Apr 24
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Guest Blog: The marine iguanas of San Cristobal island – Amy MacLeod

Amongst the black lava rocks that line the wave-lashed edges of the Galapagos Islands, the world’s only sea-going lizard can be found.  Amblyrhynchus cristatus, the marine iguana, is a remarkable and well-known endemic reptile of the Galapagos Archipelago.  Though widespread and highly abundant on certain islands, small, declining and genetically distinct populations on other islands are causing concern for conservationists.  One population in particular, found at the very tip of the easternmost island of San Cristobal has garnered attention not only for its critically small size, but also for being highly distinctive in genetic terms.  This ‘Punta Pitt population’, named after its location, is so genetically distinct that we are investigating whether it deserves recognition as a new species or sub-species.

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A marine iguana at Isla Lobos, San Cristobal Island. Larger males, like this one, swim and dive to forage on sub-tidal algae, whereas smaller individuals graze along the intertidal zone

 Since 2012 we have travelled to San Cristobal each year to collect information and new samples that will teach us more about Punta Pitt iguanas.  Before we started, iguanas on San Cristobal were known from only two colonies which seem not to interbreed with one another.  We began in 2012 by sailing around the island and sampling iguanas wherever we encountered them.  We found and sampled many new colonies, all on the west coast.  The entire eastern side of the island, wild and wave-battered, sadly eluded us.

Processing samples in the field at La Galapaguera, where Punta Pitt type iguanas are found

Processing samples in the field at La Galapaguera, where Punta Pitt type iguanas are found

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Weighing a young iguana at Islotte Pitt

In 2013 we returned to San Cristobal, this time to take a closer look at Punta Pitt and investigate the threat posed by feral cats, known to eat marine iguana hatchlings.  We camped at a remote beach for seven weeks.  During this time we fitted four feral cats with GPS-enabled radio collars and followed their movements.  We also collected measurements, samples and photographs of marine iguanas in order to investigate both physical and genetic differences between iguanas on the island.  Though we were only three people at the camp, we were certainly not lonely; the resident mocking birds, as curious as they are comical, watched our every move.  Constant vigilance was needed to prevent the legion of local hermit crabs from stealing all manner of things, and most evenings provided a cascade of newly hatched green turtles on the dunes, making their way down to the sea.

The resident mocking bird, who assumed ownership of all our things at camp (especially any unguarded porridge)

The resident mocking bird, who assumed ownership of all our things at camp (especially any unguarded porridge)

Frigate birds oversee the dish washing at camp

Frigate birds oversee the dish washing at camp

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The finches give our packing boxes a close inspection

Galapagos_April_2013 159

Newly hatched green turtles begin their journey down the dunes to the sea at Salinas beach

We are now in the midst of the final field-season of my PhD.  This season will be shorter, and we intend to find a way to sample the East coast.  This will involve searching for safe landing sites with an experienced fisherman, and a lot of walking along lava rocks.  If we are successful, we will have surveyed and sampled almost the whole island.  Back in Germany, we are working hard to analyse the morphological and genetic data that will tell us whether or not Punta Pitt iguanas are a new species.  In any case, the information we have gathered here in San Cristobal will be a valuable contribution to assessing the conservation status of marine iguanas on this island, where their population is the smallest of any of the Galapagos Islands.

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Punta Pitt type iguanas on the headland at Playa Cafe, the white cross is a temporary mark which indicates a sampled iguana

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Amy MacLeod is in the final year of her PhD at the Technische Universität Braunschweig in Germany. You can contact her by email at ms.amymacleod@gmail.com

Nov 9
Share 'Endangered Species of the Week: Floreana coral' on Delicious Share 'Endangered Species of the Week: Floreana coral' on Digg Share 'Endangered Species of the Week: Floreana coral' on Facebook Share 'Endangered Species of the Week: Floreana coral' on reddit Share 'Endangered Species of the Week: Floreana coral' on StumbleUpon Share 'Endangered Species of the Week: Floreana coral' on Email Share 'Endangered Species of the Week: Floreana coral' on Print Friendly

Endangered Species of the Week: Floreana coral

Floreana coral

Floreana coral (Tubastraea floreana)

Species: Floreana coral (Tubastraea floreana)

Status: Critically Endangered (CR)

Interesting Fact: The polyps of Floreana coral are bright pink in the water, and dark red-black when dry.

