Galapogos giant tortoises and climate change


This 23 March 2019 video says about itself:

Tracking Giant Galapagos Tortoises | BBC Earth

From the Ecological Society of America:

Giant tortoises migrate unpredictably in the face of climate change

Unlike many migratory species, Galapagos giant tortoises do not use current environmental conditions to time their seasonal migration

April 18, 2019

Summary: Researchers use GPS to track the timing and patterns of giant tortoise migration over multiple years. The tortoises often take the same migration routes over many years in order to find optimal food quality and temperatures. The timing of this migration is essential for keeping their energy levels high, and climate change could disrupt a tortoise’s ability to migrate at the right time.

Galapagos giant tortoises, sometimes called Gardeners of the Galapagos, are creatures of habit. In the cool dry season, the highlands of the volcano slopes are engulfed in cloud which allows the vegetation to grow despite the lack of rain. On the lower slopes, however, there is no thick fog layer, and vegetation is not available year round. Adult tortoises thus spend the dry season in the higher regions, and trek back to the lower, relatively warmer zones where there is abundant, nutritious vegetation when the rainy season begins.

The tortoises often take the same migration routes over many years in order to find optimal food quality and temperatures. The timing of this migration is essential for keeping their energy levels high, and climate change could disrupt a tortoise’s ability to migrate at the right time.

In the Ecological Society of America’s journal Ecology, researchers use GPS to track the timing and patterns of tortoise migration over multiple years.

“We had three main goals in the study,” says Guillaume Bastille-Rousseau, lead author of the paper. “One was determining if tortoises adjust their timing of migration to current environmental conditions. Two, if so, what clues do they use to adjust the timing, and, three, what are the energetic consequences of migration mis-timing for tortoises?”

The researchers expected the migrations to be timed with current food and temperature conditions because many other migratory species operate that way. Bastille-Rousseau says “many animals, such as ungulates, can track current environmental conditions and migrate accordingly — what researchers sometime refer to as surfing the green-wave.”

Contrary to the researchers’ expectations, however, migration is weakly associated with current conditions such as fog, rain, and temperature. For instance, if it is unseasonably arid, it appears the tortoises do not take that variation into account when deciding it is time to migrate. It is unclear at this point whether they are basing their migration decisions on memories of past conditions or if they are simply incorrectly assessing current local conditions.

Bastille-Rousseau says the team is surprised by the mismatch, stating “tortoise timing of migration fluctuated a lot among years, often by over two months. This indicates that migration for tortoises may not just be about foraging opportunities. For example, female tortoises have to make decisions related to nesting, and we still have a lot to learn about migration in giant tortoises.”

Fortunately, this sub-optimal timing may not yet have critical impact on tortoise health. Potentially due to their long lives of up to 100 years and large body size, bad timing of migration has smaller consequences for giant tortoises compared to small, short lived animals. Giant tortoises can go up to a year without eating and survive, while other migrating species must eat more regularly to sustain their energy levels.

Giant tortoises are important ecosystem engineers in the Galapagos, responsible for long-distance seed dispersal, and their migration is key for many tree and plant species’ survival. How the tortoises’ variation in migration timing will affect the rest of the ecosystem is still unclear. Because tortoises do not seem to be tracking annual variation in environmental conditions, it is quite possible that the mistiming of migration will keep increasing in the future.

“One concern is that at some point in the future,” Bastille-Rousseau adds, “migration may not be an optimal strategy for tortoises. There may be a reduction in the number of individuals doing these long-distance movements. This would likely have cascading consequences for the whole ecosystem.”

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Hammerhead sharks mating, video


This 19 March 2019 video says about itself:

The Complex world of Hammerhead Mating Rituals | BBC Earth

The Galapagos Islands are like no other place on Earth. 600 miles off the mainland of South America, this isolated archipelago lies in the heart of the Pacific Ocean. This investigation employs tagging technology, underwater mapping, cinematography, thermal cameras and other techniques to track the most mysterious creatures, solve unanswered riddles, explore ancient islands reclaimed by the sea, and encounter the islands’ volcanic underbelly.

‘Extinct’ Galapagos tortoise rediscovered


This 20 February 2019 video in French is about the rediscovery of the Chelonoidis phantastica giant tortoise on the Galapagos islands.

Translated from Dutch NOS TV, 20 December 2019:

Giant tortoise species seen again for the first time since 1906

An extinct giant tortoise has been found in the Galapagos Islands. This species had not been seen since 1906. That is why scientists assumed that a volcanic eruption had eradicated the turtle species.

It is a female Chelonoidis phantastica, a subspecies of the Galapagos giant tortoise. It only lives on the island of Fernandina. The female was discovered by local conservationists.

The proud Minister of the Environment of Ecuador announced the find on Twitter. The archipelago is part of this South American country.

Lots of striking species of lizards, iguanas and giant turtles live on the Galapagos Islands. The flora and fauna on the islands were an important source of inspiration for Charles Darwin‘s book The Origin of Species, in which he explained his theory of evolution.

