The Tölt Tales

Episode 10 - Heiðrún Sigurðardóttir

• The Tölt Tales • Season 1 • Episode 10

Share episode

For the last episode of our 1st season we welcome our first scientist. Since the creation of this podcast we wanted to invite people beyond skilled riders; so we talked with Linda Andersson, a horse nerd and veterinarian at Saxtorp Hästklinik, and with Zola Runsten, a farrier specialised in Icelandic horses.

In this episode we now talk with Heiðrún, our first scientist focused on genetics behind the gaits of Icelandic horses. She recently passed her doctoral thesis at SLU on genetic regulation of ability and quality of gaits in Icelandic horses, but listen to her she will explain that better!!

Here the link to her paper:


Music by Cob.
Follow us on Instagram and Facebook, @the_toelt_tales.

Lionel:

Hello everybody, and welcome to The Tölt Tales Podcast. Hello, Heiðrún.

Heidrun:

Hello.

Lionel:

How are you?

Heidrun:

I'm fine, very good.

Lionel:

We're super happy to have you. This is our first scientist on the podcast, so congratulations.

Heidrun:

Thank you.

Lionel:

So you will be the best scientist in our podcast for quite some time.

Heidrun:

For now, at least.

Lionel:

Yes, for now, at least, yes.

Heidrun:

That's good, yeah.

Lionel:

Yeah, you will be the best.

Heidrun:

That sounds good, sounds good.

Lionel:

Do I need to refer you as a doctor now?

Heidrun:

No, please don't.

Lionel:

No. No. All right.

Heidrun:

It's very pretentious. Yes?

Lionel:

Do it's true?

Heidrun:

It is true. It is true. I would use it if I'm in sort of a trouble or something. Yeah.

Lionel:

Oh, okay. If you're in trouble. Okay.

Heidrun:

Or if I need something.

Lionel:

To get away from a fine or something like this. This is how we start usually. We ask the guests to present themselves.

Heidrun:

Yes. So my name is Heiðrún Seiguradóttir. I am from Iceland and today I am a PhD in… I think it's animal genetics I am a PhD in.

Lionel:

Okay.

Heidrun:

Because that was my topic in my masters.

Lionel:

Right.

Heidrun:

And I specialize in horse genetics and genomics. And I am also a breeding judge for the Icelandic horse. I have been doing that since 2015, which is a lot of fun. It sort of makes you a little bit of a public person also, but in the horse world, even though I'm a very small name in it. Yeah. But and then I've been using that experience in my studies also. So and yes, I've been a horse enthusiast since I was five years old. My grandmother, she sort of introduced me to horses. And yeah, and ever since, I've been sort of a horse nerd.

Lionel:

Perfect. Yes, we're going to talk about the amount of horses you have in a minute. Can you describe a bit where did you study? I thought that was important.

Heidrun:

So I started, I took my undergraduate study here in Iceland. It was a cooperation between the agriculture university in Kvannere and also at Hålar University. Right. So I did one year in Hålar and two years in Kvannere. And then I went to Sweden and took my masters at SLU in Uppsala. In Uppsala. And then soon after I started my PhD, which was a cooperation between SLU and the agriculture university.

Lionel:

Right.

Heidrun:

In Iceland.

Lionel:

So you were, is it a part-time between the two universities or?

Heidrun:

Yes. So I started here in Iceland and I spent approximately one and a half or two years. I was doing courses, I was collecting samples and such. And then we went, I went to Sweden, fall 2022. And there I sort of finished up doing the analysis and writing.

Lionel:

Right.

Heidrun:

So yeah, all in all, it has been like over a five year period or so.

Lionel:

And that's how long it took to write your thesis?

Heidrun:

Yeah, I took, I mean, there was a one year that I took off in between.

Lionel:

So that's quite a, we're going to talk about your thesis a bit later. So let's go to the nerd part. Before we restart the recording, we were asking you if you were riding. And then you told us, how many horses do you have? How many horses do you own?

Heidrun:

I own five horses.

Lionel:

Which is a good number.

Heidrun:

It's a good number, but it's rapidly expensing.

Lionel:

How come you have five horses then?

