Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
The four-legged land vertebrates– amphibians, reptiles, birds, and mammals, collectively known as tetrapods— get around, at least mostly, on their four legs. Their front and hind limbs are attached, respectively, to their pectoral and pelvic girdles, bones that attach or closely adhere to the axial skeleton. The pectoral girdle consists of the scapula, coracoid, clavicle, etc., while the pelvic girdle is comprised of the anteroventral pubis, the posteroventral ischium, and the dorsal ilium. The ilium is firmly attached to the vertebral column by a connection to the sacral ribs extending from the sacral vertebrae. Your “hip bones”, at the widest part of your lower body, are easily felt (or seen if you’re wearing the right– i.e. not much– clothing), and these are the crests of your ilia.
Most fish, by contrast, have an unattached pelvic girdle, floating more or less free in the ventral part of the body, and free to move, evolutionarily, along the venter. The primitive condition, as seen in the bowfin, for example, the pelvic girdle has a position akin to its place in tetrapods– toward the rear of the body:
A bowfin (Amia calva)– note the paired pelvic fins well back on the body. (The posteriormost ventral fin is the unpaired anal fin. From nicholls.edu
In advanced ray-finned fishes, however, the pelvic fins may move far forward. In fact, the pelvic fins may move in front of the pectoral fins– the hind limbs are in front of the fore limbs! This is possible because the pelvic girdle is not attached to the vertebral column.
Skeleton of a Nile Perch from Norman, 1947 (via the Australian Museum). Note the pelvic bones below and slightly in front of the pectoral arch.
The reason for this disquisition on the pelvic girdles of tetrpaods and fish is that Brooke Flammang and colleagues have just published a description of a living fish with a pelvic girdle attached to the vertebral column. This is really astounding! The species of fish is Cryptotora, a rare cave-dwelling fish from Thailand, that climbs on the wet walls of the caves in which it lives. In the figure below, which is a a head-on view of the pelvic girdle skeleton, the vertebrae are green, the pubis and ischium brown, the fin itself blue, and the sacral ribs and ilium are dark purple. Note the complete bony ring encircling the body from backbone to belly.
Cave fish (Cryptotora) pelvis. Flammang et al. 2016.
Tiktaalik, the “fishapod”, had pubis and ilium, but no sacral attachment or ischium. Some early tetrapods only had a looser sacral attachment than later tetrapods. Cryptotora, an advanced ray-finned fish, is not at all close to the lobe-finned piscine ancestry of tetrapods, so this represents a quite independent evolutionary origin of an attached pelvic girdle.
Carl Zimmer in the NY Times notes the tetrapod-like way in which the fish “walks” up cave walls, with an alternating left-right motion, and also provides a brief gif of one of the fish walking. This motion is more tetrapod-like than those of other walking fish (e.g., walking catfish). The alternating left-right motion of primitive tetrapod limbs is exactly what you would expect from the lateral undulations of a swimming fish. An attached pelvis– “hips”– in a modern teleost, however, is a really neat, and not expected, finding.
Flammang, B.E., A. Suvarnaraksha, J. Markiewicz and D. Soares. 2016. Tetrapod-like pelvic girdle in a walking cavefish. Scientific Reports 6(23711):1-8. pdf
The BBC reports on an abandoned cat with “three ears” found in Norfolk. Shelter staff at Feline Care Cat Rescue in East Harling have named him “Brian”*. [JAC: several readers also sent this to me.]
Brian, the three-eared cat from Norfolk (via the BBC).
I can’t recall ever seeing such a cat, and neither could the shelter’s vet, though Jerry had apprised us of the existence of extra-eared cats a while ago. The first thing that struck me is that the cat does not have three ears, but rather three ear pinnae. Ears, in a strict sense, are the paired sensory organs at the back of a vertebrate’s head that detect vibration and movement. The pinnae are the external elaborations for directing sound waves to the ears proper that are found in most mammals. (And also in Vulcans, who are not mammals, but who are renowned for their pointed pinnae, which led to some suggestions for a Star Trek-themed name for Brian.) Most vertebrates have ears, but relatively few have pinnae. Some, such as lizards, just have holes in the sides of their heads (you can look through a lizard’s head from one side to the other by looking into its ear opening), while others, such as frogs, have the tympanum (eardrum) exposed on the surface.
