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.
Courtesy of National Geographic, here is a photo of the pacu (Piaractus brachypomus), an Amazonian fish with a set of remarkably human-like choppers. It’s no surprise that they are herbivorous — eating mainly seeds — and that they can inflict a nasty bite. They’re related to piranhas.
Photo from National Geographic website
Meet Histiophryne psychedelica, discovered a year ago in Indonesia and just described by Pietsch et al. in the February edition of Copeia. I’ve never seen a weirder fish, and what’s even more amazing is that it moves by hopping along the ocean floor using jets of water expelled from the gill slits. You can read more about it, and see its bizarre “hopping” behavior, at the National Geographic website here.
If you’re a biologist, or somebody who just likes biology, tell me that you don’t get a frisson of excitement from seeing this thing. Nature always coughs up creatures weirder than we can imagine.
Photographs by David J. Hall, from Pietsch et al. paper
Theodore W. Pietsch, Rachel J. Arnold, David J. Hall
pg(s) 37–45
A new species of frogfish of the teleost order Lophiiformes, family Antennariidae, is described from three specimens collected in shallow waters off Ambon and Bali, Indonesia. A member of the antennariid genus Histiophryne, the new taxon differs substantially from its congeners in having a broad flat face, surrounded by thick, fleshy, laterally expanded cheeks and chin, with eyes directed forward; skin of the body thick and loose, forming conspicuous fleshy folds that envelop the unpaired fins; a remarkable pigment pattern of white swirling stripes radiating from the eyes and continuing back to the body and tail; genetic divergence in the nuclear recombination activation gene-2 (RAG2), cytochrome oxidase-I (COI), and 16S rRNA genes; and a set of behavioral traits not previously known in fishes. The new species is described and compared with its congeners. Notes on habitat, locomotion, pigment pattern and camouflage, predation and defense, and reproduction and parental care are also provided.
by Greg Mayer
A couple of news items from the past month deserve a quick comment or two. First, at the American Association for the Advancement of Science annual meeting in Chicago last month, Svante Paabo of the Max Planck Institute announced the completion of a draft genome for Neanderthal man, and that it indicated that modern man and Neanderthal man did not interbreed: the Neanderthals are our evolutionary cousins, not members of our own species. The work by Paabo on the Neanderthal genome, and on ancient DNA in general, is fabulous, but two caveats must be noted: the first draft covers only 63% of the genome; and, most of the DNA comes from one cave in Croatia. So what you can say is in the 63% of the DNA they’ve looked at there’s no sign of interbreeding at this location. But we know secondary contact of differentiated populations in ice age Europe can be very complex; e.g. hooded crows would show evidence of interbreeding with carrion crows if sampled in some places but not others, so the case isn’t closed. And a personal quibble: according to the BBC
The draft genome can give us clues to the genetic regions which make us “uniquely human”, Prof Paabo told BBC News.
Besides the usual need to realize that knowing the genome of “X” doesn’t mean we know what it is that makes “X” so “X-ian”, Paabo implies here that Neanderthals weren’t human. But by any biologically coherent notion of human they were (hence Homo neanderthalensis). John Hawks (hat tip: Pharyngula) has an excellent discussion of all sorts of issues relating to the Neanderthal genome.
Second, John Long (who has a wonderful book on fish evolution) and two colleagues published a paper in Nature (abstract only) reporting internal fertilization and vivipary in a placoderm, a group of ancient fish. This is a wonderful discovery, showing again that Philip Skell doesn’t know what he’s talking about (Skell, you’ll recall, had said fossils “cannot reveal the details that made these amazing living organisms function”!!!). But the paper got twisted in media reports into these fish inventing sex. The BBC headline said “Fish fossil clue to origin of sex“, while, even more inexcusably, the British Museum (Natural History) website had “Fish knew first about sex“. Sexual reproduction originated in bacteria, probably billions of years before these fish. These fish may be the earliest vertebrates with copulation with an intromittent organ (a penis or similar structure); such organs have evolved multiple times, including four times in the amniotes (reptiles, birds, mammals). The price of journalism is eternal vigilance.