Showing posts with label pets & animals. Show all posts
Showing posts with label pets & animals. Show all posts

Near Certain Extinction for the Northern White Rhino May Yet be Thwarted

Only two female northern white rhinos remain in the world, but owing to assisted reproductive technology and a little help from their southern relatives, the species might soon make a comeback.


Northern White Rhino
Photo by Karimi Ngore, CC BY-SA 4.0, via Wikimedia Commons
By Dr Daryl Holland, University of Melbourne - October 01, 2021
This article was first published on Pursuit
Read the original article

When Sudan, the last surviving male northern white rhino in the world, died in Kenya in March 2018, the species was as good as extinct. The two remaining female northern white rhinos, who are infertile, were doomed to live out their lives as the last of their kind.

Except maybe they won’t be the last.

Science has stepped in with a possible lifeline for the northern white rhino (NWR) and other critically endangered large mammals, according to new research published in Nature Communications.

An international team of researchers using assisted reproductive technologies (ART) has combined eggs from the southern white rhino (SWR) with the cryopreserved sperm of a northern white rhino to create viable embryos and embryonic stem cells.

There are five steps needed to get to the stage where we see a live birth of a hybrid northern-southern white rhino, and Professor Marilyn Renfree, from the School of BioSciences at the University of Melbourne, who was part of the team that developed the embryos, says the first step - harvesting eggs and sperm - was one of the most challenging.

Based on the lack of males, sperm would seem to be a major stumbling block, but forward-thinking researchers had already collected and stored sperm from four northern white rhinos.

“Over the past few years, the sperm from three bulls was sampled and put in cryopreservation. Samples were also taken from Sudan after his death and frozen,” says Professor Renfree.

It was the eggs that were more difficult to collect. Professor Renfree says the key to the project was new technology developed by Professor Thomas Hildebrandt, who’s based at the Leibniz-Institut in Berlin, that for the first time allowed collection of eggs from the ovaries of rhinoceroses.

“He designed an ovum pick-up (OPU) device. This has never been done before with such a large animal,” Professor Renfree says.



The next step in the process was bringing the eggs to maturity, which was done under laboratory conditions, in much the same way as the eggs of many other species, including humans.


“Rhinos are very large (2,000 kg on average), so they have a reproductive tract that is very hard to access. Professor Hildebrandt developed a 150 centimetre-long OPU device to guide the needle to the correct place using a trans-rectal route.”

“They showed that oocytes can be repeatedly recovered from live females by this trans-rectal ovum pick-up, matured, fertilised by intracytoplasmic sperm injection (ICSI) and, for the first time, developed to the blastocyst stage in vitro.”

The device developed by Professor Hildebrandt, who is also an Honorary Professor at the University of Melbourne and lead author of the paper, is currently awaiting patent approval and could also be used to collect eggs from other large mammals.

The southern white rhinoceros is a subspecies of the white rhino and its population is currently rated as ‘near threatened’ by the IUCN Red List of Threatened Species, with about 21,000 individuals remaining.

It is also resident in several zoos around the world. Professor Hildebrandt and his team were able to collect viable eggs from both southern and from the remaining two female northern white rhinos.

The next step in the process was bringing the eggs to maturity, which was done under laboratory conditions, in much the same way as the eggs of many other species, including humans.

Step three is the in vitro fertilisation of the egg with the sperm. Understandably, given the lack of living subjects, the northern white rhino sperm were not the highest quality.

“The northern white rhino sperm, when they were thawed out, were not very good and had to be activated by an electrical stimulus,” says Professor Renfree.

Once fertilisation occurred, forming a zygote, the team stimulated the growth of the zygote for between seven and twelve days, to the developmental stage called a blastocyst – at which point it is ready to be implanted in the uterus.



Now that Professor Hildebrandt and his team have perfected the technique for egg retrieval from rhinos, they have started work to produce a pure northern white rhino embryo.


“The SWR and SWR x NWR hybrid embryos created by the team led by Professor Cesare Galli, who’s the senior author from the Italian reproductive laboratory Avantea, were very high quality and the stem cells created from two of them expressed all of the genes you’d expect them to express,” says Professor Renfree.

Two of the blastocysts have now been cryopreserved and these frozen embryos could soon be implanted into a southern white rhino surrogate to produce a baby hybrid rhino; preserving at least some of the unique genetics of its northern cousin.

Professor Renfree says the stem cells could hold the key to the survival of the rhinos, and other endangered species.

