A Dream for Discussing

This my have been a bad title, but I just woke up and dont feel like trying to create a better one.

ANYWAYS the purpose of this one is to recall a dream I had during the night that made me glad to be in evolutionary bio.

So it starts off at the beach along the, what I believe Mediterranean sea oddly enough (the name of the body was said at one point, but I cant remember it), and people from high school and middle school were all there. One guy from middle school became some fashion model (something along those lines) and so there was a photographer going around everywhere taking his picture. I specifically remember two girls from high school also being there and we were talking for a bit. There's the set up.

Beach looked more like this with a few bushes

A few minutes pass and the tide starts to move in, so everyone goes swimming. These waves got decent sized (compared to what I've seen) like 10 feet swells. It was very enjoyable, the water was not too cold surprisingly.

Then we notice a larger wave coming by, I'm guessing around 20 feet. So of course I go for it (note: I'm just swimming, no board). Just before I hit it, I turn and start swimming as fast as I can to keep up with it and start gliding on it. AND I DID! IT WAS FANTASTIC! Then it started slowing down as it was breaking under the water, and I started falling in mid air, but I wasn't really scared until I noticed something under the water as I'm falling towards it.

Anomalocaris

Under the water all I thought it was was just some rock, so naturally I'm afraid I'm going to hit it. When I splash down I don't feel any rock luckily. Thinking I just had a close call I walk back onto land, when I feel something on my leg and quickly shake it off (well it startled me). That's when I see something that I feel came out of the Cambrian time period.What I shake off is this scorpion looking thing, all black, body about the size of a lobster (20 cm long, maybe 10 cm wide, there about), stinging (I assume) tail that is maybe 30 cm long and is in beaded sections, long (40 cm) thin legs that were flattened came out from the side that go from black to red to white at the tips, and claws that are more circular, yet small at the end of maybe 10 cm long arms. (all these measurements are based of the rough size I can remember of it). It was like Anomalocaris crossed with scorpion.

So I had kicked it off my leg onto a pier pillar. It scurries around on the pillar and one of it's claws brushes up against some fisherman's leg, and he jumps up a bit. By this time the creature was on the sand, and this fisherman comes up to it and beats it with a plastic food tray killing it. The finishing blow broke the carapace and out shot a bit of blood that was black.

It is at this point when I sit there looking at it, and thinking of how it could have evolved.... This is why I'm an evolutionary biologist. Based on it's look, I would say descended from scorpions. Had the stinging tail and the claws to back up that conclusion. I don't recall seeing them, but it may have had some web-like structure between it's legs (?) to help it swim, but I don't think there was as the flattening would have provided decent locomotion. These legs looked a lot like the spines from a lion fish to give an idea of what the legs looked like, just fewer of them, I think it was eight. (At this point I wake up, but I'll continue anyways) As I had mentioned, the claws were smaller and more circular. The size could have been because it feed on small fish, larger claws would have been to hard to maneuver around smaller fish. As for the long tail, probably indicates ambush predator. My hypothesis is that it sits on rocks to blend in (recall dark body) and when a fish swims by over head, it would lift it's tail up slowly when the fish is in front and strike quickly down at spine paralyzing the fish. At this point it could swim up to it and start munching away. It was only the one specimen so I couldn't get much on mating or if there were sexual dimorphisms.

My thinking for how it became sea dwelling is that the ancestors were scorpions in the desert or some dried up ancient sea bed not too far from the ocean. Water levels then began to rise, forcing the creature to start living off dead washed up fish, or whatever it could find. Over time it developed a thicker shell to keep out the water and then began it's descent into the sea. Once in the water the tail (metasoma) grew longer to be able to attack fish better with the sting (telson), and the legs  got longer and flatter to help it swim better. I don't know this but having a beaded tail might be stealthier than a tail of consistent thickness. Based on the food source, the claws (chelea) then shrunk for a) better swimming and b) for less clumsy eating. And as previously mentioned, black coloration to blend in. Finally based on the size, I would guess this was an adult.

The ancestor of the creature

Checking for a possible family, I find Scorpionidae (so clever), but also genus Heterometrus. These are forest dwelling scorpions, but humid dwelling. So while original hypothesis gets shot down, new one just places origins in the humid forests near the ocean, and they became more adapted to live in the sea. Just get better at handling humidity to the point where 100% is no issue. This genus is located in tropical and subtropical southeast Asia, (recall I guessed about where I was so this is still plausible) and contains some of the larger scorpion species. Finally not generally lethal to humans.

So what name to give it? That's my question to everyone who reads this. What is the species name? Personally I think that giving it a name based around the fact that it swims would be good, like maybe oceanus or aquarii.

Podarcis sicula, a case for rapid evolution.

This week's science comes from a few years ago, so some may have heard about this already. Podarcis sicula, or the Italian Wall-Lizard, was the focus of a study that started nearly 40 years ago. Between 1971 and 2000 no one was allowed to the island, so study could not be conducted. When they went back they were in for a surprise. The result of this study shows us why we must keep in mind both biological and environmental definitions of a "species". In a short, 36 year, timespan (approx. 30 generations of this species) the introduced population have evolved a cecal valve in their intestines. Keep reading to find why this blows my mind!

