Posted on 01/02/2008 7:36:33 PM PST by blam
Giraffes And Frogs Provide More Evidence Of New Species Hidden In Plain Sight
Genetic subdivision in the giraffe based on microsatellites alleles. (Credit: David M Brown et al., Courtesy BMC Biology)
ScienceDaily (Jan. 2, 2008) — Two new articles provide further evidence that we have hugely underestimated the number of species with which we share our planet. Today sophisticated genetic techniques mean that superficially identical animals previously classed as members of a single species, including the frogs and giraffes in these studies, could in fact come from several distinct 'cryptic' species.
In the Upper Amazon, Kathryn Elmer and Stephen Lougheed working at Queen's University, Kingston, Canada teamed up with José Dávila from Instituto de Investigación en Recursos Cinegéticos, Cuidad Real, Spain to investigate the terrestrial leaflitter frog (Eleutherodactylus ockendeni) at 13 locations across Ecuador.
Looking at the frogs' mitochondrial and nuclear DNA, the researchers found three distinct species, which look very much alike. These species have distinct geographic distributions, but these don't correspond to modern landscape barriers. Coupled with phylogenetic analyses, this suggests they diverged before the Ecuadorean Andes arose, in the Miocene period over 5.3 million years ago.
"Our research coupled with other studies suggests that species richness in the upper Amazon is drastically underestimated by current inventories based on morphospecies," say the authors.
And in Africa, an interdisciplinary team from the University of California, Los Angeles, Omaha's Henry Doorly Zoo, and the Mpala Research Centre in Kenya has found that there may be more to the giraffe than meets the eye, too.
Their analysis of nuclear and mitochondrial DNA shows at least six genealogically distinct lineages of giraffe in Africa, with little evidence of interbreeding between them. Further divisions within these groups mean that in total the researchers have spotted 11 genetically distinct populations.
"Such extreme genetic subdivision within a large vertebrate with high dispersal capabilities is unprecedented and exceeds that of any other large African mammal," says graduate student David Brown, first author of the study. The researchers estimate that the giraffe populations they surveyed have been genetically distinct for between 0.13 and 1.62 million years. The findings have serious implications for giraffe conservation because some among these subgroups have as few as 100 members, making them highly endangered -- if not yet officially recognised -- species.
Journal articles:
Cryptic diversity and deep divergence in an upper Amazonian frog, Eleutherodactylus ockendeni. Kathryn R Elmer, Jose A Davila and Stephen C Lougheed. BMC Evolutionary Biology (in press)
Extensive Population Genetic Structure in the Giraffe. David M Brown, Rick A Brenneman, Klaus-Peter Koepfli, John P Pollinger, Borja Mila, Nicholas J Georgiadis, Edward E Louis Jr, Gregory F Grether, David K Jacobs and Robert K Wayne. BMC Biology (in press) http://www.biomedcentral.com/bmcevolbiol/
Adapted from materials provided by BioMed Central.
Interesting, but what is the significance?
I do not see how this constitutes new species.
To me it sounds like a new excuse by the envirowhacos to declare a whole new crop of endangered species and declare whole new swaths of land off limits to development.
This data just shows limited interbreeding of the same species that are separated by distance instead of geographical barriers.
The Theory of Evolution says that new species arise from existing species through genetic drift and selection, right?
Every once in awhile, a new frog species will be discovered in Borneo, or giraffes will be found to be multiple species. The consensus seems to always be: New Species! And they were right under our nose all the time! We just never looked there! Or, We just never saw them that way!
Why doesn't anyone make the claim: "A new species seems to have been formed very recently, and we will now add it to the taxonomy"?
There seems to be a consensus that we aren't going to see a new species form in front of our eyes. All the species we find will have been in place for years, and years, and years. But -- of course -- once upon a time they all arose from older species. It just isn't happening now.
Seems odd.
OK, I wish someone would explain this to me. They say limited interbreeding, which to me would suggest it’s not a distinct species, since as far as I know (and I taught biology) one of the defining characteristics of a species is that they cannot interbreed (and produce fertile offspring) with members of another species.
susie
Genealogically distinct & don't interbreed. Basically the definition of being separate species. Perhaps calling them "new" species is a misnomer because there's nothing "new" about them, we just didn't know to place them in separate categories before.
