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019 - The Genetic Time Machine

019 - The Genetic Time Machine

 Kat: Hello, and welcome to Genetics Unzipped - the Genetics Society podcast with me, Dr Kat Arney. In this episode we’re taking a trip in a genetic time machine - back into the past to discover the origins of ancient human populations, and into the future to explore the realities of personal genome sequencing. 

Before we get going, here’s a quick reminder about our listener survey. This podcast has been going for six months now, and we’d love to know a bit more about you and your thoughts on the show - what episodes have you enjoyed? What topics would you like us to tackle? Do you want to buy some cool swag?

Please fill in our short listener survey, and you’ll be entered into a prize draw to win a signed copy of my book, Herding Hemingway’s Cats. Thank you very much. 

Love your genome?

The falling cost and rising speed of DNA technology has meant that genetic tests like those offered by 23andMe are now cheap enough to be advertised as fun family Christmas presents (as long as you’re really sure who your fun family actually are…) 

But these tests only look at snapshots across the genome, rather than the whole thing.

The next frontier is direct to consumer whole genome sequencing, as I chatted about with genetics pioneer George Church a few episodes back. 

At the moment, this costs around a thousand pounds, starting to make it feasible for people with an interest in digging deeper into their genome and a bit of cash to spend. But is it a good idea?

Last month I went along to the LOVE MY GENOME event at the Francis Crick Institute in London, run in association with genome sequencing company Veritas, to see a short documentary film explaining what happened when 10 healthy individuals with a professional or personal interest in genomics had their genome sequenced for free, in exchange for sharing their thoughts about the process and the results. They also received genetic counselling before and after.

The film sparked a spirited debate between the audience and a panel of several people who had taken part, teasing out the merits and issues surrounding direct-to-consumer whole genome sequencing. 

In particular, there was discussion about how much we really know about how variations in the genome translate into effects on health and disease, and also the challenges of analysis and interpretation of whole genome sequences. 

Right now you can certainly get much of the 6 billion letters of your genome read, but there’s still only a relatively small number of genes and variations that are clinically relevant and informative.

The discussion carried on long after the event had officially ended and into the drinks reception, so I took the opportunity to grab a few of the panellists who had volunteered for the project to hear more about their stories.

One of them was Helen O’Neill, a molecular geneticist at UCL, who had a pretty nerdy reason for wanting to take part, but discovered some important information about how her body breaks down drugs, known as pharmacogenomics.

Helen:  I had always dreamt of having my whole genome sequenced. As a geneticist I think it is amazing to have the opportunity to use the tools that you take advantage of every day in the lab and have an insight into your own genome.

Kat: Before you had your genome done, were there any considerations, things that you really wanted to take into account before you got it done?

Helen:  Not really. Admittedly I went into this quite blindly, really. I thought about it from the personal perspective of being something cool to have as a geneticist.

I really wanted to look up all the various aspects of my genome but I guess maybe in the back of my mind, I could have been worried if I'd thought enough about it. Truthfully, I didn't put that much thought into it, I was just excited to get it done.

It's only I think in the day or so approaching the genetic counselling and the results that I started to think, "What if…".

Kat: And obviously your genome is not just your own, it belongs to your family too and I understand you have an identical twin sister, so did you ask her? Because it's her genome too.

Helen: Yes, she's the first person I rang. I rang and I said, "Do you mind if I get our genome sequenced?", and she said, "Cool, go for it!"

Kat: So, buy one, get one free?

Helen: Yes, absolutely. Buy none, get one free!

Kat: And when you got the results, were there any things that came out that were particularly worrying or interesting? Was there anything that concerned you?

Helen:  I think to me; the most important or interesting aspect was the pharmacogenomics report because there were two specific things that I have been given.

One of them I didn't react to at all, but in the report it said, "You are a low metaboliser", so I would have been aware of this and never prescribed it. The second one was that I would have adverse reaction to it and indeed I did, and I was told to just keep taking it and it would get better.

