Diversity in Collections, US vs. Europe

[Coelacanth18]

After reading many RCPs and looking at the growth/decline of different species over time, it seems like the AZA TAGs are in a process of trying to standardize collections as best they can. Species that are rare in captivity/inbred/unwanted/take up valuable space/have no outside founders, the AZA tries to phase out and replace with "target" species with more institutional support. It seems like the number of phase-out species shrinks every year, and while the collections will never be completely standardized (i.e. there will always be phase-outs or collections that go against the grain), there does seem to be a general trend towards fewer species with long-term sustainable populations.

My question is whether Europe and the EAZA are attempting a similar process. Zootierliste has an incredibly vast number of species listed as being held currently, hundreds in very small numbers. I didn't know if that was because of 1) there being far more zoos and 2) because of many non-EAZA zoos being listed on Zootierliste; or, if Europe was utilizing a different collection strategy than the AZA, and is more encouraging of collection diversity.

Also I know that collection standardization/TAG recommendations have created some controversy on this site before. Feel free to post opinions regarding that, as I love to hear the different sides of that debate. However, do try to be respectful and thoughtful when doing so

 

[gerenuk]

Its not about standardizing animal collections in zoos. Its about making captive animal populations sustainable. Over several decades, species in zoos have consistently gone through boom and bust cycles. When the species becomes popular again, zoos sourced new animals from the wild or zoos in other regions. Genetic diversity is also lost when these boom & bust cycles persist in captivity. At some point, captive animal populations may no longer be sourced from outside the zoos' regions. This is why sustainability is being pushed.

 

[Nikola Chavkosk]

It seems that EAZA are also working on that, look this manual who explain how the populations should be managed, it's from 2012.

There are several categories, including animals (species) do not obtain because of small founder populations, but they are not specifilly listed for wich species.

Or there are severeal management level, including the most intense breeding programme EEP, then less intensive ESB (European studbook), then Monitoring level, etc.

There is also explanation how one non-EAZA zoo could obtain some EEP animals, mostly like place for holding surplus males that will be needed in near future for breeding purpose, obtaining them on loan basis. Animals like male chimpanzees, tigers (Siberian, hybrids), leopards (Persian, hybrids, North Chinese), orangutans (males, Bornean, hybrids), mandrills (males, famillies), giraffes, hybrid animals, can easily be obtained from EAZA zoos, if you prove that you have a capacity to care for them.

http://www.eaza.net/assets/Uploads/...nt-Manual-V1.05-Council-approved-20131401.pdf


Otherwise, this is what species are managed more intensively (EEP & ESB programes):

http://www.eaza.net/assets/Uploads/CCC/Overview-EAZA-Breeding-Programmes-February-2016-website.pdf

 

[Coelacanth18]

@gerenuk: I agree with you, and that makes sense. It seems that the practices in place beforehand were never actually sustainable, and that is why they emphasize creating sustainable, long-term viable populations. However, it seems like this also decreases the number of actual species that institutions keep, since there are limited spaces and those spaces need to be divided in a way that gives the target species enough room to be sustainable.

@Nikola: Thanks for the links. I figured they had a similar process. I think the part about allowing non-EAZA zoos to take surplus EEP animals is very interesting and resourceful. I'm not sure to what extent that happens with SSP animals within the AZA, but it generally seems that movement between AZA and non-AZA zoos is minimal for SSP animals. Much more common for PMPs and DERPs, however.

If anyone knows more information about the movement of SSP animals to non-AZA facilities, please correct me.

 

[Carl Jones]

Its not about standardizing animal collections in zoos. Its about making captive animal populations sustainable. Over several decades, species in zoos have consistently gone through boom and bust cycles. When the species becomes popular again, zoos sourced new animals from the wild or zoos in other regions. Genetic diversity is also lost when these boom & bust cycles persist in captivity. At some point, captive animal populations may no longer be sourced from outside the zoos' regions. This is why sustainability is being pushed.

Good points, and this is why we need to domesticate all the commonly kept zoo animals.

Are there any good studies of these boom and bust cycles in zoos?

 

[MRJ]

My question is whether Europe and the EAZA are attempting a similar process.

Speaking from Australia there is very much an attempt to manage viable populations in the major Australian zoos. The small number of zoos with exotics (although the number has grown in recent years) = a small number of places compared with Europe and the US.

This is compounded by the expense of importation and the very time consuming and expensive requirements of Australian laws designed to protect against agricultural disease and invasive species. The latter two in fact make the importation of some taxa impossible.

