Category Archives: genetics

Water flea: small critter, big genome

Daphnia pulex (water flea) with a brood of genetically identical future offspring.

Daphnia pulex (water flea) with a brood of genetically identical future offspring. (Photo/Paul D.N. Hebert, University of Guelph)

In an interesting science factoid of the week, researchers at the University of Guelph have just found the animal with the most genes.

Ringing in at a whopping 31,000 genes, the winner is a near-microscopic crustacean called daphnia, or water flea. In case you’re wondering, humans tally a mere 23,000, about 8,000 less than this little aquatic critter.

Daphnia‘s high gene number is largely because its genes are multiplying, by creating copies at a higher rate than other species,” said project leader and CGB genomics director John Colbourne in a press release. “We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of humans.”

So let that be a lesson. Just because you’re little, doesn’t mean you can’t be big at something.


Potentially new species of lemur found in Madagascar

Close-up of a potentially new species of fork-marked lemur discovered in Madagascar. © Conservation International/ photo by Russell A. Mittermeier

Take a squirrel-sized body, and combine it with big feet, a long tongue, and black-forked markings on the face, and you have the oddly adorable countenance of a species of lemur just discovered in Madagascar.

“This is yet another remarkable discovery from the island of Madagascar…one of the most extraordinary places in our planet” said Conservation International President Russ Mittermeier in a press release, who was the first to spot the animal. Researchers believe the species to be new to science.

Finding this cutie-pie sounds like something plucked from the chase scenes of Indiana Jones. Mittermeier and his colleagues ran through dense forest at night, following the calls of the lemur as it leapt rapidly from treetop to treetop. Catching the lemur in the beam of a flashlight, researchers were able to safely tranquilize it for closer examination.

Close-up of a potentially new species of fork-marked lemur discovered in Madagascar, October 3, 2010. © Conservation International/ photo by Russell A. Mittermeier

Limited geographic range and life in a severely human-impacted environment likely means this species – of the genus phaner – is already endangered or critically endangered, said Mittermeier.

Researchers are now working on establishing the lemur’s genetic uniqueness and learning about its life history and behavior. So far, besides getting a good grip on the lemur’s looks, researchers know that this critter’s diet consists mostly of tree gum and flower nectar, they utter loud, high-pitched calls at night and practice a head-bobbing motion that is unique to this species.

Lemurs are only found in Madagascar, a country that’s lost about 90 percent of its forests and other vegetation.

“Protection of Madagascar’s remaining natural forests should be considered one of the world’s highest conservation priorities,” said Mittermeier in the press release. “These forests are home to an incredible array of species that are a true global heritage.”


Red squirrels are people too. They adopt

Red squirrel taking an adopted baby from nest. (Photo/Ryan W. Taylor)

In another life, I must’ve been a dog. Whenever I’m out walking and see a squirrel, I have an almost uncontrollable urge to see how close I can get to it before the scrappy rodent scrabbles up a tree. Inevitably, a staring contest ensues, which the squirrel usually ends up winning.

My suppressed animal urges aside, I do notice something kind of educational about squirrels. They tend to be alone. When they’re not, they are usually chasing each other like crazed maniacs in a not too friendly manner without regard to life or other happenings.

That’s why it might come as a surprise that they practice a typically human behavior – they adopt. And they adopt outside their social group. A new study by researchers at the University of Alberta determined that red squirrels will take in abandoned or otherwise parent-less young and raise them as their own, a seemingly altruistic act. The behavior turns out not to be as charitable as it sounds – the squirrels do get a survival perk. But the discovery is nonetheless an unusual one in the animal kingdom, with its own squirrely flare to boot.

Jamieson Gorrell, a Ph.D. student in evolutionary biology at the University of Alberta and lead of the study, was observing a population of Yukon red squirrels and noticed a lone female had taken a baby from an abandoned nest to raise as her own. When Gorrell sifted through 20 years of red squirrel research from the area, he found four other instances of the same behavior. Not only that, but in each account, the baby adopted was a relative.

Gorrell found that despite their antisocial tendencies, red squirrels are still able to recognize, and decide to care for, relatives. Right now the predominant notion is that the chitter-chatter squirrels screech out to mark territory or ward off others contains vocal clues about relativity. So an encroaching squirrel could hear the calls of another adult, and recognize kinship. If that other mother disappears, the encroaching squirrel may recognize the kinship of the abandoned nest and take action.

In addition to the novelty factor of the behavior, the study authors also state that this finding proves a long-standing evolutionary theory true. It is a concept known as Hamilton’s Rule, which suggests that despite “the law of the jungle and survival of the fittest,” animals can be altruistic.

Though for red squirrels, it’s a tempered altruism. The red squirrel is still helping out a member of its bloodline, and will only help one baby out of a litter. Adopting more than one is “out of the question,” according to the study, as the strain of adding more than one baby to a single mother’s already full house would outweigh any benefits.

