Cuban Spider Chows on Brown Anole

spider eats anole

More spiders eating anoles (for previous aranean saurivory, see this and that). This time it’s a brown anole, A. sagrei (also, this time), falling prey to a ctenid spider in Cuba. This one’s particularly gruesome–the head’s already digested away and eaten! The authors are Elier Fonseca Hernández and Tomás M. Rodríguez-Cabrera and the paper’s just out in the most recent issue of IRCF Reptiles & Amphibians.

Tutorial: How to measure Anolis toepad length and width using ImageJ

As a follow up to my recent posts on lamella scale counts on toepads, I thought I would share a tutorial I created for measuring toepad length and width using the program ImageJ. ImageJ is a free, open-access program that allows you to perform a suite of analyses on pictures or scans. I hope this could be a useful tool for graduate students, as well as research technicians and assistants.

Measuring the width of a Cuban brown anole (Anolis sagrei) toepad using ImageJ

Measuring the width of a Cuban brown anole (Anolis sagrei) toepad using ImageJ

Tutorial: How to measure Anolis toepad length and width using ImageJ

You can download ImageJ from here.

Feel free to use and distribute as you need! If anyone has any comments, or spots any recommendations or improvements that can be made, then please feel free to contact me.

How Many Geckos Can Fit on One Ceiling?

ceiling geckosx

Everyone knows that geckos are anole wannabees, but here in Asia, there are, sadly, no anoles (except introduced brown anoles in Taiwan and Singapore). So, in their absence, an anolologist is forced to count geckos. Fortunately, in some places, they’re not hard to find. Just how many are there on the ceiling of this building near Khao Sok National Park in Thailand?

Survey Results: How Many Lamellae Are on This Toepad?

I have now compiled the results of the survey I previously posted here on Anole Annals. I asked readers at what point on the image below would they stop counting scales if conducting toepad scale counts?

alt text

Fig 1. Lamellae numbered 1-51 on the 4th digit of an Anolis lizard hindfoot

As expected, there was a lot of disagreement! However despite some confusion, scale 32, roughly coinciding with the joining of the second to the third phalanx, was a clear favourite (Fig 2, below) (see Kevin De Quieroz’s comment here regarding some confusion with phalanx numbering).

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Fig 2. AA readers choice of where one should stop counting during toepad scale counts.

However, I was most interested in the demography of the surveyors. I have met other graduate students confused about this topic, and relevant guidance material seems limited to anecdotes. Would we then expect there to be most confusion among contributors who have never published scale count data?

Fig 3. testte

Fig 3. Survey data broken down into publication record: a) those that have never published scientific articles which include toepad scale counts (blue), b) those that have published a scientific article including toepad scale count data (red), and c) those which have published but were not responsible for conducting the scale counts (green).

The majority (60%) of votes from published researchers fell among scales 32-33, suggesting fairly high agreement on the general area. Only 40% of non-published voters selected these scales, with moderate confusion from scales 24-33 (although a peak at 32 did mirror those of published researchers). Too few votes from researchers that had published but not conducted scale counts themselves were collected to be interpretable.

This survey was not intended to standardize the position at which researchers should conduct toepad scale counts. The functional significance of toepads changes between species, and therefore that should be an important consideration in respect to the ecological/evolutionary question at hand. Those votes towards the higher end of the spectrum (scales 50-51, comprising a scale count of the entire digit) could be important data for species identification and morphological taxonomy. There could be an opportunity for a neat review/methods paper here, contact me if you are interested in more details!

How to Pronounce “Anole”: the Video

The second most viewed Anole Annals post of all time is “The proper pronunciation of “anole”” which has been viewed 9,938 times (just 121 views behind the all-time leader. *You’ll have to guess what that one is about. Or click here.).

Well, now there’s a video answering the same question and, frankly, I’m not sure everyone will agree with the answer.

 

*This post was initially drafted several months ago. In the intervening time, the leading post has gone on a tear, and now is ahead by 1,610 views! Go figure.

