Extinct Galapagos torotise has just been hiding

A species of Galapagos tortoise – thought to be extinct for over 150 years – may, in fact, be alive and well. This finding – made by geneticists at Yale University– is particularly surprising when you consider that this reptile is of giant proportions, measuring more than a metre from the front to the back of its shell and weighing more than 200 kg. How could such a behemoth have gone unnoticed for so long?

The answer, it turns out, is simple. They’ve been hiding. When Charles Darwin visited the Galapagos Island of Floreana in 1835, he found no sign of its native tortoise and assumed that whalers, pirates and human settlers had done them over. Since about 1850, there has never been a tortoise on the Island (bar one or two introduced animals kept as pets by the locals). It makes sense, therefore, that the IUCN should classify the Floreana tortoise Chelonoidis elephantopus (sometimes also Chelonoidis nigra nigra) as extinct.

A direct descendant of Chelonoidis elephantopus, alive and well on Isabela. Courtesy of Yale University

But the Yale geneticists now have good evidence that some purebred Floreana tortoises may still be alive on a different Island in the archipelago. For more than a decade, the researchers have been absorbed by the bizarre mixture of genes found in the tortoises on Wolf Volcano at the northern tip of Isabela, the largest Island in the volcanic chain. They began by studying mitochondrial sequences, which suggested that tortoises from the distant islands of San Cristobal and Espanola has somehow reached Wolf. Their guess was – and still is – that whalers and pirates were responsible. “Tortoises were occasionally stashed on various islands for safe-keeping and even tossed overboard in large numbers in nearshore areas to lighten cargo during flight or battle,” they wrote in 2002.

When I wrote my Galapagos book Lonesome George, I was fascinated by this possibility and looked hard for some first-hand evidence of such an introduction near Wolf volcano. I found it in the diaries of Captain David Porter, skipper of the infamous US frigate Essex that ruled Galapagos waters during the war of 1812.

David Porter, captain of the USS Essex

USS Essex in full sail

On 29 April 1813, with no wind to give chase, Porter sent several little boats out filled with armed men to capture the British ships Georgiana and Policy. What follows is lifted from my book:

Those on board the Georgiana and Policy were taken by surprise. If the rowing boats reached them, they would have to fight at close quarters and casualties could be heavy. With no wind, there was no escape. Their only hope was to blast the small boats out of the water. They were woefully unprepared, particularly as they had just stocked up on tortoises, which were getting in the way. ‘In clearing their decks for action, they [threw] overboard several hundred Galápagos terrapins’, wrote 12-year-old Essex midshipman David Farragut in his diary. Farragut was in one of the rowing boats closing on the Georgiana:

The appearance of these [land] turtles in the water was very singular; they floated as light as corks, stretching their long necks as high as possible, for fear of drowning. They were the first we had ever seen, and excited much curiosity as we pushed them aside.

As Farragut and his fellow men picked their way through a sea of giant tortoises, the cannon fire began. Back on the Essex at a safe distance, Porter looked on: ‘At two o’clock, the boats were about a mile from the vessels ... when they hoisted English colours, and fired several guns. The boats now formed in one division, and pulled for the largest ship, which, as they approached, kept her guns trained on them.’ None of the canons hit their mark. The boats ‘rowed up beneath the muzzles of the guns and took their stations for attacking the first ship’, Porter explained in a letter back to his superiors in Washington. The British struck their flag and stood down without a shot being fired. They then left a crew on board and took their stations for attacking the other vessel, the Policy; her flag was also struck.

‘Thus were two fine British ships ... surrendered, without the slightest resistance, to seven small open boats, with fifty men, armed only with muskets, pistols, boarding-axes and cutlasses!’ Porter boasted ‘that Britons have either learned to respect the courage of the Americans, or they are not so courageous themselves as they would wish us believe’.

As dawn broke a couple of days later, the Essex with her three prizes in tow was surrounded by about 50 live giant tortoises. They were rounded up and brought on board. According to Porter’s journal, ‘they had been lying in the same place where they had been thrown over, incapable of any exertion in that element, except that of stretching out their long necks’. He and his crew ate these tortoises in the coming months, but presumably some of those jettisoned by the embattled British ships were never recaptured. One or two, perhaps, made it to the nearest shore. We know from Porter’s letter to Washington that this would have been the northwest coast of Isabela, from which a beached tortoise could have made it to either Puerto Blanco or Puerto Bravo.

Here's David Farragut, presumably a little later in his career

It would be great to know where the Georgiana and Policy had been before they were captured, as this would give us the identity of the tortoise species they had on board. I never succeeded in locating their logbooks, which would have given this information but wouldn’t it be rather neat if they’d just come from Floreana carrying some of its last tortoises to a new life on Isabela? If anyone knows of the whereabouts of these logbooks – presumably captured by Porter and taken to the US along with the British vessels themselves – please, please let me know.

Anyway, back to the study on tortoises with which I began this post. With technological advances over the last decade and the tumbling cost of sequencing, so the Yale researchers have been able to mine the Wolf tortoise DNA in ever-greater depths. In 2007, they found evidence that this volcano might be harbouring close relatives of Lonesome George – the famed solitary survivor of the Pinta tortoise species. Using ancient DNA from museum-based specimens, they were also able to characterize the genetic signature of the Floreana tortoise and show that some Wolf tortoises have clear signs of this ancestry.

This latest study, published this week in Current Biology, takes this a step further by sampling a massive 1669 giant tortoises from Wolf, estimated to 20% of the volcano’s population. In amongst these, they have found 84 tortoises that have to have had a purebred C. elephantopus as one of their parents. They estimate that at least 38 founders would have been needed to leave the genetic footprint observed. Although most of these will have died out, it’s known that giant tortoises can live for more than 150 years and there’s a good chance there are still purebred Floreana tortoises out there.

The trouble is finding them. In 2008, it took a combined team of geneticists and rangers from the Galapagos National Park – some 40 people! – around 11 days of hard graft to sample 1/5th of the Wolf population. If purebred Floreana tortoises are still on the volcano, they are likely to be in very low numbers, says Ryan Garrick, Yale postdoc, now assistant professor at the University of Mississippi and lead author on the paper. “We would have to be very lucky to directly sample one of them.” Even if they can’t, however, their hybrid descendants could still be useful. "Hybrids may provide opportunities to resuscitate an 'extinct' species through intensive targeted breeding efforts,” he says.

