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Hi all,

My PhD research is in evolutionary biology, and I specifically use quantitative genetic (QG) approaches to answer questions concerning genetic variation in natural populations. This means that I develop large-scale experiments that involve breeding organisms, managing pedigrees, and tracking phenotypes (including fitness) over time.

I've been reading over this forum, and it's plainly obvious that there's major contention surrounding so-called "hybridizing" between morphs (I put this in quotation marks because these are within-species questions).

Before I go on, I'd like to state my intentions to make this a friendly conversation--I don't feel hostility toward any of you, the readers, and I'd like very much for this to remain a positive space in which we can all learn from one another.

With that out of the way, I'm having a little trouble wrapping my head around the major arguments against crossing morphs, because they seem to contradict much of what's in the scientific literature (and evolutionary biology in general). I'm hoping that someone or some of you might be willing to help me understand which arguments I'm missing, if any. Before anyone asks, I've been through other posts on the subject, but many/most of the arguments against the practice seem rooted in tradition/preference rather than science or empirical evidence suggesting it should be done.

Here are the arguments as I understand them and rebuttals from evolutionary biology (please feel free to speak up if I've missed any):

1) "Cross-morph breeding is bad for the frogs! Their natural within-species morphs will do better when bred together."

Evolutionary biology response: Overwhelmingly, populations of organisms do "better" (i.e. see their population-level average fitness increase) when maximizing heterozygosity at each locus--this reduces the probability of coupling deleterious recessive alleles together. Everybody's heard of the "hybrid vigor" that frequently applies when crossing species--this generally applies only to the F1 generation across species boundaries, but when outbreeding across populations (i.e. within species boundaries), we frequently see major improvements in fitness (i.e. an index of longevity and reproductive success) in the crossed offspring.

Comment on #1: An important implicit note, here, is that breeding strictly within a specific morph is very likely increasing the probability of inbreeding, which overwhelmingly moves populations in the opposite direction by increasing homozygosity among deleterious recessives (especially given the insulated populations being bred back and forth by hobbyists).
Yes, there are instances in which outbreeding depression occurs, but I can't find much evidence of this being studied in these frogs. The closest I come is here, in this publication by Wang and Summers from 2010 that mentions that reproductive isolation due to selection may be evident in "Dendrobates" [now Oophaga] pumilio. (This paper is also referenced in the Frankham et al 2011, which is the only other paper I can find that even mentions outbreeding depression in the same publication as anything Dendrobatid.) Note, though, that in the last ten years, numerous other frogs have been reclassified into different species and even genera (e.g. "Dendrobates pumilio" is now "Oophaga pumilio"), and so even the few existing concerns surrounding population divergence may be weaker arguments still with all the "splitting" that's occurred.

2) "Different morphs may show aggression toward one another due to imprinting on parents that occurs during development."

Evolutionary biology response: This is the argument that makes the most sense, but work by Yang et al in 2019 (again, on Oophaga pumilio) suggests that cross-fostering can effectively render this argument moot: the results suggest that offspring will behave "normally" toward anyone who resembles their "mother" (i.e. whichever morph of frog reared the offspring). In other words, it seems that you could rear frogs for the specific purpose of breeding with different morphs by raising multiple offspring with foster morphs.

Comment on #2: This is a little more effort than the average dart frog breeder might want to put in, and that I understand--I'm not suggesting that everyone should/must do this. I do, however, want to observe that it seems it would only take 1-2 generations of cross-fostering before you had new, "friendly-with-each-other" morphs. You could also potentially cross-foster individuals to make them more tolerant of other morphs in day-to-day life (e.g. cross-foster cobalt tinctorious with azureus tinctorious so that the cobalts could be comfortably/safely housed with reciprocally reared azureus*).

*(I know the study I mentioned above only explores Oophaga pumilio and not Dendrobates, and it may be that this doesn't apply to all species.)

3) "But why would you want to produce new morphs or cross-breed? There's so much natural variation in the wild--why can't we just enjoy what nature produces?"

Conservation response: My first thought, here, is that if you're only rearing frogs that can be found in the wild, you're encouraging more wild-catching because there's a larger/greater market for frogs that look like those in the wild. It seems like the community is (rightly) opposed to wild-collection, so this one's a bit of a head-scratcher for me.



General response to all of the above: I think it's fine if people are much more enchanted by the naturally-occuring variants than captive-bred morphs--they're really beautiful and display all kinds of cool behaviors (like biparental care sometimes-wow!), but given all of the above, I'm still a little confused about why people are so hostile toward the idea. There are countless populations of all of these naturally-occuring morphs out there, and some are bred to maintain genetic variation in case there's a need for selective "head-starting" in wild populations (if the practice is validated in the given context--it isn't always).


I know this was long, so thanks for reading all the way! Please let me know your thoughts--I'm eager to hear responses to these points and/or any arguments I might've missed (and I'll be happy to update this thread if someone makes a point that needs including, here).
 

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Hi all,

My PhD research is in evolutionary biology, and I specifically use quantitative genetic (QG) approaches to answer questions concerning genetic variation in natural populations. This means that I develop large-scale experiments that involve breeding organisms, managing pedigrees, and tracking phenotypes (including fitness) over time.

I've been reading over this forum, and it's plainly obvious that there's major contention surrounding so-called "hybridizing" between morphs (I put this in quotation marks because these are within-species questions).

Before I go on, I'd like to state my intentions to make this a friendly conversation--I don't feel hostility toward any of you, the readers, and I'd like very much for this to remain a positive space in which we can all learn from one another.

With that out of the way, I'm having a little trouble wrapping my head around the major arguments against crossing morphs, because they seem to contradict much of what's in the scientific literature (and evolutionary biology in general). I'm hoping that someone or some of you might be willing to help me understand which arguments I'm missing, if any. Before anyone asks, I've been through other posts on the subject, but many/most of the arguments against the practice seem rooted in tradition/preference rather than science or empirical evidence suggesting it should be done.