Out Damned Spot! Or, How They’d Be Loving If They Weren’t Fighting

Hey, that's not an anole! Rubyspot Damselfly (Hetaerina americana) Copyright Steve Collins

Hey, that’s not an anole! American Rubyspot Damselfly (Hetaerina americana). Copyright Steve Collins

My colleagues and I recently published a paper documenting character displacement in Anolis carolinensis following the invasion of A. sagrei into Florida. The former moved up into the trees and evolved larger toepads. We did a lot of work in that paper to show with a high degree of certainty that the interaction between the two species is what led to character displacement in A. carolinensis. However, an open question remains as to exactly what kind of interaction, or interactions, they share. Most likely, the two species are competing for food (i.e. exploitative competition). They may also be interacting indirectly through a shared predator or parasite (i.e., apparent competition), and they are  known to eat each other’s hatchlings (i.e., intraguild predation).

Today, I’d like to explore another possible interaction in depth: perhaps the two species have diverged to lessen aggressive interspecific interactions for space and territory (i.e., interference competition). For more, let’s turn to the anoles of the Odonata world (provocative statement, I know!): rubyspot damselflies (Hetaerina spp).

In a recent issue of the Proceedings of the Royal Society B, Jonathan Drury and Greg Grether investigated the role of aggressive (or agonistic) interactions in driving divergence between two species of rubyspot damselflies.

Previous work [1,2,3] in Grether’s group had shown that male competitor recognition in rubyspot damselflies depends on hindwing coloration, and that cross-species recognition and male wing coloration diverges between species living in the same area. This suggests that aggressive interactions between males of different species have driven divergence in wing color to reduce the frequency of energy-intensive, aggressive interactions between species. This divergence is consistent with a type of character displacement called Agonistic Character Displacement (ACD), which is the divergence between species in some sort of species recognition trait to lessen the negative effects of aggressive encounters.

However, another type of character displacement, Reproductive Character Displacement (RCD) is also consistent with these previous findings. RCD is divergence, usually in some sort of mate recognition trait, between two species. By diverging in such a trait (think anole dewlaps), males and females of different species are less likely to spend precious time courting or mating in wasteful, failed cross-species reproductive efforts.

By this point, you, the astute reader, may have noticed that both ACD and RCD predict changes in signaling traits–the former species recognition traits, and the latter mate recognition traits.

Whenever the same trait functions as a signal for both species and mate recognition, and that does happen often, telling apart the action of these two distinct processes (i.e., selection to reduce wasted aggressive effort versus selection to reduce wasted reproductive effort ) can be very difficult*.

Drury and Grether designed a very nice test for successfully discerning between these two hypotheses.

Continue reading

Video of Running Trunk-Ground Anole Needed

I’m looking for a bit of help and where else to turn than the dedicated readers of Anole Annals? Does anyone have a short video clip (ca. 10 seconds) of a trunk-ground anole running on either the ground or a trunk that they’d be willing to share? I’d like to use it for a couple of upcoming talks, and for teaching. Proper credit would, of course, be given. Plus I’ll buy you a beer if you ever happen to be in Nottingham. I’ve got a few short clips of sagrei but unfortunately the frame rate went screwy when I tried to convert them, hence the appeal. The point is to contrast a trunk-ground’s movement with this clip of carolinensis (shot by Leslie Bode on the Anhinga Trail, Everglades, FL):

If you have something suitable that you’re willing to share, please either leave a comment, or you can email or tweet me (adam.algar[at]nottingham.ac.uk, @acalgar).

Thanks!

That Fascinating Phallus

I probably would have never said this a few years ago, but penises are absolutely fascinating. The phalluses of terrestrial vertebrates exhibit an incredible diversity of shapes and sizes with some possessing elaborate coils, barbs, bony spines, and multiple lobes. Many of us learn about the rapid evolution of sexual characters in our undergraduate classrooms, but until recently I, for one, did not fully appreciate the striking diversity of this organ until immersing myself in the subject area.

