Saturday, May 23, 2015

Go fish! Ancient birds evolved specialist diving adaptations

Date:
           May 22, 2015
Source:
Taylor & Francis
Summary:
A new study of some primitive birds from the Cretaceous shows how several separate lineages evolved adaptations for diving. Living at the same time as the dinosaurs, Hesperornithiform bird fossils have been found in North America, Europe and Asia in rocks 65-95 million years old. This research shows that separate lineages became progressively more adept at diving into water to catch fishes, like modern day loons and grebes. 
 
Evolution of diving specializations within the Hesperornithiformes. Credit: Image courtesy of Taylor & Francis
 
A new study of some primitive birds from the Cretaceous shows how several separate lineages evolved adaptations for diving.

Living at the same time as the dinosaurs, Hesperornithiform bird fossils have been found in North America, Europe and Asia in rocks 65-95 million years old. Dr Alyssa Bell and Professor Luis Chiappe of the Dinosaur Institute, Natural History Museum of Los Angeles County, publishing in the Journal of Systematic Palaeontology, have undertaken a detailed analysis of their evolution, showing that separate lineages became progressively more adept at diving into water to catch fishes, like modern day loons and grebes.

The Hesperornithiformes are a highly derived but very understudied group of primitive birds from the Cretaceous period. This study is the first comprehensive phylogenetic analysis, or evaluation of evolutionary relationships, to ever be undertaken on the entire group.

The results of this study confirm that the Hesperornithiformes do form a single group (or clade), but that within this group the inter-relationships of the different taxa are more complex than previously thought. Additionally, this study finds that anatomical changes were accompanied by enlargement in overall body size, which increased lung capacity and allowed deeper diving.

Overall, this study provides evidence for understanding the evolution of diving adaptations among the earliest known aquatic birds.


Story Source:
The above story is based on materials provided by Taylor & Francis. Note: Materials may be edited for content and length.

Journal Reference:
  1. Alyssa Bell, Luis M. Chiappe. A species-level phylogeny of the Cretaceous Hesperornithiformes (Aves: Ornithuromorpha): implications for body size evolution amongst the earliest diving birds. Journal of Systematic Palaeontology, 2015; 1 DOI: 10.1080/14772019.2015.1036141

Taylor & Francis. "Go fish! Ancient birds evolved specialist diving adaptations." ScienceDaily. ScienceDaily, 22 May 2015. <www.sciencedaily.com/releases/2015/05/150522105222.htm>.

Tuesday, May 5, 2015

Little penguins from Australian east and west coasts stick to their own, researchers find

By Laura Beavis
Updated
Photo: Kangaroo Island is one of the few sites in Australia where penguin colonies from the east and west intermingle. (Supplied: Taronga Zoo)
Little penguins from islands off the south-eastern and south-western coastlines of Australia tend to stick to their own, a 10-year study has found, with one exception - colonies on Kangaroo Island. The scientists from the University of Tasmania, Deakin University in Melbourne, University College London and the Phillip Island Nature Park set out to examine how often little penguins leave and join different colonies.

University of Tasmania zoology lecturer Dr Chris Burridge said they wanted to find out whether penguins would travel from one colony to another to breed. "If a colony was wiped out by a predator, would penguins from other colonies come to help replenish it?" she said.

Over 10 years they took DNA profiles from penguins in colonies along Australia's southern coast from Sydney to Perth and around Tasmania. The researchers found penguins from south-eastern colonies were genetically similar, indicating a high rate of interbreeding among colonies there. The same was true of penguin colonies on the south-west coast.
Around the area of Kangaroo Island you can move only 30 kilometres between two different colonies and they'll be genetically different. ~~~
University of Tasmania zoology lecturer Dr Chris Burridge

Dr Burridge said colonies on Kangaroo Island were different, indicating populations there resulted from breeding between penguins from eastern and western coast colonies. "So in south-east Australia we found quite a lot of movement, you can go from Sydney to southern Tasmania to Phillip Island and the penguin colonies are all genetically indistinguishable," she said. "But then around the area of Kangaroo Island you can move only 30 kilometres between two different colonies and they'll be genetically different."

She said there were several possible explanations for the genetic mixing. "It could be just because that's where the penguins have happened to meet, as they've expanded back out from the east and the west," she said. "Alternatively there could be some activity in that part of the world that removed penguins, maybe anthropogenic and now they've only recently recolonised."

Dr Burridge said the interbreeding on Kangaroo Island had likely begun hundreds or even thousands of years ago. The research has been published in the Journal of Heredity.

source

Sunday, April 26, 2015

1.5m volunteers discover #penguins need to use the faeces in order to breed


Images looked at by 1.5 million online volunteers flagged up images to aid scientists in the discovery.

