> Most of the biodiversity in rainforests is in megafauna and insects

> If you want a very high degree of biodiversity the place to look is temperate deserts, where the microbial diversity is extremely high

This sounds a bit like that "you have more bacteria in your gut than you have cells in your body" fun fact. Which may be true in terms of individually countable cells, but in terms of weight it's another story.

In the same sense comparing the genetic diversity of megafauna and insects in one region to those of the bacteria in another is a bit disingenuous imo, because that's comparing two different ecosystem "categories".

IIUC, bacteria tend to leak genetic material between each other. Genes get swapped around a lot, and if some combos don't work out, well, there are uncountably other bacterial cells around. Meanwhile, megafauna and insects have much smaller populations that only swap genes through sexual reproduction, which recombines genes a lot more slowly. It's not a fair comparison.

So, I guess you don't have a biology background but: species diversity is usually judged by 16s rna diversity, which generally doesn't get swapped around.

And until recently, the dogma was that there were more insect species than bacteria species (it could make sense, as insects reproduce sexually so there's more opportunity for genetic drift), but hoo boy were we wrong (we now know from DNA panning experiments, our estimates on bacteria were low because it was mostly only culturable bacteria we were counting).

No, and while I worked for molecular neurobiologists for two years at one point in my life, that just taught me that I don't have the slightest clue how DNA works.

You're missing my point though: you replied to someone who talked about biodiversity with a remark about genetic diversity (probably without realizing it, which would be a classic case of attribute substitution[0]). Even I know that biodiversity is not limited to genetic diversity, as a quick trip to Wikipedia will confirm[1].

[0] https://en.wikipedia.org/wiki/Attribute_substitution

[1] https://en.wikipedia.org/wiki/Biodiversity

What metric do you want. In any metric up to and including ecosystem roles, microorganisms will be more diverse than macro.

Oh did you want size? Yep. Microorganisms make colonial hyphae which are bigger than any living organism except maybe some colonial trees.

Are you willfully ignoring my earlier point that pointed that out and concluded that therefore sneakily comparing megafauna to microbes is disingenous?