- Dec 2, 2018
- 1,274
- 832
- 125
Hello MFK,
I've taken a long break from the forum because school sucks blah blah blah. I'm sure no one missed me and my practically nonexistent contributions to the forum too much. I return significantly older and wiser, and with something interesting to discuss for once. If you're interested in the topic, please read the entire post. There's actual substance in here, believe it or not.
First let's start with the fact that I no longer own any fish. That's right. As everyone knows, I used to be the greatest fish expert on this forum. My Ph.D. level of expertise on extremely large RTCs was widely recognized, but alas, I am no longer worthy of the infinite praise my expertise used to command. Jokes aside, I recently moved to Washington D.C. and I had to give most of my fish to a friend. This wasn't something I wanted to do at all, but high moving costs are high moving costs, and I did have some moderately large and sensitive fish that my family couldn't ship on our moving budget.
The doradid-shaped hole in my heart still aches to this day, but I managed to fill it about halfway with something that was *almost* a fish. I managed to fish up a Louisiana Swamp crayfish (Procambarus clarkii, this is important later) from a swamp near my house, and quickly situated it in a 10 gallon. It was no Megalodoras uranoscopus, but at least I could go to sleep to the sound of a filter humming again. By the way, you do miss that sound once it's gone.
It weaned off live food much faster than expected for an adult wild crayfish, taking shrimp pellets almost immediately. I admit I haven't given it the most stellar of care due to my extremely rushed, time consuming preparation regime for the USABO, which I'm taking in February. However, I'm still an experienced fish keeper, and it's been receiving regular 60% water changes every week. It's eating well, and has molted several times without help and with complete success. Being wild, I'm sure it has at least some internal parasites, but not enough to cause extensive problems, as it seems healthy overall. For substrate, I have pebbles taken from the exact swamp where I collected it, and a healthy bit of substrate from there too, which I hoped would cycle the tank since I didn't feel like doing it myself. It worked wonderfully. The water didn't cloud, there was no surface-seeking behavior, etc. Water at a nice 74 degrees with good flow. And yes, I'm aware 10 gallons isn't exactly optimal for an adult crayfish, but this one is only a midsized female, and I have a 30 gallon HOB filter for it that seems to be doing an ok job for now. So, like I said, adequate but not optimal conditions.
Therefore it was to my surprise when I saw a tiny, transparent thing swimming backwards away from the filter. Upon closer inspection it turned out to be a baby crayfish. I looked at the new mother, and she had around 50 babies in the process of hatching clinging to the underside of her tail. All of them are free-swimming now and growing very quickly. I'm going to remove them once they get to the size that their mother would eat them or consider them a territorial threat.
My question is, how did it reproduce without a male? I'm aware that decopod taxonomy and identification is a nightmare, and that there are probably several subspecies of P. clarkii found throughout the US as it is an invasive species and lives in a wide range of habitats. However, I'm 100% sure it isn't Marmorkrebs, which is the only predominantly parthenogenic species of crayfish currently known. Other decapod species are known to be capable of parthenogenesis, but as far as I can tell it's never been documented in P. clarkii. From the wikipedia article on parthenogenesis: "Louisiana red swamp crayfish (Procambarus clarkii), which normally reproduces sexually, has also been suggested to reproduce by parthenogenesis,[56] although no individuals of this species have been reared this way in the lab."
So there are two possible ways this could have happened. If the crayfish has a normal crayfish chromosome and is diploid, than it definitely reproduced via automixis. If you don't know what that is, here's a basic diagram.
Either CFA or TFA could have occurred in this case. If it did, that would be fantastic, because according to wikipedia, no one has ever induced P. clarkii to reproduce via any of these methods in a lab, let alone whatever the hell I'm doing. However, there is a third case. If that third case is true, then that would be even more amazing.
The only other crayfish to regularly reproduce parthenogenetically is the marbled crayfish, Marmokrebs. It should tell you a lot about its taxonomy that it doesn't have a species name. The story of Marmokrebs and its origins is one of the most convoluted, confusing things I've ever had to read through. It's not even recognized by a lot of biologists as its own genus. The general consensus seems to be that at some pet store in Germany in the 1990s, one of the crayfish being bred had a genetic error that made it triploid instead of diploid, meaning it had 3/2 the amount of chromosomes it should. Triploidy is a mostly fatal genetic disorder that results in there being 3 copies of the chromosomes instead of 2. So a triploid human would have 69 chromosome pairs. Anyway, this crayfish was a Procambarus fallax, a very common crayfish species in Europe. But there was something odd about this one. It could reproduce in the complete absence of a parent. Its non-fatal triploidy somehow allowed it to clone itself, meaning every single mutated P. fallax or Marmokrebs has an identical genome. Keep in mind not all forms of asexual reproduction are cloning. Automixis isn't, for example. But however Marmokrebs seems to reproduce is.
