mc_maurer

There are tons of other insect groups that could be very easily described as similarly "minimum viable" that don't have nearly the diversity. Abundance of some group doesn't necessarily correlate with the speciation within that group. Ants are an exceptionally successful type of insect with orders of magnitude fewer described species.

I think this is much closer than the "they're a very good blank slate". There are plenty of exceptionally successful groups of organisms with far less diversity. The point is not how successful beetles are, it's how differentiated they are. Something about their ability to occupy niches that promote isolation and therefore speciation has to be involved.

Lots of beetles, but almost certainly even more wasps! Parasitoid wasps attack pretty much every known insect species, even other parasitoid wasps. If there's not a known parasitoid for a given insect species, you usually just haven't looked hard enough. Given that parasitoids tend to be specialists, attacking one or only a few other species, the math works out to there being more parasitoids than anything else around. Great paper on the topic here: https://bmcecol.biomedcentral.com/articles/10.1186/s12898-01...