More information:

Found in the Galápagos, Floreana coral is a scleractinian coral, which means that it is a hard coral with a limestone skeleton.  Floreana coral is known as an ‘azooxanthellate’ coral, as this species does not have zooxanthellae, the algae that live inside the tissues of some corals and provide the corals with food. Corals without zooxanthellae instead feed on zooplankton, capturing these tiny aquatic animals in their outstretched tentacles. Floreana coral can be found on ledges, overhangs and the ceilings of caves, at depths of between 2 and 46 metres.

Now classified as Critically Endangered (CR) on the IUCN Red List, and listed on Appendix II of CITES, the Floreana coral is thought to have once been fairly widespread around the Galápagos Islands. However, since the El Niño event of 1982-1983, this coral has only been seen at Cousins Rocks and Gardner Islet. Despite searches specifically for this species, the Floreana coral has not been seen at Cousins Rocks since 2001. This indicates that any alterations to the water temperatures surrounding the Galápagos Islands are likely to threaten this coral and cause further mortality.

The unique biodiversity of the Galápagos Islands and the surrounding waters is recognised and valued, and the region is protected by being designated a Marine Reserve and World Heritage Site. Any international trade involving the Floreana coral is carefully regulated thanks to CITES. Unfortunately, neither of these measures protects this Critically Endangered coral from the threats of natural, or man-induced, climate change.

 

Find out more about the Floreana coral at Earth’s Endangered Species, and more about the Galápagos Islands at the Charles Darwin Foundation.

See images of the Floreana coral on ARKive.

 

Phoebe Shaw Stewart, ARKive Text Author

 

Jun 25
Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on Delicious Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on Digg Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on Facebook Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on reddit Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on StumbleUpon Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on Email Share 'In the News: Lonesome George, the last Pinta giant tortoise dies' on Print Friendly

In the News: Lonesome George, the last Pinta giant tortoise dies

Lonesome George, a Galapagos giant tortoise believed to be the last of his subspecies, has died, according to Galapagos National Park officials.

Photo of male Abingdon Island tortoise - Lonesome George - resting

“Lonesome George”, the last of his subspecies

First seen by a Hungarian scientist on the Galapagos island of Pinta, or Abingdon, in 1972, Lonesome George became a symbol of the Galapagos Islands. With no other known individuals of his subspecies left, George had the unfortunate distinction of being considered the rarest animal in the world.

Giant tortoise declines

Galapagos giant tortoises were once so numerous that Spanish explorers named the Galapagos archipelago after them. However, these large reptiles were hunted by sailors and fishermen for their meat and oil, and more recently have suffered habitat loss and competition due to introduced goats and cattle. Introduced predators such as cats, dogs and rats also predate the more vulnerable juveniles.

Photo of Galapagos giant tortoise hatchling breaking out of shell

Young Galapagos giant tortoises are vulnerable to introduced predators such as cats and rats

There are a number of different subspecies of Galapagos giant tortoise, and the differences in appearance between the tortoises from different islands were among the features that helped Charles Darwin develop his theory of evolution.

Overall, around 20,000 giant tortoises are thought to now remain on the Galapagos Islands, but three subspecies have already become extinct or are extinct in the wild.

Photo of an old male Duncan Island tortoise in typical habitat

Duncan Island tortoise. Some Galapagos giant tortoise subspecies have “saddleback” shells, while in others the shell is more domed.

Failed breeding attempts

Despite efforts by conservationists to breed George with females from closely related giant tortoise subspecies, he sadly failed to reproduce successfully. With his death, the Pinta Island subspecies, also known as the Abingdon giant tortoise (Chelonoidis nigra abingdoni), is the latest giant tortoise subspecies to become extinct.

Lonesome George was estimated to be around 100 years old at his death, although Galapagos giant tortoises can potentially live up to 150 years or more. Park officials are due to carry out a post-mortem to determine the cause of his death.

