Galapagos islands, evolution and sea levels


This video says about itself:

How Have Sea-Levels Influenced Evolution on the Galapagos Islands?

This movie is a simple 0 m to -210 m geographical loop sequence at 5 m increments. Important features are the substantial gaps between Galapagos’ “core” islands even at -100 m. However, below c. -130 m the various islands begin coalescing.

Research: “Exploring the combined role of eustasy and oceanic island thermal subsidence in shaping biodiversity on the Galápagos” by Jason R. Ali and Jonathan C. Aitchison from the Journal of Biogeography.

From Wiley Research News:

The Galapagos Islands have an iconic status in the history of evolutionary study, now new research shows that the islands’ own geological past may have influenced the evolution of the chain’s native species.

Writing in the Journal of Biogeography, Jason Ali and Jonathan Aitchison explore how fluctuating sea level changes over thousands of years impacted the island chain’s ecology. They estimate that when the sea retreated, most recently 20,000 years ago, the water would have been 144m below its current level.

As a result, Santa Cruz, the island in the center of the archipelago, would have expanded, enveloping many of the smaller islands, while creating a series of shallow ‘land bridges’ between the volcanic outcroppings. Such bridges explain the range and diversity of the islands’ species, such as snakes, geckos and iguanas, which appear landlocked to modern eyes.

“As soon as I saw that that half the islands in the archipelago were sat on a single, shallow, submarine platform, I realized that the implications for biology could be significant,” said Dr. Ali. “My geological knowledge told me that sea-level falls must have regularly re-connected the islands, and that this must have profoundly shaped the landlocked biota’s distribution, and very likely its composition.”

Ecuador has declared an emergency in the Galapagos Islands, saying that a cargo ship which ran aground last week still poses a threat to the archipelago’s fragile ecosystem: here. See also here.

Enhanced by Zemanta

Saving Galapagos giant tortoises


This video is called Giant Galapagos Tortoise (extreme closeup!)

From Wired:

Inside the Galapagos Islands’ Giant Tortoise Rehab Effort

By Jeffrey Marlow

04.16.14

10:24 am

You’re sailing from the Spice Islands across the open ocean to the South American port of Guayaquil, your financial motives rooted somewhere along a broad spectrum of morality and lawfulness. Several months have passed, and food stores and morale are low. Fortunately, you know a spot that will save the day, a cluster of rocky islands jutting out of the east Pacific near the equator.

For centuries, the Galapagos Islands have been a convenience store for ocean-going journeys, the resident Giant Tortoises serving as the perfect solution to the constant challenge of acquiring fresh meat at sea. These enormous beasts could handle the rigors of shipboard life and could be harvested at any time. Ships throughout the 18th-20th centuries would stop at the Galapagos, herd dozens of tortoises onto the decks, and sail off, assured of a reliable protein source for the remainder of their journey. At one point, an American whaling vessel lost track of a captive tortoise, which ambled out of the hold two and a half years later in Nantucket. Befuddled onlookers promptly killed it and made a stew.

And so, slowly but surely, the Giant Tortoise population was decimated. By the mid-1900s, conservationists began to recognize the problem, just as the increasing rate of international tourism and commerce was introducing another mortal threat to the species.

This one came in the form of fire ants, a voracious invasive species with a taste for baby tortoise. “Within 20 minutes of hatching,” says naturalist Ernesto Vaca, “they swarm and make the baby tortoise disappear.” Other human-transported pests, like rats, dogs, and cats, have developed similar dietary proclivities. With the species now facing a genuine threat to its survival, the Centro de Crianza was founded on Isabela Island, and conservationists went into crisis mode, airlifting tortoises with helicopters and initiating a breeding program.

It took a while to develop effective breeding techniques, but today, the Centro boasts a near-perfect success rate from egg to teenage tortoise. The rescue program continues in full force, as the habitat surrounding Isabela Island’s many dome-shaped volcanoes have been deemed unsafe for tortoises because of the fire ant threat. Employees and volunteers venture into the dense forest to retrieve tortoise eggs, which are then placed into computer-controlled incubators back at the Centro. The sex of the fledglings is determined by egg incubation temperature – above 37.5 °C leads to females, below produces males – allowing the Centro to generate its ideal ratio of 60% females and 40% males. Just before hatching, the eggs are buried in sand to simulate natural conditions and ensure that baby tortoises can dig upward and outward, a capability that bodes well for future robustness. Until the young tortoises are two years old, they’re placed in cages to offer protection against rats. By five, they’re in open-air enclosures, having received microchips that will track their movements once released into the wild.