“The embryonic stem cells which are viable are potential candidates to create artificial gametes, both eggs and sperm, using a technique now being developed in mice.”

“If we could create a protocol for creating rhino gametes from stem cells, this is the most promising way forward.”

Now that Professor Hildebrandt and his team have perfected the technique for egg retrieval from rhinos, they have started work to produce a pure northern white rhino embryo.

“The team is going to harvest additional oocytes (immature eggs) from the last two female northern white rhinos who are currently in Kenya,” she says.

“They are infertile and never produced offspring, but they do have oocytes and these could be grown up in culture.”

She says this research also has the potential to help other large mammal species.

“This is a proof of concept project. These techniques have the potential to help the other endangered rhino species, including the Sumatran rhino and the Indian rhino and and other large mammals such as the Gaur, a large Asian cow that is also at risk of extinction.”




This article is republished from Pursuit under a Creative Commons Attribution-No Derivatives 3.0 Australia (CC BY-ND 3.0 AU) license/Title and subtitle have been reworded.
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BOOK REVIEW — “Wild Souls: Freedom and Flourishing in the Non-Human World,” by Emma Marris

Emma Marris' "Wild Souls" delves into the value of individual animals and species, as well as humanity's responsibilities to them.











AUGUST 27, 2021 by RACHEL NUWER

I WAS ONCE challenged by a friend to explain why it matters if species go extinct. Flustered, I launched into a rambling monologue about the intrinsic value of life and the importance of biodiversity for creating functioning ecosystems that ultimately prop up human economies. I don’t remember what my friend said; he certainly didn’t declare himself a born-again conservationist on the spot. But I do remember feeling frustrated that, in my inability to articulate a specific reason, I had somehow let down not only myself, but the entire planet.

The conversation would have gone very differently had I already read environmental journalist Emma Marris’s “Wild Souls: Freedom and Flourishing in the Non-Human World,” a razor-sharp exploration of the worth of wild animals and the species they belong to, and the responsibility we have toward them. “I wanted to know whether the massive human impact on Earth changes our obligation to animals,” Marris writes. “Our emotions about animals have always been strong, but are our intuitions about how — and whether — to interact with them still correct?”

“Wild Souls: Freedom and Flourishing in the Non-Human World,” by Emma Marris (Bloomsbury Publishing, 352 pages)

 

As Marris details throughout the book, while there are good reasons to value animals as individuals, there is in fact no unassailable single reason to protect species. However, that realization does not mean we shouldn’t do so, only that we should go about it in a more thoughtful way, with an eye also toward individuals. Ultimately, Marris argues that it’s time to renegotiate our approach to wild animals and conservation to better match the realities of our human-dominated world.

At the heart of “Wild Souls” is the tension that often exists between acting in the best interest of an individual wild animal and acting in the best interest of their overall species or environment. These things do not always line up, practically or morally. “That tension hinges on trying to compare two very different things,” Marris writes. “In some ways, this is the toughest problem of all.”

Arguing for the worth of individual creatures, Marris points to a mounting body of scientific evidence showing that many nonhuman animals are “smart, emotional, and even kind,” with rich inner lives. These animals are sentient beings, she writes — selves. Given this, ethical arguments can be made for individual animals’ rights to flourish and to live autonomous lives. This applies whether the life is that of a tiger or a mouse. “We are used to common things being cheap and rare things being valuable,” Marris writes. “But selfhood is both common and priceless.”

On the other hand, the same ethical arguments cannot be made for the obligation to ensure species thrive, especially if this comes at a cost to individuals. While “many of us have a deeply felt intuition that causing a species to go extinct is wrong,” Marris writes, “‘species’ is an abstract concept” that simply encompasses a basket of animals that share a certain set of traits at a given time. “The basket itself is not sentient, cannot suffer or feel pleasure, and is not alive,” she writes.

Evolution — the process that wove the species basket — is likewise not inherently “good,” Marris continues, but rather “is just time and sex and death and mutation and chance.” While arguments can be made for why a particular species is important to humans, she concludes, it’s more difficult to find a rational justification for why a species or ecosystem has any intrinsic or objective final value beyond the individual animals it comprises.


“We are used to common things being cheap and rare things being valuable,” Marris writes. “But selfhood is both common and priceless.”