Heidrun:

So first, I had one gelding, and then I decided I wanted to start breeding. So I bought a mare. And when I went to Sweden in 2022, I started breeding my mare because I wasn't riding her anymore.

Lionel:

Yeah, that makes sense.

Heidrun:

And during my stay in Sweden, I received three more horses.

Lionel:

Right. So then we end up with five.

Heidrun:

Yeah. So they're just three last ones are just youngsters.

Lionel:

Yeah. Do you intend them to sell them or like to?

Heidrun:

No, no, breeding for myself.

Lionel:

Breeding for yourself. You're riding your horse at the moment?

Heidrun:

Not at the moment. I haven't started yet since I got back from Sweden, but soon, hopefully.

Lionel:

Yes, summer it is.

Heidrun:

Yes, hopefully, trying to get myself into shape again and...

Lionel:

Yeah. You were not riding in Sweden?

Heidrun:

No. No? I was thinking that I should maybe take the opportunity and ride some other breeds, for example. All right.

Lionel:

Okay.

Heidrun:

But then I kind of never got around to do it and I never did.

Lionel:

Not even being Medruttari or like a co-rider for an Icelandic horse?

Heidrun:

No. No. I did almost not see any horses while I was in Sweden, except on television. So...

Lionel:

Yes, there is. How is life without horses every day then?

Heidrun:

It was different. It's a bit different, but I had enough to do.

Lionel:

Yes? Usually we ask, when is the last time you bought a horse?

Heidrun:

Yes. 2018, I think.

Lionel:

All right. And that's your mare?

Heidrun:

2017. Yeah. Yes.

Lionel:

And that's with this mare that you're breeding at the moment?

Heidrun:

Yeah. Right. Very focused on...

Lionel:

Yeah?

Heidrun:

Yeah.

Lionel:

Yes. Yeah. I mean, it's cool. It's not often that we meet people who just have not... like a horse business, and they breed their own horses.

Heidrun:

We'll see if it works. I don't know.

Lionel:

Well, you have five horses, so now you need to make it work somehow. So, let's talk about your thesis. Obviously, we contacted you because... not because you're a doctor, not because you have a PhD in... What did you say?

Heidrun:

Animal genetics.

Lionel:

In animal genetics, but more specifically because your thesis was about Icelandic horses.

Heidrun:

Yes.

Lionel:

And I even have the title, which is Exploring the Genetic Regulation of Ability and Quality of Gaits in Icelandic Horses.

Heidrun:

Very good that you have the title, because I can never remember it.

Lionel:

Yeah.

Heidrun:

I've been trying to remember it for the last five years.

Lionel:

Yes. I should have asked you before.

Heidrun:

I would have been a good test to see if it's you. Yeah, exactly.

Lionel:

Before I start asking questions to pretend I understand what you wrote, can you give us the framework of your paper? And I know it's four different papers, if I understood well.

Heidrun:

Yeah.

Lionel:

And if you can give us the dumbed down version or the public version of your papers.

Heidrun:

Yeah. So as it says in the title, the main goal was to explore the genetic regulation of the ability and quality of gates.

Lionel:

Yes. You do. You do the title.

Heidrun:

I need to think though. But that was sort of the main goal. And when we started, we... I mean, that was just looking for a needle in a haystack, really, because we didn't really know what we were going into, because it's a very complex trait with the gates. And it can be quite difficult to sort of find those Gs that are during the regulation. So we didn't really know if we would find anything.

Lionel:

Okay.

Heidrun:

So we sort of went in a little bit blindfolded.

Lionel:

Is it why the exploring?

Heidrun:

Yeah.

Lionel:

Yes?

Heidrun:

Yeah.

Lionel:

And not finding because... No, okay.

Heidrun:

It was sort of just like throwing out a... Like a fishing.

Lionel:

A fishing rod.

Heidrun:

Yeah. And then just waiting for something to like...

Lionel:

To happen.

Heidrun:

Yeah.

Lionel:

Okay. Okay. And you started with that question five years ago.

Heidrun:

Yes.

Lionel:

This is you and your...

Heidrun:

Supervisors.

Lionel:

Supervisors.