Marmokrebs has become a significant problem because it can clone itself very quickly without needing to find a mate. This has drawbacks in the long run, but it helped Marmokrebs become an exceptionally good invasive species. Even for an asexual organism, it reproduces incredibly quickly, and we have no idea how it actually works on a genetic level.
So if my crayfish reproduced by automixis, then great. It possibly gives us new insight as to what breeding conditions P. clarkii finds most suitable. Also, there's the added excitement that no one's ever done it before. So that's cool. But if the offspring of the crayfish are genetically identical to the mother, than that would mean this particular individual is triploid. This would mean that it was mutated somehow to be able to reproduce parthenogenically, like the patient zero of the Marmokrebs epidemic. That would mean there is some genetic disorder present throughout most crayfish that enables them to mutate in such a way, or something like that. It would also mean that P. clarkii would have a far greater invasiveness potential even than it already does. That would be new frontiers of science, enabling to understand the genetic mechanics of decapods far better than ever before.
The problem is, I'm not actually a scientist. Yes, I'm pretty far ahead academically ahead for my age. But at the end of the day, I've never actually done a formal study. I'm just some kid with USABO textbooks, some fish, some ants, some lizards, a crayfish, and a microscope. I don't have any lab equipment at all other than my microscope since I live in DC and the labs at both my school and the college I do dual enrollment in are closed. I imagine it wouldn't be too hard to verify triploidy on a tissue sample if I had a PCR machine or something, but I don't. I do have tissue samples, both from the mother and her babies, but I just don't have any way to verify whether they're identical, triploid, either, or both. As soon as I can get that verified, I will update. I will ask my professors and see what they can do.
If anyone has any hands-on experience with crayfish cloning, has knowledge of this topic, or has had their crayfish clone themselves with no mate, please reply. I don't know much about decapods other than just general higher-than-average levels of biology knowledge that are necessary for the USABO. I would love for someone who is an expert or actually has experience with decapods to chime in on this.
I've taken a long break from the forum because school sucks blah blah blah. I'm sure no one missed me and my practically nonexistent contributions to the forum too much. I return significantly older and wiser, and with something interesting to discuss for once. If you're interested in the topic, please read the entire post. There's actual substance in here, believe it or not.
First let's start with the fact that I no longer own any fish. That's right. As everyone knows, I used to be the greatest fish expert on this forum. My Ph.D. level of expertise on extremely large RTCs was widely recognized, but alas, I am no longer worthy of the infinite praise my expertise used to command. Jokes aside, I recently moved to Washington D.C. and I had to give most of my fish to a friend. This wasn't something I wanted to do at all, but high moving costs are high moving costs, and I did have some moderately large and sensitive fish that my family couldn't ship on our moving budget.
The doradid-shaped hole in my heart still aches to this day, but I managed to fill it about halfway with something that was *almost* a fish. I managed to fish up a Louisiana Swamp crayfish (Procambarus clarkii, this is important later) from a swamp near my house, and quickly situated it in a 10 gallon. It was no Megalodoras uranoscopus, but at least I could go to sleep to the sound of a filter humming again. By the way, you do miss that sound once it's gone.
It weaned off live food much faster than expected for an adult wild crayfish, taking shrimp pellets almost immediately. I admit I haven't given it the most stellar of care due to my extremely rushed, time consuming preparation regime for the USABO, which I'm taking in February. However, I'm still an experienced fish keeper, and it's been receiving regular 60% water changes every week. It's eating well, and has molted several times without help and with complete success. Being wild, I'm sure it has at least some internal parasites, but not enough to cause extensive problems, as it seems healthy overall. For substrate, I have pebbles taken from the exact swamp where I collected it, and a healthy bit of substrate from there too, which I hoped would cycle the tank since I didn't feel like doing it myself. It worked wonderfully. The water didn't cloud, there was no surface-seeking behavior, etc. Water at a nice 74 degrees with good flow. And yes, I'm aware 10 gallons isn't exactly optimal for an adult crayfish, but this one is only a midsized female, and I have a 30 gallon HOB filter for it that seems to be doing an ok job for now. So, like I said, adequate but not optimal conditions.