Here are the arguments as I understand them and rebuttals from evolutionary biology (please feel free to speak up if I've missed any):

1) "Cross-morph breeding is bad for the frogs! Their natural within-species morphs will do better when bred together."

Evolutionary biology response: Overwhelmingly, populations of organisms do "better" (i.e. see their population-level average fitness increase) when maximizing heterozygosity at each locus--this reduces the probability of coupling deleterious recessive alleles together. Everybody's heard of the "hybrid vigor" that frequently applies when crossing species--this generally applies only to the F1 generation across species boundaries, but when outbreeding across populations (i.e. within species boundaries), we frequently see major improvements in fitness (i.e. an index of longevity and reproductive success) in the crossed offspring.

Comment on #1: An important implicit note, here, is that breeding strictly within a specific morph is very likely increasing the probability of inbreeding, which overwhelmingly moves populations in the opposite direction by increasing homozygosity among deleterious recessives (especially given the insulated populations being bred back and forth by hobbyists).
Yes, there are instances in which outbreeding depression occurs, but I can't find much evidence of this being studied in these frogs. The closest I come is here, in this publication by Wang and Summers from 2010 that mentions that reproductive isolation due to selection may be evident in "Dendrobates" [now Oophaga] pumilio. (This paper is also referenced in the Frankham et al 2011, which is the only other paper I can find that even mentions outbreeding depression in the same publication as anything Dendrobatid.) Note, though, that in the last ten years, numerous other frogs have been reclassified into different species and even genera (e.g. "Dendrobates pumilio" is now "Oophaga pumilio"), and so even the few existing concerns surrounding population divergence may be weaker arguments still with all the "splitting" that's occurred.

2) "Different morphs may show aggression toward one another due to imprinting on parents that occurs during development."

Evolutionary biology response: This is the argument that makes the most sense, but work by Yang et al in 2019 (again, on Oophaga pumilio) suggests that cross-fostering can effectively render this argument moot: the results suggest that offspring will behave "normally" toward anyone who resembles their "mother" (i.e. whichever morph of frog reared the offspring). In other words, it seems that you could rear frogs for the specific purpose of breeding with different morphs by raising multiple offspring with foster morphs.

Comment on #2: This is a little more effort than the average dart frog breeder might want to put in, and that I understand--I'm not suggesting that everyone should/must do this. I do, however, want to observe that it seems it would only take 1-2 generations of cross-fostering before you had new, "friendly-with-each-other" morphs. You could also potentially cross-foster individuals to make them more tolerant of other morphs in day-to-day life (e.g. cross-foster cobalt tinctorious with azureus tinctorious so that the cobalts could be comfortably/safely housed with reciprocally reared azureus*).

*(I know the study I mentioned above only explores Oophaga pumilio and not Dendrobates, and it may be that this doesn't apply to all species.)

3) "But why would you want to produce new morphs or cross-breed? There's so much natural variation in the wild--why can't we just enjoy what nature produces?"

Conservation response: My first thought, here, is that if you're only rearing frogs that can be found in the wild, you're encouraging more wild-catching because there's a larger/greater market for frogs that look like those in the wild. It seems like the community is (rightly) opposed to wild-collection, so this one's a bit of a head-scratcher for me.



General response to all of the above: I think it's fine if people are much more enchanted by the naturally-occuring variants than captive-bred morphs--they're really beautiful and display all kinds of cool behaviors (like biparental care sometimes-wow!), but given all of the above, I'm still a little confused about why people are so hostile toward the idea. There are countless populations of all of these naturally-occuring morphs out there, and some are bred to maintain genetic variation in case there's a need for selective "head-starting" in wild populations (if the practice is validated in the given context--it isn't always).


I know this was long, so thanks for reading all the way! Please let me know your thoughts--I'm eager to hear responses to these points and/or any arguments I might've missed (and I'll be happy to update this thread if someone makes a point that needs including, here).
Although your evolutionary biology responses are correct, you are missing a few key points specific to dart frogs and their morphs (which can loosely be called populations). There is evidence in scientific literature that these populations have relatively low genetic flow between them, and not always due to geographical barriers. Dendrobates tinctorius azureus and sipaliwini occur very close together, yet there is little breeding between them. This suggests that there is at least some reproductive isolation between them. They will breed if put together (so this appears to be prezygotic isolation, likely behavioural), but if given the choice in a natural setting they seem to mostly restrict themselves to same or similar morph frogs. And although crossbreeding could indeed lead to increased heterozygosity, the argument against crossbreeding is to maintain these naturally occuring morphs and specific color combinations as they would otherwise be quickly lost in the hobby as a lot of morphs are no longer being imported. This partially ties in with your third answer/comment. Yes most people in the dart frog community are against collecting wild animals, which is why it is important to maintain original morphs. If everything is crossbred, the demand for "original" morphs will also increase. In my experience with plants, it is generally a good idea to flood the market with a given species/morph to greatly decrease prices and the demand for WC animals, greatly discouraging poaching of the animals because the risks outweigh the potential gains.

In theory, it would be ok to crossbreed if everyone takes this seriously and maintains proper records. But as soon as people start crossbreeding and those animals start circulating again without proper records it doesn't take long for a specific morph to disappear if everything becomes intermixed. And these things happen, especially when people quit the hobby. Add to this the fact that the hobby is often very much influenced by trends, which have already caused several morphs and even species to nearly completely disappear because interest in them dropped for a few years. Some species in the hobby are already hopelessly mixed (auratus costa rica is a mix of east and west populations and Epipedobates anthonyi usually offered without a morph name are a mix of several original morphs).

Taking this even further are the hybrid zones and speciation events through hybridization in Ranitomeya and Oophaga species. Offcource these are different from crossbreeding events, but they illustrate nicely that in dart frogs there are clear reproductive barriers that readily establish themselves in nature.
 

