Noah's modern ark: The role of ART in conserving endangered species
Berlin, Germany: Killer whales, giant pandas, cheetahs and black-footed ferrets are just some of the endangered species that are benefiting from advances in reproductive technology, the 20th annual conference of the European Society of Human Reproduction and Embryology will hear tomorrow (Monday 28 June).
But, whereas in humans the focus of assisted reproductive technology (ART) is on producing a baby, amongst wildlife conservationists the focus is on the much more basic aim of simply understanding the fundamentals of reproduction in different species.
In an invited lecture, Dr David Wildt, a world leader in animal reproductive biology, will tell the conference that it is vital to wildlife conservation that specialists from a wide variety of disciplines work together.
"The most valuable contribution of reproductive science and ART to conserving endangered animals is the powerful ability to help us understand fundamental reproductive mechanisms in a variety of species," says Dr Wildt, head of the Department of Reproductive Sciences at the Smithsonian's National Zoological Park and its Conservation and Research Center, US. "However, genuine conservation is achieved only when the reproductive knowledge and technologies are integrated with other disciplines in multi-dimensional management programmes. Conservation is like an enormous jigsaw puzzle with lots of pieces. ART is only one piece, so with ART alone one could hardly complete the puzzle and contribute to conservation. What makes our field so different (and fun) is the need to work with other disciplines. For example, in our studies of giant pandas, we work closely with veterinarians, behaviourists, nutritionists, pathologists, population biologists and geneticists, and that is only on the captive side. In the wild, we integrate our work with experts in ecology, landscape management, geographical information systems and even environmental education."
Dr Wildt and his colleagues use a variety of human ART techniques in their work, ranging from artificial insemination (AI) and IVF to freezing sperm, eggs and embryos; but the challenges are very different.
"Although we have benefited greatly from those scientists who study ART in humans and domestic or laboratory animals, we face different problems and it is clear that the high tech components of the reproductive sciences are not a quick fix for enhanced reproduction in endangered species.
"First, we are working with species that are often dangerous, if not homicidal, and essentially nothing is known about their basic biology. So we often use ART for simply understanding the reproductive fundamentals of a given animal: how long is the reproductive cycle, how many sperm are produced, how do you keep sperm alive in the laboratory, etc.
"Secondly, while human technologies allow us a baseline from where to start our studies, every species is different. What might work in a human, probably might not work in a cheetah or giant panda. Even within families of species, there is huge variation. There are 37 species of cats and they all differ physiologically! So without the knowledge generated using ART tools we'll never be able to manage and conserve these species better.
"Thirdly, there is the point about genetic management. Our goal is not simply to produce an offspring, but rather, genetically valuable offspring. We are trying to avoid inbreeding depression that occurs commonly in captivity and, increasingly, in the wild. ART has huge implications for avoiding the loss of genetic diversity, by moving eggs and sperm between institutions or for breeding animals that fail to mate naturally."
The need to maintain adequate genetic diversity is why cloning is of little or no use in conserving endangered species, says Dr Wildt. At best it might be possible to use it to save a species that is near, or recently extinct, but at worst it can distract people's attention from the need to preserve habitats. "After all, why bother saving wild places and wildlife if reproductive specialists can avoid extinctions through last-ditch heroics via technology?"
ART has played a key role in maintaining genetic diversity amongst captive populations. For instance, it is much easier to transport eggs or sperm from one institution to another, than to transport a killer whale or elephant. In addition, there are animals such as the giant panda who simply do not feel any sexual attraction to the mate chosen for them and refuse to oblige scientists by going through the motions. ART solves this problem neatly.
One of Dr Wildt's successes has been the giant panda programme that he has been leading, which involves five Chinese breeding facilities, four North American zoos and more than 65 scientists, representing seven disciplines, on the two continents. Pandas are notoriously poor breeders in captivity, with only a three-day period of fertility a year. Baby pandas have been born after AI using cooled as well as thawed sperm, and from males with terminal disease. The successful multi-dimensional management programme shows the way for the future in ART.
"We have a 10-year plan in place to produce lots of baby pandas that can contribute to a successful, self-sustaining captive population that in the future will allow successful reintroduction to the wild. The goal is something that we call metapopulation management – linking zoos to nature. In this case, I could see ART being used to collect sperm from wild giant pandas to help infuse new genes into the captive population, which is producing so many offspring now that reintroduction will be possible. All of this will be connected to extensive training programmes, creating the next generation of scientists who understand the importance of this multi-disciplinary approach."
ART has been used to understand and help many other species. "We have used ART to understand the reproductive biology of cheetahs, and have learned, for example, that they produce more than 70% abnormally shaped sperm per ejaculate. Killer whales can be trained to provide daily urine samples, which can be tested for hormone fluctuations and reproductive activity. Then AI can be performed using sperm deposited by a combination of endoscopy and ultrasonography. In the case of the black-footed ferret, which used to range across America's Great Plains and which was reduced to only 18 individuals, we have used AI to produce offspring that have been used for reintroduction of this species back into nature."
In conclusion, Dr Wildt says that ART has played a vital role in conserving endangered species, but not necessarily in the way that was expected 30 years ago at the dawn of the technology. "In the late 1970s everyone believed that ART would be the salvation for zoos, that all animals would be produced in mass numbers by AI or embryo transfer. But then we learned the importance of the uniqueness of different species. So, I firmly believe that ART has provided us with a set of tools to understand how all these species are wonderfully bio-complex and different. In addition, there are the examples of where we have got it right – giant pandas, black-footed ferrets and cheetahs – where we now know enough so that we can begin to help conservationists to genetically manage rare populations."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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