Had I known that, I never would have been prescribed it and I certainly wouldn't have persisted in taking it when I had such terrible side effects.

Kat: And I notice as well you are very large with child. You got these results when you were pregnant, was there any information that made you think? Were there things you would have wanted to know?

Helen: I think for everyone who is pregnant, there's always a worry that you're going to find out something. I was hoping more than anything it would put my mind at ease.

It definitely made me feel that going forward, the information regarding my genome and the pharmacogenomics, that is something I would want to know from the beginning of my child's life and not put them through having to take medication that would not suit them.

Kat: With pharmacogenomics, I find it's quite interesting because it feels like there's more of a definite link between - you have this variation, you probably need this drug or that drug or this dose, but when it comes to thinks like traits and disease risks, there's much more of a black box between your genome and how you actually come out.

Helen:  I think our genomes in general are black boxes. We have a rare glimpse of light which we can see out of, but on the whole we are still trying to pick away pieces to get a clearer picture. And it will be like that for a long time.

In order to get to the point where we have a very clear picture, every single one of us holds a piece of the puzzle and if we contribute that, then maybe we'll get a better picture.

Kat: Another geneticist who took part in the project was Jess Buxton, a senior lecturer in medical genetics at Kingston University, who had a personal as well as professional reason for wanting to delve into her genome.  

Jess: So my initial reason for wanting to do it was having been involved for 30 years in genetics, I was just really curious. To me it was just very exciting that we can now do this in a matter of just a few weeks.

Having done my PhD in Human Genetics, it took me three years as part of a team to identify a mutation in a single gene. Not because we were particularly slow or particularly bad at our work, but because that is how long it too --

Kat: I feel your pain.

Jess: I think there's a lot of people in genetics who are just blown away by the speed of progress in the field.

I did also have personal reasons for wanting to know if I had any of the known mutations in any of the breast cancer predisposition genes of which there are quite a few - BRCA1 and BRCA2 being the most well-known, but there are a few others.

I lost my mum, she developed breast cancer at the age of 57 and sadly passed away at the age of 60. I have other relatives on my mother's side of the family who have been affected. Not quite enough to go through the usual routes to be identified as someone who would be able to access genetic services on the NHS. So I thought, "I've got this opportunity, I would really like to know."

Kat: Tell me a little bit about the process. What did you do, what happened before and what happened afterwards when you got your results?

Jess: We basically just had to spit in a tube to provide some DNA from a saliva sample. There was a pre-test counselling session where it was explained very clearly to us the kind of information that we would get back. More importantly, the kind of information it wouldn't be possible to get back from the test. That was very clearly laid out before we got the results back.

Once the results were in, it came in the form of a report divided into; very important, medically actionable things, things you might just want to know and then what I would call recreational genetics, so whether you can taste bitter tastes or not, your ancestry potentially --

Kat: You have blue eyes and blonde hair!

Jess: Yes, so I found out I have blue eyes and blonde hair. Gosh.

Kat: I have to ask about the breast cancer genes because that was your reason for doing it. What came out there?

Jess: So, the absolute stand out finding for me was that I don't have any of the known mutations currently known to really increase the risk of breast cancer.

Of course I know that doesn't mean to say there aren't mutations that we don't know about yet that couldn't be tested for, or there might indeed be genes that we don't even know about that might be involved.

But the incredible feeling of relief I got from just knowing that I don't have any of the obvious guilty culprits, it made me realise that I didn't even realise how much I'd been worrying about it until I got this kind of all-clear.

Kat: And you have family as well, so that must have felt like a bit of a relief for them. Although as you say, these are the known mutations and there are potentially known unknowns as well.

Jess: Yes, absolutely. The other thing that I thought was really nice about the genome sequencing that we had done was it was made very clear that this was going to be a dynamic report, that this will evolve over time as new knowledge is found and this will be fed back to us. As new variants are found, we'll be told whether we do have any of those.