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Forgive me if I sound comparatively uneducated: evolutionary biology is not a strong point for me, and I’ll try to speak from a conservation perspective instead. I don’t think I’ve seen any of your points used on here as reasons not to hybridize, and it seems you may have missed the main reason. Your point #3 touches on it but doesn’t quite hit it on the head. This is what I understand to be the main reason many people on this forum are against hybridizing:

Evolution and isolation have produced a number of distinct species and morphs within those species. The frogs’ natural habitats are often disappearing, and in some cases the specific morph may only exist in captivity. If we muddy the genetic lines and also lose the wild habitat, then we have irrevocably lost something beautiful that nature produced over millions of years. As @Johanovich pointed out, hybridization could in theory coexist with this conservation effort, but in practice many people already do not keep appropriate records, and the lines would quickly become muddied.

Preservation of the purity of a species or morph isn’t a practice isolated to dart frog owners - I don’t keep dart frogs (yet) but in the plant world, there are efforts to keep species alive in cultivation when there is significant loss of natural habitat. I have considered joining a group that distributes rare Begonia seeds as a conservation effort. To be fair, there is also lots of hybridization going on mostly without judgment from the conservation-oriented folks, but I think the difference here is the relative size of the communities - dart frog keepers are comparatively such a tiny community compared to rare Begonia growers. There is a similarly strict effort going on with the small group of Parosphromenus breeders. Many zoos have breeding projects for animals that are threatened in the wild; I believe I have read in past that they have strong opinions against hybridization, and a quick Google search confirms that.

edit: it does seem there is some debate in the conservation community over the benefits of increasing the adaptability of a species vs just preserving it in its natural state. This dart frog community certainly leans toward “preserving it in its natural state”, but I do acknowledge that humans are changing environments at a rate that natural evolution cannot keep up with.
 

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I think @Johanovich hit the nail on the head for most of these.

For point #1: I would also add that by creating new morphs in captivity is very different from allowing wild "hybridization". The frogs can't choose, either due to necessity or willingness - they are forced to hybridize.

For point #2: I don't see that argument being used here much at all, at least not recently.

For point #3: I would also add that for this portion of the pet hobby, there is no want or willingness (generally) to go down the genetic rabbit hole that such animals like Ball Pythons have gone down. They are a designer pet now, and I think most hobbyists here enjoy the animals for their representation of the wild, not to be able to play god and create new types.

Just a few comments anyway.
 

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I don't hear anyone on this forum referencing either your first or second hypothetical arguments. And just to double down on what was referenced is that these frogs don't have the option to hybridize in the wild, for the most part. We see very few separate species living together and when we do it is usually just that. Completely separate species that can't hybridize. These frogs are blocked from each other in the wild by natural barriers. We don't see azureus living along side cobalts. So any hybridization would be unnatural, which, for most of us, is the antithesis of this hobby.
 

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I agree that the assertions that form the body of questioning here are basically false premises, or at least read as if they are largely more or less hypothetical positions formulated ad hoc as a foil to justify the answers. Question #3, as noted, has some relevance, but the "conservation response" to it depends on a conditional statement that is wildly simplistic in regards to the market forces in herp circles -- and also simply incorrect, since the logically equivalent 'you're not only rearing frogs that can be found in the wild (i.e. you're producing crosses) or you're encouraging more wild-catching' is patently false.

As for "arguments [you] might've missed" -- there have been numerous comments in past threads about issues within the community of captive keepers, such losing captive wild types because of a created demand for crosses, and the practical impossibility of IDing crosses:


More empirically, there have been comments on the fact that morphs are sometimes found to be different species (not mentioned in this linked thread, but this happened recently in Ranitomeya, and also in a few noteworthy reptile genera such as Lampropeltis and Lichanura, and so what looks like a morph/locale cross turns out to be an interspecies hybrid):


but many/most of the arguments against the practice seem rooted in tradition/preference rather than science or empirical evidence suggesting it should be done
It isn't exactly clear what is all implicitly entailed by "tradition/preference", but dismissing that and assuming that some sort of empirical reductionism is going to make any sense whatsoever of animal keepers' practices and motivations for those practices is likely to lead to error, and in some readers to offense (whether intended or not).
 

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I am amazed on a daily basis how much humanity is trying too intervene in the natural way off things.

If the species in nature would cross bread, then they would probably already have done so. No human needs too adjust this setting.
Evolution does not need human interverence. We destroy enough off nature as it is.

Most crossbred animals currently on this planet is mostly the result of human wanting. Not because off natural mechanics. look at the amount off snakes or reptiles that are bred and crossbred specifically too sell more or for higher prices. Nothing else.

We play god, but have no clue about the consequences. It is not a game where you can reload from a previous point in time. So changes are most likely permanent. Good or bad.
And we always loose the game against nature, nature is perfect as is, without us screwing everyting up.

My two cents about it.
 

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We play god, but have no clue about the consequences. It is not a game where you can reload from a previous point in time. So changes are most likely permanent. Good or bad.
And we always loose the game against nature, nature is perfect as is, without us screwing everyting up.
I agree with everything you say but I do want to add that the core of our hobby, which is keeping and breeding animals in captivity for our personal pleasure (not just hybridizing) is eaqualy to playing god when you look at it that way.
 

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I am glad these conversations can happen. It is interesting that we as humans can pretty much justify anything we want - this is usually not a good thing. I can see it everywhere, including in myself - where there is something controversial or clearly wrong that I or we as humans want - and we justify it through some pretty sketchy logic and willful ignorance. It is usually easy to find a bit of good in most decisions, so justification because of something 'good' coming out of it is not in itself a 'good' reason, and even 'good' definitions vary drastically. It is 'good' for my wallet to purchase cheap goods, but is it 'good' that cheap goods are most often exploitative and unsustainable?

It's also important to understand that there are many different cultures and beliefs that can have large variation in their views with respect to humanity and our relation to nature. Most often discussions/arguments are based on so many assumptions that it is better to discuss those assumptions - for example in this case probably a better question: is nature here for humanity's pleasure (to experiment, harvest, even exploit), or is it our responsibility to steward nature responsibly, or some combination? This answer to this question will vary depending on culture, geography, economic situation, personal experiences, beliefs, etc.

