Why were wolves and dogs considered separate species until recently?

[BruteForce1]

I don't get it. We always knew that they could interbreed. Here's the definition of species:BIOLOGY
a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g. Homo sapiens.

For years, wolves and dogs were considered separate species: canis familiaris and canis lupus. However, more recently, scientists generally agree they are both a sub-species of canis lupus.

https://www.rover.com/blog/wolf-vs-dog-whats-difference/

 

[Monsterboy]

a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.

This also applies to closely related species as well, because closely related species consists of similar individuals.

You know that closely related species can interbreed right ?
There are plenty of cases where closely related species interbred.

https://news.berkeley.edu/story_jum...s-a-difference-whos-the-dad-and-whos-the-mom/

“When new species are formed, there seems to be a period of transition: Closely related species are able to produce viable offspring...

 

[BruteForce1]

This also applies to closely related species as well, because closely related species consists of similar individuals.

You know that closely related species can interbreed right ?
There are plenty of cases where closely related species interbred.

https://news.berkeley.edu/story_jum...s-a-difference-whos-the-dad-and-whos-the-mom/

Not my definition. Here's from biology dictionary:

Species Definition
A species is a group of organisms that share a genetic heritage, are able to interbreed, and to create offspring that are also fertile. Different species are separated from each other by reproductive barriers. These barriers can be geographical, such as a mountain range separating two populations, or genetic barriers that do not allow for reproduction between the two populations. Scientists have changed their definition of a species several times throughout history.

https://biologydictionary.net/species/

 

[Monsterboy]

I didn't say it's your definition, what is your point ? That link in your first post doesn't open.

 

[Ygggdrasil]

It's worth noting that there isn't really a universally agreed upon definition of species. The concept of a species is quite old and pre-dates many important discoveries in biology (such as genetics and evolution), so there are some issues fitting the concept of discrete species into frameworks where populations can change genetically over time. Furthermore, it is unclear how the concept of species is different between a domesticated population that has undergone extensive artificial selection (dogs) versus a wild population (wolves).

For good discussions of the concept of species see:
https://www.physicsforums.com/threads/do-biologists-agree-on-a-definition-of-species.961251/https://en.wikipedia.org/wiki/Species#Definition

 

[BruteForce1]

I didn't say it's your definition, what is your point ? That link in your first post doesn't open.

My point is what then is the actual definition of a species and why did it change for dogs and wolves the last 40 years or so.

 

[BruteForce1]

It's worth noting that there isn't really a universally agreed upon definition of species. The concept of a species is quite old and pre-dates many important discoveries in biology (such as genetics and evolution), so there are some issues fitting the concept of discrete species into frameworks where populations can change genetically over time. Furthermore, it is unclear how the concept of species is different between a domesticated population that has undergone extensive artificial selection (dogs) versus a wild population (wolves).

For good discussions of the concept of species see:
https://www.physicsforums.com/threads/do-biologists-agree-on-a-definition-of-species.961251/https://en.wikipedia.org/wiki/Species#Definition

In other words not a good question for game-shows (Who Want To Be A Millionaire) because there is no universally valid answer...

 

[BruteForce1]

More to the thread, does anybody know why they decided to no longer group wolves and dogs as separate species? Was it with the advent of DNA or later than that?

It would seem very arbitrary if there isn't a very specific reason for it

 

[BruteForce1]

I didn't say it's your definition,

You wrote: "You know that closely related species can interbreed right?
There are plenty of cases where closely related species interbred."

I was not the one making the definition so I don't see why you adressed me

 

[Ygggdrasil]

More to the thread, does anybody know why they decided to no longer group wolves and dogs as separate species? Was it with the advent of DNA or later than that?