For the immediate present I was able to tell both my daughters who are 18 and 23, I was able to say, "I don't have this, so there's no chance really that you have any of these either."

With all the caveats, I mean they've probably heard enough genetics from me over their lifetimes, there's limitations and rare variations and blah blah but it was good news for us, as a family.

Kat: And did you do anything else as a result of what came back to you?

Jess: I did join the gym.

Kat: Have you been?

Jess: I did re-join the gym, I should say. I have been twice. I think this was a couple of months ago. Initially, the thing I thought was, wow, I've been really lucky here, not to have any of these really difficult decisions.

Some people have to make really difficult decisions, the famous example being Angelina Jolie, who had inherited BRCA1 mutation and decided to go ahead with a double mastectomy and I think also had her ovaries removed.

So I thought, well, it's all down to me really. I really should make the most of this and just get on with doing everything I can to be as healthy as possible.

But as you can see, I am holding a glass of wine in my hand at the moment. So I guess it's real life isn't it? We all try and do the best we can most of time.

Kat: Jess’ genetic test was able to put her mind at rest. But for another participant, biotech advisor Ayokunmi Ajetunmobi, known as AJ to his friends, the test led to an important medical discovery, although not in the way he’d expected.

Ayokunmi: So I wasn't particularly thinking about finding anything. As someone who has an academic background in psychiatric genetics, then went to work in a genomics start-up, I felt I was being somewhat hypocritical by not actually having had my own genome sequenced.

So when the opportunity came forward for me to actually do this, I thought, you know what? I advocate people having their own health data and this is an opportunity to own one aspect of my health data, why not go for it? Why not take that leap? And that was why I did it.

Kat: How did you find the process of going through the pre-test counselling and the post-test counselling? Was it what you expected?

Ayokunmi: It was more or less what I expected. I think probably like a lot of the participants; I was a little impatient because I felt I knew quite a lot. At least with the pre-test I felt like I knew quite a lot of the risks, the things I should be aware of --

Kat: Yada yada, genome, blah.

Ayokunmi: Yes, exactly. How DNA works and what it means and all that stuff. But right before the moment I was getting my results, there was a certain wave of nervousness, nervous anticipation and a little bit of fear. I'm not going to deny that.

Having someone there, even virtually, to walk me through the results was comforting.

Kat: What did your results tell you from the health perspective and then maybe from the other perspectives that they were looking at?

Ayokunmi: So the results, as I said in the documentary were not very interesting at all, although I did get two results that illustrated an elevated risk of certain conditions. One was lactose intolerance, which was completely new to me. The other was chronic kidney disease. It's polygenic, it's got a lot of environmental factors associated with it as well, so it's not a direct link. But I do have an elevated risk of getting that.

So that was from a clinical perspective. Like I say, not very interesting. Then you've got some cool health traits, lifestyle trait stuff that was interesting and kind of fun.

What actually was perhaps more instructive for me was that a lot of the data they were using to make decisions about what my various traits meant, weren't actually related to people of my ethnicity, right?

One of the things I think we really need to consider within the medical community, is how to democratise access to these new technologies and build better datasets that are actually more encompassing of the world that we live in.

Kat: Absolutely. It's a global genome not just a human genome.

Ayokunmi: Exactly.

Kat: And you told an interesting story in the debate afterwards, that you got your genome done, there was nothing particularly interesting in there, and then you went to the doctor. What happened then?

Ayokunmi: Yes, it was quite a funny transition. There was I think about three days or so between getting my results and then just going to get travel vaccines.

I got my results, nothing serious to worry about, I was feeling great. Then I went to get my travel vaccines and by chance the nurse said, "Let me check your blood pressure."

She took my blood pressure, it was high. She looked at my medical history and she saw that I had a history of elevated blood pressure and she said, "Maybe we should put you on a 24-hour blood pressure monitor."

