National Geographic has a nice review of the evolution of viviparity in skinks. It summarizes a recent paper by Jim Stewart et al. investigating the morphology and histology of the egg shell and calcium-producing glands in the uterus of the skink, Saiphos equalis.

Saiphos equalis is rare because there exist both oviparous and viviparous populations. Because viviparity must have evolved very recently in this species, S. equalis is therefore a great model system to see this transition of reproductive mode in action.

An indignant Saiphos equalis packed full of developing embryos. Photograph courtesy of Rebecca Pyles by way of nationalgeographic.com.

The story is particularly relevant to me since I have just begun a post-doc at the University of Sydney to study the genetic mechanisms of viviparity in S. equalis with one of the paper’s co-authors, Mike Thompson.

If you think about the transition from laying eggs to giving live birth, it becomes clear that it must have involved some significant morphological and physiological changes including retention of the embryo within the mother until gestation is complete, increasing uterine blood supply to facilitate nutrient and gas exchange with the embryo, potentially suppressing the maternal immune system to prevent rejection of the embryo, and reduction of the calcareous eggshell.

The latter process is particularly interesting because it requires a significant physiological modification of the shell-producing glands. Instead of quickly dumping a bunch of calcium to form an eggshell, the glands in viviparous mothers must instead slowly secrete calcium to nourish the developing embryo during the entire period of gestation.

Stewart et al. found that the thickness of the developing eggshell in the uterus of viviparous mothers is thinner and less developed than those in the oviparous mothers at the same stage of embryonic development. However, they also found that this is not due to the size of the shell-producing glands (i.e., bigger glands = thicker shell), and therefore some other mechanism must be responsible for the physiological changes of shell glands in viviparous mothers.

In other words, we see the hypothesized first steps to viviparity – holding embryos for an extended period of time and reducing the unnecessary eggshell.

What genetic mechanisms underlie this shift in reproductive mode? Check back with me in a year or so.

One of the things Teresa and I are working on in Curacao is a study of sperm motility in bluehead wrasses (Thalassoma bifasciatum).  I’ll talk about why that’s interesting eventually, once we get some of the results out.  One of the hard bits of doing this study is that blueheads don’t manufacture sperm in captivity – we figured out very early on that they just shut down production after a couple of days, and fish from the pet trade therefore have no motile sperm to study.

Obviously, we need to be able to measure sperm motility in the field.  There are commercial setups out there that you can buy for sperm motility, but they have several disadvantages: they’re not very portable, they’re expensive as all-get-out, and most importantly they’re (last I checked) not very flexible in the types of video you can analyze or the timing of the analysis windows.  It’s been several years since I played with a Hamilton-Thorne system, but at that time you could only specify an analysis window by manually hitting “start” and “stop”.  That’s worthless for my study because of the short motility period of bluehead wrasses – their sperm are motile for a very short period (~15 seconds!), and those little suckers are FAST. I need to be able to analyze very precise time slices post-activation, and the HT system just couldn’t do that last time I checked.

So, in the great scientific tradition, I bodged something together.  This setup is the fourth such that I’ve put together, and is by far the nicest.  Earlier versions involved CCDs and video capture direct to the laptop, but the data produced by those setups was nowhere near as nice as what I’m getting with this arrangement.  So, without further ado, here we are:

The first thing we need is a microscope.  I chose a fairly cheap model from AmScope for a couple of reasons: theft is rampant in Curacao and I don’t feel like losing a really nice scope, for one.  More to the point, though, I’m setting this up out of my own very limited funds and AmScope makes astonishingly nice hardware for the money.  Certainly sufficient for my needs.  This particular scope is their T400A-30W-DK model.  They have another model that looks better on paper, as it has an adjustable photo port.  However, the adjustable port is only adjustable within a range of distances that vary from “useless” to “uselesser”: the focal distance is only suitable for cameras where the CCD is actually down inside the photo port, and I didn’t own a single CCD that worked.  In fact, I don’t know of a good video camera that does have a CCD that will fit in there.  The 400A can also fit into this kickass aluminum case:

Which the other model can’t.  Just look at that case.  I want to handcuff it to my wrist and walk around with sunglasses on.  It also does a great job of keeping the scope in working order despite being kicked around aiports, fondled by security guards, and bashed into all sorts of things (including my face on the return trip).

Okay, we’ve got a scope and a case, we can look at some sperm.  However, what we really need is some really good video.  As mentioned above, I was initially getting video to my laptop using a variety of CCD cameras and a USB video capture device.  This works, but there are several issues to deal with.  For one thing, the resolution and framerate of most of the affordable CCDs is awful for sperm motility.  Sure, you can buy an HD CCD if you want to shell out the dough, but then you have to buy an HD capture solution for your laptop and those are (a) hard to find and (b) damned expensive.  The low-res solutions are also usually putting out interlaced video, which is problematic for sperm motility analysis – it adds uncertainty to the motility parameters if you use the video raw, and all of the deinterlacing programs I tried led to positional artifacts that were worse than the interlacing itself (e.g., I’d get a nice deinterlaced picture, but the sperm was jumping back and forth between frames).