Therefore it was to my surprise when I saw a tiny, transparent thing swimming backwards away from the filter. Upon closer inspection it turned out to be a baby crayfish. I looked at the new mother, and she had around 50 babies in the process of hatching clinging to the underside of her tail. All of them are free-swimming now and growing very quickly. I'm going to remove them once they get to the size that their mother would eat them or consider them a territorial threat.
My question is, how did it reproduce without a male? I'm aware that decopod taxonomy and identification is a nightmare, and that there are probably several subspecies of P. clarkii found throughout the US as it is an invasive species and lives in a wide range of habitats. However, I'm 100% sure it isn't Marmorkrebs, which is the only predominantly parthenogenic species of crayfish currently known. Other decapod species are known to be capable of parthenogenesis, but as far as I can tell it's never been documented in P. clarkii. From the wikipedia article on parthenogenesis: "Louisiana red swamp crayfish (Procambarus clarkii), which normally reproduces sexually, has also been suggested to reproduce by parthenogenesis,[56] although no individuals of this species have been reared this way in the lab."
So there are two possible ways this could have happened. If the crayfish has a normal crayfish chromosome and is diploid, than it definitely reproduced via automixis. If you don't know what that is, here's a basic diagram.
Either CFA or TFA could have occurred in this case. If it did, that would be fantastic, because according to wikipedia, no one has ever induced P. clarkii to reproduce via any of these methods in a lab, let alone whatever the hell I'm doing. However, there is a third case. If that third case is true, then that would be even more amazing.
The only other crayfish to regularly reproduce parthenogenetically is the marbled crayfish, Marmokrebs. It should tell you a lot about its taxonomy that it doesn't have a species name. The story of Marmokrebs and its origins is one of the most convoluted, confusing things I've ever had to read through. It's not even recognized by a lot of biologists as its own genus. The general consensus seems to be that at some pet store in Germany in the 1990s, one of the crayfish being bred had a genetic error that made it triploid instead of diploid, meaning it had 3/2 the amount of chromosomes it should. Triploidy is a mostly fatal genetic disorder that results in there being 3 copies of the chromosomes instead of 2. So a triploid human would have 69 chromosome pairs. Anyway, this crayfish was a Procambarus fallax, a very common crayfish species in Europe. But there was something odd about this one. It could reproduce in the complete absence of a parent. Its non-fatal triploidy somehow allowed it to clone itself, meaning every single mutated P. fallax or Marmokrebs has an identical genome. Keep in mind not all forms of asexual reproduction are cloning. Automixis isn't, for example. But however Marmokrebs seems to reproduce is.
Marmokrebs has become a significant problem because it can clone itself very quickly without needing to find a mate. This has drawbacks in the long run, but it helped Marmokrebs become an exceptionally good invasive species. Even for an asexual organism, it reproduces incredibly quickly, and we have no idea how it actually works on a genetic level.
So if my crayfish reproduced by automixis, then great. It possibly gives us new insight as to what breeding conditions P. clarkii finds most suitable. Also, there's the added excitement that no one's ever done it before. So that's cool. But if the offspring of the crayfish are genetically identical to the mother, than that would mean this particular individual is triploid. This would mean that it was mutated somehow to be able to reproduce parthenogenically, like the patient zero of the Marmokrebs epidemic. That would mean there is some genetic disorder present throughout most crayfish that enables them to mutate in such a way, or something like that. It would also mean that P. clarkii would have a far greater invasiveness potential even than it already does. That would be new frontiers of science, enabling to understand the genetic mechanics of decapods far better than ever before.
The problem is, I'm not actually a scientist. Yes, I'm pretty far ahead academically ahead for my age. But at the end of the day, I've never actually done a formal study. I'm just some kid with USABO textbooks, some fish, some ants, some lizards, a crayfish, and a microscope. I don't have any lab equipment at all other than my microscope since I live in DC and the labs at both my school and the college I do dual enrollment in are closed. I imagine it wouldn't be too hard to verify triploidy on a tissue sample if I had a PCR machine or something, but I don't. I do have tissue samples, both from the mother and her babies, but I just don't have any way to verify whether they're identical, triploid, either, or both. As soon as I can get that verified, I will update. I will ask my professors and see what they can do.
If anyone has any hands-on experience with crayfish cloning, has knowledge of this topic, or has had their crayfish clone themselves with no mate, please reply. I don't know much about decapods other than just general higher-than-average levels of biology knowledge that are necessary for the USABO. I would love for someone who is an expert or actually has experience with decapods to chime in on this.