I went on that, came back the next day and she said, "We've got to do something about this, this is a real concern."

A couple of days after that, I was on blood pressure medication. So I had spent all my time worrying about what my genetic results were going to tell me, but actually there was something far more pressing in front of me that I had to make actionable.

So while I was fortunate that there weren't any genetic results to be concerned about, we have to understand that it's only a part of the puzzle. It's only one piece in the picture and we shouldn't over-react to that information.

Kat: When we're thinking about the applications of this kind of sequencing, a lot of people in this room, a lot of people in the world, is this something that should become routine for everyone? Where is your sense of where this is going?

Ayokunmi: I have fairly strong opinions about this and they are probably in the minority. We know that healthcare systems are creaking all over the world because of an aging population and chronic illnesses. I think the only way to combat this is for people to own their own health.

I used the example in the debate of if I ask somebody the state of their financial health, they could take out a mobile app, they could go to their bank and they could see how much they've got in the current account, their savings account and it gives them the power to make decisions about what they're going to do next.

If I ask somebody how healthy they are, they shrug their shoulders. They tell me, "Well, the last time I went to the GP, the last time I had a health check, nothing came up." They have no way of actually making informed decisions.

So my belief is that they should be widespread. It shouldn't be done in a cavalier fashion - there should be protections and safeguards and regulations - but we need to empower people to own their own health data. Genetics is the start of that, in my opinion.

Kat: Finally, I managed to grab event organiser Alan Thornhill from diagnostic genetics company IGENOMIX. He also got his genome sequenced for the film, initially for the same reason as most of the rest of the panel. 

Alan: Mainly scientific curiosity. There was a little bit of family history, a bit of unclear family history. If I was that bothered about it, I would have gone to a GP or a geneticist and had that conversation and had some testing. So it was more curiosity than anything else.

Kat: Do you find for many of us in the field of genetics it's like, "Ooh, I do wonder what's in there. I would like to see what this is like and what's in there."?

Alan: Yes, I mean I knew basically how the tests worked and what was in the report and I knew there was ancestry, where I didn't expect any surprises and I didn't get any surprises.

I knew there were traits, which is kind of just recreational, fun stuff but obviously I did want to know if there was some risk of serious disease or something where there was a strong respect of where I could actually change something in my life and do something.

I'm a single parent looking after my three kids, and the thing they said when their mum passed away was, "You can't die." Well, obviously I'm going to die at some point, but whatever I can do to try and prolong that life, I will try and do.

Kat: So what was the process like for you of the pre-test counselling and then getting your results?

Alan: Well, it's pretty straightforward. Because I've worked in genetic testing for a while, not necessarily whole genome sequencing, I know that both pre and post-test counselling is really important. Pre- to try and understand why you're doing the test and post- to try and explain the results.

Not naming names, but I think I took it a lot more seriously - I mean, I ended up having probably the most serious result but that's kind of chance, but I think I took it a lot more seriously than a number of my colleagues, who said, "I've got 20 minutes to have that counselling session."

Now, I would be a strong advocate of making sure you're in a quiet room, make sure you have someone you can speak to afterwards, all of that good clinical advice, if you like.

Kat: And the results, what did they mean for you and for your family?

Alan: Well, I had a clinically significant result, which I think is probably quite rare if you took the general population. I have got a bit of family history which was a bit unclear, but I do have family history of breast cancer.

I’ve got a BRCA1 mutation, which gives me an increased risk of breast, prostate and pancreatic cancer. My father passed away of pancreatic. He had a lot of bad environmental risks which I think maybe contributed heavily, but that's a little concern for me.

More importantly, I have three children. They are growing up, they are 20, nearly 18 and 16, two girls and a boy in that order. Because the girls lost their mother from breast cancer they assume they are going to get breast cancer, and I think they think they are going to get it from some risk factor, genetic or otherwise, from their mum's side.

