Gene plays key role in monarch butterfly's miraculous migration

[Buster's Uncle]

Gene plays key role in monarch butterfly's miraculous migration
Reuters
By Will Dunham  2 hours ago



Monarch butterflies fly at the El Rosario butterfly sanctuary on a mountain in the Mexican state of Michoacan November 27, 2013. REUTERS/Edgard Garrido



WASHINGTON (Reuters) - The 3,000-mile (4,800-km) mass migration of monarch butterflies in North America is one of the insect world's fantastic feats, with millions embarking on the arduous journey from as far north as Canada down into Mexico and the California coast each autumn.

Scientists who scoured the genome of these colorful insects offered new insight on Wednesday into this annual airborne adventure. They pinpointed a single gene related to flight muscle efficiency that plays a major role in the monarch butterfly's migration.

Their study, published in the journal Nature, also identified the gene behind the butterfly's striking orange-and-black coloration.

"I find it amazing that these little butterflies live for months and fly thousands of miles to perform this annual migration," said one the researchers, University of Chicago professor of ecology and evolution Marcus Kronforst.

"Our study shows that monarchs have been doing this every year for millions of years. There is nothing else like this on the planet," Kronforst added.



Hundreds of Monarch butterflies fly at the Pedro Herrada butterfly sanctuary, on a mountain in the Mexican state of Michoacan, February 1, 2011. REUTERS/Felipe Courzo


The number of migrating monarchs has plummeted in recent years. Kronforst said while an estimated one billion monarch butterflies migrated to Mexico in 1996, that number stood at about 35 million this past winter. Threats to them include habitat loss due to human activities, pesticides that kill milkweed and climate change, experts say.

While mainly a North American species, monarch populations also can be found in Central America, South America and elsewhere. Those outside North America do not migrate.

The researchers carried out genome sequences on 92 monarch butterflies from around the world including non-migratory ones as well as on nine butterflies from closely related species. To study the genetic basis for migration, they compared the genetic blueprint of migratory monarchs to those that do not migrate.

"One gene really stood out from everything else in the genome," Kronforst said.

It was a gene related to collagen, the main ingredient in connective tissue, that was essential for flight muscle function. The researchers were surprised to find the gene was less active, not more active, in migratory butterflies. So rather than making them big, powerful fliers the gene favored enhanced flight efficiency.

"An analogy might be the difference between marathon runners (migrating butterflies) and sprinters," Kronforst said.

Shuai Zhan, a biologist at the Shanghai Institutes for Biological Sciences, said the study determined that the species originated in North America, contradicting the hypothesis that monarchs evolved from tropical ancestors.

Adult monarch butterflies boast wings that are orange with black veins and white spots along the outside edges. Their wingspan is about 4 inches (10 cm) and their bodies are black.

Scientists say their orange color tells potential predators they taste awful and are toxic to eat thanks to chemicals from the milkweed plants that nourish them in their larval state.

Kronforst said monarch butterflies living east of the Rocky Mountains spend their winters in Mexico to escape the cold weather while those west of the Rockies spend winters on the California coast before returning home in the spring.

(Reporting by Will Dunham; Editing by James Dalgleish)


http://news.yahoo.com/gene-plays-key-role-monarch-butterflys-miraculous-migration-170506789.html

[gwillybj]

The New York Times
Why Some Monarch Butterflies Are Marathoners
Science | Observatory
By SINDYA N. BHANOO
October 1, 2014


A monarch butterfly in Enid, Okla., in September. Credit Billy Hefton/Enid News & Eagle, via Associated Press

Monarch butterflies can be found throughout the world, but only in North America do they make a spectacular mass migration, annually flying from as far north as Canada to winter in Mexico.

Now, by sequencing genomes of 90 monarch butterflies from around the world, researchers have discovered a gene that plays a critical role in determining whether monarchs are migratory, along with new details about their origins, migratory behavior and coloring.

Until now, for example, it was thought that North American monarchs were predated by those in South and Central America. The new research suggests that the North Americans are oldest, said Marcus Kronforst, an evolutionary biologist at the University of Chicago and an author of the study, which appears in Nature.

“And then at some point,” he said, “they dispersed into South and Central America and across the Atlantic and Pacific Oceans.”

