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Category: Evolution (page 1 of 4)

11.11.2014

training your cat

An in-depth study of the cat genome reveals details about their history and behaviors.

An in-depth study of the cat genome highlights a variety of genes, including ones for digesting their meaty diets, keen eyesight and good hearing. The researchers found that pet cats also have genes that allow them to respond to positive reinforcement.  From Popular Science:

Cats also seem to have more genes related to digesting fat than other carnivores do, which is important for their super-meaty diets. (Scientists call cats, including wildcats, hypercarnivores.) Cats even have genes that may help them avoid heart disease from their high-fat diets. Polar bear genomes bear similar markers of selection for fat-digesting genes.

To look for the genes influenced by human selection, the researchers analyzed DNA pooled from 23 pet cats, including Cinnamon. They compared the domestic cat DNA with DNA from four wildcats. Among the feline genetic traits that people seem to have chosen are ones that influence how the cat brain responds to rewards. Yep, that means kitty treats! Mice that are missing the mouse versions of some of those genes are poor at learning with food rewards. Perhaps when people first brought cats into their barns and homes, they chose the ones that were more motivated to do things for people in return for tasty tidbits.

The original research appears in PNAS [subscription required].

07.02.2014

bigfoot revealed

yeti, sasquatch, bigfoot

Hair samples from the elusive yeti have been analyzed.

Science Magazine brings news of a peer-reviewed analysis of purported Sasquatch hair samples. Genetic analysis reveals that bigfoot is probably not bigfoot.

In 2012, researchers at the University of Oxford in the United Kingdom and the Museum of Zoology in Lausanne, Switzerland, put out a call for hair samples thought to be from anomalous primates. They received 57 hairs from Bigfoot enthusiasts and museums around the world, including samples from Washington, Texas, Oregon, Russia, and India—a few as old as 50 years. Some “hairs” immediately turned out not to be hairs at all, but rather plant or glass fibers; others were too worn to study.

he researchers, led by Oxford geneticist Bryan Sykes, focused on the remaining 37 samples, isolating and cleaning a 2- to 4-centimeter segment of each hair, many of which have been extensively handled by people, contaminating them with foreign DNA. To identify the evolutionary source of each sample, the team determined the sequence of a gene—found inside the mitochondria of cells—that encodes the 12S RNA, which is often used for species identification. Unlike standard DNA, mitochondrial genes are passed only from mother to offspring.

Seven of the samples didn’t yield enough DNA for identification. Of the 30 that were sequenced, all matched the exact 12S RNA sequences for known species, the team reports online today in the Proceedings of the Royal Society B. Ten hairs belonged to various bear species; four were from horses; four were from wolves or dogs; one was a perfect match to a human hair; and the others came from cows, raccoons, deer, and even a porcupine. Two samples, from India and Bhutan, matched polar bear 12S RNA—a surprising finding that Sykes is following up on to determine whether some Himalayan bears are hybrid species with polar bears.

Read the full text of the study free at Proceedings of the Royal Society B.

03.21.2013

the eerie genetic similarity of giant squid

Giant Squid

The giant squid is one of Nature’s most elusive animals. In fact, the first video of the animal in it’s natural habitat was only captured this January.  Now a new study of the DNA in squids from around the world shows that they are all the same species. The study appears in PNAS. It looks at the DNA from dead squid that had washed ashore around the world and compared the sequences. It turns out that they are all eerily similar. The species has very little genetic diversity. From Scientific American:

When the researchers looked closely at the mitochondrial DNA of the creatures, they noticed something remarkable. Irrespective of where they came from — be it be it California, Japan, South Africa, New Zealand or somewhere else — the squid were genetically very similar.

In fact, the diversity of Architeuthis is lower than that for any other marine animal, except one — the basking shark Cetorhinus maximus, whose current population is thought to have rebounded from a small number of individuals. At first, says Thomas Gilbert, a geneticist at the University of Copenhagen and an author of the study, “When we found that the global genetic diversity of the giant squid was this low, we figured we had made an error.” But then the team checked their numbers again and saw that they were correct.

The findings not only make it clear that all giant squid around the world are the same species, but they also hint that, like the basking shark, the animals came close to extinction at some point in the not too distant past. The results are published inProceedings of the Royal Society B.

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