Many biologists study the penis under the umbrellas of different research disciplines, but relatively little work has been performed to explain its anatomical diversity. For example, how many times has a penis/phallus evolved among terrestrial vertebrates? This may seem like a trivial question, but the diversity in form, function, and physiology in the adult phallus actually makes this question difficult to address. Historically there has been much conjecture, but little data to support whether the mammalian penis, squamate hemipenes, and phallus of turtles, crocodilians, and basal birds share a single evolutionary origin or are independently derived. But where comparative anatomy has struggled, comparative developmental biology has recently forged ahead. Within the last several months two independent groups have published a total of seven new research articles that help us resolve the question of phallus homology.

Figure 1 from Gredler et al. 2014 illustrating phallus  diversity among amniotes. The darker lines illustrate the sulcus spermaticus which goes on to become internalized in mammals as the urethra.

Figure 1 from Gredler et al. 2014 illustrating phallus diversity among amniotes. The darker lines illustrate the sulcus spermaticus which goes on to become internalized in mammals as the urethra.

I previously wrote about a series of five papers published from the Cohn lab (University of Florida) describing the embryology and gene expression patterns for the developing phallus. Since then this group has published a sixth paper synthesizing this wealth of information, using it to lay out a number of outstanding questions regarding phallus development and evolution. More recently, the Tabin lab (Harvard University) published a paper comparing the cellular-level origins of the genitalia in the laboratory mouse, green anole, house snake, chick, and python. I have had the distinct pleasure of working with both groups as their “anole guy.” Although these studies vary widely in their experimental and comparative breadth, together they have shed much needed light on the evolution of vertebrate genitalia. Here my goal is to discuss how this new wave of research changes what we now know, what we don’t know, and what we think we know regarding the evolution of external genitalia among vertebrates. Take a look at the original research papers for details of the developmental analyses, which represent many technical steps forward in our use of anoles as a laboratory model system and intellectual advancements in our understanding of genital development.

During the gradual transition of life onto land, vertebrates evolved the amniotic egg to facilitate their departure from moist environments. Continue reading

Brown Anole Colonizes Canada

Let’s hear it for global warming! Ryan Vince Photography’s Facebook page reported that this brown anole was found in Ontario. Probably still too cold there for the festive anoles to survive, but who know’s in a warming world? Here’s what the FB page had to say: “This little hitchhiker is a Brown Anole that has somehow made its way from Florida all the way down to Ontario, Canada (2000km). I found him in a mulch pile at a local aggregate facility. It seems that he had managed to make it through two sets of wood grinders and now resides in a Vivarium here with me.”

And this isn’t the first report of the festive one getting to Canada. Recently, we had a post reporting brown anoles not only in Canada, but Denmark. Next: the World!!!

Program for SICB 2015 Released: Anoles Abound

Winter is coming to the Northern Hemisphere, which can only mean one thing: SICB is upon us. Every January, the Society for Integrative and Comparative Biology (SICB) hosts its annual meeting. SICB 2015 will take place in West Palm Beach, Florida. Perhaps it’s due to the fact that southern Florida is the global epicenter for Anolis invasions, but talks and posters about anoles will be particularly numerous at this meeting. By searching for presentations containing the keyword “Anolis,”,  got 30 hits! That’s a much better turnout than the last few years, and hopefully a sign that Anolis presence at large annual meetings is on the rise. What’s more, there are two Anolis talks scheduled for the Huey symposium. This symposium is a competition for the best student talk hosted by the Division of Ecology and Evolution, and is named after anolologist and distinguished evolutionary biologist Ray Huey. I won’t be there this year, but I look forward to reading about all the new and interesting research involving anoles on this blog. Best of luck to all the presenters!

The Old Lizard by Federico Garcia Lorca

Photo from Imablog

In the parched path

I have seen the good lizard

(one drop of crocodile)

meditating.

With his green frock-coat

of an abbot of the devil,

his correct bearing

and his stiff collar,

he has the sad air

of an old professor.

Those faded eyes

of a broken artist,

how they watch the afternoon

in dismay!

 

Is this, my friend,

your twilight constitutional?

Please use your cane,

you are very old, Mr. Lizard,

and the children of the village

may startle you.

What are you seeking in the path,

my near-sighted philosopher,

if the wavering phantasm

of the parched afternoon

has broken the horizon?

 

Are you seeking the blue alms

of the moribund heaven?

A penny of a star?