The scientists discovered that migratory butterflies had reduced levels of a collagen gene that is involved in forming flight muscles. By using a flight monitor, they also found that the migrators consumed less oxygen and had a lower metabolic rate, allowing them to fly long distances.

“I like to think of it as a marathon runner versus a sprinter,” Dr. Kronforst said. “The migratory ones are really marathon runners.”

While most monarchs are orange and black, a small percentage of those in Hawaii are white and black.

“There’s one spot in one gene where all the white ones are different from all the orange ones,” Dr. Kronforst said.

http://www.nytimes.com/2014/10/07/science/why-some-monarch-butterflies-are-marathoners.html

[gwillybj]

The New York Times
A Virtual Butterfly Hunt
SEPTEMBER 26, 2014 8:56 PM

In the most recent N.Y.C. Nature column, Dave Taft wrote about the monarch butterfly and its migration. Unlike migratory birds, individual butterflies do not complete the trip from the northern United States to Mexico and back.

Instead, the journey is a relay of generations of the insects; how they know the migratory route remains a mystery. We asked readers of NYTimes.com to send us monarch butterfly photographs.

Monarchs can be spotted in flowering meadows on windy autumn days. These photographs were sent by NYTimes.com readers via Twitter with the hashtag #NYTmonarchbutterfly.
Credit From left: Carolynn R. Cobleigh; Sydelle Zove; Barbara Milliken

[Unorthodox]

In the most recent N.Y.C. Nature column, Dave Taft wrote about the monarch butterfly and its migration. Unlike migratory birds, individual butterflies do not complete the trip from the northern United States to Mexico and back.

Instead, the journey is a relay of generations of the insects; how they know the migratory route remains a mystery. We asked readers of NYTimes.com to send us monarch butterfly photographs.

Not ENTIRELY true. 

ONE generation heads south in one stretch, it takes several generations to make the trek back.  The one that journeys south also live longer than the others. 

Pics are both male butterflies, btw. 

[Buster's Uncle]

How the monarch butterfly lost its migration
North America can now claim monarch migration as its own
The Verge
By Arielle Duhaime-Ross on October 1, 2014 01:17 pm



Some monarch butterfly populations don’t migrate. They live in tropical areas of the world, and don’t get as much press as the North American populations that show up en masse on weather radars. But for scientists who study monarchs, they’re critical to understanding the bugs. They’re the reason that most researchers think that these insects first evolved in South America as a non-migratory species, and only started migrating a few hundred years ago, once they moved into the US. And, if a study published today in Nature is further supported, they’ll also be the reason that we were just plain wrong.

Most people — including scientists — think of migration when they think of monarchs, said Marcus Kronforst, an evolutionary biologist at the University of Chicago and a co-author of the study. That may be why so many biologists think that this behavior is one that the butterflies evolved into having, rather than one that came standard and which some monarchs subsequently lost. But today's study suggests that migration predates stationary monarchs.

By taking genetic data from over 100 butterflies and mapping it out, the researchers were able to establish that not only did the monarch start out as a migratory species, but that the non-migratory populations that live in Europe, South America, and Hawaii are actually the product of independent dispersal events.

"It looks like the most closely related butterfly to the monarch itself — the southern monarch — is also migratory," Kronforst says. Which means that at some point, millions of years ago, a butterfly evolved migration, and then split into two separate species. This, Kronforst says, is how the migratory North American Monarch came to be.

But that was far from the researchers’ most surprising finding. Because, as it turns out, only a tiny part of the butterfly's genome substantially contributes to monarch migration. And every time the researchers ran their analyses, a single gene popped up as being wildly different when comparing migratory and nonmigratory populations — a gene that’s actually related to flight muscle function. It participates in muscle metabolism, so when it’s expressed at high levels, it helps butterflies fly more powerfully.

"So clearly, we thought the migratory monarchs would have more of this gene," he says. But when they put monarchs in flight chambers, the researchers realized that this simply wasn’t the case. Migratory monarchs don't express the gene as much, so when they travel long distances, they consume less oxygen, and are therefore more efficient. "And they don't show that difference when they aren't flying," Kronforst says, "so we know it’s related to this gene."

If he has to guess, Kronforst says, his bet would be that butterflies who don’t migrate probably need to fly harder and faster so they can chase mates or evade predators. Migratory monarchs don’t experience the intense competitive pressures that non-migratory butterflies do, Kronforst says, so they can get away with having slower metabolisms and flying more slowly.