When I look at an issue, I often try to strip it to its bare bones, what are the assumptions and the assumptions that those assumptions rest on? I ask those questions until I get to the bottom question. This may seem tedious or overly philosophical, but really it is a way to try and determine if there are views I hold that are actually contradictory to my own core beliefs/assumptions/values/principles.

This is a fairly general post - I think most positions have been covered fairly well in the above posts and threads.

I will say, I am no evolutionary biologist, but I do a lot of reading in science and nature fields, and I hate the argument 'because science'. Science is merely a bunch of theories on how stuff works. The world is such a complicated place, with an insane amount of variables, conflicting studies, unfortunately corruption and exaggeration, tinkering with results - that it is crazy to think that: first, the stuff we know now is all correct, and second, that it is actually significant. Sure, there are many theories that are incredibly strong (ie. gravity), but there are so many topics that are incredibly complex or not well researched. Please don't think I hate science - I love it - but in 100 years people will be laughing at some of the stuff we think.

Lastly, my wife works in genetics, so I often have discussions with her about it - and it is a minefield in terms of ethics, and I think we will see a lot more division between base beliefs/philosophies/geographies about how to decide what is ethical and what is not. There will likely be fundamental differences on the ethics in genetics that different base assumptions will be unable to bridge a common view or practice.
 

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Hi all,

Thanks for your answers--I didn't actually see that this thread had finally been cleared or I would've done my best to address these responses in real-time as they occurred!

Let me (try to) address all of what's been said, here, but before I do, I want to try and reemphasize that I'm asking these questions in good faith and not trying to start conflict or promote any sort of hostility.

I'd like to also point out that there's a middle ground between breeding only within a single morph and creating entirely new morphs that might be worth discussing (i.e. deliberately infusing a morph with new alleles for the health/fitness benefits without eliminating the morph or producing another).

1) Addressing genetic variation:
Although your evolutionary biology responses are correct, you are missing a few key points specific to dart frogs and their morphs (which can loosely be called populations). There is evidence in scientific literature that these populations have relatively low genetic flow between them, and not always due to geographical barriers. Dendrobates tinctorius azureus and sipaliwini occur very close together, yet there is little breeding between them. This suggests that there is at least some reproductive isolation between them. They will breed if put together (so this appears to be prezygotic isolation, likely behavioural), but if given the choice in a natural setting they seem to mostly restrict themselves to same or similar morph frogs. And although crossbreeding could indeed lead to increased heterozygosity, the argument against crossbreeding is to maintain these naturally occuring morphs and specific color combinations as they would otherwise be quickly lost in the hobby as a lot of morphs are no longer being imported. This partially ties in with your third answer/comment. Yes most people in the dart frog community are against collecting wild animals, which is why it is important to maintain original morphs. If everything is crossbred, the demand for "original" morphs will also increase. In my experience with plants, it is generally a good idea to flood the market with a given species/morph to greatly decrease prices and the demand for WC animals, greatly discouraging poaching of the animals because the risks outweigh the potential gains.

In theory, it would be ok to crossbreed if everyone takes this seriously and maintains proper records. But as soon as people start crossbreeding and those animals start circulating again without proper records it doesn't take long for a specific morph to disappear if everything becomes intermixed. And these things happen, especially when people quit the hobby. Add to this the fact that the hobby is often very much influenced by trends, which have already caused several morphs and even species to nearly completely disappear because interest in them dropped for a few years. Some species in the hobby are already hopelessly mixed (auratus costa rica is a mix of east and west populations and Epipedobates anthonyi usually offered without a morph name are a mix of several original morphs).

Taking this even further are the hybrid zones and speciation events through hybridization in Ranitomeya and Oophaga species. Offcource these are different from crossbreeding events, but they illustrate nicely that in dart frogs there are clear reproductive barriers that readily establish themselves in nature.
Thank you! This is the sort of response I was hoping for: some insight into the reasoning behind the aversion to increasing gene flow across populations. I knew that their populations were insular and isolated, and I know that behavioral isolation likely plays a role where reproductive isolation persists even in overlapping populations--that is to say, these morphs don't freely interbreed in the wild--but my curiosity mostly sits on how populations are managed in the captive hobby where the naturally-occuring genetic diversity via mutation is less likely to get represented by differences in fitness among individuals (in other words, the healthier ones aren't necessarily going to get bred over the prettier ones). This is why I mentioned the inbreeding issue above and was trying to get a sense of whether anyone's considering how, for instance, 'azureus' and 'sipalwani' may not naturally reproduce but 'may' produce healthier offspring when paired (even just once in a while) than the frogs we're artificially selecting for whichever visual pattern we like best (and I know, I know, maybe not everyone is doing this, but there's a long history in captive breeding in most hobbies to favor the organism that looks best over the organism that functions best). Is there a response to the inbreeding issue I mentioned (i.e. we're really likely to see/suffer from inbreeding depression as we continue to shuffle the same frogs around as parents)?

It's also helpful/interesting to hear that there's a precedent of wild-type morphs vanishing when others become more popular, and that adds to the list of things I didn't know about this particular hobby. I appreciate your insights, here!

2) My questions are: "basically false premises, or at least read as if they are largely more or less hypothetical positions formulated ad hoc as a foil to justify the answers"

I agree that the assertions that form the body of questioning here are basically false premises, or at least read as if they are largely more or less hypothetical positions formulated ad hoc as a foil to justify the answers. Question #3, as noted, has some relevance, but the "conservation response" to it depends on a conditional statement that is wildly simplistic in regards to the market forces in herp circles -- and also simply incorrect, since the logically equivalent 'you're not only rearing frogs that can be found in the wild (i.e. you're producing crosses) or you're encouraging more wild-catching' is patently false.