It would certainly be of interest to those conservationists involved in Project Floreana, a huge initiative to put the island on a new, sustainable course, eradicating invasive species like cats and rats, restoring lost natives like the critically endangered Floreana mockingbird and bringing the island’s human residents on side. Wouldn't it be great to be able to include bona fide Floreana tortoises rather than just some stand-in surrogate?

The snag is that locating hybrid tortoises on Isabela’s Wolf volcano, transporting them to captivity and finding money to fund a back-crossing breeding programme over several decades would be seriously expensive. With Galapagos facing a multitude of pressures, not least from indirect impact that 30,000 residents and 170,000 annual visitors have on such a fragile place, is restoring the Floreana tortoise a priority? Or is it a luxury the cash-strapped conservation movement can ill afford?

This post is based on an article published on the Nature News blog on 9 January 2012.

A black and white Christmas

“The pandas are coming!” announced Edinburgh Zoo’s press office on Monday morning. The reason, I discovered, was not to proclaim the transfer of seminal fluid from male to female panda (cause for celebration as that might be), but because the Royal Zoological Society of Scotland (RZSS) finally has a date set for the long-awaited arrival of a pair of giant pandas. When the FedEx Panda Express touches down in Edinburgh on Sunday, Tian-Tian and Yang-Guang will be the first giant pandas to set foot in Britain for 17 years.

Is this Tian Tian? It's a female I photographed in 2010 at Bifengxia. Copyright Henry Nicholls

I’ve thought a lot – probably too much – about giant pandas. In 2010, I published The Way of the Panda, a popular science-cum-history book that lays out the intertwined fortunes of giant pandas and modern China as they made their respective ways towards zoological and economic world domination. In it, I reached the conclusion that captive pandas are deceptive beasts, having more in common with the cuddly toys, the abstracted WWF logo or dressed-up darlings of many-a-successful advertising campaign than with the real, wild pandas that eke out a living in the dwindling bamboo forests of China.

The Edinburgh pandas illustrate this perfectly. When China’s vice premier Li Keqiang and Britain’s deputy prime minister Nick Clegg signed off on the panda deal in January, the pandas were the subject of widespread up-beat news coverage. But within weeks, any pretentions that these were zoological entities had vaporized as the media began to dig deeper. From February onwards, the pandas had become stars in a human drama, used to draw attention to a full-on scandal that brought the zoo’s management infrastructure to the brink of total collapse.

The precise details of what took place remain unclear but for those who missed it I wasted several hours putting together a detailed timeline of events as covered by the Scottish press. In short, an anonymous dossier of serious but as yet undisclosed allegations crippled the organization, triggering suspensions and dismissals from the board. As this scandal wrought its destructive course on individuals, families and the venerable institution that is Edinburgh Zoo, the repeated appearance of pandas in photographs gave the overall impression that their acquisition had triggered the management crisis. In the absence of any direct evidence, however, this seems to have been little more than speculation based on the assumption that where there are pandas, there are men in suits filling their seedy little pockets with grubby banknotes.

Sure, captive pandas have obvious commercial promise. There is, for instance, an established graph with visitor numbers on the y-axis and time since arrival of pandas on the x-axis. There is also a version of this that shows what happens to gate receipts if the pandas manage to procreate. The zoo shop can do a nice line in panda-related merchandise. There is always the hope of landing a private sponsor, though in the current climate this could be tricky. 

But the income that captive pandas can generate for a zoo is unlikely to match the expense. It cost Edinburgh Zoo £250,000 to construct a state-of-the-art panda enclosure on the site of the former gorilla exhibit. The RZSS will be paying China around £640,000 every year for ten years for the privilege of having pandas. It will have to fork out a further £70,000 each year for food, importing most of the required bamboo from a plantation on the outskirts of Amsterdam. Then there are the salaries of keepers that will dedicate their working lives to the pandas. 

If captive pandas are so costly, why does Edinburgh want them? There are many reasons I think, but few of them have very much to do with wild pandas. The more time that passes since writing my book, the more convinced I am that there is little, if any, overlap between the lives of captive and wild pandas. In theory, the annual fee that Edinburgh will pay to China must be used to those animals in the wild. In practice, it is spent on strengthening captive institutions in China. Should Tian-Tian and Yang-Guang procreate, there will be lots of excitement but without a means of reintroducing captive pandas into the wild – a feat that has yet to be achieved – any offspring will be destined to a life as a captive with only superficial resemblance to their real, wild counterparts. 

No, the real value of captive pandas lies not in their identity as pandas but in the colossal symbolic importance we humans have invested in this remarkable species. Any zoo that can boast the face of global conservation amongst its inmates will only enhance its standing as a serious conservation concern. A pair of pandas acts like an incredibly efficient, self-sustaining PR engine, generating the kind of press coverage – most of it generous – that most press officers can only dream of. These animals open up wide and fertile new vistas for educating the public, not just about conservation of pandas, not just about conservation in China but about global conservation, full stop. 

In spite of these benefits though, I feel duty bound to point out that captive pandas can be profoundly unpredictable too. Take the case of Wang-Wang and Funi, a pair of bears that have been on loan to Adelaide Zoo since 2009. It’s been estimated that during their first year in residence, they injected $57 million into the South Australian economy. At the zoo itself, however, the pandas have not had the same effect and the South Australian government and Westpac Bank have had to step in to save it from financial ruin.

Tian-Tian translates as “Sweetie” and Yang-Guang as “Sunshine”. Only time will tell whether the Edinburgh pandas live up to their names and bring sweetness and light to the fortunes of Edinburgh Zoo and the wider city or whether the undoubtedly risky panda adventure will have a dark and bitter ending. 

An edited version of this article (with the jokes taken out) appears on the Guardian's Comment Is Free website. 

WWF at 50

Bust of Max Nicholson, courtesy of www.maxnicholson.com

If you ever get the chance to sift through Max Nicholson’s archive (which, I’ll grant you, seems a little unlikely), it's something quite astounding.