All this results in the lack of diversity in exotic fauna in Australian zoos, which is often complained about on the Australian forums!

Most managed programs for exotics in Australia are there to sustain viable populations while the majority of managed programs for Australian natives are for conservation.

 

[Carl Jones]

Most managed programs for exotics in Australia are there to sustain viable populations while the majority of managed programs for Australian natives are for conservation.

This is a global trend with zoos concentrating on working with native species, while using exotics for display and education. In maintaining self-sustaining captive populations of exotics we are essentrially domesticating them.

 

[MRJ]

In maintaining self-sustaining captive populations of exotics we are essentrially domesticating them.

I am not sure what you are saying here. If you are implying that several generations in captivity render animals unsuitable for release or involvement in conservation programs I would beg to disagree.

To be sure I would agree that multiple generations of captivity would tend to see the survival primarily of animals most suited to captive conditions.

However with proper genetic management these changes must be extremely slow. For instance recent research on the Tasmanian devil insurance population found no discernible physiological difference with the wild population.

It is also my belief that even when seemingly extreme physiological and behavioural changes have taken place they still carry the genetic material of their wilder ancestors and under the pressures of natural selection can quickly revert to a "wild type". This is commonly seen in feral populations. Look for instance at the feral populations of cats in outback Australia, several generations removed from their domestic ancestors. Their similarity to the domestic cat's wild ancestor, the African wild cat, is remarkable. They certainly look or act nothing like the domestic moggies from which they descend. Another example is the feral Indian ringneck parrot populations that infect your country. There must be a reasonable number of yellow, blue and white birds that escaped and helped establish the wild population yet all I ever see around London are wild type green birds. There are other examples I could quote.

I am not arguing against the concept that reintroductions, if that is your aim, may be most successfully performed with animals as close to f1 as possible. But I think it short-sighted to dismiss zoo populations as "domesticated".

 

[Chlidonias]

I am not sure what you are saying here. If you are implying that several generations in captivity render animals unsuitable for release or involvement in conservation programs I would beg to disagree.

this is Carl Jones' thread about it: http://www.zoochat.com/2/should-we-domesticate-most-popular-zoo-442220/

 

[Carl Jones]

I am not sure what you are saying here. If you are implying that several generations in captivity render animals unsuitable for release or involvement in conservation programs I would beg to disagree.

To be sure I would agree that multiple generations of captivity would tend to see the survival primarily of animals most suited to captive conditions.

However with proper genetic management these changes must be extremely slow. For instance recent research on the Tasmanian devil insurance population found no discernible physiological difference with the wild population.

It is also my belief that even when seemingly extreme physiological and behavioural changes have taken place they still carry the genetic material of their wilder ancestors and under the pressures of natural selection can quickly revert to a "wild type". This is commonly seen in feral populations. Look for instance at the feral populations of cats in outback Australia, several generations removed from their domestic ancestors. Their similarity to the domestic cat's wild ancestor, the African wild cat, is remarkable. They certainly look or act nothing like the domestic moggies from which they descend. Another example is the feral Indian ringneck parrot populations that infect your country. There must be a reasonable number of yellow, blue and white birds that escaped and helped establish the wild population yet all I ever see around London are wild type green birds. There are other examples I could quote.

I am not arguing against the concept that reintroductions, if that is your aim, may be most successfully performed with animals as close to f1 as possible. But I think it short-sighted to dismiss zoo populations as "domesticated".

You have raised some good points. The rate of domestication varies between species although there is increasing evidence that it can start occurring in just one generation.

People always quote the case of the feral cat and this is not a good example since they have been selected for their hunting abilities and throughout their domestication have been kept as free-living animals, not in cages. Even so feral cats have smaller brains than African wild cats and are very different in temperament, even if they show similar pelage patterns.

I very much doubt if any colour variations of ring-necked parakeets have contributed to the current feral populations. Most of the copntributors will have spent very few generationsin captivity. Birds deviating from the wild type are rapidly selected against and contribute little if anything to the makeup of the population.

I am not dismissing zoo populations as domesticated but rather we should be domesticating those that we do not intend to use for reintroductions. Those species that we are using for reintroductions need to be managed differently from the general zoo population.

 

[Giant Panda]

It is also my belief that even when seemingly extreme physiological and behavioural changes have taken place they still carry the genetic material of their wilder ancestors and under the pressures of natural selection can quickly revert to a "wild type".