As for "arguments [you] might've missed" -- there have been numerous comments in past threads about issues within the community of captive keepers, such losing captive wild types because of a created demand for crosses, and the practical impossibility of IDing crosses:


More empirically, there have been comments on the fact that morphs are sometimes found to be different species (not mentioned in this linked thread, but this happened recently in Ranitomeya, and also in a few noteworthy reptile genera such as Lampropeltis and Lichanura, and so what looks like a morph/locale cross turns out to be an interspecies hybrid):


It isn't exactly clear what is all implicitly entailed by "tradition/preference", but dismissing that and assuming that some sort of empirical reductionism is going to make any sense whatsoever of animal keepers' practices and motivations for those practices is likely to lead to error, and in some readers to offense (whether intended or not).
All of these arguments are cases I've seen made in this forum and others. Admittedly, I didn't check all the timestamps of every discussion or all the indivdiuals involved, and I don't know who's currently most active here and whether or not these perspectives all still hold. There are also 15+ (~) years of posts here, and I'm sure that, as a new member of the forum, I'm likely to have missed some (as you've pointed out). I'm sorry to have offended some of you by asking. I certainly didn't contrive anything for my own benefit, though, and I guess I don't know any of you personally to get a sense of how your responses should "read", but this feels like it might be inching toward the hostility I was trying very hard to avoid. Hopefully, I'm misinterpreting the tone of what I'm reading.

I enjoy the wild-type morphs enormously (they're obviously very beautiful and rich in fascinating traits like the biparental care I mentioned in my original post), and I'm certainly not looking to see them extirpated by designer morphs. On the contrary--if the dart frog hobby is, indeed, very small as someone mentioned above, it seems like we're very likely to run into inbreeding depression sooner or later. The solution to that doesn't have to be an azureus x sipalwani morph (or whichever--that's an arbitrary pairing I pulled from the first response to my post), but even just once, that extra bunch of alleles could be back-bred into the larger populations of each to promote health benefits. It wouldn't necessarily have to produce a "new line" (i.e. a new morph)--it could just be a mechanism to enrich the azureus population by limiting the number of deleterious recessive pairings within that existing morph line. (This I concede may be a strawman issue for now with respect to the frogs--I haven't done the legwork to investigate whether we're seeing lots of genetic issues pop up--but I think it's common knowledge that this occurs in the pet trade/hobby at large.) Happy to talk more about this with you if you'd like to keep chatting.

3) Intra-species crosses within other organisms
Forgive me if I sound comparatively uneducated: evolutionary biology is not a strong point for me, and I’ll try to speak from a conservation perspective instead. I don’t think I’ve seen any of your points used on here as reasons not to hybridize, and it seems you may have missed the main reason. Your point #3 touches on it but doesn’t quite hit it on the head. This is what I understand to be the main reason many people on this forum are against hybridizing:

Evolution and isolation have produced a number of distinct species and morphs within those species. The frogs’ natural habitats are often disappearing, and in some cases the specific morph may only exist in captivity. If we muddy the genetic lines and also lose the wild habitat, then we have irrevocably lost something beautiful that nature produced over millions of years. As @Johanovich pointed out, hybridization could in theory coexist with this conservation effort, but in practice many people already do not keep appropriate records, and the lines would quickly become muddied.

Preservation of the purity of a species or morph isn’t a practice isolated to dart frog owners - I don’t keep dart frogs (yet) but in the plant world, there are efforts to keep species alive in cultivation when there is significant loss of natural habitat. I have considered joining a group that distributes rare Begonia seeds as a conservation effort. To be fair, there is also lots of hybridization going on mostly without judgment from the conservation-oriented folks, but I think the difference here is the relative size of the communities - dart frog keepers are comparatively such a tiny community compared to rare Begonia growers. There is a similarly strict effort going on with the small group of Parosphromenus breeders. Many zoos have breeding projects for animals that are threatened in the wild; I believe I have read in past that they have strong opinions against hybridization, and a quick Google search confirms that.

edit: it does seem there is some debate in the conservation community over the benefits of increasing the adaptability of a species vs just preserving it in its natural state. This dart frog community certainly leans toward “preserving it in its natural state”, but I do acknowledge that humans are changing environments at a rate that natural evolution cannot keep up with.
Thanks for your reply!

I think it gets really slippery when the word "hybrid" gets used to describe within-species pairings for several reasons (and I know this isn't your main point, but indulge me a moment and I'll loop back around). Cross-species hybridization overwhelmingly results in low fitness in the F2, F3, etc--it can cause major setbacks for conservation causes (it's one of the problems with red wolves and coyotes right now). It makes sense that anyone wanting to preserve a species/population would want to avoid it.

Getting some within-species allelic variation, though, is much more likely to help for numerous reasons, including that "within-species" nuclear alleles are more likely to pair well with within-species mitochondria, and this can have dramatic effects on the performance (e.g. reproduction, longevity, immune function, and base ATP output) of the organism. There are lots of instances of bottlenecking--cheetahs, for instance--where an infusion of outbred alleles are desperately needed but not always available. (Point of order: this CAN vary in instances where you've effectively got "new-species-almost-done-cooking", and maybe the dart frogs are here, but as a general rule, if both are going on, outbreeding will be better for the population than inbreeding).

To try and directly address some of your points, zoos definitely do keep captive populations sometimes as reservoirs of genetic diversity (I've got friends who do this work--it's really cool to see!), and they are against 'hybridizing' across species but often favor integrating the abovementioned within-species diversity--in fact, that's often the purpose of the reservoir population: preserving the naturally-occuring genetic diversity before it's obliterated in the wild. These populations are often bred through pedigrees to try and minimize inbreeding.

As for "increasing adaptibility" vs "preserving the natural state", this is kind of a tightrope issue, because a natural population, over time, is likely to become hyper-adapted to its environment, which necessarily means less nuclear genetic diversity--if your environment is extremely stable, certain alleles are eventually going to be better suited to that environment and start eclipsing others in frequency. On the other hand, those species that reach such a hyper-adapted state are also often the most vulnerable to teensy tiny little perturbations, because they have no heritable variation with which they can respond to...anything that changes. It seems like dart frog morphs, especially if they're potentially incipient species (I think maybe Johanovich mentioned this as well, or at least pointed out the frequent separation of species into more species (this was the 'splitting' I mentioned in my first post), fall into the latter category: low naturally-occuring diversity because of hyper-adaptation. If this is the case, having a few extra alleles hanging around the pool doesn't seem like the worst idea to me in case of catastrophe, plague, etc (but that's just an opinion)! ^_^
.
Thanks again for this response!