And that, after all, is the ultimate goal, to repopulate the Galapagos with one of its most iconic species. Already, several hundred adults have been reintroduced to Espanola, an island particularly hard-hit by wave of threats over the decades. But the long-term prognosis is murky, especially as the invasive species that predate upon tortoises continue to grow in numbers. One option is to bolster the invasive species eradication efforts; another is that the animals will merely live the first few years of their lives in controlled conditions. But for now, the stabilization of the Giant Tortoise population is a victory in itself, a promising example of how conservation efforts can bring an organism back from the brink. As human impact on the unique Galapagos ecosystems increases, the model of tortoise rehab may prove useful in protecting other species from extinction, allowing the islands to maintain their unique treasure trove of biodiversity.

Enhanced by Zemanta

Saving Galapagos mangrove finches


This video is called: In the Galapagos, Mangrove Finches Fight On by Sue Maturin, Forest & Bird.

From the International Community Foundation:

International Community Foundation Announces World’s First Mangrove Finch Hatched in Captivity at Charles Darwin Research Station, Ecuador

In February 2014, twelve Mangrove Finch (Camarhynchus heliobates) chicks have hatched as part of a captive rearing program was born at the Charles Darwin Research Station (CDRS) in Puerto Ayora, Galapagos, Ecuador. This was the first success in the Mangrove Finch “head-start” program, which is designed to rescue the Mangrove Finch, the most threatened bird on the Galapagos Islands due to threats from nest parasites.

San Diego, CA (PRWEB) March 05, 2014

The International Community Foundation is pleased to announce that on 10th February 2014, the first Mangrove Finch (Camarhynchus heliobates) chick ever to hatch as part of a captive rearing program was born at the Charles Darwin Research Station (CDRS), the operative arm of the Charles Darwin Foundation in Puerto Ayora, Galapagos.

This was the first success in the Mangrove Finch “head-start” program, with eleven chicks having since hatched. This program is being conducted jointly by the San Diego Zoo Global (SDZG), the Charles Darwin Foundation (CDF) and the Galapagos National Park Directorate (GNPD).

This is a great effort that complements previous hard work on research and management with this species that has been carried out since 1997, by the CDF in collaboration with the GNPD.

The Mangrove Finch is the bird most threatened by extinction in the Galapagos Islands. Currently only 60 to 80 individuals are left in existence and the Mangrove Finch is classified as Critically Endangered on the International Union for the Conservation of Nature’s (IUCN) Red List of Threatened Species. Its entire population is restricted to a tiny range of less than 30 hectares in two patches of mangrove forest in the west coast of Isabela Island. In the past 5 years individuals from a remnant population at southern Isabela have no longer been found.

Since early February, 21 eggs and three newly hatched chicks were collected from wild nests in the mangrove forest at Playa Tortuga Negra, on Isabela. The eggs and chicks were then transported in an incubator, by helicopter, to the newly created incubation and hand-rearing facility at the CDRS. This is an area adapted as a quarantine facility, which aims to minimize the chance of the nestlings being infected by disease. Once out of the shell, the chick rearing process is a very demanding task, since, among other things, they need to be hand fed fifteen times a day.

Francesca Cunninghame, CDF scientist responsible for the project said: “After three years of planning and despite many challenges, we are thrilled with the achievements in every step of the process: collection of the eggs, incubation and hand rearing in captivity. Each success is a result of the great teamwork with the SDZG and GNPD and represents a milestone for the recovery of the mangrove finch wild population. The reintroduction of the youngsters back into the wild will be our next big challenge.”

Richard Switzer, Associate Director of Animal Applied Ecology from SDZG stated: “The San Diego Zoo team is very excited to collaborate in this critically important project to prevent the extinction of the Mangrove Finch. In our breeding centers in San Diego and Hawaii, USA, we have developed techniques to raise very small insectivorous birds. Being able to share these skills for the conservation of Galapagos’ biodiversity is a wonderful opportunity.”

Among many introduced species, the main threat to the Mangrove Finch is the Philornis downsi fly. This fly lays its eggs in the nests of the finches and subsequently its larvae parasitize nestlings, feeding on their tissue and blood, and causing a high mortality rate. Due to its tiny population, and with very few youngsters that manage to grow into adults, the population is simply disappearing. In addition, because the Mangrove Finch is only found in one small location, the species faces a particular risk from natural disasters such as lava flows, fire, or disease.