That isn't necessarily the case. Zoo populations are typically less genetically diverse than wild ones. That extra diversity isn't locked away somewhere for safekeeping, it's gone. True, it could "re-evolve" in wild populations, but that process is neither fast nor assured. In the short- to medium-term, natural selection can only work with what it's got, so lower diversity reduces its efficacy. That's particularly important in this era of global change, when "evolutionary rescue" may (may) contribute to the survival of some species.

 

[Pertinax]

Another example is the feral Indian ringneck parrot populations that infect your country. There must be a reasonable number of yellow, blue and white birds that escaped and helped establish the wild population yet all I ever see around London are wild type green birds. d

I believe the feral populaton of Ringnecks in S.E. England was already becoming established before any of the colour morphs became readily available, so they were still rare and valuable and thus less likely to have been allowed to escape. And presumably with green being the dominant colour any individual escaped 'sports' which did breed in the feral state- with green partners- wouldn't pass on their colour anyway.

 

[Carl Jones]

That isn't necessarily the case. Zoo populations are typically less genetically diverse than wild ones. That extra diversity isn't locked away somewhere for safekeeping, it's gone. True, it could "re-evolve" in wild populations, but that process is neither fast nor assured. In the short- to medium-term, natural selection can only work with what it's got, so lower diversity reduces its efficacy. That's particularly important in this era of global change, when "evolutionary rescue" may (may) contribute to the survival of some species.

Well put. Breeding species in captivity as Ark populations is severely limited.

 

[Mr. Zootycoon]

That isn't necessarily the case. Zoo populations are typically less genetically diverse than wild ones. That extra diversity isn't locked away somewhere for safekeeping, it's gone. True, it could "re-evolve" in wild populations, but that process is neither fast nor assured. In the short- to medium-term, natural selection can only work with what it's got, so lower diversity reduces its efficacy. That's particularly important in this era of global change, when "evolutionary rescue" may (may) contribute to the survival of some species.

The wild population isn't necassarily genetically more diverse than the
captive population. Zoo populations are usually less diverse as many species
have relatively small founder populations. 'Nature can only work with what
it's got' is nonsense: mutations, epigenetics, horizontal gene transfer
and behavioural adaptations can help a species to adapt to the wild again.
without the need to completely re-evolve.

Of course, a reintroduction of a completely captive held population
will propably take more than one generation.

 

[Giant Panda]

The wild population isn't necassarily genetically more diverse than the
captive population. Zoo populations are usually less diverse as many species
have relatively small founder populations.

These two sentences pretty much directly contradict each other, yet somehow neither manages to contradict what I wrote. Your second sentence was rather my point. As to your first: "Zoo populations are typically less genetically diverse than wild ones [emphasis added]". Nowhere did I claim this was absolute.

'Nature can only work with what
it's got' is nonsense: mutations, epigenetics, horizontal gene transfer
and behavioural adaptations can help a species to adapt to the wild again.
without the need to completely re-evolve.

Please don't misquote me. Your alteration of "natural selection" to "nature" completely changes the meaning of what I wrote. Anyway, both "mutations" and "behavioural adaptations" describe evolutionary processes, hence both are in fact examples of species "need[ing] to completely re-evolve." Semantics aside, however, my response to each of your examples:

*Mutations: parallel mutations were primarily what I referred to when I wrote that diversity "could 're-evolve' in wild populations", part of my post you chose to ignore. The problem with this is that rather than relying on the rate of selection (which can act very quickly), you're relying on mutation rate (which is stochastic and often slow) and escaping the influence of drift (also stochastic, also slow). Hence, maintaining standing variation is vastly preferable to waiting for mutations to re-accumulate. To again quote myself: "that process is neither fast nor assured."

*Epigenetics: I'm not an epigeneticist, but this is fairly irrelevant to the importance of total diversity loss. It may help if you could give an example relating to the "domestication syndrome" outlined by Carl Jones?

*Horizontal gene transfer: What a bizarre suggestion. You are aware we're almost exclusively discussing vertebrates?

*Behavioural adaptations: Adaptations must have evolved and, again, this requires genetic diversity, just as any morphological adaptation would. Assuming you're referring to learnt behaviours, however, these would not overcome most of the "evolved" issues under discussion. Aside from that, species differ vastly in their degree of behavioural plasticity.

