My Vert Zoo students and I were discussing last week the demands placed on fish by the medium they move through, and the degree to which their bodies have been shaped by the resulting selective pressures. I made the point that the 1000-fold difference in density of water in comparison to air make it a much more unforgiving medium. That doesn't mean, of course, that moving through air is a piece of cake. Case in point...

Migrating monarch butterflies are shaped differently from their nonmigratory cousins. New work from University of Georgia ecologists appearing online in Evolution and discussed at Science Daily examines the way in which the monumental migration, over 3,000 miles in some cases, has worked to turn the gaudy lepidopterans into more efficient fliers.

Andy Davis and Sonia Altizer looked at sizes and shapes of migrating monarch populations in the eastern and western U.S. and compared them to a number of nonmigratory populations. The map at right, from www.monarchwatch.org, illustrates the flights taken by the migrants. Davis and Altizer found that the migratory butterflies had larger and longer wings than the stay-at-home monarchs. The researchers also found that the eastern migratory population had larger body size than their western counterparts, possibly an adaptation allowing them to store greater energy reserves for their longer migratory flight. Since eastern monarchs face a number of environmental threats, their uniqueness will add fuel to the drive to protect this population.

RIP, Captain Phil...

Snow Day...

Quiet campus today.

Absolutely no idea...

...what the significance of this might be, but it's information worth having. The worm's in the bottle, but the DNA's in the mescal.

Vocab

Your Word of the Day, if you're a Merriam-Webster subscriber, is "panglossian". It's a good one, one that has a rich history for evolutionary biologists dating back to the influential 1979 publication by Stephen Jay Gould and Richard Lewontin with one of the great titles ever - "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme." Dr. Pangloss was a character in Voltaire's Candide who claimed that "all is for the best in this best of all possible worlds." His excessively optimistic view of life made him a perfect foil for Gould and Lewontin's rebuke of the assumption that we should expect organisms to be optimally adapted. As for the spandrels... Well, that's one of them up above. If you want to know where they fit into the picture, you'll have to read the paper.

Some night music...

...cause I feel like it.



We made a trip to Memphis in September of 2005, about a month after Katrina. Much of New Orleans' musical community had taken refuge in Memphis, including Marcia Ball. She was performing in B.B. King's Blues Club, and stole our hearts. At that time, no one really knew if New Orleans would ever come back. My Louisiana friends are on top of the world right now, and they deserve it. Laissez les bon temps rouler!

Google weather shows me...

....this for Friday. That can't be good.

I'm a scientist...

One of my less destructive vices is an addiction to the B-grade science fiction films of the 50s. Apparently, there are enough people out there who share my weakness to justify a spoof, and a few years ago The Lost Skeleton of Cadavra was released. A favorite scene, in which evil scientist Dr. Roger Fleming reveals the true nature of science to Ranger Brad...



Nice feller...

On second thought...

So, maybe birds didn't "come from dinosaurs" after all. Oh, there's a connection all right, but maybe not the one we've thought. New research appearing in The Proceedings of the National Academy and summarized at Science Daily adds weight to the idea that birds may have shared a common ancestor with the dinosaurs, but then proceeded down down their own evolutionary road. It goes further than that, though. It appears that, rather than dinosaurs being ancestral to birds, some of the most romanticized of the "dinosaurs" might actually be glorified flightless birds. It's a group you all know about - the raptors.

There's been a long debate regarding the origin of flight in birds that can be summarized as "ground-up" versus "tree-down". The ground-up proponents have held that flight originated when rapid little runners were able to get airborne, while the tree-down group postulate a gliding ancestry for today's fliers.

Recent fossils, particularly the "microraptor" described in 2003, have lent weight to the gliding hypothesis. Tests have revealed that the animals body would not have lent itself to powered flight, but could have managed well as a glider. The researchers believe that such animals could have given rise to flying birds, some descendants of which may have given up flight at a later date to become the raptors.