A citizen science project has found that penguins use their faeces to melt rocky breeding sites in order to lay their eggs.

The project of 1.5 million online volunteers, organised by the University of Oxford, clicked through 175,000 images of penguins and flagged up images showing strange or surprising behaviour in order to aid scientific discovery.

It suggests penguins form large groups before they start to breed with the dark colour of their faeces attracting heat faster than the lighter colours of the surrounding snow, causing the area to melt faster.
The video below shows one year of the Cuverville Island Gentoo penguin colony on the Antarctic Peninsula.



Researchers hope that over the coming year, with 500,000 new images for volunteers to look at, and cameras that will take photos every minute during the breeding season, that they will learn more about the animals through Penguin Watch.

source

Friday, April 17, 2015

Repeated marine predator evolution tracks changes in ancient and Anthropocene oceans

Date:
April 16, 2015
Source:
Smithsonian
Summary:
Scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea. Drawing on recent breakthroughs in diverse fields such as paleontology, molecular biology and conservation ecology, their findings offer a comprehensive look at how life in the ocean has responded to 
environmental change from the Triassic to the Anthropocene.
___________________________________________________










Modern dolphins (pictured) and extinct marine reptiles called ichthyosaurs descended from distinct terrestrial species, but independently converged on an extremely similar fish-like body plan although they were separated in time by more than 50 million years. In April 2015, a team of Smithsonian scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea, offering a comprehensive look at how life in the ocean has responded to environmental change from the Triassic to the Anthropocene. Credit: Courtesy of NOAA


For more than 250 million years, four-limbed land animals known as tetrapods have repeatedly conquered the Earth's oceans. These creatures--such as plesiosaurs, penguins and sea turtles--descended from separate groups of terrestrial vertebrates that convergently evolved to thrive in aquatic environments.

In a new scientific review, a team of Smithsonian scientists synthesized decades of scientific discoveries to illuminate the common and unique patterns driving the extraordinary transitions that whales, dolphins, seals and other species underwent as they moved from land to sea. Drawing on recent breakthroughs in diverse fields such as paleontology, molecular biology and conservation ecology, their findings offer a comprehensive look at how life in the ocean has responded to environmental change over time. The paper also highlights how evolutionary history informs an understanding of the impact of human activities on marine species today. More information is available in the April 17 issue of Science.

Marine tetrapods represent a diverse group of living and extinct species of mammals, reptiles, amphibians and birds that all play--or played--a critical role as large ocean predators in marine ecosystems. The repeated transitions between land and sea have driven innovation, convergence and diversification against a backdrop of changing marine ecosystems and mass extinctions dating back to the Triassic period. In this way, they provide ideal models for testing hypotheses about the evolution of species over long periods of time. Modern species of marine tetrapods now face a suite of human-driven impacts to their environment, including climate change, habitat degradation, ship collisions and underwater noise.

"We know from the fossil record that previous times of profound change in the oceans were important turning points in the evolutionary history of marine species," said Neil Kelley, a Peter Buck post-doctoral researcher in the National Museum of Natural History's department of paleobiology and lead author in the study. "Today's oceans continue to change, largely from human activities. This paper provides the evolutionary context for understanding how living species of marine predators will evolve and adapt to life in the Anthropocene."

Recent investigations in the fossil record have provided new insight into the evolution of traits that allowed marine tetrapods to thrive in the sea. In some cases, similar anatomy evolved among lineages that adapted to marine lifestyles. For example, modern dolphins and extinct marine reptiles called ichthyosaurs descended from distinct terrestrial species, but independently converged on an extremely similar fish-like body plan although they were separated in time by more than 50 million years. 

The repeated transformation of legs adapted for walking on land into fins is another classic example of convergent evolution. Species ranging from seals to mosasaurs independently developed streamlined forelimbs as they transitioned from living on land to the ocean, allowing them to move quickly and efficiently in the water. This transformation may have been achieved by parallel changes at the genome level.

"Land to sea transitions have happened dozens of times among reptiles, mammals and birds, across major mass extinctions," said Nicholas Pyenson, the museum's curator of fossil marine mammals. "You often get similar looking results but convergence is more than skin deep. It can be seen on a broad range of scales, from molecules to food webs, over hundreds of millions of years."

