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Comment by msrenee | Hacker News Reader

>Both the American paddlefish and the Russian sturgeon are endangered species.[2]

This is where I started getting suspicious about how accurate the article was. The paddlefish is vulnerable, but not endangered. They're doing pretty well in the Missouri, all things considered.

>Researchers in Hungary conducted experiments designed to test if either species could be bred in captivity.

This is where the wiki lost me. Paddlefish are relatively easy to produce in captivity. We've been doing it for decades. It generally doesn't involve sperm from an unrelated species either. I'm curious what the real story is.

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The source paper says:

> During an experiment to produce gynogenic Russian sturgeon progeny, a negative control was initiated using non-irradiated American paddlefish sperm and eggs from the Russian sturgeon. Unexpectedly, the control cross resulted in viable hybrids.

I'm not a biologist, but I guess it's the "gynogenic" part that's hard to do?

Yes - from https://edition.cnn.com/2020/07/21/world/sturddlefish-paddle... -

> The initial goal of the study was to encourage the critically endangered sturgeon to reproduce asexually. That isn’t quite how it went.

The focus of the study was the critically endangered sturgeon.

The other species was needed since:

> in gynogenesis, the DNA of the sperm specimen isn’t supposed to transfer to the offspring.

They deliberately picked a distant species (not in the same genus, and not even in the same family) to use as a negative control. But, accidentally, their negative control group "found a way to live" (in their words)!

For the description of the American paddlefish as "endangered species", this may have come from, e.g., https://en.wikipedia.org/wiki/American_paddlefish -

> American paddlefish are also protected under Appendix II of the Convention on International Trade in Endangered Species (CITES) meaning international trade in the species (including parts and derivatives) is regulated

I suppose if I want to complain about the wiki article being badly written, I should probably think about working on it myself. It's pretty misleading.

As far as these being distantly related species, they are, but they're also as closely related as you can get without being in Acipenser. They're separate families, but those are the only two families within the suborder Acipenseroidei. Super neat fishes. I highly recommend looking up videos of baby paddlefish, as they're adorable. My favorite is when they're just old enough that they start switching to filter feeding. Handling sturgeon just makes you feel like you've got something ancient in your hands, which you kind of do.

What's interesting to me is that the paddlefish shares the Missouri River with both the shovelnose sturgeon and the pallid sturgeon. Also possibly the lake sturgeon if I'm remembering correctly that they sometimes come down the Missouri a bit especially during flood years. Makes me wonder if it's just luck that those sturgeon species aren't tetraploid or if tetraploid individuals are produced and selected against as they hybridize with paddlefish for potentially less well-adapted progeny.

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