Wild Rock Dove - a species for zoo preservation?

I just read an interesting article:
https://www.cell.com/iscience/fullt...m/retrieve/pii/S2589004222008926?showall=true

My take out are:
- Wild Rock Dove in Europe is becoming genetically extinct by hybridization with its domesticated descendants - domestic pigeons, especially lost carrier pigeons. The situation is similar to extinction of Wildcats by hybridization with domestic cats.
- In Britain, only the Rock Dove population in outer Hebrides is relatively unmixed.
- Similar hybridization occurs elsewhere in Europe, including Faroes and Sardinia.
- Many 'wild Rock Doves' in aviculture and zoos are domestics, too.

I thought it makes sense for zoos to start regular breeding of wild Rock Doves.
There are advantages:
- It breeds easily in human care and some (it turns not pure) are already kept in zoos. It is also suitable even for small zoos and nature parks.
- Wild birds live in Europe, so no import restrictions.
- It is a good education animal, including nature of Europe, Anthropocene, domestication etc.

Any thoughts?

 

It’s a good idea but I’m not sure how successful it would be in terms of reintroductions. How do you ensure that bred and released individuals don’t immediately hybridise with feral pigeons? How does a captive population ensure future survival of the species if any attempts to release them would likely result in hybridisation with feral birds.

I think for this to have any real success as a conservation project, you’d almost have to perform feral pigeon genocide across much of the globe (which is essentially impossible). And given how rapidly feral pigeons breed and how adaptable they are, it really would have to be a complete wipe out as even small remaining population would quickly end up in widespread distribution of feral pigeons again.

tbh, the wild rock dove is probably doomed in the long term, simply because maintaining genetic purity is almost impossible. The distribution of feral pigeons is simply too far gone. I suspect many ‘wild’ rock dove populations have actually got high levels of inbreeding with feral pigeons upon further inspection. And so the true number of pure wild rock doves is likely a lot fewer than estimated.

 

And this species would barely be interesting for most visitors, as it looks like a very common feral pigeon.
The public could even consider the conservation of the rock pigeon as a real joke.

 

At this point its questionable whether any wild population of a species with domestic descendants is truly completely free of any hybridization. Even Przwalski's Horse with different chromosome counts then domestic horses probably had some degree of admixture with them since ancient times. I personally don't see why conservationists get so hung up with "pure wild" forms; if the species displays a wild phenotype and can survive in the wild to fill its ecological niche, its to me a wild animal despite what some decimal percentage of DNA says.

 

Because if a species has hybridised, then been bred into the population, it’s a hybrid population not the original species? The point of conservation is to preserve a species by preserving their genetic diversity, if a species has the DNA of another species within it, then it’s not the original species you’re preserving and the diversity of that species has been reduced because some of their makeup is that of another species.

And it seems odd to consider the phenotype of an animal as the benchmark of how it is conserved? If a zoo bred some Przewalski’s wild horse mares with a domestic horse, and one goal looked like a Przewalski whilst the other had a different coat colour. Is one of more value than the other?

At the end of the day, conserving a species means conserving their genetic diversity. There’s a reason species are often not evaluated on their conservation status simply by population alone. If you have 20 unrelated animals, it’s much better than 50 closely related animals. There’s 2 Northern White Rhinos left but the sperm and eggs of several individuals - boosting their chances of conservation.

Przewalski’s horses were severely bottlenecked in captivity until a single wild-caught female was reintroduced and likely saved the species from extinction. So Genetics are extremely important in conservation, and the addition of DNA from other species of domestically bred genes do not benefit the species population.

 

By most metrics, domestics are the same species as their wild counterparts, and let's be real, hybridisation has happened since ancient times. Heck, even two purely wild species that are related hybridize without the influence of humans more than we think.
In some situations, like the African Wild Ass, I can see trying to preserve the wild population because its so small and has a phenotype that is unique (even though its likely even these populations have mixture in them somewhere down the line). But in animals with both large and widespread wild and domestic populations; pigeons, ducks, boar, cats, wolves etc, let's stop determining a species conservation value by some arbitrary test that determines a difference in a fraction of a percent of DNA. More often than not the "wild" phenotype of that species is the only phenotype thats will persist in wild habitats, so if a "hybrid" individual looks, acts and fills the ecological niche exactly as the supposedly "pure" individual, why devalue it and deem it unworthy of the same coservation as the latter?