Throughout his long life, which spanned pretty much the entire 20th century, ornithologist, author and administrator Nicholson had a hand in organising or leading dozens of environmental initiatives and organizations, several of which sit right up there at the forefront of the modern conservation movement. When it came to organisation and leadership, Nicholson was quite simply second to none: he was instrumental in setting up the Oxford Bird Census in 1927 (which provided the foundation for the world-famous Edward Grey Institute of Field Ornithology); he established the British Trust for Ornithology in 1932; he drafted the constitution for the International Union for the Conservation of Nature (IUCN) in 1948; he kick-started The Nature Conservancy in Britain the following year; he helped found the International Institute for Environment and Development in 1971; he was instrumental in the instigation of the Trust for Urban Ecology in 1976; he was President of the Royal Society for the Protection of Birds in the 1980s; and he was Chairman of Earthwatch (Europe) at around the same time.

But what drew me to his archive – housed at the Linnean Society of London – was his absolutely crucial role in founding the World Wildlife Fund in 1961. The charity became a legal entity on 11 September 1961 so technically has already had its 50th anniversary, but the 10th anniversary of the Twin Towers atrocity meant WWF had to let this date come and go without celebration. Today – 28 September – offers an alternative, marking exactly 50 years since a press conference at the Royal Society of Arts in London saw the official launch of WWF-UK. From Nicholson’s papers, so neatly and completely boxed up for posterity (as you might expect of someone who studied history at Oxford University) it is possible to piece together the sequence of events that day.

There is a rather wonderful document, which Nicholson knocked off on 1 April 1961 in a grand old farmhouse in the charming folds of the Cotswold countryside, shut off from the relentless pace of life as Director General of Britain’s Nature Conservancy. In “HOW TO SAVE THE WORLD’S WILD LIFE”, Nicholson penned a rhetorical masterpiece to focus minds on the “desperate” situation facing “mankind’s natural heritage.” It would result, within the space of just six months, in the World Wildlife Fund, now the world’s largest non-governmental conservation charity with over five million members worldwide.

Here’s an extract to illustrate his style:

Existing organisations add up to something rather like a car with a half-pint fuel tank replenished by an occasional cupful. What is needed is not a new organisation to duplicate and compete with the work of existing bodies but a new co-operative international project to make their efforts effective by providing them with adequate resources – a new fuel tank with a petrol pump to fill and refill it.

Nicholson chaired nine preparatory meetings at the offices of the Nature Conservancy at 20 Belgrave Square (now, it appears, home of the Brunei Darussalam High Commission). One of the earliest key outcomes was a document now known as the Morges Manifesto, a statement of intent signed by those involved in Switzerland on 29 April 1961. With this year's Royal Wedding, WWF quite rightly decided not to mark this occasion.

Then, on the sixth of the preparatory meetings (on 6 July), it was agreed that the symbol for the new charity should be a panda and that there was to be a press conference on 28 September at the Royal Society of Arts to launch the British wing of the charity.

From a letter Nicholson sent to IUCN’s secretary general Gerald Watterson in late August, it’s clear that the plans for the event were at an advanced stage, with some 480 press invitations already dispatched. Nicholson then circulated the “proposed arrangements and programme” for the meeting “to all concerned”. With ten carefully bulleted points, it has something of military zip to it.

Point six indicates that two enlargements of the panda logo were to be on display, one just inside the entrance and the other “on the half landing of the staircase”. Then point seven, which I rather like, reads:

A larger version of the Panda symbol will be displayed behind the platform. This should pose the question “why a Panda at a meeting about African wildlife”? At the right moment this will enable the Chairman to make the appropriate remark about the problem under discussion being a world wide one.

From left to right: Julian Huxley, Peter Scott, Marquess of Willingdon Lord Hurcomb and Jean Baer.
© WWF-Canon / WWF Intl www.worldwildlife.org

And a couple of days before the day, the charity’s public relations guru Ian MacPhail circulated a letter to key members, giving a blow-by-blow outline of proceedings.

The first part of the meeting will be a report by Sir Julian Huxley on the recent African Wildlife Conference at Arusha. Mr Peter Scott will talk about the critical situation facing the wildlife of the world. Professor J.G. Baer, the eminent Swiss zoologist, who is the first President of the WORLD WILDLIFE FUND will describe the aims and objects of this new international organization. Lord Willingdon will present the WORLD WILDLIFE CHARTER – an important document signed by the world’s leading conservationists which will eventually go before the United Nations Assembly. Lord Hurcomb will be in the Chair.

Along with his letter, he sent a copy of the appeal booklet entitled “Save the World’s Wildlife”. There was also a fascinating handout showing off Peter Scott’s panda logo. Not only does it spell the genus name of the giant panda incorrectly (Ailarpoda instead of Ailuropoda), but it also claims that the panda was chosen as the Fund’s symbol “because it is one of the best-known and best-loved rare animals in the world, and because it owes its survival to the sort of careful conservation which all wild creatures deserve.” This claim looks like pure-and-simple spin, because in 1961 the first dedicated panda reserve was still a couple of years away and the idea of panda conservation had yet to be invented.

© WWF and courtesy of the Linnean Society of London www.linnean.org

The following day, Nicholson dictated a letter to the President of the German Bundestag Eugen Gerstenmaier (who was to be influential in setting up WWF in Germany) in which he described the previous day’s event: “We have just gone over the top with the World Wildlife Fund Appeal and the publicity has been excellent.”

I’ve been thinking about this because I’ve been invited to the RSA this evening to mark the 50th anniversary of this event. Unlike the original, this one is a closed meeting, with dinner, that will be attended by some very senior WWF folks, including David Nussbaum (CEO of WWF-UK), Morné Du Plessis (CEO of WWF South Africa (not the rugby player)), Carter Roberts (President and CEO of WWF US) and Jim Leape (Director General of WWF International). The main purpose of the meeting, according to WWF’s press team, is “to discuss the challenges of the next 50 years”.

Should be interesting.

If you’d like to read more on the origins of WWF, you should read my book or, for a more scholarly version, Saving The World’s Wildlife by Swiss historian Alexis Schwarzenbach.

The perfect swarm: GM mosquitoes

In a business park just outside Oxford, scientists are carefully breeding millions upon millions of mosquitoes. It’s not that they are particularly fond of these biting insects. The opposite, in fact, as their mosquitoes belong to a genetically engineered strain that could help tame the rampant spread of Dengue fever around the world.

I have the cover story in this week’s New Scientist that examines the science behind these GM mozzies and explores the potential of these and other genetically engineered species for controlling agricultural pests or invasive species.

