Unexpected, of course:
The recent assembly of the herring genome suggests this fish acquired its antifreeze protein gene by horizontal transfer and then passed a copy on to the smelt. The direction of gene transfer is confirmed by some accompanying transposable elements and by the breakage of gene synteny…
The sequential transfer of an advantageous gene between fishes leads us to suggest that these events, while extremely rare, might happen as consequence of external fertilization in a medium containing the shed DNA of all the ecosystem’s inhabitants. It will be worth examining fish for other examples of HGT.Laurie A. Graham, Peter L. Davies, Horizontal Gene Transfer in Vertebrates: A Fishy Tale, Trends in Genetics, 2021, ISSN 0168-9525, ttps://doi.org/10.1016/j.tig.2021.02.006. The paper is open access.
We don’t know that HGT is “extremely rare” in vertebrates. We know that it was unexpected so no one was looking for it.
We also know that it is extremely inconvenient for a discipline that invested so heavily in natural selection acting on random mutations (Darwinism).
Now, many must pretend that horizontal transfer is the same thing as vertical transfer. Good luck with that.
See also: Horizontal gene transfer: Sorry, Darwin, it’s not your evolution any more