Monday Science Links

This week's sciency goodness:

• Brian at Laelaps looks at the darker side of male 'pregnancy': At almost every aquarium I have ever visited with a seahorse exhibit, the plaque in front of the tank says the same thing: in seahorses and their relatives, males, not females, carry the babies. It is always interesting to watch the reactions of visitors to this curious fact. Adult men, for instance, sometimes seem unsettled by the thought of male pregnancy, but the reproductive reversal among the fish is often seen as kinda cute ("How sweet. A fishy dad taking care of his kids!"). As shown by a study by Kimberly Paczolt and Adam Jones published this week in Nature, however, there can be a dark side to male pregnancy. Male seahorses, pipefish, and seadragons (collectively members of the Syngnathidae) expend a lot of energy caring for their offspring. For these fish, mating involves the female depositing her eggs inside an expandable brood pouch on the underside of the male which both houses and provides resources (such as food) for the developing young. As noted by Paczolt and Jones, this means that the males may be able to modulate the resources they put into raising young, perhaps withholding resources during some pregnancies to invest them in later broods, and to test this hypothesis the scientists looked at the reproductive behavior of Gulf pipefish (Syngnathus scovelli).


• Bec at Save your breath for running, ponies on the funnier side of gulf pipefish males: Well Gulf Pipefish Boys, you might think this is all pretty great, being able to pick and choose (and cannibalise) your own progeny with nary a qualm in the world. But the thing is, those ugly pipefish girls you mated with in the past, they’re not just going to disappear. The ocean might be big, but it’s not that big, and you know what they say – “Mate with one ugly pipefish that time you had nine vodkas, three gins and no dinner, and you’ll end up with six months of whiny text messages and a lifetime of really awkward encounters whenever you try and go back to that particular bar because they happen to serve $5 spirits till 1am.”


• PZ at Pharyngula on hox genes that make snakes: So if you want to know where snakes came from, the right place to start is to look at their nearest cousins, the lizards, and ask what snakes and lizards have in common, that is at the same time different from more distant relatives, like mice, turtles, and people…and then you'll have an idea of the shared genetic substrate that can make a snake out of a lizard-like early squamate. Furthermore, one obvious place to look is at the pattern of the Hox genes. Hox genes are primary regulators of the body plan along the length of the animal; they are expressed in overlapping zones that specify morphological regions of the body, such as cervical, thoracic, lumbar, sacral/pelvic, and caudal mesodermal tissues, where, for instance, a thoracic vertebra would have one kind of shape with associated ribs, while lumbar vertebra would have a different shape and no ribs. These identities are set up by which Hox genes are active in the tissue forming the bone. And that's what makes the Hox genes interesting in this case: where the lizard body plan has a little ribless interruption to form pelvis and hindlimbs, the snake has vertebra and ribs that just keep going and going. There must have been some change in the Hox genes (or their downstream targets) to turn a lizard into a snake.


• At Eruptions, at look at the on-going (as of this writing) eruption at Eyjafjallajokull: The big news this morning is the eruption that started last night at Eyjafjallajokull in Iceland, producing a 1-km fissure vent. The pictures and videos I've seen so far have been quite impressive, with the classic look of a "curtain of fire", where basaltic lava erupts explosively from a linear array of vents - you can see the geometry in the image from the BBC/AP (above). Especially clear is the dual nature of the eruption, with both the explosive fire fountains and the effusive (passive) lava flows from the root of the curtain of fire. In many "curtain of fire" eruptions on Hawai`i, the curtain (see below) eventually coalesces into a single fire fountain, sometimes producing fountains that can reach a few kilometers in height. This will be something to watch for in the coming days if the eruption continues.


• And at Magma Cum Laude, Jessica looks at past eruptions at Volcán Santa Maria with plenty of pictures: On our way to visit the Santiaguito Volcano Observatory, Gustavo Chigna of INSIVUMEH (the Guatemalan equivalent of the USGS) was kind enough to take an afternoon off and show us some of the older deposits near Santiaguito. Our first stops were at an exposure of the air-fall deposit from the October 24, 1902 eruption of Volcán Santa Maria. This eruption was a devastating one, stripping the land for more than 50 km around the volcano, burying villages and fincas (plantations) in more than 3 meters of ash, mud and rock, and killing more than 7,000 people (the exact number will probably never be known). The area had already experienced months of earthquakes prior to the eruption, and activity at the crater formed in Santa Maria continued for weeks afterward.

Enjoy!