Ed Ricemeyer

speaker

141 appearances 1 recordings 1 series first heard Jul 2026 last heard 26 Jul

Ed Ricemeyer’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 1 in all, peaking in Jul 2026 with 1.

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Futureproof with Jonathan McCrea · The fish species with no males · 26 Jul 2026 podcast

So to start off, if it's okay, I'd like to just talk a little bit about sexual reproduction and why it is important.

So if you think about it on one level, sexual reproduction seems like a very complicated way to reproduce and to make new generations.

And that's because there are two big problems.

First of all, you have to find a mate, and you have to find a mate that is of the right age, the right sex, and in a place that you have a chance of bumping into them.

And then beyond that, there's also the issue of there's often a lopsided investment in reproduction between the two sexes in a species.

So if you think about mammals, for instance, the female has to carry around a fetus for a while, and then even after birth has to breastfeed it.

Whereas if you can imagine a situation in which there were no males, so if females could just make copies of themselves,

then you could think of it as having the opportunity to create twice as many offspring and regeneration.

So what is the advantage to it?

And why is it that everything, whether you're talking about single-celled amoeba or mushrooms or plants,

or, of course, animals, not just usually is able to sexually reproduce in some way, but actually almost always engages in sexual reproduction.

And the answer that biologists have come up with to this is that what happens during sexual reproduction is genes get mixed up between the mother and the father.

And this is really important because it means that in one individual, perhaps that individual has some mutations that are very helpful to it, but some other mutations that are very not helpful to it.

The shuffling of genes that happens during sexual reproduction allows the good ones and the bad ones to be separated from each other so that natural selection can act differently on the good ones and the bad ones.

And there is a concept called Miller's Ratchet, which predicts that because under asexual reproduction, no offspring can have fewer mutations than its parent, it ought to cause a species to go extinct eventually.

Yeah.

And one problem is that, sure, there are some mutations that might make it impossible to survive, but there are a lot more mutations that are more like death by a thousand cuts, where they do something that's just a little tiny bit bad.

And the problem is that under asexual reproduction, what's expected is that you should keep getting more and more of these.

No good way to get rid of them until there's so many that the species goes extinct.

So Amazon mollies, they're an all-female species.

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