In the case of deep divers such as beaked whales and seals, these species have independently evolved to have positively charged oxygen-binding proteins called myoglobin in their muscles, allowing them to survive underwater for long periods of time. Scientists also have found identical genetic sequences in different marine species, such as whales, seals and sea cows. Whether these invisible molecular similarities account for larger-scale visible patterns of convergent evolution, or whether convergent anatomy follows different genetic pathways in different groups, remains an important open question to be tackled as genomic sequences become available for more species.

Not all adaptations observed in marine tetrapods can be attributed to convergent evolution. For instance, as baleen whales evolved to live underwater, they developed a unique filter-feeding system that depends on hair-like plates instead of teeth. In contrast, toothed whales evolved to catch and feed on prey by emitting calls and using echolocation, a kind of sonar, to process the echoes from these noises and detect objects in the sea.

Kelley and Pyenson synthesized research from existing studies and referenced the Smithsonian's paleobiology collections during the course of their research. They intend that this comprehensive review will encourage future collaboration between researchers across scientific fields and lead to new insights about evolutionary biology, paleontology and marine conservation.

Story Source:
The above story is based on materials provided by Smithsonian. Note: Materials may be edited for content and length.

Journal Reference:
  1. Neil P. Kelley, Nicholas D. Pyenson. Evolutionary innovation and ecology in marine tetrapods from the Triassic to the Anthropocene. Science, 2015 DOI: 10.1126/science.aaa3716


Smithsonian. "Repeated marine predator evolution tracks changes in ancient and Anthropocene oceans." ScienceDaily. ScienceDaily, 16 April 2015. <www.sciencedaily.com/releases/2015/04/150416145547.htm>.

Saturday, March 21, 2015

From sea lions to #penguin chicks, adorable animals are dying in droves





We know and love sea lions for their soulful eyes and playful antics — they’re basically the golden retrievers of the ocean. But recently, sea lions have been making headlines for much sadder reasons: Droves of malnourished sea lion pups have been washing up all over the Southern Californian coast. More than 1,450 pups have stranded without their mothers since January, reported the Washington Post.

The cause? Starvation.

Warmer waters off the coast of California are likely driving away sea lions’ prey such as squid, anchovies, and sardines, said Justin Viezbicke, stranding services coordinator for the National Oceanic and Atmospheric Administration (NOAA). As a result, mother sea lions are having to go further from birthing grounds — usually around the Channel Islands — to forage for food, meaning that pups probably don’t get enough nutrients from their mothers when they return. The pups then wean off their mothers earlier and are underweight when they leave the island, likely to find food of their own.

“They’re leaving with a low tank of gas and there’s really not much out there to help them out,” said Viezbicke. “They’re jumping into … a challenging environment and then they’re ending up washing ashore on the mainland, starving.”

Organizations like NOAA and other animal rescue programs have been taking in pups and feeding them — but that’s only a stopgap measure.

“This is something that’s naturally occurring out there, so there’s really not much we can do other than watch and learn from the situation,” Viezbicke said. “We can’t really prevent or stop it, unfortunately.”

Left to their own devices, these stranded sea lion pups probably wouldn’t make it. (No judgement if you need a tissue here. I’ll wait.)
auklet
Fred Hochstaedter
As sad as it sounds, starvation events and mass mortality events (in which vast numbers of animals die), are becoming more and more common in this wacky, warming world. Thanks to a number of large-scale, systemic alterations (lookin’ at you, El Niño and warming ocean temps), the world’s ecosystems hang in a delicate balance.

Meet the Cassin auklet — a pudgy, fist-sized seabird with crescent-shaped eye markings and pale blue feet. They’re pretty dang cute. And thousands of them are washing up dead along the West Coast — all the way from Northern California to British Columbia.

“My volunteers alone … have found 7,000 carcasses [over the last four months],” said Julia Parrish, executive director of the Coastal Observation and Seabird Survey Team (COASST) at the University of Washington. “It’s a scary big number.”

Like the sea lions, auklets are literally dying for a meal. The birds primarily feed on zooplankton or krill. However, in the last year, a mass of warm water — very scientifically named “the blob” — drove the usual Pacific krill into deeper waters and brought in a host of zooplankton that the auklets don’t eat, reported Audubon Magazine.

When a high number of birds wash ashore dead, the events are called “wrecks.” Generally speaking, smaller wrecks are fairly normal, Parrish explained. If there’s a storm out at sea, it’s not unusual for seabirds caught in its path to die, whether from starvation or storm conditions, and later wash up on beaches. That’s just how it goes.

But this time, something is different. “This is the biggest wreck we’ve ever seen in the 16 years we’ve been doing this work,” Parrish said. “I think it’s probably the largest wreck we’ve seen on West Coast … That makes me sit up and take notice.”

