Matchmaking at the zoo

When we think about conserving wildlife, you probably think of the big stuff - pandas, tigers, elephants and other endangered mammals. But, as Dave Clarke - head of invertebrates at ZSL London Zoo - told Kat Arney, the truly endangered animals are at the other end of the scale.

Dave - We’re in our Polynesian tree snail breeding room at the moment. So we’re surrounded by tanks with loads of little snails in them. They're one of our rarest animals that we keep here and one of the rarest in the world.

Kat - When you think of a zoo, you probably think of the big things like tigers and elephants. It seems strange to me that these small snails are incredibly rare. What is their story?

Dave - Well, there's probably far more invertebrate animals that are rare than the big animals, because the big animals are easy to see. There's a lot of invertebrates which go extinct all the time because of loss of habitat. Many of that haven't even been described yet. The other thing about that is that the invertebrates are fundamental to ecosystems so can be as important, if not more important in recycling and pollination, and things like that.

So, they have a great importance which is much greater than their size. So these little guys here feed on decaying plant material which is an important job in ecosystems. They're just as worthy of conservation as a big beautiful elephant.

Kat - These are Polynesian snails. What was their journey to Polynesia to here and why have you got them?

Dave - Well, they were studied actually over a hundred years ago by someone called Crampton who was looking at the speciation of the snails. You get different types of snails in different valleys on each individual island throughout South Pacific.

That work was picked up in the 1980s and ‘90s by a group of professors. They realised that at that time, the animals are also becoming extinct in the wild and this was a slightly complicated story of biological control gone wrong because the giant African land snail was introduced into Polynesia as a potential food crop.

They became a pest and what they did to try and control their numbers was introduce a predatory snail from America called the rosy wolf snail. But the rosy wolf snail liked bite-size Partula snails and not the big giant land snails and set about the extinction of them on the islands. On one island, most of the species have become extinct within just 10 years.

Kat - Wow! And how did you manage to salvage these snails and bring them here and what have you been doing with them?

Dave - Because people were studying them, they had quite a few in captivity. We then got involved and started mounting rescue expeditions for the ones that were going extinct in the wild. Some, we were lucky with; some, we were too late. In some cases, the animals went down to tiny numbers.

There's a species over there called Partula tohiveana and they went down 23 individuals at one time. But we have the opportunity to get them going in captivity but that species is over 2,000 now and we’re have been able now to release some back to the wild.

Kat - That species, if it went down to three individuals and now, you’ve grown it back up to 2,000, and you're putting them back into the wild. Surely, that is now quite an inbred population. How have you been studying them at a genetic level to make sure that they're OK?

Dave - What probably happened with these snails was that they had a relatively small gene pool anyway because they popped up on these Pacific islands as they were coming up, volcanic activity from the ground.

So, they're less than a million or two years old in many cases. But they probably arrived just on a bird’s foot or a log or something like that so it would’ve been a small genetic base anyway. So, loss of diversity in these may not that be significant and there is perfect example there. Others, we do try to maintain as much diversity as possible.

Where we’ve been able to, we’ve collected larger numbers from the wild, and we we’ve tried to manage them on a group basis. So, unlike individuals where you might know who Derek the Gorilla is, with the Partulas, we have them in tanks and you can see these are populations of snails usually, between maybe 20 and 100 snails.

They are our base level group and we might out cross some of them to other groups of the same species. But in most cases, we keep them as direct lines and they do very well.

Kat - So you're effectively treating each tank of snails as kind of one thing, one genetic organism.

Dave - That’s right. We’ve had a stud book for snails for 20 years now. We keep records of all the different species, how many each year, who’s keeping them because it’s a worldwide programme. There are 15 institutions worldwide that keep them and we help maintain the numbers here at London Zoo.

Kat - Now, I see quite a lot these tanks are empty and you mentioned you’ve been reintroducing these snails back to the wild. Presumably, they’ve gone back where they came from. What did you do with them?

Dave - That’s right. A little earlier this year we did some reintroductions to the wild. We’re doing it for a few years now and 1,300 of the snails in this room went out to the wild alongside animals from Edinburgh Zoo and a few other zoos in the UK. That’s a global programme in trying to reintroduce the species back into the wild.

That’s obviously the main aim of any conservation breeding programme. And it isn’t always easy to get to that point but we have done so after what's over 30 years of working with these snails in captivity. It’s great to be actually putting them back in the wild where they belong.

Kat - But what about the predator that was introduced? Is it now safer for them to be there or are we just going to see them being wiped out again by these predatory snails?

Dave - Well, it’s still a complicated dynamic in the wild. So the predator snail is still there but what happened, which happens with a lot of biological controls, is there was kind of boom and bust where when they first got to the island, they went, “Yippee! Loads of food!” and spread across the island within 10 years. But now that their populations have dropped right back, there's a good chance of our Partula snails surviving even with some predation.

So, that’s what we’re looking at. It gets more and more complicated. Life is never easy. There's a little flatworm which has been introduced as well which can predate the snails, but what we’ve got is ongoing situation working with the Tahitian government, people on the ground studying the snails, looking how well they're doing, and we also know that animals that were released a year or two ago are still persisting in the wild. So everything is looking good.