Heidrun:

Yeah.

Lionel:

You just sat down and say, this is what we will try to achieve.

Heidrun:

Yeah. Shake hands. I mean, we... Yeah, exactly. We knew that we had this DMRT3 gene.

Lionel:

Yes.

Heidrun:

And we knew what that does.

Lionel:

Okay.

Heidrun:

But there are a lot of things that the DMRT3 doesn't explain. For example, some horses that should be able to pace, they don't really pace.

Lionel:

Right. Okay.

Heidrun:

And all sorts of questions like that.

Lionel:

Okay.

Heidrun:

So we, of course, wanted to try to find genes that are associated with pace and tölt, because those are the most valuable gates for the Icelandic horse. But we still kept in, like, gallop and trot and walk and everything, just because we didn't know if we would find anything about the other.

Lionel:

Right. Okay, okay.

Heidrun:

Actually, when I came into the study, I got sort of a flying start with it, because one other PhD student had identified a peak in genome-wide association study that was associated with back and croop. Okay. And that was quite interesting. It was a good signal in the association plot.

Lionel:

What would that mean? That means that when someone, like another researcher, looked at the DNA of horses, they found in the DNA of the horses something that is related to the back and croop. Yes. Is it the case of identifying that gene?

Heidrun:

It identifies a locus in the genome that is somehow associated with a certain phenotype. So we take a phenotype that is a breeding score for back and croop. And we found a correlation between the same SNP genotypes with the same scores.

Lionel:

So basically, when you were looking at a breeding assessment score, is it what you were looking at?

Heidrun:

Yeah.

Lionel:

So you were like, okay, back and croop, like high score, and you were looking if you find that in the DNA of the horses. Is it this kind of thing?

Heidrun:

Yeah, it's like not all of them, but significantly most horses with higher scores for that trait.

Lionel:

Yes.

Heidrun:

They had the same genotype within that snip or within a few snips in a certain region.

Lionel:

Yes.

Heidrun:

So the G was the genome-wide association analysis. That one pinpoints sort of the region where there is something going on that has an effect on the on the trait. Yes. But it doesn't tell you specific factors in the gene.

Lionel:

No, no, no, no.

Heidrun:

Or anything like that.

Lionel:

But you can tell you this is where it happened.

Heidrun:

Yeah. And then you can sort of go into these genomic browsers and see sort of if you take that region and put it in the browser.

Lionel:

Yeah.

Heidrun:

And then you can see which genes and which factors are in that.

Lionel:

Okay.

Heidrun:

But even though you see what genes are there, yes, most genes in horses are not investigated.

Lionel:

Right.

Heidrun:

So it's usually just the reference genome is from one horse, a thoroughbred horse, and then they can build up a sort of a...

Lionel:

Like a map.

Heidrun:

Map for the whole breed or the whole species.

Lionel:

The whole species, yes. And so you said that the moment you started your paper, someone found the back-end group location.

Heidrun:

Yeah, that was one of my PhD student colleagues at SLU. So and then I came in with some knowledge about the phenotype that they were working with. So it was a good start for me to get to cooperate with her, with her findings, so I could go do some more analysis, statistical analysis on the sort of, on the horses that carried the same genotypes and see like how they were also different in other traits. And we actually found that this region on the back-end group, this has a significant effect on tölt and pace also in the Icelandic horse.

Lionel:

Is it like eating the bingo lotto of researchers?

Heidrun:

Yeah, exactly. It was a really, really good start in my studies. I didn't really have to start from point zero, starting to collect samples and such. So they had some samples.

Lionel:

The groundwork was there. And they had samples that you can look into and study without you having to re-create your sample base, I guess?

Heidrun:

Yeah. But then this was the first paper that we published. And after that, I collected more samples because it's always better to have more samples. And then we did a new sort of GWAS analysis.

Lionel:

Yes.

Heidrun:

And now, this time with a bigger or larger dataset, we found regions that were associated with PACE.

Lionel:

All right.

Heidrun:

So that was also very interesting. And in those regions, we had genes that are associated with some function in neural tissue in humans.

Lionel:

Okay.