 

[Carl Jones]

The evidence is that zoo populations usually become genetically impoverished. There are several reasons for this, and this genetic loss, or modification, can compromise their survival when re-introduced. This whole idea that any genetic changes that occur in captivity can be reversed when the species is released, is not strongly supported. Long established captive populations can survive in the wild if re-introduced, but are likely to be less fit than their wild counterparts.

If we are breeding species in captivity for several generations and wish to use these animals for reintroduction then we need to develop the techniques and management strategies to minimise genetic change in captivity.

 

[Nikola Chavkosk]

The evidence is that zoo populations usually become genetically impoverished. There are several reasons for this and this genetic loss, or modification, can compromise their survival when re-introduced. This whole idea that any genetic changes that occur in captivity can be reversed when the species is released is not strongly supported. Long established captive populations can survive in the wild if re-introduced but are likely to be less fit than their wild counterparts.

If we are breeding species in captivity for several generations and wish to use these animals for reintroduction then we need to develop the techniques and management strategies to minimise genetic change in captivity.

That's very disapointing Carl.
But there are some exceptions, like for Siberian tigers, in wich case the captive Siberian tigers are geneticaly more diverse than remaining wild ones, because in the past Siberian tigers were catch from all regions in their areal, but with time, some genetic lines went extinct in the wild, but their related cousins remained in captivity. I read this from one research, if you want I will give you a link.

Thus it is vital to occur some periodic wild importations to captive populations, but given the present trend and regulations, that highly unlikely.

And I must mention the example with the cheetahs. It is said that they are not very geneticaly diverse, but still their population in captivity and in South Africa thrives.

 

[Giant Panda]

And I must mention the example with the cheetahs. It is said that they are not very geneticaly diverse, but still their population in captivity and in South Africa thrives.

Captive cheetah populations emphatically do not thrive. Only 20% of the North American population has bred, primarily in off-display breeding centres. They're also associated with a suite of physiological stress indicators, although recent work suggested the poor breeding record is due to lower sperm output in on-display animals, rather than chronic stress.

 

[Nikola Chavkosk]

Captive cheetah populations emphatically do not thrive. Only 20% of the North American population has bred, primarily in off-display breeding centres. They're also associated with a suite of physiological stress indicators, although recent work suggested the poor breeding record is due to lower sperm output in on-display animals, rather than chronic stress.

Thank you,

Also read that for successfull breeding of cheetahs in captivity, it is needed to provide social groupings as in the wild, with solitary female (except female with youngs), and several-male group who visits the female teritory, and bigger enclosures. I think many zoos keep male and female cheetahs together, or maybe such zoos are not many? I don't know.

 

[Batto]

The decrease of species and subspecies (of mammals and some birds) displayed in zoos worldwide is more or less a result of a change of public attitude regarding conservation and animal rights as well as the introduction of CITES in 1973 and thus the consequent unavoidable change of animal acquisition for most modern zoos. We do and will most certainly continue to see a further decrease of species diversity at European zoos due to changing national and international regulations as well as the unavoidable dying off of the last remaining specimens of certain species in captivity, may they be endangered or not.

However, I'd like to point out that in other parts of zoo husbandry, mainly regarding invertebrates, fish, amphibians and reptiles (and to a certain extent, birds), we've seen a rise of hitherto unfamiliar species displayed, thanks to a very productive (though not always legal...) private husbandry and commercial sector, from which zoos obtain specimens. Just a couple of years ago, no one would have thought of zoos displaying Emerald cockroach wasps, Australian spotted jellyfish, Kaiser's spotted newts (now even part of international zoo breeding projects) or Mangshan pitvipers [some of you will probably have to google these names just to know what I'm talking about ^^]. And this is only the tip of the iceberg when it comes to the diversity of invertebrate, fish etc. species kept and increasingly bred in private husbandries. Unfortunately, a number of zoos fail to keep these species as well as serious private keepers do, leading to significant animal suffering and losses. This can be (at least partly) also contributed to the different requirements of public vs. private animal husbandry-and the significance these species still have in comparison to the popular mammalian megafauna (pmm).

So while we can expect to see a decrease of species and subspecies of the pmm in both American and European zoos, I dare to predict that we will nevertheless continue to see "new" species of said "lesser animals" pop up on display in both, if only as fill-ins for larger exhibit complexes for the fewer megafauna representatives (i.e. a tank for [hopefully CB] Lygodactylus williamsi in the indoor visitor area of an African bush elephant complex, tanks for bullet ants at "Amazonian rainforest" greenhouses, etc. etc.).