Battle of the Sexes: 1st place at Animal Behavior Society Film Festival!

Posted by Nate Dappen at 11:05 am on August 2, 2011
Aug 022011

Last week, Indiana University hosted the joint meeting of the Animal Behavior Society and the National Ethological Conference. One of the events at this scientific conference was the 27th annual Animal Behavior Film Festival. One of our films, Battle of the Sexes, took first place in the non-commercial film category!

Battle of the Sexes highlights some my dissertation research, in which I investigate how the sexes deal with conflict that occur as a result of the sexes sharing most of the same genes while often dealing with vastly different selective pressures. I investigated this in the Ibiza Wall Lizard, Podarcis pityusensis. Check out the award-winning film below!

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WINNER of the 2011 Animal Behavior Society Film Festival (Non-commercial division).

A short film about Nate Dappen’s research on how males and females coevolve together. Nate is working on his PhD in evolutionary biology at the University of Miami, Florida. He studies sexual coevolution and color evolution in the Ibiza wall lizard (Podarcis pityusensis).

Film by: Nate Dappen & Neil Losin. Additional photography by Joris van Alphen. Narrated by John Astbury. See credits for music.

To learn more, visit daysedgeproductions.com/

Field Season 2011: Part 1

Posted by Nate Dappen at 6:23 pm on July 28, 2011
Jul 282011

A view from one of our field sites on Formentera. It's a hard job, but someone has to do it.

My field season – perhaps my last as a graduate student – ended almost two months ago. Most people who follow Day’s Edge know that I study color evolution in an endemic lizard species found on the charming Spanish Mediterranean island of Formentera. Honestly, it all went by in a flash. Seems like yesterday that I was online and disapproving of Google’s annual April Fools hoaxes. Over the last three years, I spent about ten months in the islands conducting my PhD research and enjoying island life. I posted info about some of our results from 2010 here. Also, I posted a little description of Formentera last year. You can check that out here.

This year, I spent April, May and the first week of June on Formentera. I had three main goals to accomplish: I wanted to 1) set up a breeding experiment to investigate the heritable basis of color; 2) test whether intrasexual ontogenetic conflict over color expression was occurring (i.e. are the costs and benefits of expressing color different between juveniles and adults of the same sex); and 3) investigate what might cause divergent color evolution among populations and determine whether those color difference resulted in any degree of reproductive isolation (i.e. will lizards from a blue population recognize lizards from a brown population as mates or competitors?). Needless to say, these were ambitions goals for only two months of work. Luckily, I didn’t have to do all the work alone. I brought four University of Miami undergraduates with me as field assistants. It’s amazing what you can accomplish with a team!

Field assistants from right to left: Marina Knize, Ryan McMinds & Hannah Peck. Missing from this photo is Jeremy Upsal.

The breeding experiment failed miserably. Here’s a video about my set up. Watching it now, I’m not surprised it didn’t work. Lizards kept escaping and breeding pairs seemed to hate each other. In total, I only collected four eggs—not nearly enough to estimate heritability. Additionally, I didn’t have the time or money to stay until those eggs hatched, much less rear them until adulthood. So, ixnay on the breeding experiment. It was a full-fledged failure. That’s OK. Research doesn’t always go as planned, which is why its important or researchers to be flexible.

Birds Eye view of a diverse habitat. Open habitat (brown and grays) is interspersed with patches of vegetation

Bird's eye view of a diverse habitat. Open habitat (brown and grays) is interspersed with patches of vegetation

On to project number two: figuring out whether color was under intrasexual ontogenetic conflict. In 2010 I noticed something interesting: in areas were there was patchy vegetation interspersed with open habitat, I kept seeing juveniles out in the open—tons of them. Adults, on the other hand, seemed to stay closer to vegetation. At first, I ignored this observation. But after visiting a few new islands, I also noticed that the juveniles of some islands were more colorful than juveniles of other islands. And it wasn’t simply that juvenile color was correlated with adult color from the same population. On a few islands, juveniles looked very much like their adult counterparts, while on others they were much less colorful than the adults.