On this trip we decided to leap off of the purpose-built CCD train and try something off the shelf.  We’re taking advantage of the fact that Canon’s new T2i DSLR camera allows users to capture hi-def video.  The T2i is just an awesome camera all around, but what’s particularly nice for our purposes is that you can buy decent Canon EF -> microcope photo port adapters on Ebay for about $100.  By attaching the camera to the adapter and then to the scope, we can shoot hi-def video at a better framerate (720p, 59.94 fps) than the CCD solutions with less fuss and no f*&%ing video capture hardware.  Here ’tis:

But there’s one more issue to deal with.  This microscope head does not allow users to use the eyepieces and photo port simultaneously.  But hey, not a problem!  The T2i has an AV out, and we can use a really cute little off-the-shelf portable DVD player as a video monitor.  This is the Sony DVP-FX950.  It has a higher screen resolution than most portable DVD players, as well as an RCA video input jack.  Here it is, waiting for me to shoot some video:

We are getting really excellent results with this setup.  The one drawback compared to my old video capture systems is that I don’t have control over the filenames at the time of recording.  Because of this, I have to verbally announce the identifying information for each take so that the camera’s microphone will pick it up.  That means I’m going to have to go back and rename about 500 video files before I can start analyzing data, but it’s a small price to pay.  Speaking of small prices to pay, here’s the rundown for the whole rig:

Amscope microscope model 400A-30W-DK:  $419

Aluminum case: $90

Canon T2i camera: $900

Canon EF->photoport adapter: $95

Sony DVP-FX950 portable DVD player: $140

This comes to a grand total of $1644.  While that’s a significant dent in my pocketbook, it’s about 3% of the price of one of the Hamilton Thorne systems which, last time I checked, were going for something like $50,000.

Obviously there’s something missing here – the HT systems aren’t just video scopes, they’re analysis packages with software and everything!  Never fear, the amazing contributions of the open source scientific software community will come to our rescue there.  But that’s another post for another day.

I have no idea.  There’s an interesting story about it on Boing Boing, though.

While trying to pick out the location of our first accidental trip to Watamula on a map, Alex and I noticed this area just east of there that looked like the surface of Mars. We decided to go check it out, and see if we could catch some rodents while we were there.

Alex, Ron, and Teresa setting rodent traps.

I'm tall!

Prickly cactus with an adorable little puffball on top.

Said puffball plays host to two adorable little pink flowers. Awwwwwww.

Everything at Watamula is spiky, which is nature's way of telling you to go back to your hotel.

In the course of a very short walk, Watamula goes from low bushes to cactus to being almost completely lifeless.

As you near the edge of the island, the red soil gives way to a hostile plain of flip-flop-shredding bare rock.

Fossilized coral skeletons are everywhere.

Pretty sure that's one of the lost Mars probes in the distance.

We are in the thick of it with data collection right now, so I’m just going to dump some pictures without a lot of context.

Jaanchie’s! Local food, great atmosphere.

Tons of birds hang around Jaanchie’s because of the bowls of sugar they leave out.

It’s like Studio 54 for bananaquits.

The noble bananaquit surveys his domain.

Trupial, posing awkwardly.

Trupial.

Lizardfish, looking lizardy.

Reefballs at Portomari, concrete balls designed to seed reef development and to act as fish habitat.

Teensy baby butterfly fish.

Elkhorn coral, a rare sight these days.

Teresa explains our research to a group of locals and tourists who were wondering what we were up to.

Heading down for a dive. This is Alex and Teresa.

Alex Dornburg is only three feet tall. Here he is with an average sized Diodon for comparison.

Lionfish. Pretty, but jerks.

Sometimes when a lionfish feels that you should go away, he says “hey look at all these hypodermic needles full of venom that I’ve got here”.

The amount of color variation in trumpetfish is phenomenal, and they use it to “shadow” other fish – they try to hide their identity by staying close to another fish, and then pounce out at unsuspsecting prey items who think “oh hey, that’s just a parrotfish with a banana”.

Lionfish abound at Klein Knip. Unfortunately.

On the way out at Klein Knip, we saw an octopus hanging out in the shallows. He seemed to have a very weird pale membrane attached to him. Eventually we realized that he was eating a raw chicken drumstick.

We acquired three new housemates today: Peter Wainwright, Lars Schmitz, and Ron Eytan.  There are four or five separate projects going on here right now that have little to do with one another – we’re basically just all doing our own thing and sharing the cost of lodgings.  The field station in Willemstad (Carmabi) is not the most comfortable place to stay, but by splitting the rent at Sunshine’s place in Westpunt we can stay in relative comfort for about the same price.  It’s a little cramped, but we all like each other.

Here’s the whole crew (except for me). From left to right we have Teresa Iglesias, Ron Eytan, Matt Brandley, Peter Wainwright, Alex Dornburg, and Lars Schmitz.