The second thing that occurred to me is that the extra ear pinna is moving in the opposite direction from a famous trait studied by the great geneticist Sewall Wright— otocephaly. Meaning literally “ear head”, in this condition the ear pinnae expand and extend under the ventral side of the head (1-5), the lower jaw fails to develop, and, in extreme cases, the entire front of the head fails to develop as though squeezed in from the sides, the eyes touching (7), merging (to form a cyclops: 8-9), and finally disappearing altogether in the highest grade otocephalic individuals (10-12).
Grades of otocephaly in guinea pigs (from Wright, 1934).
I had read and studied Wright’s paper on otocephaly as a graduate student, as I was interested in the genetics of traits of large phenotypic effect in vertebrates, and Wright had studied otocephaly and polydactylism (extra toes) in guinea pigs. Polydactylism is much more interesting, as changes in digit number have been important in vertebrate evolution, and some rodents also show an approach to hoof development, which is very important in mammalian evolution, and usually involves changes in digit number. Otocephaly, in contrast, has not led to any evolutionary novelties, but rather is lethal in most cases– Wright referred to otocephalic individuals as “monsters”. The late Will Provine, in his masterful scientific biography of Wright, discusses the significance of his work on guinea pigs for the development of Wright’s ideas on the importance of multifactorial inheritance and non-genetic factors. (I should record here my mourning of Provine’s passing this past September, which Jerry first alerted us to. His Origin of Theoretical Population Genetics, recommended to me when I was an undergraduate by then Stony Brook geneticist Dick Koehn, was my first real introduction to the history of science as a serious discipline, and influenced me greatly. I was much pleased when he occasionally joined the discussion on my posts here at WEIT.)
Although not important evolutionarily, otocephaly, which is known to occur in many mammals, had cultural significance, which Wright well knew. In his historical review of theories of the causation of otocephaly, he wrote the following passage, surely one of the most wonderfully erudite in all the literature of genetics:
We may pass rapidly over the theories of ancient times, according to which monsters were looked upon as the result of the play of the Gods, “ sports,” as signs of divine power or anger or as portents. The oldest known publication on the subject seems to be a brick found in ASHURBANIPAL’S library in Nineveh which gives in cuneiform the prognostication appropriate to each of a remarkable list of monsters…
[I should add that Ashubanipal’s name is in all caps because it is the style of the journal Genetics to capitalize the names of cited authorities in its papers: he’s probably one of the few Assyrian emperors cited as a reference in the scientific literature!]
Having checked up on the genetics of the merger and disappearance of the ear pinnae, I got back to our cat with an extra pinna, and turned to my bookshelf for my copy of Genetics for Cat Breeders. There, on page 168, I found the entry for “Four-ears”. It is inherited as a recessive, denominated dp, with affected cats suffering reduced fitness (as determined by a deficiency of affected cats in crosses). The head shape is peculiar, the lower jaw a bit underdeveloped (like low grade otocephaly!), and the affected cats’ behavior is lethargic, suggesting some brain abnormality (again, as found in otocephaly). The authority is Little (1957). So, Brian the cat is doubly odd: he has one extra ear pinna, not the usual two extra (when there are extras). I can’t see his right side in the photo, but I’ll take the BBC’s word that he’s oddly asymmetrical in his ear pinna numbers.
Sarah Hartwell‘s Messybeast Cats website has compiled a number of cases of four eared cats (and other ear anomalies) reported in the media, along with useful explanatory diagrams, and also interesting discussion and illustrations of a number of facets of cat biology (for example, color patterns). In her section on facial deformities, some of the cats pictured look like they are otocephalic. (Although many such enthusiast websites are, at best, unreliable, I have found Messybeast to be quite reliable, for example in its explanation of “winged cats” [I once had a winged cat myself!].)
Little, C.C. 1957. Four-ears, a recessive mutation in the cat. Journal of Heredity 48:57. (not seen; shockingly, the University of Wisconsin, Madison– the ‘public ivy’ research giant, not my home campus– does not have an electronic subscription to this well known, historically important, Oxford University Press, journal)
Provine, W.B. 1971. Origin of Theoretical Population Genetics.University of Chicago Press, Chicago.