Adult male lizard has killed and proceeds to eat this juvenile

The next thing I know, I see six cannibalism events in the span of a few weeks (to see a video of these lizards cannibalizing juveniles watch our 3-minute video ). And suddenly, I had a new hypothesis. Maybe vegetative patches are these lizards’ favorite habitats. This makes sense. There’s more food in these areas and there’s less risk of getting attacked by a bird when a lizard is in the bushes. But these patches are limited – there are only so many of them and in each patch there’s only enough room for so many lizards. Adult lizards fight amongst themselves for the best patches. The biggest, baddest males end up in their favorite bushes therefore excluding losers to marginal habitat. Juveniles can’t possibly compete with adults for these resources – especially since these little guys need to be careful not to get eaten! So, they abandon the vegetation for open areas until they are big enough to compete. But now these juveniles are out in the open, where they are vulnerable to other predators like birds. The price of being colorful in the open is much higher than it is for residents in the vegetation. Therefore, there should be strong selection on juveniles to be less colorful. The problem is that adult males use conspicuous color to advertise their fighting ability. In sum, being colorful is bad for juveniles because it makes them more conspicuous to other lizards (who eat them) and more vulnerable to detection by avian predators (more vulnerable than adults because juveniles are forced in to marginal open habitats). But being colorful is good for adult males, because it helps them win fights, which allows them access to more resources.

I think that color expression is under conflict among age groups. If colorful adult males sire colorful juveniles, the juveniles will be at a disadvantage. If less colorful males give birth to less colorful lizards, they may fare well as juveniles, but as adults, they aren’t going to win very many fights. Because color expression is probably controlled by many of the same genes in both juveniles and adults, its tough for lizards be successful in both these stages of development (hence ontogenetic conflict).

Color increases in saturation and coverage area as Ibiza wall lizards increase in size, both in males and females. The degree of this change, however, varies among populations.

Natural selection is a pretty amazing process. Generations of selection on hormonal responses (which play a prime role in the expression of color genes) have likely resulted in juveniles that are much less colorful than adults. But the fact that in some populations juveniles are still colorful suggests that there are some populations where this conflict has not been fully resolved. Wow. That was a long explanation.

I tested this hypothesis with four simple experiments. First, I did a survey to find out if there really were more juveniles in patches than vegetation by putting pitfall traps in vegetation of open habitats and seeing what we’d catch. Second, we performed a clay model predation experiment, making hundreds of clay lizard models, putting them in vegetation and open areas and looking at where they were attacked most and by what types of predators (you can see these experiments in action by watching and ). Third, we collected juveniles and inspected them for scars that came from being attacked by other lizards (see ). And finally, we tethered juveniles to a fishing pole and introduced them to adult lizards to see whether the adults would try and eat them (again, if you want to watch some lizard cannibalism, check out ).

A juvenile that we collected with two large scars from being attacked by an adult lizard.

Unlike the breeding experiment, everything work out just as I expected. We found more juveniles in open areas and more adults in vegetation. In the predation experiment, lizard models were attacked more by birds in open areas and by lizards in vegetated areas. In both areas, colorful models were attacked more than cryptic models. Out of 15 juveniles that we caught, all but one of them was covered in scars from lizard attacks and almost every adult lizard, male and female, immediately attacked tethered juveniles as if they were food items. It doesn’t get cleaner than that, folks.  The only data missing (data that I will probably never collect) to show that color is under intrasexual ontogenetic conflict, is data showing that colorful adults actually sire offspring that are more colorful than less colorful adults. For now, this is just something that I assume happens.

This post is already WAY longer than I planned, so I’m going to stop here and tell you about my final experiment in a few days.

One last note: this week was the annual Animal Behavior conference. They have a film festival at this conference. This year, Neil and I had three videos in the festival –, Battle of the Sexes, and . Who’s your Neighbor and Alpha Male can be seen on our Days Edge site and Battle of the Sexes should be up there by tomorrow. We don’t know yet how our films fared, but if you get a chance, they are worth checking out.