Galápagos Nazca boobies, females die earlier than males


This March 2016 video says about itself:

Endemic Nazca Boobies of Galápagos

Lindblad Expeditions-National Geographic guest hike on Española Island to see Nazca booby chicks. … Video by Mark Coger.

From Wake Forest University in the USA:

Mom’s reward: Female Galápagos seabird has a shorter lifespan than males

February 12, 2019

The male Nazca booby, a large seabird of the Galápagos Islands, often outlives the domineering female of the species, according to new research from Wake Forest University published today in the Journal of Animal Ecology. Why? It’s a story of rotating sex partners, the cost of being a parent and how the body falls apart in old age.

In the annual quest for the best breeding mate, the older female Nazca booby’s choice to pair with a younger mate may contribute to lifespan differences within the species, said Emily Tompkins, the lead researcher who co-authored “Sex-specific patterns of senescence in Nazca boobies linked to mating system” with biology professor David J. Anderson.

The study is the latest in decades-long research by Anderson, who studies several seabird species. He and his students have been banding Nazca boobies born on Española Island, a roughly 37-square-mile Galápagos Island outpost, for more than 30 years.

The females, which are about 16 percent larger than the males, control mating and decide when it’s time to “divorce” a current partner for one with a better chance at successful breeding. An excess of adult males in the Nazca booby population has led to this practice of “serial monogamy.” When the males enter their late teens, their chance of breeding plummets, while females continue to breed nearly every year. So, the older females of the species often choose a younger mate each breeding season. And that seems to have led to a shorter lifespan for females, Tompkins said.

“Reproducing can reduce adult survival in the following year, so the higher breeding participation by females across the lifespan, and especially in old age, probably contributes to shorter lives,” she said.

Nazca boobies can live into their late 20s, making them an excellent species for studying decline in old age.

“If you’re interested in aging patterns in human systems, we have few opportunities to collect comparative data from other species,” Anderson said. “This banded, known-age, population followed since infancy can help us understand what factors lead some individuals to age well and others to age poorly.”

Only the long-term nature of the Galápagos study has allowed the Nazca booby to fulfill that comparative role. The potentially long lifespan of Nazca boobies means that Anderson has waited decades to observe breeding behavior and reproductive success in old birds.

Several other factors might contribute to the female Nazca booby’s short lifespan, the researchers found:

  • Females receive poorer quality of care as fledglings, because parents don’t always account for how much more food the larger daughters need.
  • Females play a greater role in feeding the chick each breeding season, and that effort might take a toll over the greater number of breeding episodes.

But, Tompkins explained, we’re just beginning to understand the differences in aging among Nazca boobies.

“Some of this variation is explained by sex, environment, and other properties of individuals,” she said. “We’re so fortunate to have decades of data on hand to address this topic.”

Lonesome George, other Galápagos tortoises, new research


This 27 February 2018 video says about itself:

Galápagos Tortoise Movement Ecology Programme

The film captures the hidden mystery of the lives of giant tortoises, among the longest lived vertebrates on earth. It illustrates the diverse ecological roles played by Galápagos tortoises and how the environment has shaped complex yet predictable patterns on movement, morphology and ecological relationships among tortoises across the Galápagos Archipelago.

It demonstrates how a team of conservation biologists developed and implemented a research programme that revealed the hitherto unknown secret lives of Galápagos tortoises – one of the earth’s most iconic wildlife species. It documents the movement ecology of tortoises, their feeding ecology, their role as ecosystem engineers, and their pivotal role in ecosystems.

Touching on their conservation history from the time humans discovered the islands, and how humans will determine the fate of tortoises and their habitats. It demonstrates how scientific research can inform conservation management, and highlight the importance of pure and applied research toward understanding and conserving the tortoises and the ecosystems they shape.

From Yale University in the USA:

In death, Lonesome George reveals why giant tortoises live so long

December 3, 2018

Lonesome George’s species may have died with him in 2012, but he and other giant tortoises of the Galápagos are still providing genetic clues to individual longevity through a new study by researchers at Yale University, the University of Oviedo in Spain, the Galápagos Conservancy, and the Galápagos National Park Service.

Genetic analysis of DNA from Lonesome George and samples from other giant tortoises of the Galápagos — which can live more than 100 years in captivity — found they possessed a number of gene variants linked to DNA repair, immune response, and cancer suppression not possessed by shorter-lived vertebrates.

The findings were reported Dec. 3 in the journal Nature Ecology & Evolution.

“Lonesome George is still teaching us lessons”, said Adalgisa “Gisella” Caccone, senior researcher in Yale’s Department of Ecology and Evolutionary Biology and co-senior author of the paper.

In 2010, Caccone began sequencing the whole genome of Lonesome George, the last of the species Chelonoidis abingdonii, to study evolution of the tortoise population on the Galápagos. Carlos Lopez-Otin at the University of Oviedo in Spain analyzed this data and other species of tortoises to look for gene variants associated with longevity.

“We had previously described nine hallmarks of aging, and after studying 500 genes on the basis of this classification, we found interesting variants potentially affecting six of those hallmarks in giant tortoises, opening new lines for aging research”, Lopez-Otin said.