The Minister of Environment, Lorena Tapia, emphasized: “It is extremely important the support of various institutions, in this case the Charles Darwin Foundation and the San Diego Zoo, as due to the geographical scale of the problems we face, joint efforts are required for the conservation of a species that is seriously affected.”

The first goal of this collaboration is to implement a “head-start” program to help Mangrove Finch chicks through the major threat of Philornis. The goal is to return the young birds back to Playa Tortuga Negra, where they will be cared for in a purpose-built acclimation aviary, before being released back into the mangrove forest and monitored by the field team.

The Mangrove Finch Project is funded by SOS – Save Our Species, the International Community Foundation (with a grant awarded by The Leona M. and Harry B. Helmsley Charitable Trust), Durrell Wildlife Conservation Trust and Galapagos Conservancy. San Diego Zoo Global provides technical expertise and funding. Several private individuals have also contributed.

Scientists help Galapagos finches combat killer maggots: here.

Talking about the Galapagos; from the University of Rochester:

First-ever 3D image created of the structure beneath Sierra Negra volcano

The Galápagos Islands are home to some of the most active volcanoes in the world, with more than 50 eruptions in the last 200 years. Yet until recently, scientists knew far more about the history of finches, tortoises, and iguanas than of the volcanoes on which these unusual fauna had evolved.

Now research out of the University of Rochester is providing a better picture of the subterranean plumbing system that feeds the Galápagos volcanoes, as well as a major difference with another Pacific Island chain—the Hawaiian Islands. The findings have been published in the Journal of Geophysical Research: Solid Earth.

Enhanced by Zemanta

Galapagos islands sea urchins, video


This video says about itself:

A Tale of Two Urchins | CreatureCast | The New York Times

26 February 2014

Many different species do similar things. The pencil sea urchin and green sea urchin, for example, are both grazers in the coastal waters of the Galapagos Islands. Read the story here.

Enhanced by Zemanta

Galapagos islands tiger sharks, new research


This video is called Expedition Galápagos: Tiger Sharks.

Press release from OCEARCH:

First Tiger sharks in history of Galapagos Islands tagged

Wednesday, 19 February 2014, 10:53 am

First Tiger sharks in history of Galapagos Islands tagged, including 4-meter female named Yolanda captured in Canal de Itabaca – 66 fish, 8 species tagged in total

The Galapagos National Park Directorate, Charles Darwin Foundation (CDF), Turtle Island Restoration Network (TIRN) and the University of Massachusetts Dartmouth collaborated with OCEARCH to complete its 18th global expedition – conducted in one of the world’s treasured marine resources, the Galapagos Islands. According to OCEARCH collaborating lead scientist and Science Director of TIRN,Dr. Alex Hearn: “We brought together a multidisciplinary team of scientists and the foremost marine megafauna explorers. We made use of the world’s only oceanic research lift platform, which allowed us to handle large sharks with a minimal amount of stress. Our research, which uses methods approved by the IACUC Animal Care Committee while I was a Project Scientist at UC Davis, and by the Galapagos National Park Directorate, accomplished so much in so little time – over 66 individuals and 8 species caught, tagged and released. We have spent years working towards this study – making the leap from a shark movement study to one of the entire pelagic assemblage.”

The first Tiger sharks in the history of the Galapagos Islands were tagged and studied, including a large 4 meter female that was captured in a canal where a Navy diver had been working was concerned with its presence. The shark was named after Yolanda Kakabadse Navarro, aunt of Pablo Navarro, an employee of Caterpillar, the primary sponsor of the expedition and OCEARCH. Yolanda is the current president of the World Wide Fund for Nature International (WWF), the former Minister of Environment for the government of Ecuador and the former president of the International Union for Conservation of Nature (IUCN). She also founded the Fundación Natura in Quito and the Fundación Futuro Latinoamericano. Yolanda has dedicated her life and career to protection and awareness of the environment and environmental issues, not only in Ecuador, but worldwide.

“Tiger sharks are incredibly impressive animals, and I am excited to share my name with one. There have been serious population declines in some areas due to fishing for their fins for shark fin soup, which sadly is still seen as a delicacy in many places,” said Yolanda Kakabadse, President, WWF International. “Tiger sharks undertake incredible journeys, about which we still know remarkably little – so this tagging project will help provide crucial information for conserving these magnificent animals.”