Invasive vs. invasive (Round 2)

Posted by Neil Losin at 11:15 am on July 13, 2011
Jul 132011

Joey Chestnut, American hero.

Last week Joey “Jaws” Chestnut successfully defended his title at the 2011 Nathan’s Hot Dog Eating Contest, eating a mind-boggling 62 hot dogs in 10 minutes. It’s impressive. But imagine that instead of 62 of Nathan’s famous hot dogs, Chestnut was tasked with eating one HUGE hot dog that weighed, say, 70 lbs. Also, imagine he had to swallow it whole. And then, just to make it a challenge, imagine that the hot dog was alive at the start of the competition and struggling valiantly not to be eaten.

An invasive Cuban Knight Anole (Anolis equestris) gulps down an invasive Brown Basilisk (Basiliscus vittatus) in South Miami.

The Herculean feat you’re now envisioning is akin to the challenge faced by a Cuban Knight Anole (Anolis equestris) that we found last Friday, here in Miami. Knight anoles are among the biggest in the genus, and they are formidable predators. We had stumbled upon the end of what must have been an epic battle. Our knight anole had consumed most of a Brown Basilisk (Basiliscus vittatus), and didn’t seem to know quite how to deal with the basilisk’s long feet and tail, which were still protruding from its mouth. Judging by the size of the basilisk’s feet, it could easily have been half the size of the anole.

We couldn’t stick around and watch the conclusion – that might have taken hours! – but I wouldn’t be at all surprised if the anole finished its gargantuan meal without incident. It wouldn’t be the first time that what seems a superhuman feat to us is “all in a day’s work” in the animal world.

Eat that, Joey Chestnut.

For another invasive vs. invasive story, see this post from earlier in the season.

Miami fieldwork: an auspicious start

Posted by Neil Losin at 11:19 am on July 1, 2011
Jul 012011

Field assistant Karen Villa handles a big Cuban Knight Anole.

As I begin my third field season in Miami, it’s looking like a good one. The anoles are plentiful, we are re-sighting many of the males I marked back in April, and everything’s going pretty close to plan – we’re slightly behind schedule, but if we weren’t behind schedule, it wouldn’t be fieldwork!

I have four field assistants working with me this year: Lauren Telban (University of Tampa), Matt Martino (University of Southern Illinois), Karen Villa (Florida International University), and Danny Cueva (Florida International University). One of the experiments we’re working on is a “removal experiment,” in which we are removing males of one species from an experimental plot and observing the effects of this species’ removal on the remaining males. This is an experimental way to measure the intensity of competition between species. It’s going to be very labor-intensive, so I’m glad to have a hard-working crew of field assistants to help me.

A marked male crested anole: Turquoise-Turquoise-Blue or "TTB"

So far, we’ve been focused on marking as many males as we can catch in our study plots. In this case, “marking” means attaching a unique combination of tiny colored beads at the base of each anole’s tail. We can then read the bead combinations through binoculars to identify each male. We’ve been quite successful thus far, with the exception of a few “nemesis” males that are (so far, at least) too savvy to be captured. Once males are marked, we conduct daily surveys to record their whereabouts, mapping their territories and measuring how they use the available habitat: how high do they perch? Are they in the sun or shade? Do they prefer more or less canopy cover? After we do the removal treatment, we will collect similar data to measure the effects of the removal.

A huge centipede I found in Indonesia. That's a 77mm (about 3-inch) lens cap for scale. The centipede we saw in Miami was bigger!

In the course of our daily fieldwork, we’ve also made some interesting observations. Nothing quite as odd as last year’s unpigmented anole, but a few noteworthy sightings. I had a quick glimpse of a huge centipede, probably 8 inches long, which emerged briefly from the leaf litter before disappearing again. I had no idea there were such enormous centipedes in Florida, but after a bit of research I’m guessing it was a Scolopendra alternans.