Rationality aside, though, Marris, admits that she is deeply drawn to biodiversity — that “there’s something precious in what we call ‘nature,’ in the flow of energy, in the will to survive, in the way a lupine leaf holds a perfect sphere of rain.” She allows that overwhelming, logic-based justifications for protecting species are perhaps not necessary. Human passion alone can be reason enough to value the well-being of a rare species, even if it takes precedence over individual lives of members of that species or others.

On their own, these tensions can sound abstract. Marris gets around this by grounding the reader in real-world case studies on a number of topics, including keeping animals in zoos for educational purposes; supplemental feeding to sustain imperiled wild animals; captive breeding to bolster threatened populations or to secure genetic life rafts; and the practice of hunting as an ecological tool. As Marris explains, “I tried to look at these activities through the eyes of the individual animals as well as the framework of protecting species.”

Captive breeding, for example, usually benefits the species to the detriment of individuals, which must undergo the stress of capture and captivity — and sometimes wind up inadvertently losing their lives along with their freedom. “It’s an exercise in total domination, undertaken as part of a larger cultural project of stopping extinctions, which is arguably an attempt to reverse or reduce human domination over Earth,” Marris writes. While captive breeding does sometimes work, “does saving the kind justify restricting the autonomy of the individual?” she asks.

In the case of the California condor, the answer seems to be yes. In 1987, scientists captured the last of the world’s remaining wild condors for a captive breeding program that consisted of just 27 birds at the time. Although they were forced to forfeit their freedom, the birds likely would not have survived in the wild for much longer on their own, given the high mortality rates caused by the prevalence of lead shot in animal carcasses they were feeding on. Additionally, the species, which now numbers more than 300 in the wild, almost definitely would not have survived without intervention. So in this case, the program’s success, paired with the value of condors to humans, does seem to justify “any suffering and loss of autonomy experienced by the captured birds, especially since the levels of suffering seem quite low in this case,” Marris writes.

Marris suggests, though, that there should be limits to how far we go to protect biodiversity. This becomes particularly true, she writes, in instances when “we value ‘naturalness’ so highly that we become willing to hurt and kill animals to protect it.” Humans kill hundreds of thousands of invasive species each year, Marris estimates, and the ethics of lethal control can be weighed in a number of ways. In some cases, this method can be warranted: for example, in protecting an endangered species that humans are passionate about and that lives (or grows) on an island that is small enough for eradication of the invasive species to be done humanely. In other cases, though, killing invasive species solely on the basis of being invasive means depriving rats, feral cats, rabbits, possums, pythons, and other creatures — none of which maliciously chose to be born in a spot they did not evolve to occupy — years of life, without obvious justification.

Invasive species eradication also raises questions of where to draw the line on how we define natural. Over time, invasive species adapt to their environment and even evolve into new species, setting a new definition of natural. Climate change is also shifting many species poleward, causing “the idea that everything ‘should’ stay in its native range” to become “increasingly untenable,” Marris writes. As grizzly bears move north, for example, they are beginning to hybridize with polar bears, challenging “our cultural notions of discrete species and stable ecosystems.” Should the hybrid bears be shot, Marris asks, or “left alone to mate how they please, to respect their sovereignty?”

Perhaps the best way to save the polar bear from climate change’s deleterious impacts, she adds, is simply to “let it access the gene pool of its more flexible terrestrial cousin.”

Marris readily admits that she does not have all the answers, and that, in many cases, an answer that will simultaneously serve individual animals as well as species and ecosystems probably does not exist. What she does provide, though, is a useful set of guidelines that readers and society at large can adopt to more rigorously evaluate our attitudes toward wild animals, species, and the natural world.

As Marris argued in her 2013 book, “Rambunctious Garden,” and continues to build on in “Wild Souls,” the outdated notions of naturalness, wildness, purity, and ecological and genetic integrity — as often defined by a lack of anthropogenic influence pinned to some pre-colonial, frozen period of time — are not valuable or useful lenses through which to view environmental questions and decision-making. A more helpful and realistic set of considerations, she writes, would include the flourishing of sentient creatures, human compassion, and humility, the flow of matter and energy between living things, and biological diversity.

“Taken together, I believe these values suggest that in a humanized world, we owe nonhuman animals respect and compassion, plenty of space, a climate that is not changing too quickly, and — in some cases — intervention to help them deal with environmental challenges caused by humanity,” Marris writes. And while our “reverence for the web and flow of life” may sometimes lead us to hurting or killing animals to protect a species or ecosystem, “we must not take life lightly.”



This article was originally published on Undark. Read the original article.

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