It would seem very arbitrary if there isn't a very specific reason for it

According to Wikipedia:

In 1758, the Swedish botanist and zoologist Carl Linnaeus published in his Systema Naturae the binomial nomenclature – or the two-word naming – of species. Canis is the Latin word meaning "dog",[21] and under this genus he listed the dog-like carnivores including domestic dogs, wolves, and jackals. He classified the domestic dog as Canis familiaris, and on the next page he classified the wolf as Canis lupus.[3] Linnaeus considered the dog to be a separate species from the wolf because of its cauda recurvata - its upturning tail which is not found in any other canid.[22]

In 1999, a study of mitochondrial DNA indicated that the domestic dog may have originated from multiple grey wolf populations, with the dingo and New Guinea singing dog "breeds" having developed at a time when human populations were more isolated from each other.[23] In the third edition of Mammal Species of the World published in 2005, the mammalogist W. Christopher Wozencraft listed under the wolf Canis lupus its wild subspecies, and proposed two additional subspecies: "familiaris Linneaus, 1758 [domestic dog]" and "dingo Meyer, 1793 [domestic dog]". Wozencraft included hallstromi – the New Guinea singing dog – as a taxonomic synonym for the dingo. Wozencraft referred to the mDNA study as one of the guides in forming his decision.[1] The inclusion of familiaris and dingo under a "domestic dog" clade has been noted by other mammalogists.[24] This classification by Wozencraft is debated among zoologists.[25]

https://en.wikipedia.org/wiki/Dog

 

[Buzz Bloom]

I remember a commonly used definition from the 1950's. It was that the members of a species interbreed and produce reproductive offspring in the wild at least 20% of the time. That is, if two groups interbreed in the wild and produce reproductive offspring less than 20% of the time, they are different species. As I understand it, in more recent definitions the term species has become more vague and less important, and the concept of clade has become more useful.

Another complication is a ring species in which a group as a whole live around a circular region, and subgroups near by interbreed with neighbors, but at one point of the circle, the neighbors on each side of that point do not interbreed. I think I first came across this concept in The Ancestor's Tale by Richard Dawkins.

 

[BruteForce1]

I remember a commonly used definition from the 1950's. It was that the members of a species interbreed and produce reproductive offspring in the wild at least 20% of the time. That is, if two groups interbreed in the wild and produce reproductive offspring less than 20% of the time, they are different species. As I understand it, in more recent definitions the term species has become more vague and less important, and the concept of clade has become more useful.

Another complication is a ring species in which a group as a whole live around a circular region, and subgroups near by interbreed with neighbors, but at one point of the circle, the neighbors on each side of that point do not interbreed. I think I first came across this concept in The Ancestor's Tale by Richard Dawkins.

That's strange because the cut-off I read according to some Quora contributor is DNA overlap. But that's apparently not true?

 

[BruteForce1]

In the case of dog and Grey Wolf, the DNA overlap is 99.9%.

 

[BruteForce1]

According to Wikipedia:

https://en.wikipedia.org/wiki/Dog

Outdated.

"It turns out that today's dog breeds may not have evolved from the gray wolf, at least not the kind of gray wolf that exists today.

A study in the current issue of PLoS Genetics suggests that, instead, dogs and gray wolves share a common ancestor in an extinct wolf lineage that lived thousands of years ago

 

[BillTre]

Interbreeding is not always a great way to figure out if animals are different species or not. I have just interbred two species of Devario fish, one from Assam, one from some Himalayan foothills.
It became popular for a while (IMO) because it was easy to explain and made sense from a genetic isolation point of view. However, there have always been situations where it did not seem to work well with the facts and people's ideas of what different animals were in different species.
There are variants on this idea involving breeding in the wild or breeding under certain circumstances, but they have their problems also.
For example, only a species if not breeding to some extent in the wild: What if a physical barrier to interaction between two potentially interbreeding populations (populations that could interbreed if they were able to come in contact with each other) arose or went away. Does this physical change in the environment cause the two populations to become the same species or different species? Does not make a lot of sense for classification purposes.
Another possible example @Ygggdrasil mentioned is the ability of populations in the same evolutionary lineage, but separated in time, to breed (if they were able to get together). This is theoretically possible now that sperm can be frozen and stored for extended periods (or with seed banks). As one species evolves through time, earlier members can change (genetically or morphologically) which can result in biological barriers to breeding of various kinds. When does this reach the level of being different species.

