Showing posts with label zoology. Show all posts
Showing posts with label zoology. Show all posts

Tuesday, September 4, 2018

Mole Rat Mind Control

From PNAS via The Atlantic “Naked-Mole-Rat Queens Control Their Subjects by Having Them Eat Poop":
And according to a new study from Japan, naked-mole-rat queens use their hormone-rich poop to govern their subordinates. When the subordinates eat the hormone, it turns them into attentive caretakers of the queen’s own pups. It’s mind control, via poop. 
Naked mole rats had interested Kazutaka Mogi, a biologist at Azabu University, because of their unusual social structure. Like ants and bees, but unlike almost all other mammals, naked mole rats live in large colonies where the queen is the only female that reproduces. Her subordinates take care of the pups, and they never make sex hormones of their own or become sexually mature. Mogi and his team had investigated parenting in mice, and they knew that hormones play a key role in triggering parental behaviors in mammals. If the bodies of the subordinate naked mole rats aren’t making any hormones, how do they become such attentive caretakers—to pups that aren’t even their own? 
… 
The team collected fecal pellets from pregnant queens and gave them to a handful of subordinate females, which soon became much more responsive to the cries of pups. Then they repeated the experiment to make sure the hormones were really the key component of the poop. This time, they took fecal pellets from nonpregnant queens and added estradiol—a type of estrogen—to only half of the pellets. Only the naked mole rats that ate the estradiol-supplement poop became more responsive to pup cries. 
Mogi was excited. He had never seen hormones work like this before. Hormones are powerful mediators of behavior, but their effects are normally limited to the body of the animal making them. Here the queen seems to be making hormones to alter the bodies of totally separate animals. Insect colonies have sometimes been called superorganisms for the way thousands of individuals behave as one unit; in this case, hormones seem to be acting on naked-mole-rat colonies as a single superorganism.
This is pretty amazing stuff that I would not have expected in mammals.

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.

Monday, October 6, 2014

Personalities Aren't Just For Humans

Recent studies show that animals far removed from mammals have recognizable personalities.

There are extroverted and introverted sharks in the same species.  The extroverts scare away threats by hanging out in groups.  The introverts head off alone to isolated places and rely on camouflage.

There are also aggressive and docile female communal spiders, common in the American Southeast.  Different mixes of personality are favored in different locations, with the proportion of each personality, which are hereditary, providing the first solid evidence of group selection.  The personality proportions remain the same, even in places where the radically different mix of aggressive and docile females found in local spiders of the same species would be more adaptive.

Anthropologists have demonstrated fairly convincingly that there are differences at the level of coherent ethnic, regional and national cultures in what would normally be considered to be personality traits, such as differences between cultural norms in Northern China, which was traditionally a wheat and millet farming area relative to Southern China, which was traditionally a rice farming area.  One of the ongoing debates in cultural history, anthropology and genetics is the extent to which a nation's "national character" is purely a product of cultural transmission, or instead involves (at least in part) differences in population genetic make up with group selection favoring different mixes of personalities in different environments that continue to manifest even as migration and cultural change make old the balancing selection that produced the ancestral mix of personalities of a "nation" dysfunctional in a new environment.  (The evidence concerning the wheat v. rice farming dichotomy in China tends to favor a cultural rather than a genetic source, by the way, which is the leading view, for the most part.)

While some seemingly complex phenotypes really do have complex genotypes as their source, other seemingly complex phenotypes can arise from just a single genetic locus (in the reference, butterfly wing patterns).  There are also a variety of candidate simple genes with apparent impacts on personality.  Scientists have similarly identified a very simple single locus that can be used to make fruit flies homosexual or heterosexual.

The relatively discrete personality categories observed in some species, patterns of balancing selection within groups of personality types, and the fact that, for example, the personality distribution of humans with high IQs is quite similar to the personality distribution of other humans, suggests like unlike massively polygenetic traits like IQ or stature with a quite continuous range of values and strong bias towards the fitness enhancing direction, that a fairly modest number of common genetic variants may account for personality differences.

