The gene tree images now have little intron “ticks” on them showing how the intron position is placed relative to the protein sequence. An example is shown above. Each tick is a little black line on each side of the green protein bars, on the right. As intron positions have been remarkably stable on the “chordate” side of the metazoan tree (ie, the deutrosomes), one should expect that the introns line up – if they do, it is good evidence that the alignment is right.
There are some interesting things. Ensembl models small frameshifts to create open reading frames around erroneous data as tiny introns. In this code you cannot distinguish these two classes of introns, but as these errors normally come in patches, a run of intron ticks unique to a genome is probably a set of errors (an example is in Gorilla). I’ve enjoyed browsing around some of my favourite genes to check out that the introns make sense.
There is some more to go here. The fact that the intron ticks disappear on collapsed nodes is a bit frustrating – it would be nice to see “consensus” intron positions (though this is a bit complex to execute underneath).