Heidrun:

And that is sort of a good clue to that they might be also having some effect on the movement system, because that's the neural system that is controlling movements.

Lionel:

And what does it show related to the PACE? Does it mean that you could, looking at the DNA of a horse, say it's most likely a good PACE horse, or not a good PACE horse? Is it this kind of...

Heidrun:

I always find it a little bit difficult to say, this is like it is, because we only have statistics on it. But the statistics tells us that horses with a specific genotype in each region are better PACEers than the others. And even though they have the AA genotype in the DMRT3 gene. So to some extent, these genes do segregate a little bit between the 4-gated and 5-gated horses that all have the same DMRT3 genotype.

Lionel:

So that means that you, again, statistically, you could say if it's a 4-gated and a 5-gated.

Heidrun:

Yeah, you could really, yeah. If you could genotype horses for these two locations, then you could sort of get a sort of a prediction on it.

Lionel:

You reasonably could say it's most likely a 4-gated and most likely a 5-gated. Can you go even further than that, saying how good of a pacer is? Or it's not there?

Heidrun:

No, not really. Because, I mean, what is a good pacer?

Lionel:

Right, okay.

Heidrun:

Is it like, because when we are assessing pace at breeding field tests, then we are assessing the speed, we are assessing the beat, we're assessing the stride length, we're assessing the sort of body posture. We're assessing a lot of things, the security and the sprint. And so, one thing is, yes. Yeah. And so these phenotypes are really sort of complex as well. So even though we get a hit on, like these two regions do have some sort of influence on pace, we can't really say what it is, no, okay. What influence it is.

Lionel:

Yes, okay.

Heidrun:

So that is something that we need to investigate further.

Lionel:

Okay.

Heidrun:

And we were able to do like one more step in my studies, to we had some whole genome sequenced, a whole genome sequence analysis. So by that, we sort of get more dense data on the genome.

Lionel:

Yes.

Heidrun:

So we could go into these regions that we had already identified and pinpoint some possible causative factors.

Lionel:

Okay.

Heidrun:

And in one of those regions, we found what is called a frame shift mutation, which causes an alteration in the protein coding. And then it produced a premature stop codon. So horses carrying this mutation, they sort of produce a shorter protein than the others. And those horses seem to have less ability to pace.

Lionel:

Oh, right. Okay.

Heidrun:

Or at least they got lower scores.

Lionel:

Lower scores.

Heidrun:

Okay. So, and this has actually been seen in mice.

Lionel:

Okay.

Heidrun:

That when there is a loss of this protein, they sort of lose some ability for movements. I mean, with this group of horses, with the whole genome sequenced, I mean, they were only 39 horses. Right. So, we can't really say that any... There is no statistical differences in that... No, not in that data set, but we just... We had that statistics from before, so we just used that to go like...

Lionel:

One step down, or... Yeah, yeah.

Heidrun:

So, it's always difficult with these more data sets.

Lionel:

Yes.

Heidrun:

So, we... Yeah. We didn't expect to get any sort of statistical differences in groups with different genotypes, but...

Lionel:

The way to go about it would be to sample more horses, I guess?

Heidrun:

Yes, but I think...

Lionel:

Oh, it's not even the question.

Heidrun:

It's not really the question, because, I mean, we found this frameshift mutation and all these horses that had this genotype that we had previously established as giving lower scores for pace, they all had this mutation. So, it's like you don't really need to...

Lionel:

No, okay, you know that there is a relation.

Heidrun:

So, the next step would be to do a functional analysis. So, we would go into some tissue analysis to the RNA and such. But I've never done that, so I can't read. No, that's not my sort of specialties.

Lionel:

Specialties, no, no, no.

Heidrun:

But that would be very interesting to cooperate with people in that field and go a little bit further with it.

Lionel:

A little bit further away, yes, or down, or I don't know.

Heidrun:

See the expression, and yeah, exactly.

Lionel:

From the DNA to the actual material, tissue, etc.

Heidrun:

Yeah, yeah.

Lionel:

At the beginning, we discussed about what exactly you were doing. We talked a lot about Pace. Did you have anything about Tölt?

Heidrun:

I mean, we saw that both this region that was associated with Bakkenkrupp did also influence Tölt.