But, large scale comprehensive searches for personality genes in humans have mostly come up empty.  Yet, there is strong evidence that personality has a strong hereditary component from sources like twin studies that strongly suggests that at least some genotype plays a major role in shaping a person's personality.  As recent studies of schizophrenia reveal, one problem with these studies may be insufficiently precise definitions of personality types to capture the link between genotype and phenotype.

* * * *

Not quite on topic, but also fascinating is a newly discovered species of parasitic ant that evolved from the species of ant for which it is a parasite (something confirmed with a genetic analysis), in the very same ant colony.  This is essentially the insect equivalent of vampires evolving as a new parasitic species of humans within a single human community.

Thursday, July 25, 2013

Xenolinguistics

Researchers have deciphered a class of words in the language of wild dolphins that make up about half of their conversations.  Specifically, they have learned to identify the names that wild dolphins use for each other (also called "signature whistles"), established that these dolphin whistles, first distinguished in the 1960s, really are names of individual dolphins and learned how these names are used in dolphin conversations.
[D]olphin signature whistles are exclusive to individuals, rather than being part of a shared repertoire. They’re social sounds, unlike bird songs which are largely used to attract mates or defend territories. And they’re learned; many animals like birds and monkeys use distinctive calls to refer to specific objects (like different types of predators), but these are innate and inherited behaviours. “The use of new or learned sounds to label an object or class of objects is rare in the animal kingdom,” says King.
This combination of traits makes the signature whistles unique in the non-human world, at least for now. It’s possible that parrots and other birds might use similar calls. 
Reference: King & Janik. 2013. Bottlenose dolphins can use learned vocal labels to address each other. PNAS http://dx.doi.org/10.1073/pnas.1304459110

The fact that so much of the conversations of dolphins consist of proper names also suggests that while dolphins do have a more human-like language than most other species of animals that their language probably has considerably less lexical content (i.e. fewer words) than even the most primitive human language.  A dictionary of dolphinese would have a huge directory of individuals with only a modest vocabulary beyond that.  The way that the signature whistles are used, however, suggest that there is a fair amount of "grammatical context" to what one means and when one uses one based on context and intended meaning.

Thursday, January 31, 2013

Does The Basilisk Have Roots In A Real Snake?

Many writers, some of non-fiction, and many of fiction drawing on a mixed fiction and non-fiction tradition, have written about the reputed venomous animal called the Basilisk.  Does this legend have roots in a real animal.  This post argues that it does and identifies the most likely candidate based on the earliest written account of one and the relevant candidate species of venomous reptiles.

Per Wikipedia:
One of the earliest accounts of the basilisk comes from Pliny the Elder's Natural History, written in roughly 79 AD. He describes the catoblepas, a monstrous cow-like creature of which "all who behold its eyes, fall dead upon the spot,"[3] and then goes on to say,
"There is the same power also in the serpent called the basilisk. It is produced in the province of Cyrene, being not more than twelve fingers in length. It has a white spot on the head, strongly resembling a sort of a diadem. When it hisses, all the other serpents fly from it: and it does not advance its body, like the others, by a succession of folds, but moves along upright and erect upon the middle. It destroys all shrubs, not only by its contact, but those even that it has breathed upon; it burns up all the grass too, and breaks the stones, so tremendous is its noxious influence. It was formerly a general belief that if a man on horseback killed one of these animals with a spear, the poison would run up the weapon and kill, not only the rider, but the horse as well. To this dreadful monster the crow of a rooster is fatal, a thing that has been tried with success, for kings have often desired to see its body when killed; so true is it that it has pleased Nature that there should be nothing without its antidote. The animal is thrown into the hole of the basilisk, which is easily known from the soil around it being infected. The weasel destroys the basilisk by its odour, but dies itself in this struggle of nature against its own self."[4]
Footnotes 3 and 4 are to "Pliny the Elder, eds. John Bostock, H.T. Riley (translators) (1855). "The Natural History". link. Retrieved 2009-06-10."

Cyrene is a historical province of the Roman empire basically along the western border of modern Egypt in modern Libya. 

Pliny the Elder had served as a senior Roman civil servant in Tripoli and Northern Libya about five years before his work was published, although not in Cyrene itself, and had traveled to almost all parts of the Roman empire during his career as a student, soldier, civil servant and natural philosopher.

