Footprints on Genetic Islands.

Footprints on Genetic Islands. The giant Galapagos tortoise once flourished on Floreana Island but was thought to have become extinct shortly after Charles Darwin made his historic voyage to the Galapagos Islands in 1835. Because these colonies remained isolated from each other, tortoises evolved into distinct species that helped inform Darwin on his theory of natural selection. It was possible that some tortoises could have cruised to neighboring Isabela Island on pirate or whaling ships.

Scientists from Yale found genetic evidence of these giant tortoises in young (~15 yr old) hybrid individuals found on Isabela Island’s Wolf Volcano indicating that the purebred parents (expected to live up to 200 years) may still alive. To do this, they analyzed fast evolving genetic markers (DNA microsatellites) from 84 hybrid tortoises and calculated that there would need to be at least 38 founders of the supposedly extinct Chelonoidis elephantopus species.

This raises the hope that this historical species may be resurrected using captive breeding programs. This is also the first time that a species may have been rediscovered by tracking genetic footprints of its hybrid offspring. All that’s left is to track their physical footprints on Isabella Island!



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27 Responses to Footprints on Genetic Islands.

  1. Awesome! I think I recall reading (within this past year) that the tortoise he brought back with him had recently died?

  2. Marika Patto says:

    going to Galapagos has always been a dream of mine

  3. Rajini Rao says:

    Chad W Darroch , I had not heard that but a quick google search revealed that indeed, Harriet the tortoise passed away in 2006 at the age of 176 yrs.

  4. Rick Overly says:

    listening and looking at your work is always a pleasure.

  5. Oops! I guess it was longer than a year ago 🙂

  6. Rajini Rao says:

    Chad W Darroch , in tortoise years, it was just yesterday 🙂 Thank you, Rick Overly ! Shinae Nae and David Haddad , I agree….the image was so surreal that I had to share.

  7. Rich Pollett says:

    Good news, I’d hope they can eventually find a few of the calculated 38 to perpetuate the species.

  8. John Midkiff says:

    Genetics to the rescue once again!

  9. DaFreak says:

    Great picture! I loved the side story that pirates kept these in their hulls as a food source. Apparently they can go an entire year without food and water and they have lots of meat on them which means that they are the perfect living food storage system. Slow, deaf, almost completely defenseless, durable food sources, made out of crafting materials, … Poor things… No wonder they were almost extinct :p

  10. Rajini Rao says:

    Rich Pollett according to the authors, “Theoretically, 20 or more founder genome equivalents are the approximate genetic base necessary for a viable ex situ population” (don’t know the basis for this number) it does seem hopeful. Koen De Paus , we owe them a genetic resurrection, then!

  11. Rajini Rao says:

    David Haddad , here is what I got from the Wiki page, which is really quite nicely done: The Galápagos Hawk was formerly the sole native predator of the tortoise hatchlings, as Darwin wrote: “The young tortoises, as soon as they are hatched, fall prey in great numbers to the buzzard”. The hawk is now much rarer, but introduced feral pigs, dogs, cats and black rats have become predators of eggs and young tortoises. The adult tortoises have no natural predators apart from humans, as Darwin noted: “The old ones seem generally to die from accidents, as from falling down precipices. At least several of the inhabitants told me, they had never found one dead without some such apparent cause”.

  12. Jon Teriini says:

    Go Yale! That’s great news.

    I have to post this episode of QI which deals with the subject. They make the terrible history of the Giant Tortoise, terribly funny:

  13. This is a brilliant book – The Last Tortoise: A Tale of Extinction in Our Lifetime, BTW I hope they can locate the parents. These tortoises are legendary!

    BTW, watch Lonesome George the Galapagos Tortoise – Explore – BBC

  14. good picture……… And good morning

  15. Rickie B says:

    Very interesting stuff Rajini – so, much like the Dodo bird and the giant elephant bird one assumes, but here Darwin must have been amazed at such variation and such specificity – it all posits a newer theory that is open to mutation as standard, maybe? Rsj

  16. Tom Lee says:

    Very interesting indeed! Love it.

  17. What a wonderful post Rajini Rao! Thank you!

  18. very interesting. They are so big.

  19. those turtles are beautiful.Rajini you post such interesting things. thanks.

    today- what is interesting in my life is that my brother is coming to visit

  20. Rajini Rao says:

    Thank you, JoEllen Donahue Hermes ….enjoy your brother’s visit 🙂

  21. Mmm… I learnt that genetic markers can also specifically say the parent of a hybrid is a purebred. I thought the markers only indicate any one going back to a great^n grand parent or some thing like that was a purebred. Given the long life of species what can be a purebred really? Only to the extent they were isolated by environment.

  22. Rajini Rao says:

    Sowmyan Tirumurti , the authors used fast evolving genetic markers that could show changes over one or few generations. These tortoises are severely isolated by their environment, of course, being on the remote Galapagos islands. The isolation is what helped generate distinct species on different islands.

  23. i wish i was someone like them

  24. nice  in a regular pattern

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