4) Checking assumptions

I am glad these conversations can happen. It is interesting that we as humans can pretty much justify anything we want - this is usually not a good thing. I can see it everywhere, including in myself - where there is something controversial or clearly wrong that I or we as humans want - and we justify it through some pretty sketchy logic and willful ignorance. It is usually easy to find a bit of good in most decisions, so justification because of something 'good' coming out of it is not in itself a 'good' reason, and even 'good' definitions vary drastically. It is 'good' for my wallet to purchase cheap goods, but is it 'good' that cheap goods are most often exploitative and unsustainable?

It's also important to understand that there are many different cultures and beliefs that can have large variation in their views with respect to humanity and our relation to nature. Most often discussions/arguments are based on so many assumptions that it is better to discuss those assumptions - for example in this case probably a better question: is nature here for humanity's pleasure (to experiment, harvest, even exploit), or is it our responsibility to steward nature responsibly, or some combination? This answer to this question will vary depending on culture, geography, economic situation, personal experiences, beliefs, etc.

When I look at an issue, I often try to strip it to its bare bones, what are the assumptions and the assumptions that those assumptions rest on? I ask those questions until I get to the bottom question. This may seem tedious or overly philosophical, but really it is a way to try and determine if there are views I hold that are actually contradictory to my own core beliefs/assumptions/values/principles.

This is a fairly general post - I think most positions have been covered fairly well in the above posts and threads.

I will say, I am no evolutionary biologist, but I do a lot of reading in science and nature fields, and I hate the argument 'because science'. Science is merely a bunch of theories on how stuff works. The world is such a complicated place, with an insane amount of variables, conflicting studies, unfortunately corruption and exaggeration, tinkering with results - that it is crazy to think that: first, the stuff we know now is all correct, and second, that it is actually significant. Sure, there are many theories that are incredibly strong (ie. gravity), but there are so many topics that are incredibly complex or not well researched. Please don't think I hate science - I love it - but in 100 years people will be laughing at some of the stuff we think.

Lastly, my wife works in genetics, so I often have discussions with her about it - and it is a minefield in terms of ethics, and I think we will see a lot more division between base beliefs/philosophies/geographies about how to decide what is ethical and what is not. There will likely be fundamental differences on the ethics in genetics that different base assumptions will be unable to bridge a common view or practice.
Thanks for writing--I think this is a great point! The whole concept of a "pet trade" or a "dart frog hobby" sits outside of what occurs in nature, and we may have different assumptions about the purpose of that trade or values within it.

The impression I get--and please, anyone feel free to weigh-in, here--is that the dart frog community, as a whole, seems to value these things (not an exhaustive list):
  • Preserving natural 'morphs' (i.e. localized phenotypes specific to populations adapted to a very specific environment) for people in the hobby to enjoy
  • Discouraging wild collection
  • In some cases, insulating descendants of certain populations from being overly outbred as to make individuals available to help restore natural populations should the need arise

If I had to throw an extra value on the pile that I haven't heard mentioned (but I'm sure is important to some people), it would be:
- Keeping populations of dart frogs, in the hobby, healthy and viable



I'm very sorry if I didn't address anyone else's points--this is already a really long reply that's taken me some time to put together.

Is there any sort of "chat" space, here, in which people can talk in real-time? I'm happy to respond here, but I'm always afraid that forum-based interactions are going to regress into a "facebook" state where it's eventually just arguing (yes, a marketplace of ideas is great--I just don't want to feel adversarial).

Thanks again to those who took the time to respond and address my questions/points! It's much appreciated! ^_^

(I'd also be interested to hear how you guys got into the hobby--you sound like a diverse bunch based on your responses!)
 

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Is there any sort of "chat" space, here, in which people can talk in real-time? I'm happy to respond here, but I'm always afraid that forum-based interactions are going to regress into a "facebook" state where it's eventually just arguing (yes, a marketplace of ideas is great--I just don't want to feel adversarial).
There are no conversation areas except these public forums and PMs (called 'conversations' on this platform).

As for avoiding (mere) arguing, typically avoiding contentious topics that have already been discussed to death (as has been mentioned at least ten years ago, just to relink two threads that I linked above) is one good way to do it. That may sound a bit harsh, but I don't think there are very many folks here who have any reason to believe that a discussion of this topic is going to turn out any better than it has in any of its past versions. Especially since the last post spent essentially no time responding to six earlier posts that offered factors that have nothing to do with the handful of biology concepts that seem to be mostly getting shoehorned in.

What the endgame is here, we can only speculate, but trying to convince a group to disbelieve something that has been fairly central to their practices for decades using arguments that are tangential to the heart of the issue isn't the wisest plan, in my experience.
 

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Hi all,

Thanks for your answers--I didn't actually see that this thread had finally been cleared or I would've done my best to address these responses in real-time as they occurred!

Let me (try to) address all of what's been said, here, but before I do, I want to try and reemphasize that I'm asking these questions in good faith and not trying to start conflict or promote any sort of hostility.

I'd like to also point out that there's a middle ground between breeding only within a single morph and creating entirely new morphs that might be worth discussing (i.e. deliberately infusing a morph with new alleles for the health/fitness benefits without eliminating the morph or producing another).

1) Addressing genetic variation:


Thank you! This is the sort of response I was hoping for: some insight into the reasoning behind the aversion to increasing gene flow across populations. I knew that their populations were insular and isolated, and I know that behavioral isolation likely plays a role where reproductive isolation persists even in overlapping populations--that is to say, these morphs don't freely interbreed in the wild--but my curiosity mostly sits on how populations are managed in the captive hobby where the naturally-occuring genetic diversity via mutation is less likely to get represented by differences in fitness among individuals (in other words, the healthier ones aren't necessarily going to get bred over the prettier ones). This is why I mentioned the inbreeding issue above and was trying to get a sense of whether anyone's considering how, for instance, 'azureus' and 'sipalwani' may not naturally reproduce but 'may' produce healthier offspring when paired (even just once in a while) than the frogs we're artificially selecting for whichever visual pattern we like best (and I know, I know, maybe not everyone is doing this, but there's a long history in captive breeding in most hobbies to favor the organism that looks best over the organism that functions best). Is there a response to the inbreeding issue I mentioned (i.e. we're really likely to see/suffer from inbreeding depression as we continue to shuffle the same frogs around as parents)?

