Friday, September 16, 2016

All About Animals

* The ability of a horse to have a gait called an "amble" which is a very useful thing if you ride horses, is tied to a single gene (based on this paper). A subsequent paper with overlapping authors, looked into the origins of this mutation.
The researchers analyzed DNA from 90 ancient horses dating to over 5,000 years ago, and found the first instance of the mutation occurred in two horses from the York Archaeological Collection, dated to between 850 and 900 A.D. 
The horses originated in medieval England, they say, and were likely taken to Iceland by the Vikings, where they were interbred to produce a population of the gaited variety. From there, these superior comfortable horses spread across Europe, resulting in the wide distribution and diversity of gaits evident today. . . Today, horse breeds ranging from the North American Saddlebred to the Indian Kathiawari possess the ability to amble.
* More progress is being made in understanding the linguistic nature of communications between dolphins.  The article doesn't acknowledge, however, that previous attempts to decode dolphin communication have concluded that an exceptionally large share of the dolphin vocabulary compared to human spoken languages, consists of proper names. A paper discussing a dolphin's complex brain structure is here.

* There is such a thing as a "patchwork virus" in animals as well as plants and fungi.  
Scientists found a virus that is made out of 4 to 5 separate components - it infects mosquitos, and they have to catch at least four of those components to get infected, the smallest, fifth component is optional. For plants and fungi, similar viruses were known before, but (at least according to the study) this is the first example in animals studied in detail. 

The one discovered doesn't affect humans, but a similar virus seems to be present in Ugandan monkeys. More generally patchwork type rearrangements of chunks of genetic material that are already part of the human genome, are important in human genetics and evolution.

* The first genome of the ocean sunfish has been sequenced in the following paper:

Hailin Pan et. al. "The genome of the largest bony fish, ocean sunfish (Mola mola), provides insights into its fast growth rate." GigaScience 5:36 (9 Sept 2016).

It is the world's largest bony fish and grows fast from a tiny size.
Wrinkled and colored a sickly shade of gray, the sunfish doesn't exactly shimmer. However, its pallor isn't nearly as distracting as its awkward shape -- the fish is usually taller than it is long. Moreover, the sunfish's mouth is constantly agape, granting it a dumbfounded look of everlasting surprise. With that gaping maw, the sunfish primarily consumes jellies, a less-than-sumptuous prey. Yet it is on this slimy diet that sunfish can attain weights of over 1,000 kilograms and lengths of nearly six feet. The largest sunfish weighed in at 2,300 kilograms and extended over ten feet in length! Not bad for a fish that, as a baby, begins life measuring just four millimeters across. . . . Researchers recorded a captive sunfish ballooning 880 pounds in fifteen months, an average of 1.8 pounds per day. That's far, far above other ray-finned fish, even ones that are similar in size to the sunfish.
* While dinosaurs were basically wiped out 66 million years ago (except for birds), mammals didn't have an easy time either.  About 93% of mammal species were wiped out at that time as well.  But, those that did make rapidly filled the many niches left vacant by extinct dinosaurs in a period of rapid speciation.
The biggest animals to survive on land would have been no larger than a cat. The fact that that most mammals were small helps explain why they were able to survive. 
Yet the researchers found that mammals also recovered more rapidly than previously thought, not only gaining back the lost diversity in species quickly but soon doubling the number of species found before the extinction. The recovery took just 300,000 years, a short time in evolutionary terms.
The paper is:

N.R. Longrich, J. Scriberas, M.A. Wills. "Severe extinction and rapid recovery of mammals across the Cretaceous-Paleogene boundary, and the effects of rarity on patterns of extinction and recovery." Journal of Evolutionary Biology, 2016.

A nice account of that event is found here.

* One of the placental mammals that survived that event was the solenodon, a venomous insectivore (who knew there were any venomous mammals?), which diverged from other mammals around 78 million years ago. It mitochondrial genome was the last to be sequenced of the major branches of placental mammals. It is now an endangered species. The paper is:

Adam L. Brandt, et al., "Mitogenomic sequences support a north–south subspecies subdivision withinSolenodon paradoxus." Mitochondrial DNA Part A (2016).

* Ancient Moose DNA thousands of years old was found and sequenced in Western Siberia where that clade went extinct in the last glacial maximum.

* Empirical evidence supports breed specific laws related to dogs.  Half of dog fatalities are due to pit bulls and a small number of other breed account for an outsized share of the rest. The source for the article is here.

* A highly contagious dog disease is spreading across the country and killing some of the dogs that get it, but not nearly enough for my liking.

* A new specimen of a newly discovered species of type of rodent that went extinct 18 million years ago, called a gundi or "comb-rat", was identified from remains found in Israel.

* The world's largest rabbit is 4'4" and "three and a half stones" (i.e. about 49 pounds) in weight, but may soon be surpassed by an even bigger son.