The idea is based on the so-called “sterile insect technique” (SIT) and is brilliantly simple: you breed up vast numbers of your target pest in the laboratory, render them sterile and let them loose in the environment. Provided these infertile imposters mate with their wild confreres (and not just with each other), a whole load of barren eggs should bring the population close to collapse.

Since its first deployment in the 1950s, SIT has been a powerful tool for the management of insect pests, used to control the Mediterranean fruit fly across large areas of Latin America, the codling moth in Canada and the new world screwworm from the United States, Central America and North Africa to name but a few examples.

Now, with the help of cutting-edge molecular techniques, SIT is getting a 21st century makeover. Rather than relying on radiation to induce sterility as has been the case in most SIT campaigns in the past, it is now possible to use genetic engineering to achieve the same result.

Oxitec's offices near Didcot

In May, I paid a visit to Oxitec, the biotech company in question, and interviewed its founder and chief scientist Luke Alphey at length. In the interests of transparency, and because Dr Alphey said a lot of interesting things that I was not able to include in my feature, here is a cleaned-up transcript of our conversation:

Henry Nicholls: What are the drawbacks of using radiation to sterilise insects?

Luke Alphey: The sterilising dose of radiation is going to be bad for the insects and the extent to which that makes them sickly or short-lived or less competitive, specifically less able to find and compete for mates in the field, [matters a lot]. You have to release more insects to compensate for that. If that’s a small effect it’s no problem. If it’s a big effect it’s a huge problem.

HN: Are mosquitoes more troublesome in this regard than other insects?

LA: Yes. It varies from one species to another. It has been a problem for mosquitoes to find a sterilising radiation dose that doesn’t weaken them too much.

HN: Do we know why that is?

LA: I don’t. The SIT programmes that have worked have all found a sterilising dose that isn’t too bad. You want to do it just before you release them. Radiation is much worse on proliferating cells than on non-proliferating ones. So ideally to minimise the damage, you would irradiate the adults but they are much harder to handle than pupae. Mosquitoes are all spindly so that if you pack them into any kind of space, they all tangle up and you sort of end up with legs and wings and a lot of physical damage. You can irradiate pupae but that gives you not-very-happy adults. So the net effect is that there hasn’t been large-scale radiation-based SIT for mosquitoes. Chemical sterilisation worked moderately well in the 1970s using mutagenic chemicals.

HN: So a genetic approach to sterilisation bypasses all these problems. But it’s also an opportunity to introduce far more subtle consequences for the organism isn’t it?

LA: Exactly. You can further refine the phenotype you want. With irradiation you inevitably get sperm with damaged DNA. Eggs die before hatching. One of the things we can do with the mosquitoes is arrange that they die later in development rather than earlier. This is quite important for container-breeding mosquitoes like Aedes aegypti [the main vector for Dengue Fever]. They are breeding in pretty clean pools of water – rainwater, human-stored drinking water that sort of thing. So the larvae are competing for food in this little pool. If you were to arrange for some of them to die as embryos then the others would have more food and the larvae tend to do better.

HN: So your intervention could be counter-produtive?

LA: It could, in theory. Mathematical models say it could. If there’s strong density-dependent competition, eliminating some of them as embryos could actually mean you get more out than you would have done before.

Aedes aegypti by James Gathany, CDC.

HN: So why did you settle on Aedes aegypti as the target species as opposed to, say, the Anopheles species, which transmit malaria?

LA: There’s a whole series of reasons. Biological, sociological, economic.

1. Dengue is transmitted really only by this mosquito. There are one or two minor secondary vectors in some parts of the world of which the Asian tiger mosquito Aedes albopictus is the best known. It’s debatable whether that can sustain an epidemic at all. It’s certainly epidemiologically not significant compared to A. aegypti. So basically around the world you’ve got one mosquito transmitting this disease and our technology is exquisitely species-specific. So the sterile males that are released will only court and mate with wild females of the same species and not even with other species of mosquito let alone with bees and butterflies and whatever it is in the environment. So from an environmental point of view that’s extremely attractive. But if the particular thing you want to deal with [like malaria] is [transmitted by] a dozen different species that’s obviously more of a problem. So with Dengue, where it’s clear that in every epidemiologically relevant setting it’s this one mosquito that’s the problem that’s very attractive when you’re thinking about a species-specific technology.
2. Dengue is not as big a disease as malaria but it is a huge problem – there are 50 to 100 million cases a year and unusually for an infectious disease it is increasing in prevalence and severity around the world. There are no drugs and no vaccine. There is nothing apart from mosquito control and there aren’t many tools for that. So the universe of Dengue-control technologies is pretty simple and where we would fit into that is pretty clear. With malaria, there are more options. Drugs, ACT therapy, bed-nets. There’s a wider range of things you might do for malaria. The upshot of that is that our technology will be very, very widely applicable for Dengue. I think it will be beneficial in just about every major transmission setting you can think of. For malaria, I think it’ll be one of the tools in a larger arsenal. It’ll turn out to be extremely valuable in some areas, a piece of the jigsaw puzzle in other areas and perhaps not that relevant in other areas.
3. It’s important to release only males. First, only females bite and males don’t so you can release lots of males and they won’t do any harm, they won’t transmit disease, they won’t bite people. They are harmless. Whereas females – even sterile ones – would bite and would potentially transmit disease. So you don’t want to release sterile females if you can avoid it. Second, if you release lots of sterile males along with lots of sterile females then the sterile males that you released will hang around and court the sterile females you released alongside them. And they won’t so enthusiastically – to anthropomorphise for a moment – go out and look for the wild females. Those sterile females are effectively distracting sterile males from doing what you want them to do. So they are not even neutral to the program but actually negative operationally as well as being damaging, annoying, whatever. So for both those reasons you would very much prefer to release only males. In A. aegypti we have physical sex-separation methods that work really well. It turns out that the female pupae are quite a bit bigger than the male pupae and you just effectively sieve them. Most insects you can’t do that. Medfly and even Anopheles mosquitoes don’t really have that difference and then you need to go to genetics-based sex separation method.
4. In all places that you think about Dengue as a problem, it’s actually an invasive species. It’s native to a part of Africa and it’s been inadvertently spread around the world by humans relatively recently in the last few centuries, sometimes in the last few decades so from an environmental perspective it’s not a native species in the first place in these areas and there’s no initial reason to think – although you’d want to look on a case-by-case basis – that there would be members of the ecology that would be dependent on them or that it would be a key part of the ecology. So there’s really a whole series of reasons around why we started with this mosquito. You want to start with something that looks like a good target.
5. The mosquito is very robust and easy to rear.
6. Even if you felt there were currently adequate control solutions for Dengue, which I don’t think very many people in the field would say or for malaria, then you should still be developing new ones because the current one have a lifespan that is probably measured in years rather than decades because they will lose efficacy because of resistance.

