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DNA analysis reveals there are four distinct giraffe species, not one

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Re: DNA analysis reveals there are four distinct giraffe species, not one

#51

Post by Dylan16807 »

openasocket wrote: post #47
dschiptsov wrote: post #27

The classic operational definition of different species, as far as I remember, is that cross-breading between species is not possible.

If only it was! But then we discovered "ring species" ( https://en.wikipedia.org/wiki/Ring_species ) which threw a monkey wrench into what was once a simple definition. Basically, there are populations of animals A, B and C, where A and B can inter-breed, B and C can inter-breed, but A and C can't. So our definition of species no longer satisfies the transitive property, and it all falls apart. As far as I know, this…

We discovered setups where A, B, and C exist at the same time in different places. That's interesting, but it's not a new challenge. The very simplest version of evolution also involves A, B, and C, existing at different times in the same place. The difference with a ring species is that you can't dodge the complexity by ignoring extinct things. But the complexity was always there.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#52

Post by danieltillett »

dalke wrote: post #25
MustardTiger wrote: post #16

Earlier quoted context omitted.

>The paper is about species, not subspecies. And my reply is about subspecies, and our refusal to apply the same standards we apply to other animals to ourselves. I do not understand your confusion. >Humans do not meet the phylogenetic criteria which justifies the use of "subspecies" We have greater genetic difference between races than ANY example of subspecies in existence. I am very aware that a large group of peo…

Yes, my complaint is that you are highjacking an article on species differentiation in giraffes to talk about purported human subspecies. No, we emphatically do not have that high of a genetic difference. Quite the opposite. The diversity in human genetics is relatively small compared to other species. For example, quoting http://www.nature.com/ng/journal/v27/n2/full/ng0201_155.html : > The extent of DNA sequence var…

Yes humans are more genetically similar to each other than some other species, but this has nothing to do with the question if there are different sub-species of humans or not. You can't answer questions about speciation like this.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#53

Post by Dylan16807 »

MustardTiger wrote: post #50
saynsedit wrote: post #29

Earlier quoted context omitted.

Physical difference is not the same thing as genetic difference. Humans may subjectively look very different but genetically humans aren't very different. This is empiracle fact. Stop living in the 19th century.

Physical difference has nothing to do with the discussion. That is a complete red herring you just pulled out from no where. The empirical fact is that humans are genetically quite different. The genetic distance between human races is greater than many species, and virtually all subspecies distinctions made in the animal kingdom. Stop denying science because of a false belief that lying will somehow get rid of racis…

Humans have accumulated an enormous amount of genetic variation between groups in only a few thousand years? Citation needed.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#54

Post by danieltillett »

DougWebb wrote: post #48
dalke wrote: post #25

Earlier quoted context omitted.

Yes, my complaint is that you are highjacking an article on species differentiation in giraffes to talk about purported human subspecies. No, we emphatically do not have that high of a genetic difference. Quite the opposite. The diversity in human genetics is relatively small compared to other species. For example, quoting http://www.nature.com/ng/journal/v27/n2/full/ng0201_155.html : > The extent of DNA sequence var…

If human races (which clearly exist) are not genetically distinct enough to be considered subspecies, how about the inverse? Can you point out examples of animal species/subspecies that have races? Are different dog breeds the equivalent of human races, for example?

Many animal species have races (or sub-species).

Dogs breeds are not generally considered as different species despite it being impossible for many to interbreed (think chihuahuas and Great Danes). Isn't biology wonderful :)

Re: DNA analysis reveals there are four distinct giraffe species, not one

#55

Post by MustardTiger »

Retric wrote: post #46
MustardTiger wrote: post #38

Earlier quoted context omitted.

What you quoted supports his rebuttal, not your claim. You are completely backwards, the trend is away from that. The myth that interbreeding makes them the same species was never accurate, but it is completely unused in modern times. For example, the very article that started this discussion saying that giraffes are 4 species not one. We classify them as such based on DNA evidence. The fact that all 4 species can pr…

The long term definition was more or less 'A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.' This brings up the arguably semantic idea that physical separation is enough even if they are still genetically compatible. So, in theory you can have genetically compatible separate species as soon as they are no longer capable of interbreeding. However, as Humans an…

>The long term definition was more or less 'A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.'