Lionel:

Okay.

Heidrun:

And it's the same with these two regions that we found associated with Pace. One of them had an influence on Tölt as well. But we did not find any direct association with Tölt scores. But I think that is probably due to the sort of the phenotypes that we are using.

Lionel:

Okay.

Heidrun:

And also that we were mostly working with horses that have been presented at these breeding field tests.

Lionel:

All right.

Heidrun:

And these horses are heavily preselected. I mean, it's only about 10 to 15% of the population that is assessed, and these horses are preselected.

Lionel:

So it's a bit of an elite already, is it what you mean?

Heidrun:

Yes. Yeah.

Lionel:

It's not like you run around in Iceland or in Sweden, for that matter, grab a horse and...

Heidrun:

No, because we need the phenotype.

Lionel:

Yes.

Heidrun:

So if we go and grab any horse, then they most likely don't have a phenotype recorded. So we need that to do the association.

Lionel:

The association between the score and what you're going to find.

Heidrun:

So we were a little bit limited by this. If we could have sort of maybe do the assessments, choose horses, both very bad tulltars and very good tulltars, and we could do the phenotyping ourselves, we could maybe get some interesting results from that. But because we mainly have horses that are really good at Tölt, then it's difficult to find any region that really segregates between the good and the bad, because they're all good.

Lionel:

And also the goal of the breeding assessment is breeding. So if you have a bad, if you know your horse is not a bad horse, but that doesn't have what it takes to be a breeder, you will not show it to a breeding assessment.

Heidrun:

No, it costs money and doesn't make sense to do. Even though me as a scientist, I would like all horses to come there.

Lionel:

Then you will have a perfect map of the actual quality of the...

Heidrun:

Exactly. But now, I mean, with all these advances in technology, with AI and such, we could perhaps in the future do some phenotyping with AI, with help from AI, and then get very cheap assessments for horses.

Lionel:

You ask a horse to go in the four or five gates analysis of the video and give a score that is somehow a score.

Heidrun:

Hopefully, we could do that, and then we could have some more sort of data to get more results. I think the phenotypes today is the limiting factor in our studies.

Lionel:

It's funny how we go from talking about pure a horse, which is down to earth, to we do all those methods, methodology of scientists going through, or maybe AI could help us. It's quite funny how deep you can go into that.

Heidrun:

I think there are actually already some free software online where you can start to take videos and teach the machine to... Yeah, so it will become easy probably in the future.

Lionel:

There is an interesting part where you're like, where do the Icelandic horse come from? Do we know or do we have a better idea now where they come from?

Heidrun:

I mean, the historic records and some DNA analysis, they sort of concur on that they came from Scandinavian countries and the UK and from that area. I mean, the Icelandic horse is also related to the Mongolian one, and that was probably because many of the Vikings in the Scandinavian countries. I mean, these horses were, I'm guessing that those horses were kind of comfortable to ride.

Lionel:

Right, yes.

Heidrun:

Some of them with the DMRT3 gene, and so probably many of them were used for transportation and taken to Iceland. And taken to Iceland. And it has also been shown that it's actually very difficult to pinpoint the exact place where the origin of the DMRT3 mutation arises.

Lionel:

The DMRT3, what is the role of that? Is it a gene?

Heidrun:

That's a gene, and that's the gene that is responsible for the lateral movement of horses.

Lionel:

Is it what we call the gatekeeper, or what you put as the gatekeeper?

Heidrun:

Yeah, the gatekeeper is the mutation in the gene.

Lionel:

Okay, and what does this gene allow then? Sorry, I cut you off.

Heidrun:

Yeah, yeah. So, the wild type is the... That's the sort of the three basic gates, the walk, trot and encounter. So, horses, the sport horses and Thoropreds, they are all fixed for the wild type. But then, there's this mutation.

Lionel:

All right.

Heidrun:

And in the Icelandic horse, this mutation allows them to tölt, and with two copies of the mutation, they can pace.

Lionel:

All right.