This winter’s wreck could be especially bad if enough of the dead auklets turn out to be adults, because an entire reproductive group may have been wiped out. They won’t know for sure until the birds return to their breeding grounds. Until then, it’s a lot of waiting and counting dead birds.
beachedaucklets
D. Derickson/COASST
So is this climate change at play? Scientists are hesitant to say.

Dee Boersma, a conservation scientist and founder of the Penguin Sentinels Project at UW, compares the vulnerability of seabirds to weather and climate to the vulnerability of a human crossing a busy street: You could get hit by a truck, but it doesn’t happen every time. And just as it’s hard to predict exactly how likely you are to survive a street-crossing as a human, the same goes for storms and their effects on Magellanic penguins, she said.

In 2014, Boersma and other penguin researchers published a study in PLOS ONE which found that climate change was directly responsible for the deaths of more than 200 Magellanic penguin chicks from 1983 to 2010 in Punta Tombo, Argentina. There, climate change is increasing the intensity and frequency of storms, while lowering the reproductive success of Magellanic penguins, the study reported.

During the 27-year-long study, young penguins perished at a high rate due to a combination of starvation and overexposure during exceptionally rainy and hot seasons. The chicks’ feather coats keep them cozy when they are dry, but that changes when they get wet: The fluffy down isn’t waterproof, like adult penguin feathers. So if a penguin chick gets caught in the rain during a storm, it’s like a human “being stuck outside and naked in a wet sleeping bag … the penguins basically die of hypothermia like you or I would,” said Boersma.

Plus, a lack of food leaves the chicks unprepared to cool themselves down when things heat up, since they rely on the food their parents bring them for all of their water. Without adequate hydration, the chicks can’t depend on evaporation to keep cool and become vulnerable to heat stress.

It’s a lethal combination: Over the course of the study, an average of 65 percent of the Punta Tombo chicks died every year, with about 40 percent dying of starvation.
Chicks that died of hypothermia after a rainstorm.
Chicks that died of hypothermia after a rainstorm.
Dee Boersma / University of Washington
So what was that about climate change again? Mass animal die-offs and starvation epidemics are shocking no matter what, even to hardened scientists. Climate change is just exacerbating these kinds of things.

“The fact is that we have populations responding to warming events, whether the warming is temporary or inexorable,” said Parrish, the researcher studying the dying auks.

The world’s ecosystems are hanging on as best they can, but small things can throw them out of balance. It’s unfair to compare the temperatures that a wild ecosystem can withstand to the temperatures humans can, because we have tools and technology on our side. “Wildlife needs habitat,” Parrish said. “In today’s crowded world, habitat only exists in certain places — places that we protect. And when the climate warms, those places change.”

“[Even one degree] is a huge deal,” Parrish points out. To understand and support conservation efforts, humans need to “think like a fish, a clam, or an oyster, and not like a person.”

Guess it’s time to get in touch with your inner oyster or auklet — getting hungry yet?

source

Tuesday, March 17, 2015

Penguin waddle put to the test




Thinkstock  
A penguin's waddle is one of nature's weirdest walks
"Come on Puddle… You can do it!" yells Prof John Hutchinson.
Puddle - a Humboldt penguin - seems more than a little bemused.
And with good reason.

***
 
A team of scientists have come to Penguin Beach at London Zoo, installed a hi-tech track and are now trying to lure Puddle and his penguin pals across it.
"Go Puddle, go!" encourages Prof Hutchinson, from the Royal Veterinary College (RVC).
And at last - with a fishy treat to help him along the way - the little bird waddles along the runway.
It is this distinctive walk that scientists from RVC and University of Texas at Austin are here to study.
Beneath the track lie force plates loaded with sensors, which allow the researchers to analyse how these birds get around.

"Penguins move in a really weird way," explains Prof Hutchinson.
"They have a very upright posture like a human, but they also have very short, crouched legs - it is very comical."Prof John Hutchinson on the eccentricity of the penguin's walk
He adds: "But when I see an animal do something weird, as an evolutionary biologist, I want to know how that evolved, how it got that way.
"And with these experiments, we're trying to tie what we know about penguin evolution with penguin physics."

