So I’ve read the paper. According to it, and it seems very plausible to me, we have some reason to suspect we seriously underestimate number of SDA families, and most widely distributed SDA families are most likely to be known (those often happen to occur in multiple groups), and less widely distributed families are least likely to be known (those often happen to be one group only).
The actual percentage of shared SDA families is almost certainly lower than what we can naively estimate from current data. I don’t know how much lower. Maybe just a few percent, maybe a lot.
Not mentioned in the paper, but quite obvious is huge amount of horizontal gene transfer happening on evolutionary scales like that (especially with viruses). It also increases apparent sharing and makes them appear older than they really are.
Third effect is that SDA family that diverged long time ago might be unrecognizable as single family, and one that developed more recently is still recognizable as such. This can only increase apparent age of SDA families.
So there are at least three effects of unknown magnitude, but known direction. If any of them is strong enough, it invalidates your hypothesis. If all of them are weak, your hypothesis still relies a lot on dating of eukaryote-prokaryote split.
So I’ve read the paper. According to it, and it seems very plausible to me, we have some reason to suspect we seriously underestimate number of SDA families, and most widely distributed SDA families are most likely to be known (those often happen to occur in multiple groups), and less widely distributed families are least likely to be known (those often happen to be one group only).
The actual percentage of shared SDA families is almost certainly lower than what we can naively estimate from current data. I don’t know how much lower. Maybe just a few percent, maybe a lot.
Not mentioned in the paper, but quite obvious is huge amount of horizontal gene transfer happening on evolutionary scales like that (especially with viruses). It also increases apparent sharing and makes them appear older than they really are.
Third effect is that SDA family that diverged long time ago might be unrecognizable as single family, and one that developed more recently is still recognizable as such. This can only increase apparent age of SDA families.
So there are at least three effects of unknown magnitude, but known direction. If any of them is strong enough, it invalidates your hypothesis. If all of them are weak, your hypothesis still relies a lot on dating of eukaryote-prokaryote split.