Heidrun:

And that's in the Icelandic horse. But then, you have like the cold-blooded trotters in Norway and Sweden. They also carry this mutation in lower frequency than the Icelandic ones, though. But for them, it sort of helps them to gain more speed without sort of jumping out of the gate.

Lionel:

Okay.

Heidrun:

So, I've heard in some cases that this gene has also, or the gatekeeper is called gatekeeper for Icelandic horses, but it has sometimes been called loss of gallop or something like that in other horses.

Lionel:

Okay.

Heidrun:

So, it kind of lose.

Lionel:

It's like a positive or...

Heidrun:

Yeah.

Lionel:

Okay. Okay. You give some, you take some.

Heidrun:

Yeah, exactly. And this gene is sort of the reason why you get these softer gates and easier to write, like softer to write. So it's, what I was saying is that the origin of this mutation, many, many years back, it's very difficult to pin point the location of it. They can pin point about the time when it arose, but not really the location, because it spread so wide, because it made the horses comfortable to ride, and so they sort of spread really fast with people.

Lionel:

Right, okay. So it's a combination of genetics and also just how humans use those, like, oh, I want to ride for a long time, so I know that this horse is comfortable for a long time. Yeah.

Heidrun:

And then it spreads like, oh, what is your horse?

Lionel:

My horse is comfortable. Let's have a fall out of this horse.

Heidrun:

Yeah. So with, like, migration of people, it's just migrate as well. So it's a bit difficult to pinpoint the location of it.

Lionel:

In your paper, you talk also about the genetic pool.

Heidrun:

Yes, like the original gene pool. Yeah. I mean, so, historic records, they say that the settlers, they brought sort of a limited number of horses with them because transportation was not very easy at that time. So it is widely believed that the Icelandic horse originates from a relatively small amount of horses. Yeah, but there are no records of the number of horses. And I mean, they may have been coming in for a few years. It's not like all in one.

Lionel:

No, no, no, in waves. Yeah, obviously.

Heidrun:

But I think I read somewhere, but I don't know if it's based on any facts or anything that it might have been maybe around 5,000 horses or something like that.

Lionel:

Which is not a lot, right?

Heidrun:

No, no, it's not a lot.

Lionel:

Do we see a correlation of the current genetic pool now and that? Is it a problem? Is it a problem that the pool was so small at the beginning?

Heidrun:

I mean, it doesn't seem to be a problem for the Aztec horse. It's quite healthy.

Lionel:

Yeah.

Heidrun:

But you can see that there are quite a lot of these shorter runs of homo-psychosity, so-called.

Lionel:

Okay.

Heidrun:

So, long sequences, not long, but relatively short sequences of homo-psychos regions.

Lionel:

Okay, but does it mean inbreeding or?

Heidrun:

Yeah, yeah, it means inbreeding.

Lionel:

Yeah, okay.

Heidrun:

So, we can see there was quite a lot of inbreeding.

Lionel:

Yes.

Heidrun:

But we didn't see in my study that we have a lot of recent inbreeding.

Lionel:

Yeah, during your presentation, you talk a bit about it, no? You show that a bit, no?

Heidrun:

Yeah, we did. So, because we had this data set that we had, we also analyzed these genetic diversity in inbreeding and did some analysis of signatures of selection.

Lionel:

Okay.

Heidrun:

Just because we had the data and it's, it's a, yeah, I think it's very important for populations.

Lionel:

Yes.

Heidrun:

Like the S&D cores, which are closed populations. So we need to monitor that the genetic diversity is not like decreasing or such. And we saw that the small, these runs of homozygosity that we found in the S&D cores, they are most likely due to this small gene pool in the founding group. Yes. But, and also due to some DNA purging during the sort of the development of the breed.

Lionel:

Okay.

Heidrun:

Because the negative or the bad alleles, they get sort of purged out.

Lionel:

Ah, this is what you mean by purging.

Heidrun:

Yeah.

Lionel:

Yeah, okay.

Heidrun:

Yeah. So the environment, it's just the...

Lionel:

The weaker horses died faster, like the evolution...