So obviously, it was quite a big deal to find out actually they've got a breast cancer mutation risk from their dad's side, which came from my dad's side.

Now, I must make it clear that I found it quite a devastating result because I was worried about telling them. But we don't know that they're positive. We've got a genetic coin to flip for the three of them so far, but they've been told now and we move forward and deal with it as we have dealt with some difficult things in the past.

Kat: What were their reactions to it? Are they keen to get tested themselves?

Alan: It turns out - and I was aware of this but obviously I had to keep my mouth shut a little bit whilst the whole testing and filming process was going on and they were in the middle of their exams - so this is not a case of I withheld some information because it suited me. I've changed timings to suit them and they understood that when I told them. They all had significant exams this year and I told them, "The reason I didn't tell you straight away…", even though I was burning to tell them, "…was because you've got enough stuff to worry about.

Their reactions though, obviously they were disappointed and they said, "We knew this bad news was going to come at some point." Obviously they thought it was going to come from a different direction. So in a way they were prepared for it.

They had already had conversations between themselves about what the likely implications are if they turn out to be positive, for example having a mastectomy. They've already talked about that and thought about it.

But we've got another road to go down now, where we actually get properly tested, properly counselled and so on.

Kat: There has been a lot of debate tonight about the pros and cons of it. Having been through this process yourself, do you think this is something that should be made compulsory among the population or made much more widespread? What has this whole process left you feeling about whole genome testing?

Alan: I have no commercial interest in trying to promote it as everybody should do this, it should be compulsory, it should be widespread. I think it's something that people should know about, but I've always thought that about things I'm involved in. Have some knowledge, understand it and then make an informed decision.

One of the questions tonight concerned informed consent. It's very difficult to have fully informed consent these days, there's so many nuances. I think we shouldn't be paternalistic and patronising for the so-called general public, I think we should do our best to try and educate people.

I've heard someone saying, Whole Genome is Coming, like Winter is Coming. It kind of is, but it doesn't mean we need to do it badly.

We can inform people, educate them but what we must do is make sure that it doesn't get taken over by people who are not prepared to put the work in, put the genetic counselling and the informed consent in.

If they just say, "Hey, buy one of these from WHSmith and this will solve all your health problems." That would be a burden on the NHS. Doing it properly - and I'm not saying how to do it properly, I'm just saying there's a chance to do this properly - is going to improve people's lives.

There's a long way to go and there's a lot more to learn, but I think we can do a good job of that.

Kat: We've now got to a point where genome sequencing is cheap enough, it's fast enough that it really does become effectively a consumer product. We're starting to see, I guess, early adopters of this. How does it feel to be one of those?

Alan: Well, it feels exciting but given my result, it's also not something to be taken lightly. The good news is that I didn't take this lightly from the beginning. I knew that whatever result I got I should treat it with some kind of respect.

I don't really think of myself as an early adopter, but obviously being middle class and privileged and educated yes, I am in that lucky group to be an early adopter. But it isn't like buying a new iPhone.

I think this comes with a bit of responsibility, which is why we've done this event. This event, even though it may not be perfect, was about opening the doorway and saying, "Okay, we understand genetics quite well and we're struggling with some of the results, so is there a way to improve how we can deliver this?"

Because if we can't get it right, I'm pretty sure, having some commercial involvement in other things myself, that it's very easy for the commercial ball to roll down the hill without all the checks and balances.

So I don't think a purely academic direction of travel is right and I don't think a purely commercial one is. I think we've got to work together to make this a good, effective offering with the best information available to whoever adopts this test.

Alan Thornhill, speaking to me at the LOVE MY GENOME event last month. And you can trust that Genetics Unzipped will be doing our very best to talk about the issues and implications of personal genome sequencing as best we can as we move ever further into this brave new world.

Take a trip in the genetic time machine

Kat: Not only can our DNA tell us a lot about who we are and our risks of various diseases, it can also reveal at least some of the story about where we’ve come from. 