Foot swing

Previous studies of the penguin's ungainly gait have revealed that the waddle is in fact the most energy efficient way for them to get about on land.
But these experiments will reveal exactly how they are doing this.
"They are applying forces left and right as they swing their bodies from side to side," says Prof Hutchinson.
"But what is not known about penguins is how the legs do that, how big are the sideways forces on penguin legs and how that compares to other waddling birds.
"And that's why we need these force platforms to measure the forces in the legs individually."
Waimanu  
 
The Waimanu is one of the oldest penguins discovered - and most likely had a more horizontal posture
But it turns out that penguins didn't always waddle. Fossils reveal that their ancient ancestors moved in a different way.
"We have all kinds of fossils as far back as 60 million years ago from the Southern Hemisphere," says palaeobiologist James Proffitt, who has come from Texas to study the birds.

"That gives us a chance to understand how these unusual anatomies and behaviours have evolved in deep time and how we have all these bizarre things we see today."
The bird bones show that the first penguins were a varied bunch: some were tiny, but others grew as tall as humans, hunting large fish with their spear-like beaks.
James Proffitt is particularly interested in a genus of penguins known as Waimanu.
These birds, unearthed in New Zealand, are the oldest-known penguins, living between 58-60 million years ago.

Mr Proffitt explains: "We know that penguins such as Waimanu were also flightless, wing-propelled divers based on things like their wing proportions and their relative size.
"But in many ways they were different, and they probably moved about differently on land based on the anatomy of their legs and hip bones."
The team believes that these proto-penguins had a more horizontal posture, and their walk would have looked similar to that of a modern-day albatross.

Today's penguins most likely evolved their unusual anatomy and resulting waddle as they became better and better adapted to swimming.
As their body shape changed to help them fly through the water with ease, they became more and more clumsy on land.

Penguin Penguins use their wings to fly through the water

Back at the running track, and the penguins seem to be enjoying not quite doing what they are told.
But Zuzana Matyasova, London Zoo's deputy team leader for the bird department, has found a way to attract their attention.

A combination of some dangling string, a tennis ball on a stick - or some fish - is proving hard for some penguins to resist.
"Some of the youngsters are really inquisitive: anything new in their enclosure is almost like a challenge and they want to be the first ones to try it out," she explains.
She's hoping all this hard work will shed light on these birds.
"I work with them every day, and I wonder about their way of moving - their distinctive waddle is just amazing."

While not every bird fancies taking a waddle down the runway, after several days, the scientists manage to collect enough data to begin their analysis.
And by comparing this with their studies of ancient penguins, they hope to establish how and when one of nature's most distinctive walks evolved.

 source

Thursday, March 5, 2015

#Penguins Rapidly Conquered New Zealand After Humans Ate Rivals

by Becky Oskin, Senior Writer   |   March 03, 2015

Sunday, March 1, 2015

Genetics reveal Antarctica was once too cold for #penguins

 
 
Emperor penguins are adapted to the bitter cold of Antarctica, but a new study reveals that during the last ice age it got too cold even for them.
Not too hot, not too cold, but just right. Gary Miller/Australian Antarctic Division, Author provided
Emperor penguins are truly remarkable birds – they thrive in the coldest environment on Earth and live year-round on the ice. Breeding colonies congregate on sea ice during the Antarctic winter and must withstand temperatures that regularly drop below -30C.

In fact, emperor penguins are so adapted to cold conditions that they become heat stressed when temperatures climb above 0C. Emperor penguins are therefore particularly threatened by climate change, and their numbers are expected to decline in the coming decades.

However a new study, published today in Global Change Biology, shows that it was once too cold even for emperor penguins.

Penguins past and present

In our study of how changing climate has affected emperor penguins over the past 30,000 years we found that, during the last ice age, emperor penguins were roughly seven times less common than today. What’s more, it appears that only three populations survived the last ice age. The Ross Sea was a refuge for one of these populations.

In the first continental-scale genetic study of emperor penguins, we examined genetic diversity of penguins modern and ancient to find out how they’re related. We collected genetic samples from eight breeding colonies – no easy feat given that emperor penguins live in some of the remotest places on Earth in conditions that would send most people running for a roaring fire and a hot cup of tea.
A rookery near Mawson station. Chris Wilson/Australian Antarctic Division, Author provided
Reaching the colonies involved weeks on the notoriously wild Southern Ocean (and considerable seasickness), helicopter journeys over pristine expanses of sea ice, and long snow shoe and ski traverses. The “A” (for Antarctic) factor was a constant presence, with delays caused by heavy sea ice that trapped ships for days at a time and blizzards that grounded helicopters.

Nevertheless, the effort paid off. Analyses of genetic data allowed us to reconstruct the population history of penguins, and correlate it with environmental conditions inferred from ice core data. The findings indicate that approximately 12,000 years ago, after the ice age ended and temperatures began to rise and sea ice around Antarctica decreased, emperor penguin numbers began to climb.

