Why Genetic Diversity Matters in Vulnerable Dog Breeds.

Population Genetics Made Simple: -Blog 2 in the Vulnerable dog breed series

Population genetics sounds like a complicated scientific subject, but the basic idea is actually quite simple.

Population genetics is one part of a much bigger conversation about what makes a dog breed vulnerable and how we preserve enough healthy, diverse bloodlines for the future.

It is about looking at the genetic diversity across a whole population rather than focusing only on one dog, one litter or one pedigree.

For dog breeders, that means asking a much bigger question:

How much genuine genetic choice does this breed still have?

That question becomes particularly important when we are talking about vulnerable or rare dog breeds.

A breed may have reasonable numbers globally, but that does not automatically mean breeders everywhere have access to all of that diversity.

Here in New Zealand, geography changes the picture considerably.

The global population and the New Zealand population are not the same thing

When I think about population genetics, I start by looking at the breed around the world.

How many dogs are there? Where are they? How closely related are they?

Then I narrow that down to what breeders can realistically access within a particular country or geographical area.

That is where things become very different.

A breed may have hundreds or even thousands of dogs internationally, but if only a small number of those bloodlines are represented in New Zealand, our practical breeding population is much smaller.

I sometimes think of it like a library.

There may be thousands of books in the entire library, but if you can only reach one small shelf, those thousands of books do not give you thousands of choices.

Dog breeding can work in much the same way.

There may be enormously useful genetics sitting in Europe, North America or elsewhere, but until breeders can actually access those bloodlines, they are not really part of our available population.

Population genetics is really about preserving choices

Genetic diversity gives breeders options.

It gives us more possibilities when we are trying to maintain the health, temperament, structure, movement and characteristics that make a breed what it is.

That does not mean every dog in a vulnerable breed can be completely unrelated to every other dog. That is simply not realistic.

The aim is to maintain as much useful genetic variety as the population can reasonably support.

In a rare breed, we may already be working with limited choices.

The danger comes when those choices become narrower and narrower with every generation.

If the same ancestors repeatedly appear throughout the available pedigrees, eventually breeders may have very few genuinely different directions left to go.

Population genetics asks us to recognise that before we reach that point.

Diversity does not mean losing breed type

One concern people sometimes have when we talk about widening genetics is that we will somehow lose what makes the breed distinctive.

That should not be the aim at all.

The purpose is to retain genetic diversity while still preserving the temperament, structure, movement and characteristics of the breed.

For me, temperament comes first.

At the end of the day, I have to live with these dogs.

With Newfoundlands, temperament is one of the great hallmarks of the breed, but I believe temperament should matter enormously in every breed.

After temperament, I am looking at the whole dog — structure, movement, type and whether it resembles what that breed is supposed to be.

So preserving diversity does not mean ignoring breed type. It means trying to preserve both.

Breeding for one trait can narrow the picture

One simple way to understand this is to think about breeding strongly for a particular visible trait.

Take Dalmatians and their spotting as an example.

If breeders repeatedly favour one very particular appearance and continually return to the same related dogs to achieve that look, they may gradually narrow the wider population at the same time.

The colour or pattern itself is not necessarily the problem.

The problem is what may be happening to genetic diversity while breeders concentrate heavily on producing one particular feature.

That is why numbers alone can be misleading.

You can have plenty of puppies being born and still have a population becoming genetically narrower if those puppies are coming from the same limited group of ancestors.

The same ancestors appearing repeatedly make me stop and look

When I look at a pedigree, one thing that makes me pause is seeing the same relatives appearing repeatedly.

There is no simple rule such as saying a particular ancestor appearing a certain number of times automatically makes a mating wrong.

Different breeds have different population sizes and different histories.

Instead, repeated ancestors tell me that I need to look more closely.

I would want to consider the coefficient of inbreeding, or COI, as well as the wider population and the actual lines available to that breed.

COI deserves its own discussion, and we will come back to it later in this series.

For now, the important point is that pedigree repetition is a signal to look at the bigger picture rather than relying on one number or one rule.

Sometimes breeding is about alternating priorities

There is also a very practical side to this.

Imagine I had two possible sires.

One might be exactly the style of dog I like.

He might suit my bitch beautifully and be likely to produce the type, temperament or structure I want to strengthen in my line.

I may decide to use him.

But that does not mean I then keep returning to the same type of pedigree generation after generation.

Once I have strengthened or established the characteristics I want, the next generation may be where I deliberately look for a more distant line.

You are balancing two things.

You are preserving the type you value, while trying not to paint yourself into a genetic corner.

That is where breeding becomes both science and judgement.

New Zealand sometimes has no choice but to look overseas

For small New Zealand breed populations, eventually there may simply not be enough diversity available locally.

That is when breeders start looking overseas.

That may involve importing a dog.