Or perhaps

you’ve been reading a volume

of Lamartine, and you relish

the plateresque trills

of the birds?

 

(You watch the setting sun,

and your eyes shine,

oh, dragon of the frogs,

with a human radiance.

Ideas, gondolas without oars,

cross the shadowy

waters of your

burnt-out eyes.)

 

Have you come looking

for that lovely lady lizard,

green as the wheatfields

of May,

as the long locks

of sleeping pools,

who scorned you, and then

left you in your field?

Oh, sweet idyll, broken

among the sweet sedges!

But, live! What the devil!

I like you.

The motto “I oppose

the serpent” triumphs

in that grand double chin

of a Christian archbishop.

 

Now the sun has dissolved

in the cup of the mountains,

and the flocks

cloud the roadway.

It is the hour to depart:

leave the dry path

and your meditations.

You will have time

to look at the stars

when the worms are eating you

at their leisure.

 

Go home to your house

by the village, of the crickets!

Good night, my friend

Mr. Lizard!

 

Now the field is empty,

the mountains dim,

the roadway deserted.

Only, now and again,

a cuckoo sings in the darkness

of the poplar trees.

Anolis maynardi Uses that Long Snout for Biting!

maynardi vallee 5

Mike Vallee, a dive instructor on Little Cayman, spends his spare time watching that island’s delightfully long-schnozzed anole. What a great hobby! He says the “anoles are often found in and around the local agave plant. They are the perfect color match and their spiked leaves provide protection from birds and other predators.” He also commented on the photo above, in reference to a previous post on the long snout of this species, that we now know one thing they do with their pointy front end.

Here’s some more lovely pics he took.

little cayman anole

Photo by Mike Vallee

maynardi vallee2

Photo by Mike Vallee

Photo by Mike Vallee

Photo by Mike Vallee

Photo by Mike Vallee

Photo by Mike Vallee

A Failed Anole Predation Attempt

In the wake of the distressing news that even monkeys eat anoles with abandon, it’s a relief to see that there are at least some creatures that try to eat anoles, but fail. A 1979 report in The Wilson Bulletin by van Riper et al.  describing the the habits of the Red-Whiskered Bulbul in Hawaii, says this about these birds’ attempts at saurophagy:

On August 3rd 1977, a bulbul was observed chasing a large (ca. 20 cm in length) chamelion (Anolis sp.) in a circular pattern down an octopus tree; it was unsuccessful in capturing the reptile.

Such a vivid image, one that’s noteworthy for two reasons. First, while data on successful predation events are rare, descriptions of failed predation attempts are even rarer.  As bulbuls are mostly frugivorous, it isn’t too surprising that this lizard got away.

Second, like the battle between anoles and day geckos that we’re all eagerly anticipating, this interaction between two invasives, a New World lizard and an Old World bird, epitomizes the Anthropocene.

Red Whiskered Bulbul in southern India. Photo by adrashajoisa on Wikimedia.

Red Whiskered Bulbul in southern India. Photo by adrashajoisa on Wikimedia.

Carib Mountain High: Size, Elevation, and Convergent Evolution

In a recent paper in The American Naturalist, Martha Muñoz, Johanna Wegener, and Adam Algar noted an interesting pattern in two clades of Caribbean anoles evolving independently on Cuba and Hispaniola: high elevation species tended to have smaller body sizes than lower elevation species*.

Body Size - Elevation Relationships in Hispaniolan (cybotes clade) and Cuban (sagrei clade) anoles. The x-axis is elevation (on the log scale). The colors represent individual species within each clade.

Figure 1: Body size-elevation relationships in Hispaniolan (cybotes clade) and Cuban (sagrei clade) anoles. The x-axis is elevation in meters (on the log scale). The y-axis is SVL, or snout-vent length, a measure of size. The colors represent individual species within each clade; grey represents A. cybotes and A. sagrei on Hispaniola and Cuba, respectively.

Having found that the two groups converged independently on a similar evolutionary pattern, the authors wanted to know: was the underlying evolutionary progression also the same?

