Giraffes May Be Six Separate Species

The BBC reports on research, published in BMC Biology, pointing to the possibility that there may be at least six species of giraffe in Africa. Quoting: "'Using molecular techniques we found that giraffes can be classified into six groups that are reproductively isolated and not interbreeding,' David Brown, the lead author of the study and a geneticist at... UCLA told BBC News. 'The results were a surprise because although the giraffes look different, if you put them in zoos, they breed freely.'"

Breeding?

[FroBugg]

Although the giraffes look different, if you put them in zoos, they breed freely.

Assuming they produce viable offspring, isn't that one of the primary definitions for a single species?

Re:Breeding?

[srussia]

Although the giraffes look different, if you put them in zoos, they breed freely.

Assuming they produce viable offspring, isn't that one of the primary definitions for a single species?

There is no rigorous definition of "species". See http://en.wikipedia.org/wiki/Species_problem [wikipedia.org]

Re:Breeding?

[dancingmad]

Someone can correct me if I'm off my nut here but:
I think that's the major definition, but further categories can be made on things like different physical or (like in this study) genetic characteristics. Also, if the populations are genetically (and possibly morphologically, as the summary suggests) and do not interbreed in the wild that would suggest that giraffes may be well divided into subspecies.

Re:Contradiction?

[ferd_farkle]

Reproductive isolation is a major characteristic of speciation. Lions and tigers, horses and donkeys, etc are different species, but under unnatural conditions may mate and even produce offspring. Depending on how unrelated the species are, the offspring may or may not be viable.

Speciation is not as cut-and-dried as you might think. Reproductively isolated populations diverge more and more over time, and the speciation becomes more and more pronounced.

The definitive word on giraffes

[Nerdposeur]

They call this science? Bah. Everything you need to know about giraffes is contained in this brilliant, revolutionary book:

http://www.amazon.com/Giraffes-Doris-Haggis-Whey/dp/1932416978

For example:

The legs of giraffes are filled with various types of fruit juice. You see, giraffes love drinking fruit juices - pineapple, boysenberry, mango-lemon - but their bodes have no real use for fruit juice, so it all trickes down to their legs where it stays and squishes around. This should have been obvious to you.

Re:Breeding?

[shellbeach]

wouldn't it be better to say 6 subspecies of giraffe?

IAAB, and yes, that's absolutely correct. They're subspecies.

You get the same thing with the house mouse, mus musculus -- subspecies that are genetically distinct and geographically isolated, but which will interbreed in captivity (and in bordering zones in the wild). It's presumed that a lower fitness in the offspring of cross-subspecies matings in bordering zones keeps the subspecies separate.

Re:Contradiction?

[Baron_Yam]

I doubt it is a static number - it would depend heavily on the selection pressures on the two separated groups.

Re:Contradiction?

[pigah]

Most people are familiar with what is called the Biological Species Concept, which defines species as a reproductively isolated group of organisms that can all interbreed among themselves and produce fertile offspring. This works pretty well for most animals, but terribly for plants and many animals. Plants that are quite different can interbreed frequently, but do not because they are isolated by things such as flowering time, pollinator species etc... Then you get into weird intransitivity issues such as: population A can breed with population B, population B can breed with population C, but A and C can't breed. These issues mean that a species is not a very well defined thing anymore. There have been many attempts to unify what we understand about the biology of reproductive isolation and genetic differentiation into one species concept, but we are left with many different "species concepts". I can't remember them all, but many are based genetic differentiation. It becomes crazy because under some gene-based concepts you could be defined as a species for one gene analysis and not another. There is a new idea which may have showed up on slashdot that is called the genetic bar code and those scientists believe that there is one (or just a few) genes where a specific amount of differentiation in this area will define a species. They predict that they can create a machine that you can just put tissue samples in and have a determination of what species it is within minutes. It is a controversial line of research, needless to say.