Goldilocks penguins

The emperor penguin’s relationship with sea ice can be described as a Goldilocks phenomenon.
The penguins need stable sea ice to stand on during their breeding season. If the sea ice extent is too great then the journey between the colony and their feeding grounds in the ocean may prove too costly in terms of energy reserves.

If there is too little sea ice or if the sea ice is not stable enough, then the penguins cannot establish successful breeding colonies. The duration of the sea ice season is also important – if the season is too short for the chicks to adequately mature, then they may not have time to grow their adult, waterproof feathers and will not survive at sea.
Some like it hot… but not emperor penguins. Frederique Olivier/Australian Antarctic Division, Author provided
During the last ice age there was about twice as much ice as there is today. Emperor penguins were probably unable to breed in more than a few locations around Antarctica. The distances from the open ocean, where the penguins feed, to the stable sea ice where they breed was probably too great in most of their modern breeding locations.

The three populations that did manage to survive the ice age may have done so by breeding near polynyas – areas of ocean that are kept free of sea ice by wind and currents. One of the most important of these polynyas was located in the Ross Sea.

Uncertain future

Because of this Goldilocks relationship emperor penguins are facing an uncertain future. Antarctic sea ice extent has been measured using satellites for the past 35 years. In this time, large changes with very different trends in different regions have been observed.

For the past three years in a row winter sea ice has broken records for total maximum extent. This overall increasing trend masks major regional changes in the extent of the sea ice field and the duration of the sea ice season.
Emperor penguin colonies are found right around the Antarctic continent. Jane Younger, Author provided

In some areas, such as the Bellingshausen Sea, there has been a large decline in sea ice while in others, including the Ross Sea, sea ice is increasing. These fluctuations in sea ice are likely placing a huge strain on emperor penguin populations, which is set to continue into the future. As areas suitable for emperor penguin breeding become scarcer it is becoming increasingly important to conserve areas known to support penguin populations.

It’s clear that the Ross Sea was a critical area for emperor penguins in the past and this suggests it will provide an important refuge for breeding colonies in the future. This emphasises the need for careful protection of this vital part of the Antarctic ecosystem.

A marine protected area, to protect roughly 1.34 million square kilometres of the Ross Sea from commercial fishing, was proposed by New Zealand and the United States at the last meeting of the Commission for the Conservation of Antarctic Marine Living Resources in October 2014. The proposal was rejected, but a Ross Sea marine park is likely to be on the agenda again at the 2015 meeting.

Emperor penguins are remarkably hardy birds, surviving in one of the harshest environments on earth. However their reliance on a narrow range of suitable habitat highlights their fragility, and raises concern over their future in a world undergoing its most rapid environmental change in history.

What does the future hold for Emperor penguins? Gary Dowse/Australian Antarctic Division, Author provided
 
source 

Monday, February 16, 2015

Sweet? Bitter? #Penguins Can't Tell, Research Suggests

Feb 16, 2015
                                               Wikimedia Commons/Tekken50

NEW YORK (GenomeWeb) – Penguins appear to lack taste receptor genes governing three of the five tastes, according to a genomic analysis conducted by a trio of researchers from the US and China.

The trio, led by Jianzhi Zhang at the University of Michigan, searched through the genomes of the Adélie penguin (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) and other birds for taste receptor genes. Penguins, they found, lacked receptors involved in perceiving sweet, bitter, and umami taste, but have retained salty and sour taste receptors, as they reported in Current Biology.

"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," Michigan's Zhang said in a statement. "These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas."

Zhang and his team searched for genes that encode taste receptors — sour's PKD2L1, salty's ENaC, umami's Tas1r1–Tas1r3 heterodimer, sweet's Tas1r2–Tas1r3 heterodimer, and bitter's Tas2r genes — in Adélie and emperor penguins, as well as in the little egret and a dozen or so other birds whose genomes were publicly available.

None of the birds had the Tas1r2 gene, which encodes part of the sweet taste receptor, though the researchers did find the gene in mammalian and reptile outgroups.

Tas1r3, which makes up the other part of the sweet taste receptor heterodimer as well as part of the umami taste receptor heterodimer, was also lacking in penguins. It was, the researchers noted, present in other birds.

The other half of the umami taste-specific receptor, Tas1r1, is actually a pseudogene in penguins, the researchers found, as it contains a two basepair deletion that leads to a premature stop codon.
Other penguin species shared this pseudogene, but other birds have working copies, Zhang and his team reported.

Similarly, the researchers identified three Tas2r pseudogenes in penguins while most other birds had working copies of the gene behind bitter taste. They noted, though, those three penguin pseudogenes were orthologous to the two working copies and one pseudogene version of Tas2r found in the little egret.