You can read more about the study in the online journal Nature Communications, or visit this link http://www.redsquirrel.ca/KRSP/Media.html to get more info, cute pics, and free copy of the study.


Oops! Endangered tuna unwittingly served at sushi restaurants

Yellow fin tuna (Thunnus albacares) and short-beaked common dolphin in a diorama of the eastern tropical Pacific at the AMNH's Milstein Family Hall of Ocean Live. (Image/R. Mickens/AMNH)

Next time you head out to your favorite sushi restaurant, you might want to think twice about ordering the tuna. There’s a good chance the fish on your plate could be an endangered species.

A new study by the American Museum of Natural History conducted DNA investigations on tuna at restaurants in New York City and Denver and found that nearly 30 percent of the tuna tested was actually endangered bluefin, and less than half of that was labeled as such.

A single bluefin tuna can sell for tens of thousands of dollars at market, a popular draw for the fishing industry. But that popularity comes with a price. Western stocks of northern bluefin tuna now hover around 10 percent of their “pre-exploitation” numbers. And last October, the country of Monaco nominated northern bluefin tuna for a listing under a complete international trade ban by the Convention on International Trade in Endangered Species (CITES), according to a press release.

The serving up of a critically endangered fish is not necessarily on the shoulders of the restaurants. They might not know they’re doing it, just as consumers might not know they’re eating it. This is because the eight species of tuna are so genetically similar – closer than humans are to chimpanzees – that even with DNA testing, it’s hard to distinguish the difference, and once tuna arrives to the U.S. market, the U.S. Food and Drug Administration-approved marketing label is simply “tuna.” A new and improved method of genetic detective work just might help change all that.

“When you eat sushi, you can unknowingly get a critically endangered species on your plate,” says Jacob Lowenstein, a graduate student affiliated with the Museum and Columbia University in the press release. “But with an increasingly popular technique, DNA barcoding, it is a simple process for researchers to see just what species are eaten at a sushi bar.”

DNA barcoding can be used to identify what animal became which product, even down to the origin of a leather handbag, according to the press release. In the case of the bluefin tuna, DNA barcoding defines a genetic key of 14 nucleotides exclusive enough to identify whether the tuna being served is bluefin. A similar method has been used to identify endangered whales on the Asian market and wildlife being sold in the African bushmeat trade.

With any luck, researchers will develop a handheld barcoding machine that can be used to identify fish on-site.

This study can be found in the current issue of PLoS ONE.


Monarch flycatchers: Catching the moment one bird species becomes two

Plumage variations of the monarch flycatcher. (Photo/Courtesy J. Albert Uy)

Plumage variations of the monarch flycatcher. (Photo/Courtesy J. Albert Uy)

How do you measure the instant one species becomes two? Well, in the Solomon Islands, biologist J. Albert Uy is trying to pick a fight with monarch flycatchers to find the answer. The fight’s tipping point has to do with a bunch of feathers, a change in plumage colors that is allowing scientists to capture a snapshot of evolution in action.

A territorial flycatcher (Monarcha castaneiventris castaneiventris) aggressively responding to a taxidermy mount during our mount presentation experiment. We used mount presentation and song playback experiments to test if divergent plumage color and song are used in species recognition between sister taxa (described in Uy et al. 2009). (Photo/Courtesy J. Albert Uy)

A territorial flycatcher (Monarcha castaneiventris castaneiventris) aggressively responding to a taxidermy mount during our mount presentation experiment. (Photo/Courtesy J. Albert Uy)

Flycatcher males are territorial and will launch an avian smackdown towards perceived rivals trespassing on their turf. But a flip of a single gene is turning the monarch flycatcher into a bird of a different color, and in the process changing the social dynamics of rival birds.

It seems that though they are technically still the same species, the black-feathered flycatcher didn’t get the memo about their chestnut-bellied kin, and vice versa. Uy tested this by invading flycatcher territory with dummy birds. What he’s found is that the two don’t see each other as rivals, and are therefore probably more interested in mating with their like-feathered counterparts.

At least in the case of the monarch flycatcher, this single gene and spot of color heralds the birth of an entire new species.

J. Albert Uy (Photo/ C. Low, courtesy J. Albert Uy)

J. Albert Uy (Photo/ C. Low, courtesy J. Albert Uy)

We often hear about species being lost, but rarely do we learn of one being created. Uy’s work provides a glimpse of the “fork in the evolutionary road” as it happens in real-time, and what that could mean for our understanding of bird life.

Uy’s work appears in the current edition of American Naturalist, and you can read more about monarch flycatchers in the 2005 New York Times article, “In Give and Take of Evolution, a Surprising Contribution from Islands.”


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