Species S may no longer interbreed with species T, but that does not imply they’ve separated completely. There may exist intermediate species U...Z that link them together (https://en.wikipedia.org/wiki/Ring_species)
Viral infections modify host DNA, and can also incorporate host DNA -- this is a mechanism by which lateral gene transfer can occur between macroscopic organisms. The platypus has mammal, reptile and avian DNA, and they seem to have come about long after those branches diverged -- evidence that lateral gene transfers occur between macroscopic organisms.
Show me some paper on this. I mean an actual scientific paper, not a paper used to roll a yard-long spliff.
https://news.ycombinator.com/newsguidelines.html
(I took a quick look at your account's past comments and didn't see any previous history of this, which is great.)
Regardless, horizontal gene transfer certainly does happen.
But then accidentally discovered this about gene transfer albeit in another area: https://www.sciencedaily.com/releases/2018/07/180709101216.h...
"This process is called horizontal transfer, differing from the normal parent-offspring transfer, and it's had an enormous impact on mammalian evolution." For example, Professor Adelson says, 25% of the genome of cows and sheep is derived from jumping genes.
OK, thanks!
> the whole kingdom-order-genus-species thing is muddy and ill-defined
Well yes, it's somewhat an arbitrary construct for human convenience, but isn't much of the muddiness down to our limited understanding of the true relationships?
Regarding "cadherin/catenin or how epithelia are formed to see how a tissue is much more than a bundle of cells." could you give a link cos this is so far outside my area I really don't know what to look for (wiki article on Catenin wasn't very revealing of your point, sorry if I missed it)