Provine, W.B. 1986. Sewall Wright and Evolutionary Biology. University of Chicago Press, Chicago.
Robinson, R. 1971. Genetics for Cat Breeders. Pergamon Press, Oxford.
Wright, S. 1934. On the genetics of subnormal development of the head (otocephaly) in the guinea pig. Genetics 19: 471–505. pdf
Late this past summer, I caught a brown snake (Storeria dekayi) at the Root River Environmental Center in Racine, Wisconsin, so that the REC (as it’s known) could put it on display in a terrarium for visitors to see. Although I did not realize it, it was a pregnant female, and she gave birth to a litter of babies within a week. On September 27, the REC staff and I liberated the mother and her offspring behind the building, just a few yards from where the female had been captured. Can you spot the babies? And, how many of them are there?
Baby brown snakes (Storeria dekayi), being released at the REC, Racine, WI, 27 September 2015.
Brown snakes feed on earthworms and slugs, and there was an abundant supply at the REC. Here’s a video the staff made of one of the babies feeding on a garden slug.
This is where we released them; the mother was caught about 10 feet to the right of the picture. (The grass and weeds around the spot I caught her had been trimmed, so we released them in denser cover.)
Snake (and slug) habitat behind the REC building, Racine, WI.
For the snake counting, we can distinguish an easier headcount (i.e., count them only if you can see their heads), from the total count. Answers, of a sort, in a couple of days.
As Jerry is about to, or has just completed, a trip from Europe over the Atlantic to North America, I thought I’d share a photo of a fellow traveler– this hemipteran, or “true bug”, that arrived today at a furniture store in Racine, Wisconsin, in a shipment of furniture from Norway.
A Norwegian hemipteran, after it’s arrival in Racine, Wisconsin, USA.
Although many people call all insects (and other small creatures) “bugs”, only insects of the order Hemiptera are called “bugs” by entomologists, and hence are often distinguished from hoi polloi bugs as “true bugs”. Introduced organisms of all kinds– gypsy moths, rabbits, cane toads, brown snakes, goats, etc.– can cause ecologicalhavoc, and some, such as the zebra mussel, have, like this bug, hitched a ride on commercial shipments. I’ve seen lizards, frogs, snails, and ants that have arrived in nursery shipments. Our little friend above, however, will cause no havoc– he has been corralled, and is wending his way to me, for handing over to my department’s entomologist
Once it’s here, she’ll want to identify it, but as a Norwegian species, our local keys and ID guides might not get much past family-level identification. Are there any Norwegian or other European readers with an expertise in insects who would care to venture an identification? Please let us know in the comments.
WEIT stalwart Stephen Barnard sent Jerry some more gorgeous photos from Idaho with his comments.
Bald Eagles (Haliaeetus leucocephalus). The first two photos show the difference in size between the female and the male. That’s Desi on the left and Lucy on the right.
This American Kestrel (Falco sparverius) has been patrolling my backyard. It likes to perch high in a 40′ spruce that gets good evening sun. This same perch is favored by many other birds — Red-tails, Flickers, kingbirds, and doves — as in the last photo I shot moments before the Kestrel showed up. It’s good hunting here. I keep my feeders full.
This large bull moose was getting frisky with some cows. A smaller, less well endowed bull tried to horn in and the big guy chased him off.
There were at least eight moose in the field across the creek and in my yard — by far the most I’ve seen at once.
Thank you, Stephen, for sharing these amazing photos.
In a previous post here at WEIT, I’d reported on some toads and a painted turtle that I’d rescued from stair and window wells, and then released back into the wild last spring. I’d mentioned at the time that I periodically check these places, especially a deep (ca. 20 feet down) window well on the west side of the building my office is in, because it faces a pond and woods, and animals coming out of the woods regularly fall down into it. So at the beginning of the semester in early September, I took my vertebrate zoology class out during our first lab period, and we investigated the window well. There was a pretty good ‘crop’ this fall– eleven American toads (Bufo americanus), and 23 green frogs (Rana clamitans).