Dr. Hearn described the discovery of the Tiger sharks after capturing tagging and releasing 27 other sharks: “Just before the end of our trip, we were approached by a concerned member of the Ecuadorian Navy to ask for help with a large tiger shark that they were frequently encountering whilst doing dive maintenance work. Thanks to this conversation, the Navy gave us permission to attempt to catch and tag the shark. We ended up catching all four of our tagged Tiger sharks at this site. From a perceived threat, these sharks became overnight conservation icons for the Galapagos community, and their movements will be followed simultaneously by the Navy divers, local schoolchildren, the National Park officials who witnessed the tagging, and the scientists involved in the study.”

“This is an important project for the management of the Galapagos Marine Reserve because of the immediate scope of migration data on individuals and aggregations of shark species,” said Arturo Izurieta, Director of the Galapagos National Park. “It’s a project that has been strengthened in recent years with contributions from conservation partners such as Charles Darwin Foundation, OCEARCH and the Ministry of Environment of Ecuador leading the process of generation of information applied to management.”

Hearn was pleased with the breadth of species: “In all 31 sharks were captured, tagged, sampled and released including 4 Tiger, 8 Hammerhead, 9 Silky and 10 Blacktip sharks. A total of 35 bony fishes were captured, tagged, sampled and released including 5 Yellowfin Tuna, 10 Wahoo, 10 Skipjack and 10 Rainbow Runners. This huge sample of open water fish from across the food chain will help us understand how marine protected areas around oceanic islands contribute to the conservation of the open water species assemblage as a whole.”

Swen Lorenz, Executive Director for the Charles Darwin Foundation attributed the success to collaboration and previously unavailable capacity: “The combination of CDF’s scientific knowledge and OCEARCH’s capacity to capture, handle and release large mature animals resulted in an extremely successful expedition where 100% of the research goals were achieved.” More detail from Swen on the expedition can be found on his blog post “Tagging a Tiger in the World’s Most Pristine Tropical Archipelago”.

Expedition Leader and Founding Chairman for OCEARCH, Chris Fischer commented: “We came here to serve the ocean, Ecuador and its people, the scientists and the Galapagos National Park. I am proud of the endurance and tenacity our team demonstrated. Furthermore, a shark that would have likely been targeted and killed as a nuisance or threat was instead tagged with multiple technologies so public safety officials, local residents and the science team can track its movements in near real time. The fear of the unknown is a powerful negative force that we hope to remove by replacing that fear with the facts.”

Dr. Pelayo Salinas de León of the Charles Darwin Foundation summed up the expedition: “Being able to work with Chris and all the OCEARCH team has been a unique experience and has allowed us to achieve all our research goals. Satellite and acoustic tagging the first adult tiger sharks and large Yellow Fin Tunas in the Galapagos Marine Reserve was a lifetime experience and it was only possible thanks to the OCEARCH unique platform. Thanks to this expedition we will be able to track the movements of these apex predators for the next 10 years to come. This research will provide very valuable information to further understanding our knowledge on the ecology of these key species and to inform the Galapagos National Park management plans. Also, we will obtain very accurate data on the regional migratory patterns of these species and this information will be very valuable to promote regional conservation actions through initiatives like the Eastern Tropical Pacific Corridor.”

David Acuña Marrero of CDF added: “OCEARCH has provided us with the best possible resources in the world to tag sharks: the most experienced and proactive team in shark’s handling and tagging, in a boat that performs perfect for this purpose. OCEARCH’s platform makes handling and tagging big sharks an ‘easy’ task, as we saw ourselves the last day of the expedition tagging a 4m beautiful tiger shark.”

Heather Marshall of UMass Dartmouth, working to collect blood samples for Dr. Greg Skomal of the MA Marine Fisheries for the study of stress physiology, said: “I was pleased to see, from initial analysis in the field, that stress indicators were not significantly exacerbated throughout the tagging process. Indeed, when the sharks were released, their stress response looked low across the board based on the initial data.”

“We envisage a series of peer reviewed publications arising from this research, including regional analyses of movement patterns of Silky and Tiger sharks using data previously collected on OCEARCH expeditions at Cocos Island, Costa Rica in 2011 and at the Revillagigedos Islands, Mexico in 2010. The science team expects to present its results at relevant international conferences, including the American Elasmobranch Society meeting in 2015”, adds Dr. Hearn.

