Major Evolution in Action

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The discussion centers on the concept of endosymbiosis, a significant evolutionary process where different types of cells merge to create new life forms, such as eukaryotes and plants. The conversation highlights recent research indicating the potential for endosymbiotic events to occur, which can lead to major evolutionary advancements. Key points include distinguishing endosymbiosis from simple symbiotic relationships, emphasizing the irreversible nature of one cell enveloping another and the genetic transfer from the internalized symbiont to the host. This genetic integration is crucial for establishing dependence between the two organisms, marking a clear evolutionary transition. The discussion references various scientific articles that explore these themes, underscoring the importance of endosymbiosis in the history of life on Earth.
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Two lifeforms merge in once-in-a-billion years evolutionary event
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This is an interesting article about the likelihood of endosymbioses (combining two different kinds of cells together to make a new evolutionary line) occurring.

These can be major events in evolution (like making eukaryotes or plants), but maybe not always.

Here is a link to a thread I made on a similar Nature article a few years ago:
https://www.physicsforums.com/threads/new-eukaryotic-endosymbiont-found.1000450/
It involves a ciliate (eukaryote, normally with mitochondria) with a degraded form of mitochondria that acquired a bacterial symbiont that could make metabolic use of nitrate to generate ATP.

How might endosymbiosis be distinguished from just a symbiosis between cells exchanging nutrients adjacent to each other in their environment?
Here are some possibilities:
  • irreversible envelopment of one by the other. The internalized symbiont could be dependent on its host cell for a variety of reasons. If visualized as cell lineages (like a phylogenetic tree) the lineages of the internalized symbiont would be forever limited to being in the lineage of the host organism. Most likely the host would be dependent on the internalized symbiont in some way.
  • gene transfer (usually from the internalized symbiont genome to the host genome. This would provide a clear basis for the dependance of the internalized symbiont on the host.
 
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