution of life on earth.
The human tendency is to focus on the evolution of vertebrates, or mammals (versus the dinosaurs, oh my!), or human evolution and ancestral precursors (who has Neanderthal DNA?), or consciousness (“the universe observes itself”), or intelligence, now including AI. But there were other evolutionary leaps even more profound. Some of them even managed to change the climatic composition of the whole planet (ahem), like in the Great Oxidation Event. These fundamental biological changes were at the cellular level.
Evolutionary leaps of this type — when an external organism internalizes to become an organelle — have only been known to happen twice in earth’s history: with mitochondria and chloroplasts.
Scientists have now discovered a third case.
This is pretty crazy: Two lifeforms merge in once-in-a-billion-years evolutionary event (newatlas.com)
Scientists have discovered that it’s happening again. A species of algae called Braarudosphaera bigelowii was found to have engulfed a cyanobacterium that lets them do something that algae, and plants in general, can’t normally do – "fixing" nitrogen straight from the air, and combining it with other elements to create more useful compounds.
Nitrogen is a key nutrient, and normally plants and algae get theirs through symbiotic relationships with bacteria that remain separate. At first it was thought that B. bigelowii had hooked up this kind of situation with a bacterium called UCYN-A, but on closer inspection, scientists discovered that the two have gotten far more intimate.
Source: New Atlas (from Berkeley Lab; reports in Cell and Science journals)