It might mean accessing a dog from Australia.

Or increasingly, it may mean using imported frozen semen.

Those outside genetics can be incredibly valuable, but the question should never simply be:

Is this a nice dog?

The bigger question is:

Does this dog genuinely bring something different to what we already have?

If an imported dog's pedigree ultimately leads back to the same lines already heavily represented here, then we may have imported another dog without substantially increasing our genetic options.

So paper matters. Pedigrees matter. Understanding where those genetics actually come from matters.

Choosing an overseas sire is very different

When you choose a sire overseas, you often do not have the opportunity to put your hands on that dog.

That changes how you assess him.

You may begin by looking at the pedigree and asking how diverse that pedigree is in relation to what you already have.

Then you build the rest of the picture.

What are the health results? What is known about his temperament? How does he move? What does his structure look like? What have previous offspring been like?

Photographs and video are useful, but so are trusted reports from people who actually know and live with the dog.

A pedigree can tell you whether a dog may offer something different genetically.

It cannot tell you everything about the dog.

New Zealand could also contribute back to the world

This is the part of the conversation I think deserves far more attention.

We often talk about what New Zealand needs from overseas breeders.

But New Zealand can potentially offer something back too-not just The All Blacks😉.

If a genuinely different bloodline is established here and carefully maintained over several generations, that line can develop into a New Zealand branch of a wider international population.

That does not happen by simply importing one dog and using it repeatedly.

It requires planning.

For example, imagine that New Zealand already had three bitches from three genuinely different lines.

Ideally, we might then bring in three dogs from another three different lines.

Rather than immediately mixing everything together, those bloodlines could be managed carefully and kept separate for as long as practical.

That preserves options.

Then, when it becomes necessary or beneficial, those different branches can gradually be combined.

Over time, some of those genetics might eventually travel back overseas again.

New Zealand then becomes more than a recipient of genetics.

It becomes another place where valuable lines can be preserved, developed and potentially returned to the wider international population.

Unfortunately, dogs do not follow plans drawn on paper

This is where population genetics becomes very real.

It is easy to design beautiful breeding plans on paper.

Real dogs do not always cooperate.

A bitch may only have two puppies.

You may get all dogs when you needed a bitch.

A puppy you hoped to breed from may turn out not to be suitable.

Fertility may fail.

A litter may not produce what you expected.

Health, temperament or structure may change the decision later.

One of my own Newfoundland litters is a perfect example.

We had two puppies — one dog and one bitch.

Sadly, we lost the bitch at four days old.

I had wanted to keep a bitch myself, while the dog had already been promised to another home.

So I repeated the mating.

Ironically, the second mating produced six bitches.

Suddenly, the options looked completely different.

That is breeding.

One litter can severely restrict the choices you thought you would have.

The next can open them right back up again.

Repeating a mating does not necessarily mean narrowing the population

Repeating the same mating does not create new genetic diversity.

The same two parents are still contributing the same genetic pool.

But repeating the mating can give a breeder more representatives of that particular combination.

And that can be enormously useful.

If the first litter gives you one suitable dog and the second gives you several suitable bitches, suddenly those offspring can go in different directions.

One bitch might later be bred to one unrelated line.

Another might go to a completely different line.

Another might never be bred from at all.

So rather than creating diversity immediately, repeating the mating can provide more practical ways to use the same genetic slice later.

That is an important difference.

Real population management is about keeping doors open

This is probably the heart of the subject for me.

Population genetics is not about achieving some perfect pedigree where nobody is related.

In vulnerable breeds, that may never be possible.

It is about keeping as many sensible doors open as we reasonably can.

Sometimes that means bringing in new genetics.

Sometimes it means repeating a mating.

Sometimes it means deliberately choosing a more distant sire in the next generation.

Sometimes it means strengthening the type you want first, then widening the pedigree afterwards.

And sometimes the animals produced simply force you to change the plan.

There is no perfect spreadsheet that can predict every outcome.

Good breeding requires looking at the population, the pedigree and the actual dog standing in front of you.

The future matters more than a single litter

That is why population genetics needs to be viewed across generations.

The question is not only:

Will this mating produce nice puppies?

It is also:

What choices will those puppies leave behind?

Will the next breeder have several different directions available?

Or will every road lead back to the same few ancestors?

For vulnerable breeds, that question matters enormously.

We cannot preserve these breeds simply by producing more dogs.

We need enough different, healthy, functional and breed-typical dogs that breeders still have meaningful choices in the future.

That is what population genetics gives us a way to think about.

It allows us to step back from the individual litter and look at the future of the breed as a whole.

And once we start doing that, another issue quickly becomes obvious.

What happens when one particularly successful male becomes so popular that his genetics begin appearing almost everywhere?

That is where we will go next in this series: the popular sire effect.