Extinct may not be forever for some species of Galapagos tortoises

September 23, 2008,
Hybrid tortoise on Volcano Wolf. Image: Claudio Ciofi

Yale scientists report that genetic traces of extinct species of Galapagos tortoises exist in descendants now living in the wild, a finding that could spur breeding programs to restore the species, The report appears in Proceedings of the National Academy of Sciences.

When Darwin first visited the island of Floreana in 1835 and wrote about the giant tortoises, heavy human exploitation was already decimating the population. Within a few decades, 4 of the 15 known species had disappeared. On some islands, tortoises were sacrificed for oil that was used to light the streetlights of Quito, Equador. Others were taken as food or ballast for pirate and whaling ships.

Museum specimens and current molecular technology, coupled with 15 years of field work studying the tortoise population present now on the Galapagos archipelago by Gisella Caccone and Jeffrey Powell, faculty in the Department of Ecology & Evolutionary Biology, has painted a new picture of the origins and future of some of the tortoises.

"Connecting the past and present through genetic markers identified in the museum specimens — including the extinct species — has been key," said Caccone.

The database they established includes information from more than 2000 animals — so they know the genetic profile of each population. Their data show that all the known species and taxons of tortoises are genetically unique, which allows them to identify animals whose genetic information came from another species.

Matching museum specimens to current populations showed both distinct lineages and intermingled species. Of particular note, the team found tortoises on Volcano Wolf of the island Isabella — the furthest separated island of the archipelago — that had both the mitochondrial DNA and nuclear markers of the Floreana lineage.

"The population on Volcano Wolf is the most heterogeneous population we have seen," said Powell. He postulates that this island was the last stop for whaling and pirate ships heading out across the ocean to jettison their tortoise "ballast." Before they could retrieve the tortoises on a return trip, they the animals likely wandered and interbred.

Genes of the famous "Lonesome George" were also found in the Volcano Wolf population.

Hybrids of the extinct Floreana tortoise line theoretically now could be bred, the researchers say, and over a long span, revive this species. With this in mind, an expedition on Volcano Wolf is planned in December 2008 to look for tortoises bearing the Floreana lineage. Work is also under way to completely sequence the tortoise genome to gain a better understanding of these animals.

An interview with Caccone and Powell is available on iTunesU and online at Yale at streaming.yale.edu/opa/podcast … e/caccone_091508.mp3

Citation: Proc. National Academy of Sciences: (online September 23, 2008).

Source: Yale University

Explore further: Turtles can make great pets, but do your homework first

Related Stories

Galapagos iguanas transferred due to overpopulation

May 30, 2018

Six land iguanas, endemic to the Galapagos Islands, have been relocated within the Pacific archipelago due to food shortages and overpopulation on the islet where they lived, Ecuador's Galapagos National Park said Tuesday.

Worm-eating mice reveal how evolution works on islands

May 16, 2018

Australia has a bunch of kangaroo species, Madagascar has multiple species of lemurs, the Galapagos Islands have boulder-sized tortoises—islands get lots of cool animals. That's because when animals are isolated on islands, ...

Tortoise populations can withstand fires every 30 years

July 19, 2011

Populations of spur-thighed tortoises (Testudo graeca), a species classified as vulnerable and at risk of extinction, can withstand fires if outbreaks occur once every three decades or more. However, the youngest tortoises ...

Recommended for you

Detecting metabolites at close range

June 22, 2018

A novel concept for a biosensor of the metabolite lactate combines an electron transporting polymer with lactate oxidase, which is the enzyme that specifically catalyzes the oxidation of lactate. Lactate is associated with ...

How community structure affects the resilience of a network

June 22, 2018

Network theory is a method for analyzing the connections between nodes in a system. One of the most compelling aspects of network theory is that discoveries related to one field, such as cellular biology, can be abstracted ...

Research team uncovers lost images from the 19th century

June 22, 2018

Art curators will be able to recover images on daguerreotypes, the earliest form of photography that used silver plates, after a team of scientists led by Western University learned how to use light to see through degradation ...

Unconfirmed near-Earth objects

June 22, 2018

Near-Earth objects (NEOs) are small solar system bodies whose orbits sometimes bring them close to the Earth, potentially threatening a collision. NEOs are tracers of the composition, dynamics and environmental conditions ...


Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (3) Sep 23, 2008
Finally some interesting environmental science! Some environmental science focused on a realistic way to make things better rather than prattle on about how the rest of the unwashed masses should live our lives!

The environmental sciences could do with more scientists and fewer preachers. Thank you for this.
4 / 5 (1) Sep 23, 2008
Perhaps the current species of tortoise is better adapted. So, why bring back the old species?
not rated yet Sep 23, 2008
Playing the devil's advocate here....

Because it seems that the current vogue in environmental science is that change is bad and that we have to keep things static/"sustainable".

Too bad the only constant in the universe is change.
not rated yet Sep 23, 2008
There is no well thinking person who would expext a static universe, anyone with a decent education will conclude that it never will be.

Enviromental science knows that of course too, they are no idiots(some probably are ,despite their knowlede ,but in general)
What they warn about usually is the changes that are too big for humanity to deal with in the normal way of doing things.

1 / 5 (1) Sep 24, 2008
Anyone who thinks human beings aren't as natural to "the system" as hermit crabs IS an idiot...which includes most environmental scientists.

Anything humans do is "bad", unnatural, unsustainable, or otherwise outside nature's "will" (as if a simple cycle of chemical processes driven by solar heating can have a will).

What they all mean to say is that they'll get more grant money if they pretend man is unnatural and stroke certain folks' political agendas.
1 / 5 (1) Sep 24, 2008
Yes there is a big secret orgainisation that gives out grants to scientists that can prove that humans are bad.Because they believe humans are bad, its that simple really.

Its all a big conspiracy.

not rated yet Sep 24, 2008
Actually it's not a secret organization and it's well documented who gets what grant money for this kind of thing...and it most certianly ISN'T the folks who say there's nothing to worry about.

After all if there's nothing to worry about, then why do you need money to study it.
not rated yet Sep 24, 2008
Explain how the corrupt system works and please give some credible sources, it really sounds like a conspiracy.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.