HN: How would an insect be able to develop resistance to genetically engineered sterility?

LA: There are good reasons to think that resistance will be 1) less of an issue and 2) manageable. I would be very wary of anyone who says their particular intervention has no possibility of resistance. If we could find breeding sites for these mosquitoes and pour concrete in them, they will develop resistance to that. You might say that’s ridiculous but they will because they will start being selected to use a wider range of breeding sites. They will start to use breeding sites that perhaps they wouldn’t have used before because of the lack of current ones. So you could have behavioural resistance to concrete. It would be very foolish for anyone with drugs, vaccines, genetics – any kind of intervention - to say “you can never have resistance to this,” but the fact is that in the 50 year history of radiation-based SIT there has been very little resistance and the obvious one is behavioural resistance. So if the females can in any way recognise and discriminate against the sterile insects versus the wild ones then there would be strong selection for the ones that preferred to mate with wild ones. It has been documented for classical SIT but I’m only aware of one moderately well-documented case in the whole 50 year history of SIT which suggests it’s a pretty hard thing to develop.

You could also imagine biochemical resistance: now something arises in the wild population that neutralises the effect of our lethal genes so although they have it they no longer die because they are somehow resistant to its function. We have looked for that kind of incipient resistance and never seen the slightest hint of it in any of the species in any of the populations that we’ve tested but you have to imagine it could arise and then how do you get around that. If these were chemicals you’d say ‘if you get resistance, what’s your pipeline? Do you have alternatives?’ and we have absolutely heaps of alternatives. Because we’re expressing something inside the cell, there are any number of ways you can kill or disrupt a cell and we can use wildly different biochemical classes of effector against which you would not expect cross-resistance. So firstly we don’t see resistance and secondly we have a wide range of effectors to get around it should it occur.

HN: So how do you breed up a species in huge numbers that carries a lethal gene?

LA: [We use tetracycline-controlled transcriptional activation (TTA)]. In the presence of [the antibiotic] tetracycline you don’t get expression of the effect that’s going to sterilise them or kill them or whatever it is you’re interested in. In the absence of tetracycline [once they are released into the wild] you do.

I was very keen to have repressible rather than an inducible sterility because it gives you a biocontainment aspect. These insects are now not wild-type insects. They are fundamentally sterile and you’re keeping them alive by giving them an artificial antidote.

HN: How do you prepare for releasing a genetically engineered strain into the wild?

LA: We have a phased series of trials of increasing scale, first in the lab then in the field. Essentially what you want to do is predict everything it will do in the field short of actually doing it and so that’s a combination of lab experiments and simulation modelling and the two inform each other because the simulation modelling will tell you that some parameters are more important than others or more important than you thought or whatever it is in relation to the field performance. Fundamentally, does the construct do what you want it to do and then have you inadvertently made any changes usually negative performance changes to the strain in the course of the genetic engineering? Do you get the positive effect that you wanted and then have you inadvertently done something to damage the insect along the way? Because if you have you’re back in the radiation situation where you’ve got the sterilization that you wanted but you have also unavoidably damaged the insect in the process. Can you make genetically engineered insects that are reasonably competitive in the wild or are they unavoidably, inevitably weakened in a way that will compromise their ability to find and mate with wild females?

HN: Tell me about the OX513A strain and the journey you have taken to field trials?

Mosquito cage at Oxitec.

LA: [Males are homozygous for a repressible lethal dominant gene that disrupts the development of their offspring so they die as late larvae or pupae]. We developed the strain in about 2002. The key thing is can your males find and mate with wild females? You can test this in the lab but those trials will be in cages of rather small size – 30cm cages. You can say in that – if you put in ten engineered males, ten wild-type females, ten wild-type males – who do females mate? If they are equally competitive on average it would be 50:50. With this strain, we got equal mating. Of course we make very large numbers of constructs and strains and they often don’t perform as well as we’d like so there’s a huge winnowing in the process, as there is in drug discovery. Mating competitiveness, longevity, dispersal. Some of these things you can test up to a point in the lab but it’s very hard to know whether the males can find females over a distance of 10 m or 100 m in a laboratory experiment. So the first experiments were limited releases and the very first thing is just how long do they live and how far do they fly in the wild because we know what a regular wild insect would do, pretty much. And if they are dramatically worse than that it’s a problem. In the lab they live pretty much as long. It’s a classic mark, capture, release experiment. In some of those experiments we released transgenic males with wild males so you can have a direct comparison. How far do the wild-type ones go and how far do the genetic ones go?

HN: The next stage presumably is to find out if they can compete successfully for wild females?

LA: That’s what we did in Cayman in 2009 in collaboration with the Cayman Islands Mosquito Research and Control Unit. We released them relatively uniformly through an area over a four-week period. At the end of that you can look at who the females have mated, which we can do very easily because we just put out artificial breeding sites and the females can lay eggs in them and we collect those eggs, hatch them out and for each one say ‘does it have the fluorescent [DsRed] marker?’ This tells us who the females are mating and then we can also track adults and say what ratio of sterile to wild male we have and just compare those two numbers and that broadly tells us what the relative competitiveness was like.

HN: And how was it?

LA: If you just take the means then in round numbers our males were about 20% of the total males – just under in fact about 16% - and about 10% of the eggs had a transgenic parent – again just under. So you got about half as many transgenics as you’d expect for the male, which is fantastic. [Remember,] it’s a laboratory-adapted strain, reared in the lab, it’s got the transgene in it, it was handled, it was just put out in the field uniformly without any knowledge of where the wild ones were. A whole bunch of those males you’d just put in the wrong place. Net of all of that, to have 50% of wild-type mating competitiveness is fantastic. It’s also way more than you need for success in these kinds of experiments. In big programmes that have worked really well, that number would have been 0.1 or more like 0.01 rather than 0.5. That’s way better than we needed and was extremely encouraging.