A male striped basilisk (Basiliscus vittatus) in South Miami.

We also spotted a striped basilisk (Basiliscus vittatus) holding a still-struggling green anole (Anolis carolinensis) in its jaws. Luckily for the anole, it thrashed itself free and scurried up a tree to safety. For another remarkable anole survival story, check this out). The basilisk is another non-native species (native to central America). I suspect that basilisks prey regularly on anoles, both the native green anoles and the invasive species that I study, but this was the first natural occurrence of attempted predation that I’ve seen. One of our male anoles (Orange-Black-Black or “OKK”) recently acquired a rather dramatic wound on its neck, and I suspect that a basilisk [or perhaps a Cuban Knight Anole (Anolis equestris)] is to blame.

Male crested anole "OKK" with its well-healed neck wound, quite possibly caused by a predator attack.

When you’re working with marked individuals, you get a new appreciation for the hazards that these animals face in nature – and a new respect for their resilience. The other day, we re-captured a male that I had marked back in April. While I was re-measuring him, I noticed that his jaw didn’t seem quite right. Recalling that I had marked a male with a broken jaw, I made a note of it. Sure enough, I consulted my records and this was the same male. Not only had he survived the broken jaw, but the break had healed quite nicely and here he was, more than 2 months later, still holding a territory just a meter away from where I had first captured him in April!

I’ll surely have more to report as the field season progresses, and with luck I’ll have more time to take pictures and video as well! Stay tuned.

Day's Edge in the news

Posted by Neil Losin at 11:33 am on June 24, 2011
Jun 242011

After winning the NESCent Evolution Film Festival this week in Norman, Oklahoma, Cold-blooded Cannibals got an excellent write-up in the Guardian science blog “Punctuated Equilibrium.” Check out the full blog entry here. Nice work, Nate and Joris!

New video! Agonistic Character Displacement

Posted by Neil Losin at 1:18 am on June 20, 2011
Jun 202011

Here’s another new video for you. In this video, my advisor () talks about a seldom-studied evolutionary process called agonistic character displacement, or ACD. Basically, ACD is a process by which aggressive interactions between species (like fighting) can drive evolution in those species. In the video, you’ll see a remarkable example of ACD in Mexican damselflies in the genus Hetaerina (the featured research was conducted by Dr. Chris Anderson, now a postdoc in our lab, and Dr. Grether).

This was an interesting piece to make – other than the interview footage and the animations, the content of the video came from other sources. There are some beautiful still images by Dr. Grether, Chris Anderson, J. P. Drury, Andrew Chao, and Patrick Green. The video clips were shot by Dr. Grether. And the music, once again, was graciously provided by the talented Dan Warren. Here’s the video:

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Despite the disparate sources of content, I think the video came together well. I’d love to know what you think! This video, like Nate’s recent video with Joris van Alphen about dietary adaptation in Ibiza Wall Lizards (Podarcis pityusensis), was submitted to the National Evolutionary Synthesis Center (NESCent) video contest, and both videos will be shown at the NESCent Evolution Film Festival, which will take place at the annual Evolution meeting in Norman, Oklahoma tomorrow night! If you’re at the meeting, please be sure to check out the film festival and vote for our films if you like them! The film festival takes place tomorrow (Monday 6/20) from 6:30 to 7:30 in Boomer Room A&B.

If you aren’t at the meeting, you can see all of the videos entered in the NESCent Evolution Film Festival here. There are some great entries (including “Climate Change and Evolution in the Columbian Ground Squirrel” by our friend )!

Field Vision - Entry 3: clays lizards part 2

Posted by Nate Dappen at 7:05 pm on April 22, 2011
Apr 222011

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In this segment of “Field Vision” one of my field assistants and I report on the results of a clay model predation experiment that we just conducted.

Field Vision - Part 2: Clay Lizards!