This of course calls into question the importance of counting the number of species in the first place, IMHO.
To me it sounds like a new excuse by the envirowhacos to declare a whole new crop of endangered species and declare whole new swaths of land off limits to development.
Perhaps. Actually, I think there's an irony here because the ease with which they find "new" species actually puts the lie to a constant envirowacko refrain: that we are "losing" however-many species per year.
Right? They are always saying that, making sweeping definitive claims on how the "number of species" in the world is supposedly decreasing. Which, supposedly, is automatically bad. Well, to know such a thing, they'd have to have a reasonably accurate count of how many species there are at any given time, right?
Well, obviously they don't. From time to time they find "new" species that they didn't know were separate species. They don't know "how many species" there are, at any given time. Not at all. There could be twice as many species as people think, for all we know.
Just something to remember next time you hear the "we're losing species!!" lament.
This data just shows limited interbreeding of the same species that are separated by distance instead of geographical barriers.
Maybe. Or maybe the interbreeding is so limited that indeed it makes sense to call them different species, because the distance is simply the cause of speciation or near-speciation.
I guess where I'm coming from is, so what? People seem to have a mental image of "species" that is something akin to how they think of "individuals" or "critters". Critters are cute and we want more of them => species are cute and we want more of them? The automatic, subconscious instinctive reaction is always - "more species = good, fewer species = bad". With this mindset it becomes very very important to count the number of "species" at all times, to determine whether these two critter-sets are different "species" or not.
But does anyone stop and explain why it's important in the first place? Whether these groups are indeed separate species or not, they are what they are: separated critter populations that don't interbreed much, and you can't tell them apart.
Big deal if they're "different species". Or not. What difference does it make to anything?
bingo!
Different species can interbreed and it happens all the time. I keeep snakes. I have a Yellow Anaconda. This is a different species than the Green Anaconda. Yet the two can interbreed.
The same is true of Kingsnakes, Cornsnakes, Milksnakes. They are close, yet different.
In the wild.
Lions and tigers also interbreed under artificial coditions but they are different species because they do not interbreed in the wild.
Also, keep in mind that on the way to speciation is diminished fertility. It’s not an on/off switch.
Don’t know anything about snakes... Are the offspring fertile? Like horses and donkeys the offspring is a hybrid (mule) and cannot procreate. My father an old-time farmer (back in the 30’s and 40’s, God rest his soul) told me one time that ocassionally a mule was not infertile. I’m not sure he was correct.
Well hopefully one of the species will grow a neck long enough not to have to squat to quench their thirst. Which would make their predators a bit unhappy I suppose.
Offspring are just as fertile. Lots of babies from them.
There isn’t a spectrum of genetic attributes. THere is a definite clumping of grouping of two distinct types.
Liberals?
There are recorded and proven instances of mules producing offspring. There are also different kinds of mules. The fertility depends on whether or not the hybrid is a male or a female and which species the father was...was it a male horse and female donkey, or was it a female horse and a male donkey. You wouldn’t think it would matter, but for some reason it does.
Don’t quote me on this, but I’m pretty sure the standard “mule” is a male offspring of male horse mated to a female donkey. Any other combination is usually not called a mule, but some other type of hybrid and is traditionally considered garbage...not useful as a working animal.
I wonder what would happen if you used the same analysis on modern humans. Boy could that open up a can of political correctness worms. :)
“one of the defining characteristics of a species is that they cannot interbreed”
I think you may have taught me. How many species of dogs are there, btw?
Biology. the major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but are not able to breed with members of another species.
In fact, that is the current definition according to dictionary.com. I understand that there are some cases in which the rule is broken (so to speak) such as bison and cattle which can be crossbred and produce fertile offspring. It would appear to me that the definition for the word species has changed.
susie
That means more laws and more money. I'm reminded of the Florida panther, once thought to be a separate species is now known to breed with other panthers.
I suspect you are correct. When I was a kid and worked on a neighbor's farm, they bread a pair for a mule. That was the formula. Might have been a coincidence though.
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