That also enables us to say in that area, we released this number and we got this amount of mating so if we want to adjust the amount of mating to half the females mating or something like that how many more males do we have to release to get there? In the next year 2010 that’s what we did. We released the number calculated and with some adjustment got to a level predicted to suppress the target population and indeed it suppressed the target population.

In Brazil we are essentially recapitulating what we did in Cayman. It seems pretty likely that what happened in Cayman will happen in Brazil but it’s a different place, the mosquito population could be different so it’s worth repeating that. It will show whether the Brazilian population behaves the same or whether it doesn’t.

HN: You have another strain in development OX3604C?

Mosquito eggs at Oxitec.

LA: The beauty of it is you can get the sex-separation and the sterilization equivalent from the same genetic thing. [Females are flightless, so unable to feed or find males, they die without mating]. With the female specific system you can just release eggs, knowing that they are going to grow up in the absence of tetracycline and only males will make it. If you were going to say we’ve got these isolated communities and you want to send them some material they can use themselves in a totally community-based method really you want to be sending them the eggs. The eggs are fantastic. The eggs will stay dormant, dry for months. They are incredibly light and easy to ship around. 1 million eggs will weigh a gram or something, just nothing. Doesn’t need refrigeration, doesn’t need anything special, just sit around for a couple of months, delayed transport doesn’t matter.
These mosquitoes grow in a very wide range of rather simple breeding sites, which is one of the reasons why they’re such a pest and so hard to deal with. But we can turn that to our advantage by saying well actually they are really very easy to grow. Just add water and you get instant mosquitoes.

HN: How did you come across this strain?

LA: We went out and looked for it. We wanted something that was late, so in pupae, and female specific so we looked at the differences in genes expressed in female pupae and the genes expressed in male pupae. We got a number of them and we analysed them and another group led by Tony James did the same experiment and got some of the same genes. It turns out to be specific to the female flight muscle. It is in fact a flight muscle actin. The indirect flight muscles, which power flight in insects, are very specialised muscles. Drosophila has its own indirect flight muscle actin different from normal flight muscle actin. But it’s the same gene in males and females. In mosquitoes it isn’t.

HN: Why would female have different flight muscles?

LA: We don’t know.

HN: But you must have thought about it?

LA: I have. For that to be maintained, to be advantageous you’d have to think there is some difference in flight between males and females and it’s a little hard to see what that might be. The female has to fly after taking a blood meal so she has taken on a small multiple of her own body weight in blood so has to be able to fly with a much heavier load than a male ever has to. The other is around courtship. The males and females modulate their wing-beat frequency in different ways.
There’s clearly scope for investigating that further. I would love to do that. It’s just not part of my current mission to do that. But you find these things along the way that raise lots of pure biology questions that I would love someone to pick up.

HN: What are your plans for this strain?

LA: We’re planning to recapitulate trials much like what we did with OX513A. I think we will have trials of within the next 18 months or so. The regulators will take whatever time it takes for them to be satisfied with it.

HN: There are presumably lots of people who are opposed to this technology, just because it’s GM. How do you respond?

LA: I don’t think there is a big negative reaction to genetic engineering per se and my reason for saying that is look at genetically modified insulin look at genetically modified vaccines. People inject themselves frequently with recombinant insulin, which is clearly a genetic engineering product, so it’s quite hard to say there’s a fundamental opposition to the technology itself. Ditto vaccines. But clearly there has been in some countries in the context of food. I think part of the reason [for some opposition to GM] is that we’re sitting here in Europe which is one of the more anti-GM areas (though that’s not universally the case even for food) but one of the issues is “where’s the benefit?” In Western countries we’re used to effectively unlimited supplies of clean, cheap, safe food, where is the benefit of applying genetic engineering to the individual consumer, voter, citizen? Maybe there’ll be a few pence off your maize, probably not. Maybe a few less chemicals will be used out in the environment but you don’t see that in the first place and don’t really believe it anyhow. Where’s the benefit? If you can’t see any benefit, why would you agree to some changes, some technology that other people say is scary and dangerous and you’re not too sure about?

Whereas, if you go to a Dengue-endemic country and talk to people about Dengue, everyone knows about Dengue. Everyone has either themselves or a close family member suffered from the disease, it’s a very painful disease, very worrying, there’s no specific therapy for it, there’s no protection for it. Everybody agrees that Dengue is a bad thing and also that current methods are inadequate for controlling it. It’s very well known, partly because of its prevalence, partly because one of the lynchpins of such control as there is is trying to get citizens to clean up breeding sites, to clean up water sources and so on. There’s a lot of public information about Dengue and its association with mosquitoes. Everybody agrees that new measures and doing something about it would be a good thing. So we then have that huge common ground. Now we’re just discussing the method. With GM crops in Western Europe, you just don’t have that common ground. We’re just not in that situation. There are a whole host of other differences with food about the fitness consequences of the transgene and implications for spread. You’re trying to make a beneficial thing stronger by giving things that’ll help it like herbicide resistance and insect resistance and those are traits which you can imagine under some circumstances might possibly spread. Whereas we’re putting in things with huge, huge fitness penalties like sterility and death into something that’s undesirable in the first place and trying to get it to go away and it’s clear that those transgenes are not going to spread even were they to go outside the population area where you want them. Many of these crop plants have weedy relatives with which they could hybridize. These insects have cleaner species so that route for spread is not available. There’s no equivalent of conventional agriculture. So one of the issues with GM agriculture in Europe is its coexistence with conventional agriculture and how are you going to do that, how are you going to separate them, how are you going to avoid genetic contamination between them? You know, there is no established set of conventional mosquito breeders who are going to be upset with our release of geneticially engineered mosquitoes. There is a big health benefit that everyone understands.

We’ve had a little more concern about the GM aspect in the Malaysian press than in Cayman and Brazil. It’s going to vary from one country to another, one culture to another. GM maize in Mexico was such a big issue. GM cotton was much less controversial. It’s going to differ a bit from one country to another but on the whole I think the fact that it’s for health and the big public benefit and public good derived from success really puts us in a different space from GM crops, at least GM crops in Western Europe.