It's also helpful/interesting to hear that there's a precedent of wild-type morphs vanishing when others become more popular, and that adds to the list of things I didn't know about this particular hobby. I appreciate your insights, here!

2) My questions are: "basically false premises, or at least read as if they are largely more or less hypothetical positions formulated ad hoc as a foil to justify the answers"



All of these arguments are cases I've seen made in this forum and others. Admittedly, I didn't check all the timestamps of every discussion or all the indivdiuals involved, and I don't know who's currently most active here and whether or not these perspectives all still hold. There are also 15+ (~) years of posts here, and I'm sure that, as a new member of the forum, I'm likely to have missed some (as you've pointed out). I'm sorry to have offended some of you by asking. I certainly didn't contrive anything for my own benefit, though, and I guess I don't know any of you personally to get a sense of how your responses should "read", but this feels like it might be inching toward the hostility I was trying very hard to avoid. Hopefully, I'm misinterpreting the tone of what I'm reading.

I enjoy the wild-type morphs enormously (they're obviously very beautiful and rich in fascinating traits like the biparental care I mentioned in my original post), and I'm certainly not looking to see them extirpated by designer morphs. On the contrary--if the dart frog hobby is, indeed, very small as someone mentioned above, it seems like we're very likely to run into inbreeding depression sooner or later. The solution to that doesn't have to be an azureus x sipalwani morph (or whichever--that's an arbitrary pairing I pulled from the first response to my post), but even just once, that extra bunch of alleles could be back-bred into the larger populations of each to promote health benefits. It wouldn't necessarily have to produce a "new line" (i.e. a new morph)--it could just be a mechanism to enrich the azureus population by limiting the number of deleterious recessive pairings within that existing morph line. (This I concede may be a strawman issue for now with respect to the frogs--I haven't done the legwork to investigate whether we're seeing lots of genetic issues pop up--but I think it's common knowledge that this occurs in the pet trade/hobby at large.) Happy to talk more about this with you if you'd like to keep chatting.

3) Intra-species crosses within other organisms


Thanks for your reply!

I think it gets really slippery when the word "hybrid" gets used to describe within-species pairings for several reasons (and I know this isn't your main point, but indulge me a moment and I'll loop back around). Cross-species hybridization overwhelmingly results in low fitness in the F2, F3, etc--it can cause major setbacks for conservation causes (it's one of the problems with red wolves and coyotes right now). It makes sense that anyone wanting to preserve a species/population would want to avoid it.

Getting some within-species allelic variation, though, is much more likely to help for numerous reasons, including that "within-species" nuclear alleles are more likely to pair well with within-species mitochondria, and this can have dramatic effects on the performance (e.g. reproduction, longevity, immune function, and base ATP output) of the organism. There are lots of instances of bottlenecking--cheetahs, for instance--where an infusion of outbred alleles are desperately needed but not always available. (Point of order: this CAN vary in instances where you've effectively got "new-species-almost-done-cooking", and maybe the dart frogs are here, but as a general rule, if both are going on, outbreeding will be better for the population than inbreeding).

To try and directly address some of your points, zoos definitely do keep captive populations sometimes as reservoirs of genetic diversity (I've got friends who do this work--it's really cool to see!), and they are against 'hybridizing' across species but often favor integrating the abovementioned within-species diversity--in fact, that's often the purpose of the reservoir population: preserving the naturally-occuring genetic diversity before it's obliterated in the wild. These populations are often bred through pedigrees to try and minimize inbreeding.

As for "increasing adaptibility" vs "preserving the natural state", this is kind of a tightrope issue, because a natural population, over time, is likely to become hyper-adapted to its environment, which necessarily means less nuclear genetic diversity--if your environment is extremely stable, certain alleles are eventually going to be better suited to that environment and start eclipsing others in frequency. On the other hand, those species that reach such a hyper-adapted state are also often the most vulnerable to teensy tiny little perturbations, because they have no heritable variation with which they can respond to...anything that changes. It seems like dart frog morphs, especially if they're potentially incipient species (I think maybe Johanovich mentioned this as well, or at least pointed out the frequent separation of species into more species (this was the 'splitting' I mentioned in my first post), fall into the latter category: low naturally-occuring diversity because of hyper-adaptation. If this is the case, having a few extra alleles hanging around the pool doesn't seem like the worst idea to me in case of catastrophe, plague, etc (but that's just an opinion)! ^_^
.
Thanks again for this response!

4) Checking assumptions



Thanks for writing--I think this is a great point! The whole concept of a "pet trade" or a "dart frog hobby" sits outside of what occurs in nature, and we may have different assumptions about the purpose of that trade or values within it.

The impression I get--and please, anyone feel free to weigh-in, here--is that the dart frog community, as a whole, seems to value these things (not an exhaustive list):
  • Preserving natural 'morphs' (i.e. localized phenotypes specific to populations adapted to a very specific environment) for people in the hobby to enjoy
  • Discouraging wild collection
  • In some cases, insulating descendants of certain populations from being overly outbred as to make individuals available to help restore natural populations should the need arise

If I had to throw an extra value on the pile that I haven't heard mentioned (but I'm sure is important to some people), it would be:
- Keeping populations of dart frogs, in the hobby, healthy and viable



I'm very sorry if I didn't address anyone else's points--this is already a really long reply that's taken me some time to put together.

Is there any sort of "chat" space, here, in which people can talk in real-time? I'm happy to respond here, but I'm always afraid that forum-based interactions are going to regress into a "facebook" state where it's eventually just arguing (yes, a marketplace of ideas is great--I just don't want to feel adversarial).