This, Zhang and his colleagues said, indicates that the common ancestor of all penguins lost the umami and bitter tastes, while the sweet taste was lost even earlier in the avian lineage.
The receptor gene for sour taste was present in all birds, including penguins, as were the genes encoding the subunits of the salty taste receptor, ENaC.

Zhang and his colleagues said they suspect that the penguin's ancestral stomping grounds of Antarctica might have had a role in this gene loss.

Trpm5, which is involved in transducing the sweet, umami, and bitter tastes, doesn't work well at lower temperatures. At freezing temperatures, the researchers suggested that it might not work at all, leading to the inability to taste sweet, umami, and bitter, and then to the loss of the genes linked to those tastes.



Journal Reference:
  1. Huabin Zhao, Jianwen Li, Jianzhi Zhang. Molecular evidence for the loss of three basic tastes in penguins. Current Biology, 2015; 25 (4): R141 DOI:10.1016/j.cub.2015.01.026

Tuesday, February 10, 2015

#Penguin change stuns scientists


Yellow-eyed penguin. Adult standing showing wing 'flippers'. Otago Peninsula, January 2006. Image © Craig McKenzie

Dunedin
When yellow-eyed penguins arrived in New Zealand just decades after the country's native waitaha penguin became extinct, it became one of the most rapid prehistoric animal turnovers ever found, University of Otago researchers say.

The team of researchers used carbon dating and DNA analysis of penguin remains from coastal New Zealand to establish the timing of the waitaha's extinction and the colonisation by yellow-eyed penguins from the subantarctic.

University of Otago postdoctoral research fellow Dr Nic Rawlence, who carried out the study, said the combination of ecology, archaeology and DNA in this way was new and was also being used to investigate if similar patterns exist with New Zealand sea lions, Stewart Island shags, elephant seals and fur seals.

Previous research had shown at the time of human arrival, New Zealand was inhabited by the waitaha penguin. ''Hunting and habitat change apparently caused the extinction of this unique mainland penguin, before the yellow-eyed penguin later arrived here from the subantarctic,'' Dr Rawlence said.

The new dating study showed waitaha went extinct around the same time as the giant flightless moa, within 200 years of Polynesian settlement of New Zealand - before 1500 AD. The yellow-eyed penguin then replaced the extinct penguin within about 20 to 30 years, in the early 1500s. ''It's one of the most rapid biological turnovers ever documented.''

Associate Prof Ian Smith, who was also involved in the study, said the very rapid biological shift implied a substantial change in human pressure around that time. ''Interestingly, recent archaeological studies similarly suggest that the Maori population in southern New Zealand declined around 1500 AD, and coincided with a major dietary shift.''

Dr Rawlence said if there had not been the dietary shift from large animals to fish and shellfish, yellow-eyed penguins would not have been able to fill the niche left by the waitaha. ''Yellow-eyeds would have arrived and then become extinct if there hadn't been that change.''

The near absence of the yellow-eyed penguin from the mainland before the extinction of the waitaha was similar to what happened to New Zealand's sea lions.

A University of Otago study published last year found today's sea lions replaced an extinct prehistoric New Zealand sea lion. The Marsden and Allan Wilson Centre-funded research on penguins included team members from the Universities of Auckland, Otago, Adelaide and Oslo, as well as Canterbury Museum and Te Papa.

The team's findings were published this week in the leading international journal Quaternary Science Reviews.

source

Tuesday, January 20, 2015

Climate Change Puts Picky #Penguin Eaters At Risk

By Jenna Iacurci
Jan 20, 2015 
 
penguins
Climate change is putting picky penguin eaters at risk, according to a new study. (Photo : Rachael Herman, LSU) 
 
Climate change is putting picky penguin eaters at risk, according to a new study.

Chinstrap and Gentoo penguins live in close proximity to one another in the Antarctic Peninsula, especially during the summer breeding season. So in order to peacefully co-exist and avoid competition for food resources, they evolved different feeding strategies over time. Now, however, this seems to be backfiring on one of the two species.

Named for the black stripe under their chins, Chinstrap penguin populations are decreasing while Gentoo penguins, recognized by their bright orange beaks, are actually increasing in number.

"Our data shows Gentoo penguins have a more diverse and flexible diet than Chinstrap penguins, which forage farther offshore and preferentially feed on Antarctic krill during the breeding season," lead author Michael Polito, from Louisiana State University, said in a press release.

