Elephant DNA Studied

randomErr writes "Africa may harbor three species of elephant instead of just two, suggests a study based on DNA extracted from dung. If that is confirmed, it means that roughly 12,000 elephants living in western Africa are a distinct and endangered species, due to their small scattered populations as reported here at Newsday."

Comments

Toothpaste used...

[GusherJizmac]

And in other news, some food was eaten!

Not convinced

[greenhide]

The results suggest the western elephants have been isolated from the other elephants for some 2.4 million years, Eggert said.

I'd like to know what the term "isolated" means in this context. Obviously, not geographically, since apparently these elephants can be found in the same habitat as the other two species.

I myself am skeptical of these findings. There are no details given as to the distinctions in the DNA between the different species. Does anyone know what the cut-off point is for defining a species by DNA?

Also, has any actual animal behavior been found which suggests that this group of elephants isolates itself from other species of elephants? Maybe to elephant specialists "all elephants look alike" (probably not!), but surely differences between species -- their behavior, their appearance -- should have been observed. If not, can the elephants themselves tell the species apart?

Re:Not convinced

[Yohahn]

I haven't looked at the article, but if they are looking to see how distant 2 sets of elephants are genetically, they are probably using mitochondrial DNA.

Since mitochondrial DNA is passed from mother to offspring, it should (in theory) stay the same, never changing. However, mutations occur, so you can tell the genetic distance by the differences in mitochondrial DNA by counting differences in the mitochondria (assuming some of them have common females).

The limit, of course, depends on the odds you count for mutation in this dna. None of this is purely exact. It's all statistically determinable.

There's talk of how most of those of European decent are related to 1 of 7 women in their past.
It's documented in a book called "The Seven Daughters of Eve".

Really interesting stuff.

IANA Biologist, but my girlfriend just got her MS in Bioinformatics! :)

Re:Not convinced

[rakarnik]

The term species is defined quite subjectively, but in this context, "species" are probably defined as groups that have been sexually isolated from one another. So the three groups cannot (maybe the sperm from one species cannot fertilize the egg of another properly) or do not (they dont like each others smell, for instance) reproduce with each other. Isolation thus need not be geographical. Over the years after the isolation event, their DNA becomes less and less alike.

These researchers sequences certain DNA sequences in all these elephants and clustered the seqeunces. They found that the seqeunces clustered into 3 main groups, i.e. the sequences within the groups showed more similarity than the sequences in the other two groups. Two of these obviously corresponded to the existing known species, but the third probably looked just like one of the others, and yet was isolated sexually some time ago.

More details are in the abstract of the paper.

-Rahul

Re:Not convinced

[Yohahn]

The sequence analysis of mitochondrial DNA is *not* a valid way to define a species. Rather, it is a way to define lineage. I doubt that you would consider several different lineages of Europeans to be separate species!

Agreed. I figured I'd just show one way you can show that populations have been separated.

When I read the article I wondered how they were going to find (from DNA) which elephants could mate with each other. They offered no method in the article.

You know the answer?

Unnatural Selection

[drox]

Large land mammals are basically a relic. Natural selection has weeded most species out.

That would depend on whether you think human intervention is "natural".

Even without the encroachment of man into their world, I think the elephant is a species that will probably eventually die out.

Why? What else would kill them? What else would drive them from their ranges? They seem to have been a rather successful species (or group of species) until humans started to exceed their carrying capacity.

With the africa continent slowly turning into desert, I am not sure what can be done to preserve the natural wild african elephant.

There is some evidence that desertification in Africa is, at least in part, caused by human activity such as overgrazing and attempting to grow row crops on unsuitable land. But even if it's entirely due to non-human factors, it's unlikely to be deadly to all large land mammals. Habitats may grow or shrink, but barring things like asteroids slamming into the planet it's not likely that they'll vanish completely, particularly on a large land mass like Africa. Small island environments are another matter.

What is a species?

[geoswan]

I'd like to know what the term "isolated" means in this context. Obviously, not geographically, since apparently these elephants can be found in the same habitat as the other two species.

Is it possible that the article meant that species one is found in savannah areas, that species two is found in forest areas, and that species three is found in both savannah and forest ares -- without meaning that their areas overlap?

I myself am skeptical of these findings. There are no details given as to the distinctions in the DNA between the different species. Does anyone know what the cut-off point is for defining a species by DNA?

Can't interbreed isn't it? We discussed elephants and mammoths a couple of months ago. I found that there hobbyists who cross lions with tiger, and various other kinds of cats. And there are others who cross zebras with donkeys, and other horselike animals. Just like mules, the cross between horses and donkeys, the offspring are infertile.

Here is an interesting link to an online book that discusses the reintroduction of extinct species.

Just goes to show you

[anthony_dipierro]

how little the term "endangered species" really means.