Your genome is a genetic time machine enabling us to see back in time, linking modern populations to our ancestors all over the world (and, if you go far enough back, all the way to the very first humans to emerge in Africa). 

To find out more about some of these ancestral genetic secrets, I went to meet Marc Haber at the Sanger Institute, who is investigating the origins of ancient people and how they are connected to populations today. I started by asking the really big question… how did we get here?

Marc: People have been trying to answer those questions for a long time using different techniques, using different types of genetic data. Now we are using whole genome sequencing, before, people used just a few ‘snips’ or variants on the DNA for people to understand or to look at those questions.

We know enough now to say that we have as modern humans, originated in Africa around 60,000 years ago. Maybe there was some population structure that started in Africa around 100,000 years ago, even older then went people exited Africa.

People exited Africa around 60,000 years ago, they went to occupy the globe very quickly after 60,000 years. So we know the big picture quite a bit now.

People started looking in more detail at how Europe was populated and what the relationship is between Europeans, East Asians, Middle Easterns. So we have the big picture, we are kind of certain about how it came to be but we are more looking at the details now.

Kat: So, tell me about some of those details. What sort of samples are useful when you're trying to pick out these details of; let's look at a part of the world, a region, let's look at the populations there and figure out how they are related to each other, and then how they are related to ancient history? How does that process work?

Marc: More samples is usually better to understand the full history of a region, for example Europe. You need samples from all over Europe, but modern DNA is not enough in this case.

People have studied Europe for decades using modern DNA, but then when people started looking at ancient DNA, they found very different processes that gave the modern population in Europe their genetic diversity.

So your question is, what samples are important? Modern samples are important, but also layers of ancient samples are important. I'm speaking about time layers of getting those samples.

Kat: So something like digging around in graveyards from 100 years ago, 400 years ago, further back - how far back can you go?

Marc: Archaeologists for many years have catalogued sites according to culture and they have some ideas about what cultures were important in some regions and what cultures have spread.

So there is always this study of a culture spread by spreading their genes or just spreading their ideas. Geneticists here come and look at those hypotheses, we try to give answers about those old hypotheses from archaeologists.

Kat: And what have you found? I know you had a study recently looking at the population in Lebanon and seeing where they might have come from historically?

Marc: Yes, so in Lebanon we had a challenge. Ancient DNA would degrade with time, so this is why when you look at the ancient DNA samples which have been studied and published, most of those are in the recent few thousand years ago, because ancient DNA would degrade with time.

Another complexity is climate. Ancient DNA would degrade with hot climate. Warm, hot, humid climate is very bad for DNA preservation. So we had this challenge in the East. Very few samples come from the East. So we had attempted to sequence samples that were around 4,000 years old from Lebanon.

We found that if you take the genomes of those people who lived around 4,000 years ago and people who are living today in Lebanon, they are very similar. This was very surprising to us because the region’s history is very vivid.

You have a lot of migrations, conquests in this region. But this seems to have contributed little on the genetic side. You have this continuity going from 4,000 years ago until today.

Now, people who were living 4,000 years ago in this region were a mixture of two populations. One population that arrived from people who were hunter-gatherers from this region, then a migration from people coming from the East - a massive migration mixing with those people, giving rise to the civilisation that was prospering 4,000 years ago in Lebanon.

Kat: It's absolutely incredible to think that the kinds of times that were written about in ancient texts, you can now get insights into the DNA of people that lived at that time and went through some of the historic events that are described.

Marc: Yes, this is amazing. It's kind of a time machine. Ancient DNA is a recent tool. It's a very powerful but a recent tool. It has evolved because sequencing technology has evolved.

Now we are able to sequence better and at a lower cost, so this is how ancient DNA evolved. Before we had ancient DNA, we had to make models or make some predictions.