Thanks again to those who took the time to respond and address my questions/points! It's much appreciated! ^_^

(I'd also be interested to hear how you guys got into the hobby--you sound like a diverse bunch based on your responses!)
One thing I didn't see directly addressed, which may be pertinent to your questions and discussion regarding tracking of lines to minimize excessive bottlenecks within the genetic code, is that many responsible breeders (probably some would argue all responsible breeders, as some people list it as a requirement to be considered responsible as a breeder within the hobby) do track what lines and original imports the parent frogs originated from, and will provide parental/ancestral line information to buyers. This allows people to make informed decisions about how close the breeding lines are between frogs chosen for attempted pairing. Those of us who have reasonable concerns about inbreeding depression can decide to acquire animals of the same locale but from different lines or import dates to maximize captive diversity within the specific locale, without resorting to out crossing between locales.
 

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Those of us who have reasonable concerns about inbreeding depression can decide to acquire animals of the same locale but from different lines or import dates to maximize captive diversity within the specific locale, without resorting to out crossing between locales.
Actually it's usually the opposite. There are many frogs in the hobby we only breed by import year or importer because there can be no way to discern if a frog from a 2011 import from one importer is the same as a 2013 import from another importer. There are other frogs, like understory imports, where we typically don't know what year the animal was brought in.
Outside of tincs I'm having a hard time coming up with frogs we actually do cross lines on. I guess the older lines of terribilis as well. We definitely line breed in this hobby though and in-breeding and out-breeding depression have been talked about at length on this forum. The best you can do in many cases is to get your frogs from multiple sources to have the best chance of diversifying genetics.
 

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While there are flaws in our system. I just don't see that there is a better and practical way to direct the how the general public breeds their dart frogs then the social pressure to keep them as pure as possible. Anything less then that and I'm pretty sure things would be a mess.
 

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I knew that their populations were insular and isolated, and I know that behavioral isolation likely plays a role where reproductive isolation persists even in overlapping populations--that is to say, these morphs don't freely interbreed in the wild--but my curiosity mostly sits on how populations are managed in the captive hobby where the naturally-occuring genetic diversity via mutation is less likely to get represented by differences in fitness among individuals (in other words, the healthier ones aren't necessarily going to get bred over the prettier ones).
There is an enormous amount to unpack here in this thread. I have neither the time nor the skill to address all of this, but this particular snippet stuck out to me. Dart frogs stick fairly close to their phenotype across offspring. There might be slight variations in appearance that would cause someone to choose one individual over another, but there aren't typically broad trends that would cause people to consistently favor one "look" over another. This, to me, is a good reason to preserve the morphs, even though they are sub-species taxa (or, really, non-taxa?). If one starts "hybridizing" (using this term incorrectly, but on purpose :) across morphs/locales, one will invariably introduce the possibility that certain appearances will be selected for non-randomly. That would increase the likelihood that healthy alleles could be reduced in the captive stock we have available due to this cosmetic artificial selection. In animals that already trend toward small populations, this could hasten genetic difficulties.

Also, if the hobby stops frowning on the type of cross-breeding (again, probably the wrong term...) you are talking about, it becomes the wild west in terms of which stock is added to which stock. There won't be any sort of group-wide regulation (or even discussion) about which genetics should be added for the sake of health. It will just be every breeder for themselves. This will not, in my estimation, result in the kind of healthy addition of genetic diversity that you are discussing. It would, however, almost certainly result in loss of "pure" wild-type genetics, which, if I understand correctly, will result in additional pressure to import from the wild stock to start over again. The only situation I can think of where the animals win is where there is a population with known genetic issues like US highland sirensis once were. The injection of European import genetics seems to have made a huge difference in the availability of animals in the hobby. I should point out, though, that these were theoretically the same morph, just different populations.

Good discussion, though. I think it's worth rehashing this periodically, especially with the involvement of people who actually have a background that would help us sort out the technicalities.

Mark
 

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The impression I get--and please, anyone feel free to weigh-in, here--is that the dart frog community, as a whole, seems to value these things (not an exhaustive list):
  • Preserving natural 'morphs' (i.e. localized phenotypes specific to populations adapted to a very specific environment) for people in the hobby to enjoy
  • Discouraging wild collection
  • In some cases, insulating descendants of certain populations from being overly outbred as to make individuals available to help restore natural populations should the need arise
I didn't see anyone else comment on the above, so I will quickly:

  • First point, I think, is correct generally. It is worth adding that the education aspect of these animals also helps raise awareness and support for protecting the wild spaces that these animals live in.
  • Second point - it should be added that wild collection is frowned upon when not done sustainably. There is some conservation breeding that takes place (WIKIRI / TESOROS to name a couple), and of course some animals that are sustainably collected and offered. In many cases, this also helps support local conservation as the local people can now use the animals as an income, helping preserve their natural habitats from destruction. It is worth mentioning these here.
  • I do not think there are any assumptions here that our hobby animals will ever be used to restore wild populations.
 

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  • I do not think there are any assumptions here that our hobby animals will ever be used to restore wild populations.
I'll triple down on this. For the most part, ignorance does not prevail in this hobby. We understand what it takes to use a "captive" population of frogs to reintroduce that species in the wild and it's not coming out of our offices and basements. We have zoos and other conservation groups doing that. Our job is to preserve the frogs in their natural state so we can limit the need for illegal harvesting of wild fauna. And also so we can enjoy these magnificent animals.

...Actually why are we even talking about this? These frogs are perfect. Why would you want to muddy up something so beautiful. Did you want to go draw smiley faces on The Starry Sky? Paint dancing fish on The Great Wave off Kanagawa? We're not here to ruin masterpieces.
 

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I agree with everything you say but I do want to add that the core of our hobby, which is keeping and breeding animals in captivity for our personal pleasure (not just hybridizing) is eaqualy to playing god when you look at it that way.
I recon that is how you look at it. Dunno if god actually has pleasure watching us right now. ;)
 
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