Enabling local scientists to perform fieldwork is an important part of the OCEARCH mission. The organization is working closely with the Galapagos National Park Directorate, Charles Darwin Foundation (CDF) and Turtle Island Restoration Network (TIRN) in every step – from planning to execution and data analysis. Ecuador is a member of the Permanent Commission for the South Pacific – a regional agency tasked with developing a regional Plan of Action for Sharks that integrates national plans, with a focus on transboundary species. The research team is part of a regional network (http://www.migramar.org), which has a seat on the CPPS Shark Committee. All relevant results and ensuing recommendations will be presented at meetings of this Committee and used in the development of the regional Plan of Action.

Outreach and education were core components of the expedition. Chris Fischer and the science team spoke at 2 local schools and 2 sharks were named after the schools: Oswaldo Guayasamin and Tomas de Berlanga, so they had their own sharks to follow. Tomas de Berlanga, Bishop of Panama, is credited with discovering Galapagos Islands in 1535. Oswaldo Guayasamin, Ecuador’s most famous painter and sculptor was a voice for the poor and dispossessed in Latin America, and received the UNESCO International Jose Marti Prize after his death in 1999.

The Global Shark Tracker is a web-based near real time satellite tracking tool for sharks that will eventually be expanded to other species. …

To stay updated on the daily activities, visit www.OCEARCH.org where you can see the daily Expedition Blog, experience the Global Shark Tracker and see all social media links.

Enhanced by Zemanta

Galapagos tortoises and island ecology


This is a video of the Galápagos tortoise from the BBC’s Life in Cold Blood documentary series.

From Discover magazine:

We Discovered Too Late That Tortoises Are Expert Landscapers

By Elizabeth Preston | January 27, 2014 10:00 am

Countless biology students have dutifully learned to associate the Galapagos Islands with finches. Here Darwin noticed that birds on different islands had different beak shapes, and ta-da, theory of evolution. But galápago is Spanish for “tortoise,” and young Darwin also learned from watching these huge reptiles lumber across the archipelago. Today, the galápagos are only a fraction of their former population. And as they’ve disappeared, the landscape of the islands has transformed—because although Darwin didn’t know it, the tortoises were driving the evolution of an entire ecosystem.

The story starts before Darwin ever reached the Pacific island chain. So to get details from a time before naturalists were taking notes, Swansea University ecologist Cynthia Froyd and her colleagues searched a different set of records: fossilized tortoise poop.

There used to be 100,000 to 250,000 tortoises living and relieving themselves in the Galapagos. Those numbers dropped after European settlers arrived in the 16th century—the slow-moving giants were eaten, hunted for oil, and tormented by invasive egg-eating rats. By the 1970s their numbers had dropped to 14,000 or fewer.

Now Galapagos tortoises are being reintroduced to the islands. But has the ecosystem changed in their absence? Froyd wondered specifically about the islands’ highest points. These areas are mostly empty of tortoises today, even though the animals are known to travel to higher ground for water during the dry season.

Froyd took sediment samples at lofty bogs on the island of Santa Cruz. (This island is also called Indefatigable, like a tortoise climbing an 800-meter volcano.) These bogs are packed with moss, surrounded by lush vegetation, and frequently covered in a cold, thick mist called garúa.

The researchers scoured the ancient mud samples for fossilized fungus spores, pollen, and plant remains. At all three of their sample sites, they found “dung-affiliated” fungi—species that grow on the droppings of herbivores. This was a clue that a large plant-eater used to live and poop at those spots. Judging by radiocarbon dating, the animal had lived in the bogs for thousands of years, but disappeared around 500 years ago. Dung-rich areas were also full of plant pollen, as from the gut of a grazer. All signs pointed to the Galapagos tortoise, the only large herbivore around. (There’s also an “extinct giant rice rat” that could have left enough dung, the authors note, but it wasn’t known to hang out in swamps.)

When the researchers collected fresh tortoise dung and examined it in the lab, they saw similar patterns of fungus to those in their ancient samples. The same was true of sediment samples taken from a pond where tortoises still live today.

At the same time the dung fungi disappeared, about 500 years ago, certain plant species disappeared from the dirt samples too. The plants that vanished were those that prefer a muddy, churned-up environment—like the home tortoises would have provided as they trampled and sloshed through a wetland. Some of these plant species are now rare or extinct in the Galapagos.