Heidrun:

Exactly. And those who can't take the cold, they die. So it's like adaptation and survival of the fittest. And that's the DNA purging with the environment. The environment, yes. It really does that. Yeah. So that is probably the reason for most of the inbreeding that we can see in the Icelandic horse. All right. Because we couldn't find really a lot of longer segments of these homozygous regions. And it's... According to the literature, you have... If you have very long sequences, they are most likely new or recent.

Lionel:

Okay.

Heidrun:

And if you have very short ones, then those are most likely ancient, because of the recombination during Maio's cell divisions.

Lionel:

Yes.

Heidrun:

You always... The chromosomes always recombinate.

Lionel:

Okay.

Heidrun:

And with more higher number of recombinations with every generation, then it's more... The likelihood of the sequences breaking up is higher.

Lionel:

Right. Okay.

Heidrun:

So, if you understand what I'm trying to do... Yeah, yeah.

Lionel:

But just to back a bit, when you say shorter period, you found in Icelandic horses that there is a little amount of time with a lot of inbreeding, and that is better than a long period of time of inbreeding, is it?

Heidrun:

Longer sequences, like the sequence of homo-psychosis, yes, low size.

Lionel:

Okay.

Heidrun:

Low size. So, it's like, yeah, if you have a very long one, yes, that's most likely recent inbreeding. Right. And we didn't have much of that.

Lionel:

No, okay. Okay, okay.

Heidrun:

Yeah. So, but the inbreeding coefficient based on the genomic data is quite high. It's 0.20.

Lionel:

Okay.

Heidrun:

According to my analysis, at least.

Lionel:

Okay.

Heidrun:

But then again, my analysis is different from any other analysis. And these kinds of analysis are always difficult to compare because it's so highly dependent on the settings that you apply in the analysis.

Lionel:

But what you found is the data that you have in the analysis that you made, which with every code mark that we can put and like this is based on your work, is that the inbreeding coefficient is high?

Heidrun:

The inbreeding coefficient is quite high. It's 0.20 and usually it's like recommended to not exceed 0.05. So 5% inbreeding is like limit.

Lionel:

Okay, and we are 20?

Heidrun:

Yeah, and we have...

Lionel:

Oh, you found 20.

Heidrun:

The mean inbreeding coefficient was 0.20, so 20%. But 96% of that inbreeding coefficient is due to these short sequences.

Lionel:

It's ancient more than new now.

Heidrun:

Yes.

Lionel:

Right.

Heidrun:

So 96% is ancient inbreeding. And that is, as I said, probably due to the small gene pool.

Lionel:

So basically, we inherit, that's the heritage of the Icelandic horses, that they started from very few horses. And since then, we carry that inbreeding, in a sense. But it didn't increase or it didn't...

Heidrun:

No, it seems, according to my analysis, that people or breeders, they have tried to avoid inbreeding. Yes. And so the genetic diversity in the breed is quite stable for the last generations.

Lionel:

Okay.

Heidrun:

Which tells us, that the breeding system is promoting sustainable breeding, which is quite good to see. And I think that one of the reasons for why the breeding is relatively sustainable is that we have this breeding goal with very many factors in it. So we're not only focusing on, for example, speed. We are focusing on five gates and also the conformation.

Lionel:

The conformation, yes.

Heidrun:

And so, and because like every breeder is unique. Yes. And some choose one trait more than the other.

Lionel:

Yes.

Heidrun:

And everyone is free to breed as they like. There is no sort of rules to how this should look like or anything like that is. So we have a lot of diversity in the breeders and in the horses. And so I think it's a fairly good system, I think we have.

Lionel:

Are you then, with your knowledge, a super breeder?

Heidrun:

No. I would not say that, no.

Lionel:

Did you use your horse as a testing ground?

Heidrun:

No. Well, my gelding, he doesn't have an assessment, so I didn't use him. But I regret not taking a sample from my mare.

Lionel:

But you still didn't take a sample from her to this day?

Heidrun:

No, I don't have a sample from her.

Lionel:

Would that be the first?

Heidrun:

I will probably do it at one point.

Lionel:

Is it because you're scared of seeing what...

Heidrun:

No, no, not really. It's just... I didn't... I don't know. I don't know why I didn't do it.

Lionel:

No? Okay. And the stallion that... Oh, maybe you use multiple stallions? Yes. Did you?