One of the features of this technology is that it protects an area and it protects everybody in that area irrespective of their wealth, power, status or education or whatever, which from an equity basis is quite attractive actually. Our aim is to reduce the burden of Dengue in vulnerable populations but if this helps promote a more nuanced discourse about genetic technology in general, that would certainly be a welcome side effect.

HN: Could this sort of technology be used to control a mammal like the rat?

LA: A large number of adult male rats – sterile or not – is probably not the way you want to go.

Darth Ailuropoda

Is the panda really endangered?

Weird isn’t it, but we still don’t know how many giant pandas there are.

So it’s time for another census of this curious beast. The final figure, when it comes in a few years time, is really rather important. For it’s this estimate that will inform where the giant panda sits on the IUCN’s Red List of Threatened Species and this matters to a lot of very influential people.

The face of modern China: Premier Wen Jiabao or the giant panda?

Photo of Wen from www.kremlin.ru

Last week, for example, Chinese Premier Wen Jiabao (the most powerful man on earth?) confirmed the imminent arrival of giant pandas to Edinburgh Zoo, trading on the pull that their Red List status has on our emotions. Although (as I argued in a brief discussion with Jon Snow on Channel 4 News) this kind of panda politics may not be as effective as it once was, the panda is still a more appealing ambassador for modern China than the wooden-miened Wen (and he knows it).

But what if it wasn’t really endangered?

At the last count, completed in 2001, China’s State Forestry Administration arrived at the figure of 1596 adult pandas, curiously specific when you consider this was reached by counting poo. Don’t get me wrong; since it’s virtually impossible to see the pandas themselves, it is eminently sensible to look for another way of counting them and poo is the perfect proxy: the bamboo-munching bear gets through so much of this prolific but nutritionally poor plant that its dung lies everywhere and, unlike the animal, its excrement doesn’t run away long before you reach it.

Panda poop, courtesy of disgrasian.com

But it doesn’t take a genius to spot the drawback of using faeces to estimate the population size of pandas. You see one poo, then another, but how do you know whether they came from the same panda? It would be completely stupid to assume that one poo equals one panda – you’d end up with a rosy figure in the tens of thousands. At the other equally ridiculous extreme, would be the idea that all faecal chunks of mulched bamboo must come from one rather incontinent animal. Obviously, the reality lies somewhere in between, but where?

Between 1974 and 1977, when China carried out its first “national survey” of its “national treasure”, some 3000 people were sent into the countryside to tot up sightings and spoor. The search for pandas was divided between the three provinces with pandas – Sichuan, Gansu and Shaanxi – and further broken down within each province to the county level.

What happened next is hard to believe. With each county keen to boast more pandas than the next, it seemed as though the panda population was incredibly healthy. In Sichuan, for example, the sum of all county-level counts came to around 4000 animals. At the same time, however, China wanted to the international community to get behind panda conservation so told the world there were only 800 left in the province.

When conservationist John MacKinnon arrived in China in 1987 as chief scientific advisor to the Worldwide Fund for Nature, he confronted forestry officials with this bizarre discrepancy. “All the numbers were politically decided and not scientifically decided,” he told me over lunch in a quiet Beijing restaurant in March 2010. “They were surprised that I was so naive as to imagine the numbers should add up.” With 150-200 for Shaanxi and a further 100 for Gansu, the first national survey came up with an official estimate of 1050 to 1100 pandas. Period.

The second census, conducted between 1985 and 1988 with WWF’s input, took a more scientific approach, a small and stable team of 35 people moving methodically from one county to the next. Their mission was to work out the distribution of pandas, estimate numbers but also to collect data on the forest, the bamboo and the people. The figure they came up with was 1,120 plus or minus 240. A straight comparison from the first to the second survey would suggest that panda numbers were going up, whereas everything indicated the opposite. “The range had shrunk and the bamboo area had shrunk and the number of bamboo patches had shrunk,” says MacKinnon. The two censuses were so different that comparing them is meaningless, but at least the second survey had set a figure that would be used to gauge conservation success over the coming decades.

Or had it? In the third national survey, carried out between 1998 and 2001, the methodology changed again, this time with a dedicated focus on panda poop. Data collected by the Chinese panda expert Hu Jinchu (presented in a paper published in 1987) suggested that the size of faecal deposit and the length of the bamboo fragments it contained could help distinguish between the poo from a cub, juvenile, adult or senile panda. So measuring the length of bamboo bits inside panda droppings could indicate whether several piles of faeces lying nearby had come from just one or more pandas. With this unsavoury methodological twist, the survey team dissected some 3,800 scats into that strangely precise figure of 1,596 pandas.

This is, at best, a very rough estimate. If you’re in any doubt about this, just look at a paper published in Current Biology in 2006 and the controversy it whipped up. The authors explored the possibility of improving on the existing size-and-content-method of working out which panda laid which turd. Surely, a DNA profile from each scat would be both cleaner to obtain and yield cleaner results? When they did this in the Wanglang Reserve in Sichuan, they found DNA from 66 different pandas, more than double the 27 adults that appeared to be resident in the third survey conducted just five years earlier.

They reached a bold conclusion: “if similar disparities between traditional and molecular census estimates are found for the other key giant panda reserves…it seems likely that many more individuals are extant in the wild than estimated in the Third National Survey,” they wrote. Just to ram home the implications of these results, they added that “there may be as many as 2,500–3,000 giant pandas in the wild.” That is almost double the 2001 estimate of 1596!

Not everyone appreciated this suggestion. In a response published in the bear journal Ursus (a PDF of which is archived here), several experts acknowledged that extending the bite-size method “to separate individuals was probably beyond the rigor of the technique” but questioned whether the DNA-based approach “was necessarily more accurate”.

They had two main problems. One was that the Wanglang faeces had been collected over the course of a year, so represented “the cumulative total of pandas that ventured into and defecated in the reserve, even if they only resided there for a few weeks.” Pandas, they presumed, had been coming and going with gay abandon, resulting in an exaggerated figure. DNA profiling is also not error-free, they pointed out, and “Genotyping errors may be another source of population overestimation.”