So to get a feel of this experiment, the main species in this study P. sicula, come from a small island Pod Kopiste (0.09 km^2) in the south Adriatic Sea. Five mating pairs from this ancestral population were placed on the island of Pod Mrcaru (0.03 km^2), where P. melisellensis lived. After 36 years the endemic species was extirpated and P. sicula became common. Keep in mind the size of these islands as this is very important for later analysis.

Further P. sicula was primarily insectivorous with less than 10% of it's diet being vegetation.

Using mitochondrial DNA they were able to determine that the two populations are indeed still the same species. However this is mitochondrial DNA, not cellular DNA.

After 36 years on Pod Mrcaru, the study found that the lizards now have a diet consisting of about 35% vegetation in the winter, to over 60% in the summer. Along with this was the finding of heads that were longer, deeper, and all around larger with more jaw muscle for extra chomping power. If you didn't know, these are very large changes in and among themselves. Evidence of evolution, I would think so! (Recall evolution is the change in allele frequencies over time.)

What huge new trait came about though? The existence of cecal valves, structures in the gut used to slow the progression of food for better absorption. Why so important? Cecal valves are present in <1% of all known squamates! Let me repeat that for full understanding, less than 80 of all known lizards and snakes have this structure. This wouldn't be too interesting if it weren't for the fact that it isn't present in the Pod Kopiste population nor is it present elsewhere in the genus. This is an entirely new structure! Because of the incredibly low frequency of these valves in other lizards and utter lack of them in amphibians, it is a safe conclusion to say that these structures are not ancestral.

What does this all mean though? Simply, evolution can occur even faster than previously suspected. With a simple selective pressure, changes occurred within the life span of a human. Typically this is seen in insects or bacterium, but now it has been seen in vertebrates. If only they could have seen this development in action!

Remember I said to keep in mind of the size of the island? With that small of an island, genes get passed around very quickly within the population, this means that there is fast genetic flow. So when a positive trait occurs, it can get through the population in a relatively short amount of time.

Original paper -> Rapid large-scale evolutionary divergence.

One More to Go.

So I now have done 3 of 4 of my finals. Strangely though, I feel good so far. After the A on the astronomy final I feel like things may be going well this first quarter.

Yesterday was chemistry, which I feel went rather well. Chemistry was hard, don't get me wrong. I finally sat down and studied for that painful experience. There were a few instances when I was stuck on a problem then randomly, "THIS CHAIR IS FUN!!!!!" AND IT REALLY WAS! That stupid thought crossed my mind a few times though. I felt a little bad with my TA sitting in front of me, watching me as I randomly started to spin around in my chair. It was the weirdest thing. I had never sat on a chair that was on a swivel arm from between two chairs before. On top of that, the chair twisted on the arm! I was like," TWO DEGREES OF SPIN, OMFG, WTF!!" Back to the test though. I'll admit there were some things on there that caught me for a bit, though I think I got them for the most part. We'll see how it ends up, I figured out that I needed around 180/210 to get like 85% in the class, so with curve that should end up being an A.

Today was Anthro, which I just got back from. Fun. There were a few questions that made me laugh at either the simplicity, or that they were on the practice, verbatim. The last one especially. People kept on sending emails out asking how to do it when it was a simple Hardy-Weinberg question. Not sure why people thought that was so hard... simple 1=p^2+2pq+q^2, where p is frequency of dominant allele and q is frequency of recessive allele. Remember to always mind your p's and q's. Quite possibly my favorite question on there though was about someone running for senator of Delaware in 1998 stating her ignorance of evolutionary theory. "If evolution were true, then why aren't monkeys evolving into humans?" That was her quote. It still shocks me how people holding offices of power in this country can be so ignorant, and proudly so, of high school science. Sadly, it's this ignorance that has made me less fond of a few people I know. Like they're smart, but they hold this veil to shield themselves from any evidence that contradicts their world view. Oh well. Perhaps sometime I convince them, but until then, I'm going to continue enjoying the truth.

Well, only have one more to go. Calculus. They vain of many people's existence. It's on Friday so I have time to prepare and study, I mostly just need to refrain from making stupid mistakes. Last test, the only questions I missed were due to me just over looking one little aspect of the question. As soon as I got the test back I did each question I missed in under 5 min. On one I forget to multiply an integral by y, and the other I did half of it right with the other half needing to be done in the same exact way.... How do you over look that? Clearly I was looking for that in the problem, but I didn't see it happening twice? RAGE!! Everything else, oh just dandy. Had to go and screw up those two with itsy bitsy over sights. Must not happen again.

Finally, I would like to inform people that I try not to do anymore stories on Drew. He has asked me not to because he finds it annoying. Some may say this is censorship, but I feel it's more about his rights and respecting him. But the previous ones will remain up because they have comedic value.