Thanks to climate change, the Antarctic Peninsula is the fastest warming region in the Southern Hemisphere, according to the British Antarctic Survey. Over the past 50 years, the annual air temperature has risen by about 5 degrees Fahrenheit (2.8 degrees Celsius).

"For a region that for most of the year hovers around the point of freezing, a few degrees plus or minus is the difference between freezing and melting, particularly of sea ice," Polito explained.
This isn't just bad for penguins, but for the Antarctic krill that they mainly feed on, which use sea ice for protection from predators. Krill also feed on algae that grow beneath these slabs of ice, so as temperatures warm the lack of sea ice means fewer krill are around for penguin species to eat.

Based on the laws of supply and demand, there isn't enough krill to go around - especially during breeding season when penguins have to worry about feeding their chicks. So Chinstrap penguins whose diet relies on Antarctic krill find themselves in a tough spot.

On the other hand, adaptable Gentoo penguins are doing just fine, even amongst rapidly changing environmental conditions. They are flexible in their diet and breeding location, and also likely ease the transition of their chicks into adulthood by feeding them for a longer period of time.

Researchers determined the species' feeding habits by examining their stomach contents, studying the ear bones of fishes to determine if the penguins were feeding nearshore or offshore, and analyzing breast feathers from fully grown chicks to see how much krill versus fish they were fed. The results showed two very different strategies.

"These may be the reasons why Gentoo penguins in the Antarctic Peninsula are benefiting from changes in climate and their populations are increasing, but Chinstrap penguins are decreasing," Polito said.

The results are described further in the journal Marine Ecology Progress Series.

source

Friday, December 19, 2014

Antarctic tourism may pose disease threat to #penguins

  • 19 December 2014 by Penny Sarchet
A take-off in tourism could open the door to new bird diseases <i>(Image: Frans Lanting/National Geographic Creative)</i>
A take-off in tourism could open the door to new bird diseases (Image: Frans Lanting/National Geographic Creative)

For those who go, it's the trip of a lifetime – and it wouldn't be complete without a selfie with penguins. But growing tourism to the Antarctic, in combination with its warming climate, could be placing penguins at a risk of infectious diseases.

Antarctic species are believed to have weaker immune systems due to their long isolation from the world's common pathogens. Humans only started visiting Antartica roughly 200 years ago.
Antarctica is no longer a stranger to human contact: more than 37,000 people visited the continent in the 2013-14 season as part of a growing tourist industry, compared with an estimated 8000 just twenty years earlier. An additional 4400 researchers can be accommodated simultaneously in Antarctica during peak months.

"The effects of both a growing tourism industry and research presence will not be without consequences," says Wray Grimaldi of the University of Otago in Dunedin, New Zealand. "Penguins are highly susceptible to infectious diseases." She bases that on a survey by her team of penguin diseases in captivity, reaching as far back as 1947. It found reports of Salmonella, E. coli, West Nile virus and Avian pox virus infections, among others.

Widespread deaths

The team also found evidence of a number of mass penguin mortality events across the Antarctic since 1969. A number of infectious agents are implicated, including Avian pox, which killed more than 400 gentoo penguins in 2006, and caused 60 per cent mortality rates throughout another outbreak in 2008.

Grimaldi says disease agents may have arrived in Antarctica via migrating birds like skuas or giant petrels, although some pathogenic bacteria could have been introduced by humans. There isn't enough evidence to test either possibility, she says.

Yet, as the climate warms, more birds are expected to visit Antarctic regions, bringing their pathogens with them, while diseases borne by other animals could expand their ranges southwards.

But Norman Ratcliffe of the British Antarctic Survey in Cambridge, UK, says there is not a lot of evidence that wild penguin populations have been significantly affected by disease, adding that the Antarctic's tourism industry has been very active for 20 years and takes appropriate precautions.
"The tour companies are quite careful to make sure everyone cleans their boots before they go ashore," he says. "They don't allow any animal products to be taken ashore."

Warming warning

Grimaldi warns that climate change could help drive the emergence of new penguin diseases in Antarctica. Claire Christian of the Antarctic and Southern Ocean Coalition, a group of environmental NGOs, agrees.

"Climate change may result in a number of stressors that make it more difficult for penguin populations to deal with disease," she says. In addition to prompting the arrival of new pathogens or species carrying pathogens, warming temperatures could have a negative impact on food sources like krill, which might leave the penguins less able to fight off illness, she adds.

"A coordinated monitoring system needs to be in place," argues Grimaldi. "That way, responses can be directed by science." Christian agrees, but she says research alone is not enough – the countries that are signatories to the Antarctic Treaty also need to cooperate in implementing protective and precautionary measures.