Photo of male Abingdon Island tortoise - Lonesome George - feeding

Lonesome George feeding

Conservation efforts

Fortunately, conservation efforts are underway to save other Galapagos giant tortoise subspecies. For example, a programme running since the 1970s raises hatchlings in captivity until they are large and robust enough not to succumb to predators in the wild.

This programme has shown encouraging success, increasing the population of the Critically Endangered Hood Island tortoise (Chelonoidis nigra hoodensis) from just 13 individuals in the 1970s to over 1,000 in the wild today.

Read more about Lonesome George at BBC – Last Pinta giant tortoise Lonesome George dies.

View photos and videos of the Galapagos giant tortoise on ARKive.

Liz Shaw, ARKive Species Text Author

Jan 10
Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on Delicious Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on Digg Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on Facebook Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on reddit Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on StumbleUpon Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on Email Share 'In the News: ‘Extinct’ giant tortoise may still be alive' on Print Friendly

In the News: ‘Extinct’ giant tortoise may still be alive

A species of Galapagos giant tortoise believed extinct for over 150 years may still be alive, according to scientists.

Photo of Volcan Alcedo tortoise walking

A Volcan Alcedo tortoise (Chelonoidis vandenburghi), a relative of the ‘extinct’ giant tortoise from Floreana

The species, Chelonoidis elephantopus, was once found on the island of Floreana in the Galapagos, but was hunted to extinction by whalers who visited the Galapagos Islands during the 19th century.

However, a team of scientists from Yale University have now discovered hybrid tortoises which appear to have the ‘extinct’ species as one of their parents. The hybrids were found among a population of Volcan Wolf tortoises (Chelonoidis becki) living at the northern end of the island of Isabela, another of the Galapagos Islands.

Pure-bred individuals may still exist

After the hybrid tortoises were found, the team originally speculated that by careful cross-breeding over many generations, it might be possible to re-create the extinct giant tortoise species.

Photo of several Volcan Alcedo tortoise pairs mating in shallow pool

Volcan Alcedo tortoises mating

However, further expeditions to Isabela have found a number of individuals that appear, from a study of their genes, to have pure-bred C. elephantopus as one of their immediate parents. As some of the hybrids are only 15 years old, this suggests that their pure-bred parents may still be alive, particularly given that giant tortoises can live for over 100 years.

Unique island inhabitants

Giant tortoises are endemic to the Galapagos Islands, where they are likely to have originally arrived by floating from the shores of South America.

Photo of old male Duncan Island tortoise in typical habitat

Duncan Island tortoise (Chelonoidis duncanensis) reaching for food. The distinctive ‘saddleback’ shell of some Galapagos giant tortoises enables them to reach taller vegetation.

The distinct appearance and variety of shell shapes shown by giant tortoises on different islands helped inspire Charles Darwin’s theory of evolution – as populations on the different islands were relatively isolated from one another, they evolved in slightly different directions as they adapted to different conditions.

For example, C. elephantopus of Floreana Island has a distinctive saddleback-shaped shell, while species from neighbouring islands have a more dome-shaped shell.

Captive breeding

The scientists believe that the tortoises from Floreana Island were most likely transported to Isabela on whaling ships, and subsequently became established on the island.

Photo of young James Island tortoises at Charles Darwin research station

Young James Island tortoises (Chelonoidis darwini) at Charles Darwin Research Station. Captive breeding may be essential in ‘resurrecting’ the giant tortoises of Floreana Island.

Despite being the largest living tortoise species, giant tortoises can be surprisingly difficult to locate.

According to Dr Gisella Caccone, one of the scientists, “The landscape on Volcano Wolf is hard, the vegetation thick with lots of bushes and nooks, and the carapaces are translucent so you need a trained eye to see the shininess of the shell.”

However, if the suspected pure-bred individuals can be found, they could potentially form the basis of a captive breeding programme aimed at bringing back this unique reptile species.

Read more on this story at BBC News – ‘Extinct’ Galapagos tortoise may still exist.

Read the original article at Current Biology – Genetic rediscovery of an ‘extinct’ Galápagos giant tortoise species.

View photos and videos of Galapagos giant tortoise species on ARKive.

Liz Shaw, ARKive Species Text Author

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