Some of those were good. Some of those were able to tell us how the modern human diversity exists. But the problem with models is you always pick up the simplest model.

Human history has been very complex. This is why ancient DNA is very important. It can tell you things that modern DNA cannot tell you or models cannot tell you.

So it's a time machine to go and look at the genetics of people who lived thousands of years ago, and how they relate to our genomes

Kat: With the study in Lebanon, what made you particularly interested to do this work?

Marc: I am a typical Lebanese. I have the genome which is present. We can see it in present day Lebanese. It's related to the Bronze Age samples that I have studied, it's very similar to people who lived 4,000 years ago in Lebanon.

Kat: That must have been incredible, to feel that connection, that your DNA is their DNA?

Marc: Yes, it's very interesting to look at where you come from, basically, and look at your ancestors who lived 4,000 years ago. Yes, it's very exciting.

Kat: And finally, what are you working on now? Are there populations that you're so interested in, you want to know where they've come from and why that group of people is here and the journey that brought them to this place?

Marc: So, since our last study in Lebanon on the Bronze Age samples, we came across a very unusual burial that archaeologists were struggling to understand. I think this is where genetics can start solving those mysteries and this is what we're working on now.

Kat: So what, trying to find out who was this person and where did they come from?

Marc: Yes, it's a group of people who apparently died in a very brutal way, but they seem to be not from this specific region.

Kat: Oh god, you're not from around here so we're going to murder you?

Marc: Well, we're trying to solve it with genetics, and genetics is giving us a lot of clues about it.

Kat: Wow! When are you going to have answers to that one? This is like a whodunnit!

Marc: In a couple of months, probably.

Kat: Right, I'm definitely going to come back to you about that one.

Marc: Yes, sure.

Kat: The Sanger Institute’s Marc Haber taking me for a trip in his genetic time machine. And you can find out more about some of the fascinating results from his research on ancient Lebanese people and also a recent study on the genetics of the Crusaders by following the links on the page for this podcast at

Shark attack

Kat: As Marc has shown with his work on ancient humans populations, genetic studies can tell us a lot about the relationships between populations. That’s also true for animals such as blacktip reef sharks, which are the topic of a new paper in Heredity, the Genetics Society’s journal. 

But, as study author Gavin Naylor explains to James Burgon in the latest Heredity podcast, the results from this research can be misleading unless you’re very careful.

Gavin: We have long studied the diversity of different species of sharks, but we hadn't really explored the diversification within a species and in the few instances where we had looked a diversification within sharks, they seemed to be genetically fairly homogenous.

That is not the case with the Carcharhinus melanopterus, the reef blacktip shark. In that particular instance we saw that sharks which were derived from different island systems seemed to be genetically distinct.

Therefore we thought that this would be a fairly good study species to evaluate patterns of genetic variation in the context of a range expansion.

Kat: You can hear the full interview in the latest Heredity podcast - just search for Heredity in your favourite podcast app, or follow the link from the page for this podcast at  

That’s all for now. Next time we’ll be back with more stories from our series exploring 100 ideas in genetics, telling some tales about sex and death.

You can find us on Twitter @geneticsunzip or email us at with any questions and feedback. Please do take a minute to subscribe on Apple Podcasts, or wherever you get your podcasts from, and it would be great if you could rate and review - and more importantly, please spread the word so more people can discover the show.

Genetics Unzipped is presented by me, Kat Arney, and produced by First Create the Media for the Genetics Society - one of the oldest learned societies in the world dedicated to supporting and promoting the research, teaching and application of genetics. You can find out more and apply to join at  Our theme music was composed by Dan Pollard, and the logo was designed by James Mayall, transcription is by Viv Andrews and production was by Hannah Varrall. Thanks for listening, and until next time, goodbye. 

References and further reading:

020 Sex and Death

020 Sex and Death

018 Cut. Paste. Pair. Repeat.

018 Cut. Paste. Pair. Repeat.