The name "Basilisk" has Greco-Roman origins "from Latin basiliscus, from Greek basiliskos "little king," dim. of basileus "king" (see Basil); said by Pliny to have been so called because of a crest or spot on its head resembling a crown."  Thus, the name basically meant "little king snake."

Many later Basilisk accounts which arose in the Middle Ages and later, seem to be derived from Pliny's account and then exaggerated or distorted in the retelling by people in places that no longer had any cobras of any kind, and had never travelled to any place that did.

While various candidates for the origins of this myth have been suggested, discussion has focused on several kinds of snakes commonly called cobras, although from several different subtypes of them.  This post argues that the Nubian Spitting Cobra is probably the source of the Basilisk account made by Pliny the Elder in his Natural History in 79 CE.

The Case For The Nubian Spitting Snake As The Source Of The Basilisk Myth

* Pliny describes the Basalisk as a kind of serpent, which would suggest at least a reptile and probably a snake.

* The "upright and erect upon the middle" mode of locomotion language in Pliny's description is very distinctive as a means of distinguishing cobras from non-cobras.  Many species of cobras also have a distinctive hiss.

* The King Cobra, sometimes discussed, is a poor fit as it is too big to fit the "twelve fingers" description and also is native to Asia, rather than North Africa, an error that Pliny was probably too close to the source to mistake. 



* Many cobras also have distinctive hood markings that could be interpreted as a diadem pattern, but not the geographically more plausible and very lethally venomous, Desert Black Snake.  These are pure black without a diadem pattern (although juveniles in eastern North Africa have a pattern of reddish crossbars on the back), and don't look stereotypically cobra-like even though they are actually a kind of cobra, although it is not part of the distinctive Naja genus of the subfamily of snakes that that do have this distinctive appearance.  Here is what a Desert Black Snake looks like:



Black desert snakes do not spit venom.

* There are sixteen species of Naja genus cobras found in Africa or the Middle East.  But, only two of those species: the Egyptian Cobra and the Nubian Spitting Cobra would have had habitats in or near the Roman province of Cyrene in the historic era.

* The geographically fitting Egyptian Cobra looks the part, but does not spit venom, a trait present in other African cobras which could explain the myth that those who look into its eyes can be afflicted from a short distance even if they are not bitten. An image of an Egyptian Cobra is below:


* Geography (they are found in northeastern Africa in parts of Egypt, Sudan, Chad, Niger and Eritrea), the venom spitting trait, and distinctive hood markings do coincide, however, in the case of the Nubian spitting cobra.  An image of one is below:



The deadly Nubian spitting cobra "likes to hide in holes, brush piles or any other ground cover during the day. If provoked or threatened, it will raise its forebody, spread its hood and readily spit jets of venom at the face of its predator or threat. It prefers to prey on amphibians (such as frogs and toads) if and when they are available, but will feed on rodents, birds and probably snakes." 

These facts fit the notion that roosters incubate its eggs, something that could be wrongfully inferred because rooster feathers would likely be found in the Nubian spitting snake's nest. 

This also fits the notion that the Basilisk lives in burrows, and the notion that they are found in environments where shrubs and grass are present (at least until poisoned) as opposed to more lush environments where most other kinds of cobras are found.

The association with weasels is like a reference to the venom resistant cobra killing mongoose (who cobras sometimes kill by constriction), which look a great deal like weasels (and don't actually use smell to defeat cobras).  The range of the mongoose overlaps signficantly, even today, with the range of the Nubian spitting cobra.

Monday, May 7, 2012

Early Native Americans Co-Existed With Megafauna

Improved dating technologies confirm the widely expected finding that early Native Americans co-existed with megafauna.

Monday, April 30, 2012

Octopi Still Smart

Brains aren't just for vertebrates. One of the smartest creatures on Earth is the octopus. A recent learning experiment conducted on them illustrates their intelligence. A kidnapped octopus from the harbor unable to carry out a difficult task to reach food was able to learn it quickly and effectively after seeing a trained octopus carry out the task.