American toads just outside Greenquist Woods, Kenosha, Wisconsin, 17.ix.2015. There are clearly six of them, the same ones as in “Spot the toads“.
The toads fell into two size classes: medium (in picture above), about 55 mm snout-vent length, and small, about 40 mm. The green frogs were all about the same size– 35 mm. These latter were probably all a single age class, having metamorphosed from tadpoles earlier in the summer, and then hitting the building and falling in the window well as they began to disperse away from their natal pond. Bullfrogs (Rana catesbeiana) are also common in the pond, but we’ve never found them in the window well– they must have different dispersal behavior.
Chris Noto helps to release American toads in Greenquist Woods, 17.ix.2015.
Frogs and toads are collectively known as anurans— it means “not having a tail”– and adult frogs and toads do, of course, lack tails. The anurans we rescued from the window well had been there varying lengths of time, but most were in at least decent shape, though some were thin and dehydrated. We kept them in the lab for a couple of weeks, feeding them and rehydrating them. We then released them on two warm days just as autumn was about to begin. My colleague Chris Noto was teaching a lab on a floor looking out over the woods, and he saw me encumbered with toads as I attempted to take their pictures and carry them back out to the woods. He came down and helped with the pictures and the release (which were featured in two “Spot the __” posts, on frogs and toads).
Small American toad, about to be released into Greenquist Woods, 17.ix.2015.
The green frogs were released a few days later.
Green frogs anxiously await their transfer to the pond, 20.ix.2015.One last picture.Well, maybe just one more.And then it’s time to re-enter the pond.Green frogs queue up to enter Greenquist Pond, 20.ix.2015.
[JAC: a video of the release. I have to commend Greg for both taking the time to rescue these frogs and also calling them to our attention. Frogs are not only underappreciated animals, but are harbingers of human damage to the environment, climatic and otherwise. And I’ve always said that if frogs hadn’t evolved, we simply wouldn’t be able to imagine them!]
There are at least a dozen or more different sorts of anurans around the world that are worthy of their own vernacular name, but because only two sorts occur in England, we are stuck with calling them all either “frog” or “toad” in English. The American toad and the green frog do, however, correspond to the two sorts found in England (what are sometimes called the “true toads” and the “true frogs”, respectively).
Anurans are amphibians, and like most amphibians, have a complex life cycle. The word “amphibian” alludes to this– it means “both lives”, because a typical amphibian lives both on the land and in the water. Reptiles and their descendants (the amniotes, including birds and mammals), do not have this dual life cycle. One of the former candidates for the title of “first reptile” was the 270 million year old Seymouria, which has reptile-like features; but when it was found that its close relatives had aquatic larvae with gills, it was clear they were not reptiles, but rather led the “both lives” of an amphibian.
“Both lives” does not seem to adequately summarize the life of a typical amphibian, such as the American toad. They begin life as eggs in water, hatch out as tailed, gilled, tadpoles, that then swim about, eventually losing their tails and gills and sprouting legs to transform into toadlets, which then move onto land. After sexually maturing, they return to the pond each spring, to resume an amphibious existence, there to mate and reproduce. The adults then leave the pond for the summer to live wholly on land, while their eggs begin the complex cycling again. To paraphrase The Who, “Amphibians? They’re bleeding Quadrophibians.”
A further salientian post is coming, but since people seemed to have such fun finding the frogs, I thought I’d add a quick post on spotting the toads.These are American toads, part of the same “rescue” as the green frogs featured yesterday. I think getting the count right on this one is actually a bit trickier.
Bufo americanus next to Greenquist Woods, Kenosha, WI, 17.ix.2015
Regarding those frogs from yesterday and how many there were, I had released 18 of them, and did not know how many were in that particular picture, as I just snapped a few shots as they scurried away. The frog-like thing in the lower right is, as several readers noted, a rolled leaf; it does look froggy at first glance, but zooming in reveals its true nature. (On my screen, clicking, and then clicking again, produced the usual magnified image– I’m not sure why it didn’t work for many readers. At least we all learned about ctrl + scroll (crtl+<+> also works)!) I count four frogs. However, regular reader Jim Knight, who is a very experienced field herpetologist, said he saw five, so I’m not excluding the possibility I’ve missed one myself.