Not only can domesticated dogs breed with wolves, but other canids can breed with each other (wolves coyotes for example), so the issue is not restricted to just dogs/wolves.
Cross species breeding is known in many situations with different effects on species naming.
Some fish species have an extensive history of interbreeding which has generated a reticulate (branching both apart and together) pattern of evolution.
Some sunflowers form different species (in an isolated breeding population sense of the word) when they interbreed because they become polyploid and therefore genetically incompatible with either of their parental populations. They can only breed with other polyploids.
Some insects become separate breeding populations when infected with particular parasites which make them incompatible with uninfected hosts. This can be cured by antibiotics. What is that?
In the last case, DNA similarity would not be very revealing since the DNA would have little time to evolve any differences.
DNA can be useful to rule out organisms being in the same species however (very different DNA, probably not the same species)

There have been morphology based definitions (species all look alike, which is probably out of date, but an initial clue).
There are also other more vague definitions like they evolve together as a group and share a common evolutionary history (which makes sense from a theory point of view, but is kind of hard to use as a functional definition in actual experiments or observations).

Probably the best advise would be to define your terms and use them consistently.
Here is a wikipedia article that describes several different species concepts based on quite different ideas.

 

[jim mcnamara]

Okay. I trained in this field. This is a Helen Quinn moment. (See the link below)

Specialists get what is happening, non-specialists do not get it. It is a problem foist on the specialists to get through. Correctly. Our fault if it fails. Species is an inherited concept that has morphed with increased understanding.

@BruteForce1 == You could have chosen Panicum virgatum, switchgrass, to make your point. You can pick out a clump of it and then find a nearby clump. You have about a 20% chance the two can reproduce together. P. virgatum plants have ranges of polyploidy.

On the other side you could have chosen 'horizontal gene transfer' where unrelated bacteria can swap DNA through a tunnel with other unrelated bacteria or even eukaryotic cells - which are worlds apart.

This is the answer: people who write the stuff you are quoting mostly are aware of a subset of what goes on in biology. Or are trying to dumb it down. Or both.

Why? ...cubby holes.
Someone encounters a problem or some biological "thing" they are clueless about, new or old. The first notion is to classify it. Math students do this. They can determine enough about problem to classify it. But they still cannot solve it. What they did was to cubbyhole the problem. And confuse cubbyholing with really understanding it.

Taxonomy is cubbyholing. Period. The End. It may or may not reflect anything deeper than something looks like something else. Somehow. The species concept from binomial nomenclature is a cornerstone of Taxonomy. Modern taxonomy began with Linnaeus and binomial nomenclature. We are still cleaning up the fallout from the use of the mid-1700's level of knowledge to catalogue living things. And a progression through steps of understanding to now.

Example: nomen confusum. There are examples of this throughout all of the phyla. What really is one species (using the applicable definition) has more than one binomial assigned to it. At one point North American orioles (birds) were catalogued in more than a single species. Turns out they are all in the same cubby hole. Old bird field guide books show more than one species. And they do look different. Newer books do not list but one with several pictures of "phases" or "subspecies".

And. Any highly domesticated species has this issue. Dogs are bad in this regard. So bad we commonly think of breeds as separate cubby holes. So, corn (Zea mays) follows in the same footsteps. There are varieties of corn you would not recognize as corn.

Modern humans have remnant functioning DNA found to originate in Neaderthals and Denisovans. So were they separate species from Homo sapiens or not? You could clean 'em up, dress 'em, and put 'em on the 42nd street bus at rush hour. Nobody would know.

So do we lose cubby holing or use it? Do we toss National Geographic while we're at it?

The answer is: it is what we have now. Live with it. It will get better and better, just like lots of Science.

Helen Quinn:
https://ned.ipac.caltech.edu/level5/March07/Quinn/Quinn.html

 

[DrClaude]

With this very instructive reply from @jim mcnamara, the OP is answered.

Thread closed.