You guys have “eye donor” checked on your driver’s licenses, right?

Ok, good.

Science isn’t always pretty. Here’s Lars demonstrating the easy way to get a fisheye lens.

Lars shows us the lens from the eye of a fish. It’s hard to see from pictures just how clear and pretty these things are.

Peter disemboweling a lionfish in preparation for preserving it. I was proud to have caught this guy because (a) it’s a damn cool fish, and (b) they’re invasive reef predators, and are a potential ecological disaster for the Caribbean.

Lionfish are also nasty to catch because they basically have an array of hypodermic needles filled with venom. These guys aren’t deadly, but some in their family are.

Alex demonstrating one of his “alternative” funding sources for graduate school.

I’m way behind now, but I’m going to make an effort to catch up.  These pics are from Playa Martha, which is located in an abandoned (and wrecked) resort.  We’re doing a lot of behavioral observations and catching fish on these dives, so there’s not a lot of time to snap pictures.

Teresa posing with the remnants of an airplane that crashed here.

Lovely anemone.

The remains of a little beach bar.

Sand dollar eating lunch.

Lovely little chunk of coral.

http://matt.might.net/articles/phd-school-in-pictures/

Here’s a funny and somewhat sobering infographic about the Ph.D. process, although it could apply just as easily to an entire scientific career.  While it’s easy to look at something like this and feel a little insignificant, it’s amazing to think about how many people are simultaneously making their little dents in the big circle of human knowledge, and what the net effect of all of those contributions has been.  We may be moving a mountain with a teaspoon, but there are a lot of us with teaspoons!

We were lucky enough to spot some tarpons while inspecting a sunken barge at about 110 feet. Seeing them made me realize I know very little about these fish, spurring a bit of fun internet reading.

Tarpons are members of a group of fish known as elopomorphs that also include bonefishes and eels. One cool thing about elopomorphs is that all members of this group of fishes all have leptocephalus larvae, which look like really flat eels with glassy transparent bodies. If flat mini eels with see though bodies sounds delicious to you, eel leptocephalus (or elvers) are considered a delicacy in the basque region of spain.

The atlantic tarpon, Megalops atlanticus, cruising around near sunken wreckage at 100′. Although we only saw two, we were told a school of four are hanging around the wreck.

Prime tarpon habitat in Curaçao

A Leptocephalus larvae, the larval stage shared by tarpon, eels, and their relatives

Matt swimming towards a tarpon

A tarpon cruising along the sunken barge

The remains of the crane the barge was carrying

There are two species of tarpon, with only one (Megalops atlanticus) found in the atlantic and caribbean (that is the species you see in the pictures above).  They can grow up to 8 feet in length, though most tarpons average between 2 and 4 feet. I had always assumed that these were pelagic fishes that would rarely come near shore, but I was apparently wrong. Instead, tarpon live in brackish, fresh, and saltwater.  

Additionally, they have a bizarre swim bladder that functions as a respiratory organ. While this is not uncommon in fishes, tarpons are the only pelagic teleosts to use their swim bladder this way. In fact, if juveniles cannot come up to the surface to breathe, they will drown. Adult tarpons keep this air breathing function and use it to augment oxygen uptake during exercise, and this may also explain why tarpon can often be found in waters with a low oxygen content. In Curaçao, a school of four individuals are apparently long-term residents of the sunken barge.

As a side note, the barge was carrying a cargo of cars and a crane when it sank. Today, you can see this now decayed cargo strewn about the ocean floor.

Alex and Matt set out some rodent traps last night, and Alex and I went to check them this morning.  We didn’t actually find any rodents, but we did get a lot of pretty pictures of Cnemidophorus.  We also found a back road to a place called Watamula.  Watamula is said to be the best dive on Curacao, but it’s really only easily accessible by boat.

Alex checks a Sherman trap.

No visitors, so we fold it up and move on.

Alex is baiting his traps with balls of peanut butter and bird seed.

Lifting a pallet.

Cnemidophorus, posing.

And from the other side.

Posing with a pen Matt lost in this spot the previous day.

Check out my coool neck articulation!

And posing again.

Mammal count stands at zero, but the crab count has just gone up by one.

Just hangin’ around.

What’s this?

Oh.

A microteid. Crazy hard to catch, since they basically swim in leaf litter.

Big boulder at Watamula painted with the Curacao flag.

Rufous collared sparrow at Watamula.

The rock at Watamula has been carved into amazing shapes by the waves, and the water actually comes up under the land through tiny channels.

Or in this case, effin’ HUGE holes in the ground.

Although dramatic in its own right, Watamula is like a more mellow Shete Boca. We’ll post pics from Shete Boca soon.

Watamula. Not the most hospitable place.

Adult Cnemidophorus showing off his pretty tail.

Just keeping an eye out.

The lifting of pallets is a sacred ritual for herpetologists, as pallets are the natural habitat of many lizard species.  It is widely believed that T Rex routinely relaxed under the megapallets of the late Cretaceous.  Widely believed by me, anyway.