Put's Velociraptor in a whole new light.

A better tree?

I keep telling my zoology students that I don't dwell too much on taxonomy, and don't expect them to either, because it's in such a state of flux. As soon as I make them memorize a taxonomic scheme, it gets changed. That's probably going to accelerate as we train our genetic artillery on more and more groups. Evidence here, and this is pretty big.

A group of researchers led by Jeff Schultz and Jerry Regier at the Center for Biosystems Research at the University of Maryland Biotechnology Institute have compared genetic sequences among 85 different species of arthropods with the goal of redrawing the phylogenetic tree for this largest (by far) of the animal phyla. They've come up with some very unexpected results. Maybe the most surprising nugget is the placement of the little-known Xenocarida as a sister group to the the Hexapoda. Hexapoda? That's the insects, comprising some 80% of the earth's named animal species. The figure at left is from an earlier publication by the group that appeared in Systematic Biology in 2008. The placement of the insects squarely in among things like ostracods and copepods means that the crustaceans do not represent a monophyletic group, i.e. one containing all the descendants of a common ancestor. Time to rewrite that chapter in Hickman.

Another interesting result involves Triops. You may recognize this guy - they're marketed as "dinosaur shrimp", a throwback to the Triassic Period. My daughter gave me some to rear a couple of Christmases ago (if you know my daughter, you know that this is completely in character). They were actually pretty interesting little guys, pre-flush (sorry, Jess). Anyway, the new work indicates that Triops has a much more recent origin than was previously believed. I expect the good folks at Triops.com will keep that little piece of information under wraps.

The work is reported online at Nature, and summarized here by Science Daily.

You gonna eat that?

Well, at least cook it first...

I'm not sure this surprises me, but eating reptiles brings with it some risks. I'm conferring with my microbiological pals, but I can't help but wonder just how different they are from birds - in a gastronomical context, I mean. I've eaten my share of turtle and gator (might as well be a staple in Louisiana), and I've eaten the requisite rattlesnake that any Southern man has to have consumed to be able to stay in the conversation at the bar. Still kickin'.

Fish business

The little Google weather icon is showing me snow showers on Friday. If that comes to fruition, it'll push our field work back - again. But, sometime soon, we'll be headed out to start looking at some ecological interactions involving freshwater fish in a few of our local streams. We're planning a series of microhabitat studies using darters, a group of small freshwater fish in the Family Percidae, to investigate how environmental factors influence community structure. That's a rock darter, Etheostoma rupestre, to the right, and we know that it prefers very specific microhabitats. Other species, like this blackbanded darter (Percina nigrofasciata) have very different affinities. It's ecology, but there are some evolutionary questions as well, i.e., how has selection shaped different darter species for different environments. Both of those images, by the way, come from the tremendous web site put together by the Alabama Department of Conservation and Natural Resources.

The overlap between ecology and evolution is par for the course. I find myself talking about many of the same topics in my ecology classes and my evolution classes. The two disciplines are often looking at similar questions, with only the time factor distinguishing one from the other.

Well, the line's blurring a bit more. A new study coming out in The Proceedings of the National Academy and referenced at Science Daily has used another group of fish (guppies) in streams in a different part of the world (Trinidad) to examine the way in which evolution can influence environment. It's usually the other way around, of course. We normally see the way in which environmental pressure leads to selection for certain traits, leading to evolutionary change. That's because, normally, we don't think that evolution can happen fast enough to bring about ecological effects. But that's obviously not always the case. This study, led by David Reznick of the University of California - Riverside, is a great illustration.

Reznick and his coworkers worked in two tropical streams with very different fish communities. One stream contained a fish assemblage including guppies and a diverse group of predators, some of which fed on the guppies. The other stream had a much simpler community structure - just a few guppies and a few other, non-predatory species. In previous work, Reznick and his team had demonstrated that predation could bring about fairly dramatic changes in the life histories of the guppies - guppy communities exposed to intense predation reached sexual maturity quicker, produced more young, and even developed different body shapes.