 

Presumably because an animal that is not genetically pure and contains domestic or hybridised DNA will not have the same genetic fitness to survive in its environment as a genetically pure animal which has evolved to perfectly fulfill its ecological niche. Less fitness = less conservation value to the survival of its ‘species’ (and I put species in parentheses here because we’re talking about hybrids). Remember also, domestics are significantly more inbred than their wild counterparts simply by the nature of what a domestic breed is - selective inbreeding of genetically similar individuals for desired traits. So wolves with stray dog DNA or Przewalski’s horses with domestic hire DNA or Scottish Wildcats with domestic cat DNA are simply not going to have the same genetic fitness to deal with environmental stochasticity as pure individuals whose genetic makeup is 100% adapted to thrive in its environment. A wolf with dog DNA may not be as adapted to surviving cold weather, or even mixed subspecies in zoos where one subspecies may be adapted to warm climates and the other cold (if you released these hybrids, where would you release them? Alaska? Mexico?). They may also be more predisposed to cancers and other conditions due to their part domestic makeup. Releasing them into the wild could add these undesired genes into the population. Not to mention an animal that phenotypically looks the same won’t necessarily produce offspring which are, simply by how genetics work. So you release said individual, then it has offspring which look vastly more like the domestic phenotype and you could quickly erase the phenotypic makeup of the population (which in this case you are saying is more important than the genetic makeup).

I’d lastly like to also mention the that yes, there are hybridisations of separate species in the wild. But they clearly aren’t selected for - either because offspring are non-viable, can’t reproduce or are simply outcompeted by the pure populations of the two species they were bred from. Hence the less fitness point when it comes to hybridisation.

 

Could also just, have them in a breeding set-up behind the scenes, no?

Also wouldn't it be a phenomenal species for education about why its such important to have this population of genetic backup because of the whole issue the pigeons come with?

 

I'd like to see proof of domestic hybridization actually effecting fitness of a wild population? Not just so-called pollution of pure individuals, but actually leading to less likelihood of survival in the wild? The hybrids would anyways be extremely unlikely to survive and mate if they were truly less fit, making the whole idea of genetic pollution a moot point. If anything, a little domestic flow may be a good thing as it may help these animals survive around human-changed environments. Feral/wild boar mixes are extremely successful, more so than either of their parents for example. Wildcat hybrids are far outcompeting purebred Scottish Wildcats in Britain and are better suited for the new environment, which won't be going away as long as us humans are alive.
Meanwhile, the effects of inbreeding are really only disastrous if it is generational. A domestic/wild hybrid individual will not be much 'inbred' anymore, and any deleterous effects will be culled out as the individual and its descendants mate into the genetically diverse wild population.

 

Your opinion is, fortunately, fringe.

First, is not true that wild-domesticated hybrids survive better than wild animals. Feral animals thrive in places without wild species (like feral pigs in the Florida where no wild boar exist and most predators were wiped out). Elsewhere, replacement of wild species by ferals is result of genetic swamping by large number of escapees. It is long known that birds of prey preferably attack domestic pigeons than wild ones, but there is simply too many domestic escapes.

Then, humanity wants to protect biodiversity for itself and for its possible future uses as yet unknown. So whether an animal currently survives well in the wild is not relevant. For example, big effort is made to preserve rare domestic races of pigeons and other animals, even if they neither survive in the wild nor are currently useful.

28 collections in EAZA keep Rock Doves, and 100s keep some races of domestic pigeons. So yes, pigeons are interesting.

BTW, my personal opinion is that tamed wild Rock Doves would be good education / presentation animals. Domestic pigeons are common, and for most visitors interaction with an animal matters more than the animal is colorful or not.

 

So domestic pigeons are preferred prey for predators, how does that prove that some degree of hybridization will doom the species? If anything it just shows that any of the potential deleterous effects of domestication will be weeded out. Also, there are many studies that show that most Eurasian animals with domestic counterparts do have a degree of gene flow between the two other thousands of years.
My point is at what point do we consider an animal no longer pure? And frankly in the case of Rock Pigeons or any other animal in a similar situation, who are you or any other person to say that the populations who've survived thousands of years perfectly fine with some degree of admixture are less valuable than supposedly "pure" forms that are essentially exactly the same as those mixed forms save for some arbitrary genetic taxonomic study, something even experts don't agree on?
Mind you, I'm not against preserving rock pigeons who are supposedly pure. I just don't think we can determine that they are the "ideal" wild pigeon and the rest of the populations that have been doing just as well with admixture are nothing but hybrid bastards who's long term fate is to be victims of genocidal culls in favor of the populations some humans decide is better. If my opinion is fringe, I'm glad it is.

 

Luckily for Rock Doves, it is easy to determine how pure are the birds, and which populations are least mixed, using genetic testing.

The article, on figure 2 additionally has some cues how wild Rock Doves differ from wild-type feral pigeons. I compared them with diverse photos of zoo 'rock doves' at Zootierliste. Caveat: it is not written where these photos were taken. But it looks that most zoo 'Rock Doves' really have visual marks of feral pigeons.

https://www.cell.com/iscience/fulltext/S2589-0042(22)00892-6?_returnURL=https://linkinghub.elsevier.com/retrieve/pii/S2589004222008926?showall=true

 

It is not, but from past experience you probably don’t want me on your side of the discussion. ;-)