"The section on demographic history is spectacular," says Francis Villablanca, an evolutionary biologist at California Polytechnic State University who did not participate in the study. The paper, he says, provides answers to many questions that researchers have long wished someone could answer.  "In one fell swoop, this paper provides the context for us to be able to think about and understand the origin of and the differences between populations."

The study’s findings also matter for monarch conservation, Villablanca says. Monarch populations have been dwindling because humans have waged a war against the monarch’s host plant, the milkweed. But this study shows that each monarch population is genetically unique, which means protecting as many monarch populations as we can suddenly becomes more important. "They may all be descendants of an ancestral North American population," he says, "but it would be difficult to recreate any of them because now they contain unique characteristics."

Moreover, Kronforst says, most scientists think that monarch migration is just a few hundred years old. But his study’s results suggest that the behavior is much older than that — thousands upon thousands of years older. So "if you think of migration as just being a very recently evolved thing, then maybe you care less if it disappears," he says. But "it’s actually very old, and we might be witnessing the very last days of it." For some reason, he says, that seems far worse.


http://www.theverge.com/2014/10/1/6880687/how-the-monarch-butterfly-lost-its-migration

[Buster's Uncle]

How the monarch butterfly became a migrant
AFP
By Mariette Le Roux  7 hours ago



Monarch butterflies in the Oyamel forest at El Rosario sancturay in Angangueo, Mexico on March 18, 2008 (AFP Photo/Luis Acosta)



Paris (AFP) - The monarch butterfly's annual migration from North America to Mexico, a spectacular event at risk of disappearing forever, is the result of a single, millions-year old gene, biologists said Wednesday.

Analysis of the insect's long-guarded genetic secrets has changed what we knew about its history, migration and distinctive bright orange-and-black wing colouring, they wrote in the journal Nature.

"Prior to our work, monarch migration was thought by some to be a very recent phenomenon, but we have shown that it evolved millions of years ago," study co-author Marcus Kronforst told AFP of the findings that he said "overturn past thinking about monarch butterflies".

"I believe this raises the stakes considerably when we consider that we may be witnessing the end of an amazing biological phenomenon that these little insects have been carrying out every year for the past two million-plus years."

There has been a sharp decline in the number of monarchs who undertake the annual trek from as far north as Canada to Mexico for the winter before their descendants, over several generations, make the journey back north for summer.

In 1996, about a billion of the fluttering insects known to scientists as Danaus plexippus, completed the gruelling north-south trip, but only 35 million in the past year, according to the study authors.

The drop has been blamed on deforestation, drought and a sharp decline ascribed to herbicide use in the milkweed plants on which they feed and lay eggs.

"You used to see huge numbers of monarchs, clouds of them passing by," said Kronforst. "Now it looks quite possible that in the not too distant future, this annual migration won't happen."

At the same time, many groups that used to migrate are morphing into stationary populations.


- 101 genomes -

Kronforst and an international team of experts sequenced 101 genomes of butterflies from around the world, including non-migratory and white Danaus varieties.

Because most members of the monarch butterfly family outside North America are tropical and non-migratory, the common ancestor was long thought to have had those same characteristics and to have acquired migration much later.

Under that theory, monarchs first crossed the Pacific and Atlantic oceans in the 1800s.

However, the mapping of their gene tree has shown that the insects originated from a migratory ancestor in North America about two million years ago.

From there, they moved into Central and South America some 20,000 years ago and probably crossed the Atlantic and Pacific already 2,000 to 3,000 years ago, said Kronforst.

Today, they exist as far afield as Europe, Africa and Australia.

To their surprise, the team discovered that migratory ability, a complex animal behaviour, was linked to a single gene implicated in wing muscle formation and function.

It was likely responsible for the long-haul fliers' more efficient oxygen consumption and flight metabolism.

"The butterflies that moved out of North America lost migration," Kronforst added, and the migratory gene "changed".

"I believe our results have implications for helping conserve the monarch migration simply by accentuating the biological significance of the phenomenon," the researcher said.

The team also found that a different single gene was responsible for the monarch's famous colouring.


http://news.yahoo.com/monarch-butterfly-became-migrant-192854287.html