Heidrun:

Uh, yes.

Lionel:

Ah, okay, okay. We're getting there. We're getting there.

Heidrun:

Yes. Two of them I had. One of them I had sample from, and one of them I had sample from the sire of that stallion. So I did some testing to see if it was a good DNA.

Lionel:

Okay. Based on what you wanted out of your phone?

Heidrun:

Yeah. But what I'm mostly dealing with in my breeding is that I need to have a stallion with good temperament.

Lionel:

All right.

Heidrun:

Because I have a little bit of a crazy mare.

Lionel:

You have a crazy mare. Okay. But you looked for a good temperament in the stallion.

Heidrun:

Yes. I looked to see what kind of DNA they had.

Lionel:

All right. Do we know where to find the temperament gene in the horse?

Heidrun:

For the temperament?

Lionel:

Yes. No?

Heidrun:

No, no, no. That's much more complicated, I think.

Lionel:

Maybe one day you will find it.

Heidrun:

Maybe one day we'll see.

Lionel:

Is there a difference between the Icelandic horse in Iceland and the Icelandic horse in Sweden?

Heidrun:

Yes, I would say...

Lionel:

That you can see at least. I mean...

Heidrun:

I don't think there's a difference between the horses, but I think there's a difference between the breeders.

Lionel:

All right. OK.

Heidrun:

So I think there are more people in Sweden that are willing to bring their horses to breeding field tests, regardless of how good they are. Yes. So it's very valuable for researchers to get those horses also. So I think the preselection is a little bit lower in Sweden than in Iceland, I think.

Lionel:

Which is good for you because then your sample size is bigger.

Heidrun:

So that was a very good sort of factor to have.

Lionel:

The positive spin on the OK, we get more.

Heidrun:

But I'm not saying that the horses are better in Iceland or something. It's just it's a different behavior of the breeders. And I'm very grateful for the ones who bring any horse, really.

Lionel:

I mean, at the beginning of our talk, you said the limiting factor is the assessment. So if one country says, but we will want to make more assessment. It's a good deal for you.

Heidrun:

Yeah.

Lionel:

Regardless of the quality of the horses, which this is not what you're looking at anyway. So no. One last question. You said you were a judge.

Heidrun:

Yes.

Lionel:

Did your judge experience help during this research?

Heidrun:

I think my knowledge of the phenotypes is was quite good. So it was easier to interpret the results that sort of, if you have a, if you find a region in the genome that is associated with one phenotype, right, then you sort of need to know what the phenotype tells you. Because otherwise you don't really know what is going on. So, yes, it helped a lot, I think, that then I could also just come up with ways to do statistical analysis just to sort of go a little bit deeper into what the actual influences of this region was and such.

Lionel:

Since when you judge you?

Heidrun:

I started 2015 to judge.

Lionel:

Right, it's been some years, 10 years?

Heidrun:

Yeah, that was during the time I did my masters.

Lionel:

Okay.

Heidrun:

Yeah, and I don't know, when I was doing my masters at SLU, I saw all these people doing these research on genomics and bioinformatics, and I got really interested in that area. And then I sort of got this project into my hands, and it was like a no-brainer to go ahead with it.

Lionel:

To go for it. All right, thank you so much, Heiðrún, for talking to us.

Heidrun:

You're welcome. Thank you for having me.

Lionel:

It's been a pleasure. I hope we did... I didn't say too much stupid things, but...

Heidrun:

And I hope that you or the listeners understood something that I said.

Lionel:

Yes, I hope so. Yes. We will put a link to your paper in the description of the episode, so they can read in plain English what you wrote. Perfect. So thank you again, and thank you everyone for listening. We will come back soon with a new episode. In the meantime, do not hesitate to share this episode before leaving you. We would like to mention that you can follow us on Instagram and Facebook, The Tölt Tales, for more news and story. Thank you, Heiðrún, and goodbye.

Heidrun:

Thank you. Goodbye.

Podcasts we love

Check out these other fine podcasts recommended by us, not an algorithm.

Nattfari Podcast Artwork

Nattfari Podcast

Johan Häggberg & Elsa Andersson