No, that was one long discredited idea of species. It has not been used in decades. Why are you so insistent on pushing this false claim that brown bears and polar bears are the same species? Look it up, they are not. One is Ursus arctos and the other is Ursus maritimus. There is no ambiguity or dispute.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#56

Post by MustardTiger »

Retric wrote: post #21
MustardTiger wrote: post #15

Earlier quoted context omitted.

People have been separated far longer than just since the ice age. And no, some people think brown bears and polar bears should be reclassified, others do not. As it stands, they are separate species. Take the 2 seconds to google basic information before posting incorrect things that are so easy to verify. Even if you reclassify them, it still supports my point: humans consist of several subspecies.

People also talk about Europe and Asia as separate despite being a contiguous landmass on the same plate. Genetically brown and polar bears can and in reality often do interbreed producing viable offspring and exchanging genetic information between populations.

>People also talk about Europe and Asia as separate despite being a contiguous landmass on the same plate

That analogy is not useful at all. Continents are not biological organisms.

>Genetically brown and polar bears can and in reality often do interbreed producing viable offspring and exchanging genetic information between populations

And yet they are separate species. Just like the 4 separate species of giraffe the article is about, which can and do all interbreed. The concept of species is in no way reliant on an inability to produce fertile offspring.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#57

Post by danieltillett »

Retric wrote: post #31
adekok wrote: post #28

Earlier quoted context omitted.

> ~14,000 years as separate populations. Perhaps even less. http://www.andrewcollins.com/page/articles/romanbust.htm There was at least some contact between North America and Europe, close to 2K years ago.

The baring strait is also only 51 miles so there was likely quite a bit of accidental crossings if nothing else. For comparison Australia was populated around 65,000 to 75,000 years ago and that takes more than 200 miles by sea.

I don't think there is any good evidence for Australia being populated before 45,000 years ago. Modern humans hadn't even left Africa 75,000 years ago.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#58

Post by Dylan16807 »

nitrogen wrote: post #39
guessmyname wrote: post #36

Earlier quoted context omitted.

How? Every time I scroll down to click one of the links the website scrolls my browser back up and loads a new article below the one I was reading. I don't want to read more articles, I want to click the links at the bottom of the website!!! I was not asking if the links work, they probably do, I am asking how do I "click them" if the website keeps moving the webview back up when I scroll to the bottom?

Are you talking about the linked site? HN cerainly doesn't do that. As for infinite scrolling, I am definitely not a fan myself, and this is an example of why.

Infinite scrolling is fine as long as you don't try to also have a footer. And as long as it's not the only option.

Re: DNA analysis reveals there are four distinct giraffe species, not one

#59

Post by dschiptsov »

alexbock wrote: post #34
dschiptsov wrote: post #27

The classic operational definition of different species, as far as I remember, is that cross-breading between species is not possible.

Two individuals may be capable of breeding and reliably producing fertile offspring but still be considered different species if they would never mate "naturally". This may be due to geography, different mating seasons, different songs or appearances, etc.

So, are there different species of people?)

Re: DNA analysis reveals there are four distinct giraffe species, not one

#60

Post by dogma1138 »

kristofferR wrote: post #19
bcraven wrote: post #8

Earlier quoted context omitted.

https://en.wikipedia.org/wiki/Species_problem The word "Species" is mixed up in all manner of biological and sociological turmoil. I was even of the impression that becuase of DNA sequencing the term is falling out of favour amongst researchers.

Would DNA sequencing just make it easier to distinguish different species (like in this case) from each other instead of making the term more problematic?

Well it depends on how you define a "species" this isn't a technical problem this is a philosophical one.

The most commonly used definition of a species today is a group that is capable and commonly practices interbreeding between its members.

There are different species that are capable of interbreeding and even producing fertile offsprings but they do not breed for various reasons this can be as simple as a geographical barrier or as nuanced as a small visual difference like a red patch of feathers vs a black one that restricts them from breeding outside of their group.

A more wider definition of a species is the largest gene pool of individuals technically capable of breeding but this one is not often used.

Overall there would be more loose and more strict definition of species that would be used based on the subject matter at any given moment.

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