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Elephant DNA Studied

Posted by michael on from the african-or-european dept.

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."

3 of 25 comments (clear)

  1. Re:Not convinced by Yohahn · · Score: 5, Informative

    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! :)

  2. Re:Not convinced by rakarnik · · Score: 2, Informative

    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
    --
    Genebrew
  3. What is a species? by geoswan · · Score: 3, Informative
    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.