Every year the Genetics Society awards a number of prizes to outstanding researchers. The JBS Haldane prize recognises an individual for outstanding ability to communicate topical subjects in genetics research to an interested lay audience, and this year’s winner is Professor Enrico Coen from the John Innes Centre in Norwich. He’ll give his prize lecture on the 21st of November in the hallowed red velvet lecture theatre of the Royal Institution in central London. It’s open to the public and tickets are on sale now. Kat Arney caught up with Enrico ahead of his talk, and asked him why Haldane - a brilliant evolutionary biologist and geneticist - is such a great icon for science communication.

Enrico - Haldane was a fantastic scientist and communicator. He had great ideas about the theory of genetics and how he might develop that theory, and also an appreciation of experiments. But he also communicated it to a very broad audience. He wrote several popular science books, wrote articles about science, and I think he was just generally fascinated by the challenge of how you can relate complicated ideas to a broad audience.

Kat - But why do you think it’s important to actually communicate genetics, communicate science to the public? You know, it’s hard stuff. why do people need to know about this?

Enrico - Science is just one of the most amazing things that we’re able to appreciate and it’s part of our world. It’s part of how the world works. It’s part of the fascination with how things are. I think it’s just our duty in a way to try and share what we’ve discovered about that world.

Kat - So in terms of your own work, what is your passion? What is your genetic interest?

Enrico - One is to do with the development of shapes and forms and how is it that a group of cells, a small group of cells in an embryo, or in a bud of a flower can turn themselves on their own into amazing structures. Not just humans but plants, flowers with amazing shapes, leaves with all sorts of different contortions.

How does that happen because nobody is telling the plant how to do that? The plant has to do that somehow on its own. So, when you put a seed into the garden and that turns itself into a daisy or a rose, how does that work?

The other thing is the historical question – how did that variety of forms arise? How did it evolve? What were the factors, the forces in evolution that led to this diversity of different shapes and forms, and colours that we see when we look out in our garden? So both of those aspects fascinate me – both the development of structures and how they’ve evolved overtime.

Kat - You'll be doing your JBS Haldane lecture. What will you be talking about? Give me a little run through, a sneak peek of what people can expect.

Enrico - So, I’ll begin by really asking the audience to imagine they're a Martian landing on Earth and trying to make sense of the amazing things that humans have made.

So suppose you went around and did see things like cars. One of the first things you might think about is how humans have made things that seem to be tailored to their environment. Cars have wheels so they can go efficiently on roads. Boats have hulls so they can float in the water. Snow mobiles have skis to steer them. So everything seems to be adapted to its environment.

But then if you look a bit more closely, what you see is actually there's lots of things that humans make that aren't – strictly speaking – related to adaptations. For example, in some countries you find people drive in the left. In another country, the people drive on the right. That’s not to do with adaptation to local conditions. There's something else going on there. So what's that about? There's some historical process that’s somehow creating boundaries and differences between these different countries.

And in the same way, what I try and convey in my talk is how, when in a sense we’re Martians, when we’re trying to understand how biology works, we want to make sense of all these different biological forms that we find – plants or animals or microbes.

What I want to talk about is how we’re discovering all these processes really in a way that we’d never appreciated before, the advances we’ve made in being able to study genes. It’s now possible to sequence genomes, entire genomes very quickly and that’s revolutionising the way we look at organisms and it’s showing us this historical component that we only have a sort of hint of previously and it’s now being revealed for the first time.

Kat - If JBS Haldane was alive today and he could see the genetic revolution, all the information we have, what do you think he would say? What would be really blowing his mind today?

Enrico - I think what would blow his mind is the fusion that’s happened between people who study gene functions and people who study populations. Because one of Haldane’s great contributions was the idea that genetic variation should be studied not just in terms of small families but whole populations, thinking about the frequencies, or the rates at which mutations happen in the population as a whole.

And because we can now sequence genomes and discover their structure across lots of different individuals, first of all, he'd be amazed if that’s possible at all to be able to sequence an entire genome and understand the genetic code. But also, I think he would struck by the fact that we can now look at populations in a totally new way. We can look at variation across a whole population of individuals and appreciate how that variation is behaving.

Kat - In the work that you do studying particularly plants, are there any that you really think, “Wow! Look at them. How on Earth did they get like that?”

Enrico - I suppose the scientific love of my life are snapdragons. About 100 years ago, snapdragons were actually the best understood plant in terms of its genes than any other plant. They fell out of fashion for a while, largely because you can't eat snapdragons. I mean, they're not very tasty things to eat, but they were very good for studying genes.

So really, over the last 30 odd years, I’ve worked consistently on these plants trying to understand how their patterns and forms generated and they’ve been remarkably sort of fruitful.

Kat - Do you grow them in your own garden?

Enrico - Yes. We have some in our garden and I always look at them in a slightly different way perhaps than I would look at all the other flowers in the garden. They're my friends. I know them very well. I know the variations that I see. Instantly, I can tell that’s that gene that’s segregating, that variant between one snapdragon and another. So yes, they're like familiar friends that live with me.

Kat - Enrico Coen from the John Innes Centre in Norwich. And you can buy tickets now for his award lecture on Tuesday 21st november, starting at 7pm at the Royal Institution - tickets available from the RI website.