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Tag: 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].

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.

01.24.2013

dogs, wolves and carbs

Domesticated dog breeds evolved long ago from the wolf. In a study published in Nature, researchers examined differences in the genomes of modern domesticated breeds and wolves and made some interesting discoveries. They expected differences in the nervous systems since the species behave differently. They also found many differences in genes effecting metabolism, especially digestion of carbohydrates. Domesticated breeds digest starches much better than wolves.  From Science News:

The new study focuses on genetic differences between 60 dogs representing 14 breeds and 12 wolves from around the world. Those changes, the researchers reasoned, could identify genes that were important in separating dogs from wolves.

The researchers determined the genetic makeup of groups of dogs and compared the results to those from wolves, concentrating on parts of the genetic instruction book that differ between the two species. As they had expected, the researchers uncovered differences in many genes relating to the brain. But the search also revealed lots of genes involved in starch digestion and metabolism, and in the use of fats. Dogs, the team found, have more copies than wolves do of the AMY2B gene, which produces an enzyme that breaks starch into easily digestible sugars.

Other genetic variants seem to contribute to dogs’ increased ability to convert a sugar called maltose to glucose, the sugar that cells prefer to burn for energy. Yet other genetic changes improve dogs’ ability to move glucose into their cells. Combined, the tweaks alter dogs’ metabolism so they can get more energy out of a carbohydrate-rich diet than wolves can, the researchers conclude. The scientists confirmed the effect of the genetic variants by identifying biochemical differences in starch metabolism in blood and tissue samples from dogs and wolves.

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