Posted by Nate Dappen at 10:08 am on April 21, 2011
Apr 212011

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In this segment of “Field Vision” I give a quick summary about on of the clay-model predation experiments I am conducting here on Formentera to see if more colorful lizards suffer greater predation.

Invasive vs. invasive!

Posted by Neil Losin at 5:44 pm on April 20, 2011
Apr 202011

A pair of crested anoles (Anolis cristatellus) copulating. The male sometimes holds the female's head or neck in his jaws.

Studying anoles in South Florida means that I see interesting behaviors every day. For example, I had never seen a complete “courtship” sequence until a few days ago. I had seen many pairs of anoles mating, but I hadn’t observed the events that immediately preceded copulation. Mating can last several minutes, so it’s fairly easy to see, but the courtship sequence is much quicker.

I was getting ready to catch a small male crested anole (Anolis cristatellus) when a female approached from a nearby branch and jumped to the twig where the male was perched. He perked up and darted toward her. In a fraction of a second, he was holding her head securely in his jaws. His response looked so much like an aggressive encounter between males that I wondered whether I had misidentified the sex of the arriving “female.” But sure enough, the male then maneuvered his tail under hers and mated, her head still clamped firmly between his jaws. Did the female approach with the intent of mating, or did the male simply take advantage of the situation? Forced copulations occur in many animals, including Anolis, so perhaps that’s what I observed.

On my last day in Miami, I saw something even more unusual: an anole eating a snake! Yes, you read that correctly. Anoles often fall victim to snakes (especially Black Racers [Coluber constrictor], which are abundant where I work in Miami), but I’ve never heard of the tables being turned before. I was trying to capture some photos of my marked male anoles, so when I spotted an unmarked male in less-than-ideal light, I was prepared to move on. Then I noticed something long and thin hanging from the anole’s mouth. I directed my lens toward the anole, and as the image in my viewfinder came into focus I realized the anole was eating something worm-like, and this prey item was longer than the anole’s entire body!

A male brown anole (Anolis sagrei) consuming a Brahminy blind snake (Ramphotyphlops braminus) tail-first.

Upon closer inspection, I saw a tiny mouth at the end of the “worm” – it wasn’t a worm at all, but a Brahminy Blind Snake (Ramphotyphlops braminus)! The blind snake is a tiny, fossorial (burrowing) snake that specializes in eating the larvae and pupae of ants and termites. Blind snakes are rarely seen above ground, so I’m not sure how the anole found its prey. But the blind snake, with no venom and tiny jaws specialized for small, helpless prey, was no match for the anole. It took a few minutes, but the anole managed to swallow the entire snake – a very impressive meal!

The photo I captured isn’t a work of art – the light was far from ideal – but it shows the unusual behavior. I love seeing new interactions between species, and in a place with as many invasive species as South Florida, such encounters are commonplace. Amazingly, every Brahminy Blind Snake ever collected, both in Florida and the snake’s native range in Africa and Asia, has been female. Female blind snakes can produce genetically identical female offspring without fertilization, a process called parthenogenesis. This unusual ability is probably part of what makes the blind snake such a good colonizer – only a single female needs to arrive in a new habitat to start a whole population!

Day’s Edge in the news!

Posted by Neil Losin at 3:58 pm on April 19, 2011
Apr 192011

We’ve had two bits of exciting news yesterday. First, my research on anoles was highlighted on the National Geographic blog, along with the Day’s Edge film “Who’s Your Neighbor.” I also did a radio interview with Boyd Matson for National Geographic Weekend (click on the link below to hear the interview!).

Yesterday’s second bit of news was that the pilot of launched at GenerationWild.tv! You can watch the 15-minute pilot episode below. I recently blogged about the team’s visit to my field site to catch lizards, and as promised there’s a short segment featuring Neil and the crew catching anoles. Ian Shive and Wild Collective did an amazing job producing the pilot – the cinematography is beautiful, the editing is great, and the whole production has just the right feel. It really makes you want to get out there and have outdoor adventures of your own! I recommend watching it in HD and full screen to appreciate the amazing cinematography.

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