But, as with just about everything to do with pandas, this was about more than just numbers: “Over-estimation of panda numbers would not just be an academic error," acknowledged the Ursus authors. For the population size is crucial in deciding how threatened the panda actually is. According to the Red List entry for Ailuropoda melanoleuca, the giant panda qualifies as “Endangered” because it meets the criterion C2a(i) in the 2001 Categories & Criteria (version 3.1). Put succinctly, the panda population is estimated at “fewer than 2500 mature individuals”, is experiencing “a continuing decline…in numbers of mature individuals” and “no subpopulation [is] estimated to contain more than 250 mature individuals”. If the extrapolation to 2,500-3,000 individuals were correct, the giant panda would have to be downlisted from the high-profile position of “Endangered” to the far less worrisome status of “Vulnerable”.

Since two of the Ursus authors – David Garshelis and Wang Dajun – are both members of the IUCN Species Survival Commission Bear Specialist Group that assesses the panda’s Red List status, it is understandable that they should have picked up on the extrapolations made in the Current Biology paper:

“For a politically-sensitive, conservation flagship species such as this, where the success or failure of conservation initiatives is gauged largely by periodic assessments of total numbers, scientists should exercise great caution and critical analysis when producing population estimates.”

Which is why, at their latest assessment in 2008, Garshelis and Wang (and colleague Lu Zhi) ruled that the giant panda should still be considered “Endangered”. In their justification, they argued that “there seems to be little doubt that there are less than 2,500 mature giant pandas in the wild; additionally each population is believed to have less than 250 mature individuals. At least until recently there has been a general population decline, although there is hope that this has been reversed by general habitat improvements — nevertheless, this remains an uncertainty.”

So will the forthcoming “Fourth National Survey” clear up any of this uncertainty? It seems unlikely. The plan, according to a story released through China's Xinhua news agency, is to use the molecular method to count pandas through their poo. This will almost certainly get us closer to the "true" number of wild pandas but this figure has little significance to conservationists without the means of comparing it to the 2001 estimate. This will only be possible if the survey team also collects old-school data on bite size, a point stressed by the authors of the Ursus paper. Only then would we be able to get a feeling for the direction in which the panda population is going and the success or failure of conservation measures implemented over the last few decades.

As there are plenty of scientists involved in carrying out the forthcoming census, we can be pretty confident that everything will be done to facilitate this comparison. Still, it'll be really interesting to see what happens if the evidence suggests the giant panda should no longer be classified as "Endangered”. Call me cynical, but with such vague baseline data and so many influential folk keen to keep the world’s attention on the panda (modern China and the Worldwide Fund for Nature for starters), there will be plenty of pressure to keep things just as they are.

******

Additional note (added 2 August 2011): In the "supplemental experimental procedures" of the Current Biology paper, the authors describe how they "sampled twice, first October - December 2003 (47 feces and one blood sample left on snow in Wanglang, 7 feces in Baima), and second, February - August 2004 (254 feces in Wanglang, 27 in Baima, 25 in Wujiao, 13 in Huanglong)." This tots up to a collecting period covering ten months, which is presumably why the Ursus authors reached the conclusion that "the fecal collection in Wanglang was conducted over nearly a year". Mike Bruford (senior author on the Current Biology paper) informs me, however, "We collected samples from Wanglang in October-December 2003 and then broke for the winter, finishing in April. The samples collected in August were from Jiuzhaigou and Huanglong." Collection in Wanglang was therefore either over three months (October to December) or six months (if they broke for the winter, returned to Wanglang in February and finished there in April).

Sand martin sex. Where do they do it?

It is almost exactly 10 years ago that I handed in my PhD on sand martins. What better way to mark this milestone than with some Riparia riparia-related news.

I got a press release yesterday from the Wildfowl and Wetlands Trust spreading the word about a sand martin colony at the London Wetland Centre in Barnes. They have installed a CCTV camera in one of the nests, providing “amazing close-up views of their nesting habits and their chicks”.

“The centre’s sand martin nest bank currently houses a colony of 40 breeding pairs. One of the cameras is located on the front of the bank so that visitors can watch the sand martins in flight and – in true Springwatch fashion – another is sited inside a nest tunnel with views of the sand martins raising their young. A large screen located inside the bank enables visitors to watch the fast, agile flight of these pretty birds and also to see and hear them on their nest, chattering to each other and their young as they bring food for their growing family. As well as the on-screen action visitors can learn more about sand martins’ behaviour, habitats and migratory patterns.”

It makes me feel a little old to think that back when I worked on sand martins in the 1990s, CCTV was a pretty new idea, at least when it came to studying wild animals. I remember thinking about inserting cameras into nests, mainly to find out if this is where mating (or, more accurately, copulation) takes place.

In spite of the fact that lots of people had studied sand martins before me, it remained something of a mystery where this species actually got down its reproductive business. Indeed, I spent hours carrying out essentially unproductive focal watches and scans of telegraph wires in the beautiful rural village of Szabolcs, where thousands of martins would happily sit and, I assumed, occasionally mate. I got a great insight into village life, but not much dirt on sand martins!

So, as I say, it would have been nice to look inside nests, where sex – though undoubtedly a cramped affair – might have been taking place. But the cost of CCTV equipment back then was prohibitive and the idea of working my way through stacks of analogue tapes was not appealing. More than that, perhaps, it would have been a logistical nightmare to get a camera into the nest of a wild bird without it moving on elsewhere. Ornithological wizard Tibor Szep, who kindly let me study “his” sand martins on the fabulous Tisza River in Hungary, had somehow managed to get weighing scales into a wild nest to measure the growth of chicks but it required an extraordinary level of interference. “Nest materials with nestlings were dug out and placed in a specially designed nest box called a Riparibox,” he and his colleagues wrote in their 1995 description of the “Use of an electronic balance with bank swallow nests”.

So I didn’t bother, concentrating instead on getting desperate male sand martins to mate with a dead female propped up outside the colony (don’t ask). Now though, with CCTV equipment so affordable and artificial banks like that at the London Wetland Centre obviating the need to do any disruptive digging, it’s pretty simple to get this kind of sneaky insight into what goes on inside the nests of holed up birds like the sand martin. I’ve asked if there have been any copulation sightings in the run-up to egg laying. It might make a short communication somewhere.

I’ve been meaning to go to the Wetland Centre for years and now, if I needed one, I have my excuse. As Simon Barnes noted in his Wild Notebook in The Times on Saturday, seeing sand martins in a city is (with a nod to Scott Fitzgertald) “like seeing a flock of sheep turning into Fifth Avenue.” Looking forward to it.