All this evidence added up to tell a story: Tortoises used to cover Santa Cruz Island, from the coasts to the highlands. At the top of the island they wallowed in wetlands with open ponds or lakes. Here they drank, grazed on plants, and kept their bodies cool. Then, around the time humans settled on the island, the turtles left the highlands. It’s still not clear why—their reduced numbers from hunting may have meant less competition from other tortoises, and thus less need to travel for water. There might also have been a shift in the island’s climate that discouraged tortoises from hiking the volcano.

As tortoises left the wetlands, they filled in and became peat bogs dense enough to walk on. Other plant species that had lived there were choked out. Open, freshwater wetlands became rare all across the Galapagos. Charcoal found in the soil samples suggests that as tortoises munched away less of Santa Cruz’s plant material, fires may have become more common too.

Today humans are bringing tortoises back to the islands—though with 5 of the original 14 subspecies now extinct, those tortoises aren’t always the same ones that lived there in the past. The results at Santa Cruz show that just replacing the missing animals won’t turn back the clock. Globally, Froyd says, “we may be missing some of the impacts that past loss of large herbivores has had on ecosystems.” Conservation scientists around the world can learn from the tortoises that when even one animal species leaves, it may carry an entire ecosystem on its back.

When in the Galapagos, Charles Darwin and his Beagle chums ate a couple of dozen giant tortoises, tossing their empty shells over board en route to Tahiti. But in his Narrative of the voyage, captain Robert FitzRoy made it clear that a few small tortoises had survived. “Several were brought alive to England,” he wrote: here.

Enhanced by Zemanta

Island lizards less scared of people


This video is called Marine iguanas of the Galapagos islandsBBC wildlife.

From Nature:

Islands make animals tamer

Lizard study supports Darwin‘s hunch that lack of predators leads to unwatchful behaviour.

Ed Yong

08 January 2014

When Charles Darwin visited the Galapagos Islands, he noted that many of its animal inhabitants were so unafraid of people that “a gun is here almost superfluous”. He swatted birds with his hat, pulled the tails of iguanas and sat on giant tortoises.

These antics fuelled his famous idea that animals become tame when they live on remote, predator-free islands. Now, William Cooper Jr of Indiana University–Purdue University in Fort Wayne has tested Darwin’s hypothesis on 66 species of lizards from around the world and found that island dwellers tended to be more docile than their continental relatives — the strongest evidence yet for this classic idea. The results are published this week in Proceedings of the Royal Society B1.

Several studies and unpublished reports have shown that particular species are more approachable on islands where there are fewer predators, or quicker to flee on islands that contain introduced hunters such as feral cats. But despite this largely anecdotal evidence for island tameness, “no one has ever established that it’s a general phenomenon in any group”, says Cooper. “We showed that for a large prey group — lizards — there really is a significant decline in wariness on islands.”

Taming of the few

Island tameness is an old idea, but there have been few tests of it,” says Dan Blumstein, a behavioural biologist at the University of California, Los Angeles. “This is a needed paper that convincingly shows some of the drivers of island tameness in lizards.”

Cooper and his colleagues scoured past studies and collated data on the distance at which lizards start to flee when approached by a researcher. They took a conservative approach, discarding studies in which researchers had pointed at the lizards, walked towards the animals faster or slower than a particular fixed speed, or studied populations that were habituated to humans.

Cooper and his team ended up with data for 66 species, from the Eurasian common lizard (Zootoca vivipara) to the Galapagos marine iguana (Amblyrhynchus cristatus). The results clearly showed that humans can get closer to island-dwelling lizards than to mainland ones, and that lizards become more approachable on islands that are farther from the mainland.

Island ecology is so important that it overrides any effect of evolutionary history, Cooper and his co-authors say. They also showed that even closely related lizard species have different escape behaviours depending on where they live, and that their evolutionary relationships were mostly irrelevant.

The results do not explain why island lizards are tamer than those on the mainland, although the relative lack of island predators is the most likely reason. Animals with skittish dispositions can needlessly abandon valuable resources, and natural selection would be expected to weed out such responses if predators are rare or absent.

Cooper wants to test this idea, but says that it is hard to get decent data on the numbers, densities and types of predators on different islands.

See also here. And here.

Enhanced by Zemanta