The current study goes a step further. The researchers collected guppies from the two streams and put them into identical artificial streams, designed in such a way as to mimic the natural streams from which they were collected. After a month, they found that the guppies from the two different types of communities had had dramatically different effects on their new streams. It started with feeding habits - guppies from the high-predation streams fed heavily on insect larvae, while guppies from predator-free streams had more of a taste for algae. This led, in turn, to differences in productivity and nutrient-cycling in the two artificial streams. The evolutionary impacts on the guppies was leading to environmental differences in the streams in which they were found. Furthermore, the results seem to correspond to conditions the researchers see in natural streams in the region.

Not surprising, maybe. But something else to think about when we're rock darters out of Alamuchee Creek.

Lots of interesting ideas coming out of studies of stream fish. Another one coming up later this week.

Great tits...

Got your attention, right? Well, the bird at right is Parus major, more commonly known as the great tit. So, what were you expecting? (On a side note - you'd be surprised what you find when you're searching for an image of one of these birds) Anyway, great tits are common woodland birds across much of Europe. They've figured heavily in a number of ecological and evolutionary studies, and a new one is coming out. Researchers at Bavaria's Max Plank Institute of Ornithology have been investigating the tit genome, particularly variation shown in a gene known as dopamine receptor D4, or DRD4. A couple of years ago, they found in laboratory studies that tits possessing a particular allele at this locus were more "curious", i.e., they engaged in more exploratory behaviors. Now, they've extended their study to the field. Examining wild birds collected at a variety of locations across Europe, they assessed whether enhanced exploratory behavior is associated with the same DRD4 variant as was observed in the lab populations. The goal is to determine the universality of the relationship between a variant in DRD4 and this "personality-related behavior".

Interestingly, they found this to be the case in one wild population, but not in three others. This has been the case in other studies examining relations between genetics and personality traits, including studies focused on human behavior. Many studies have identified the relation between the same DRD4 gene and exploratory behavior in humans, only to find dramatic differences between populations; other studies in humans have found no relationship between teh DRD4 gene and curiosity. The authors hope that further examination of the great tit populations might help explain the variation seen in studies with humans.

Here they come...

Remember the first time you saw a fire ant mound in your backyard? Probably not - if you live in the lower Southeast, you've no doubt been familiar with Solenopsis invicata your entire life as they spread rapidly across the region after being introduced through the port of Mobile, Alabama in the 1930s. Same story with a lot of our invaders - kudzu, honeysuckle, coyotes, armadillos.... the list goes on. Most southerners probably can't point to the time that they saw one of these exotics for the first time.

But, I'm willing to bet that the first python you see in your backyard will leave a lasting impression. And, mark my words, they're on their way.

Coolest thing you'll see in the next few minutes...

Promise.



That's from National Geographic by way of Pharyngula.

Crocodile rock...

Paleontologists from the University of Florida report the discovery of a new species of crocodile from the Cerrejon formation in northern Colombia. This croc is a member of the extinct crocodilian family Dyrosauridae, most members of which were large fish-eaters with long, pincer-like jaws. The new guy, Cerrejonisuchus improcerus, is the runt of the litter, topping out at 6-7 feet.

Of course, down in the modern-day Everglades, pythons and alligators are gettin' down and dirty. It appears that the gators win a few, and the big snakes win a few. Sometimes, it seems, nobody wins. Well, the snake/gator thing may have historic roots. The UF researchers found the new crocodilian in 60 million year old deposits that have previously yielded fossils of the giant constrictor Titanoboa, a 45-foot long monster that may have been the largest snake that ever lived. In fact, fossils of the snake and the crocodile are often found within a few feet of each other. Given their relative sizes and the obvious mutual affinity of the two reptiles, there is a distinct possibility that Titanoboa enjoyed an occasional croco-treat.

No science today - it's a day for voodoo

For a city reborn. Who dat?