To answer this question, the authors took advantage of the fact that the two clades harbored multiple species. By measuring body size-elevation patterns within each species, and then asking how those patterns combined with interspecific patterns to create the overall body size-elevation cline (SEC) observed across all species, Muñoz & Co. could discern subtle differences between clades in the evolutionary trajectory towards convergence. For example, one clade might build its overall size-elevation cline by having the same SEC relationship present in each species, with species also sorting themselves by elevation and size (Model H1). Whereas another clade might build its size-elevation cline just through interspecific differences in size and elevation, without an SEC relationship within species (Model H2).

Figure 2: Two models, of eight that the authors proposed, which might explain how body size-elevation clines evolve. Within-species clines are represented by different colored/dashed lines. Across-species clines are best visualized by drawing an imaginary line through average size and elevation of each species . In H1, each species has the same size-elevation relationship (i.e., the negative slope) and is found at different elevations. This creates a size-elevation relationship that depends on both intra- and interspecific patterns. In H2, each species has no size-elevation relationship (i.e., the flat slope) but is found at different elevations. Here, the size-elevation relationship is driven purely by interspecific differences in elevation and size.

The authors developed eight models for how elevation and size might be related within species and across species. They tested which of those eight models best explained variation in the relationship between size and elevation within species and clades, while accounting for spatial autocorrelation among collection localities and differences in elevational range among species . They then compared best models across clades to see whether convergence was reached by similar or different evolutionary pathways.

What did they find?

space holder for now
Figure 3: Intra-specific size-elevation clines (SECs) for Hispaniola (left panel) and Cuba (right panel). Solid lines represent significant SECs; dashed lines represent non-significant SECs.

On Hispaniola, each species tended not to show any significant intraspecific SEC relationships: note the flat slopes of the dashed lines in the left panel of Figure 3. Instead, much of the overall SEC comes from interspecific differences in size and elevation, consistent with Model H2 (Figure 2).

On Cuba, in contrast, the authors found some significant within-species SEC relationships–the solid lines in the right panel of Figure 3–but found that interspecific differences in size and elevation explained very little of the clade’s overall SEC (Figure 4)**.

The model most consistent with the Cuban data.

The model most consistent with the Cuban data.

Thus the authors answered their question: “Although the precise mechanisms underlying inverse size[-elevation] clines remains  unknown, it is clear that they were constructed in different ways on Cuba and Hispaniola.” In other words, the two clades show a pattern of convergence to small size, but they took different routes of intra- and interspecific evolution to get there. It reminds me of Yogi Berra’s response when asked directions to his house: “When you get to the fork in the road, take it!”

 

CITATION: M.M. Munoz, J.E. Wegener, and A.C. Algar. 2014. Untangling Intra- and Interspecific Effects on Body Size Clines Reveals Divergent Processes Structuring Convergent Patterns in Anolis lizards. The American Naturalist 184: 636-646.

 

* This pattern was measured from 16 Anolis species: nine in the sagrei clade (Cuba) and seven in the cybotes clade (Hispaniola). The finding of small body size at high elevations is the inverse expectation of Bergmann’s rule. Bergmann’s rule, as originally conceived, states that endothermic species living in colder climates should be larger (or have a larger surface area to volume ratio), all else equal, to conserve heat. As lizards are ectothermic, one would expect an inverse Bergmann. Perhaps we could call the inverse cline Nnamgerb’s rule? It does have a certain charm to it, no?

** I wonder if the authors might chime in in the comments section. What does it mean that a size-elevation cline wasn’t found on Cuba when using the mean size and elevation of each population (Fig 5 below), but it was found when species identity was ignored (Fig 1 above)? Is this an example of Simpson’s paradox?

Screen Shot 2014-11-04 at 5.24.59 PM

 

Puerto Rican Giant Green Anole Mating

 

Anolis cuvieri. Photo by Alejandro Sanchez.

Anolis cuvieri. Photo by Alejandro Sanchez.

Photo by Alejandro Sanchez.

Photo by Alejandro Sanchez.

Father Alejandro Sanchez has done it again! Previously, he posted some wonderful photos of Anolis cuvieri moving around, now he’s caught them in flagrante delicto. Here’s the backstory: “The pics were taken around 10:30 AM. The lizards were about 10 meters above ground. I cannot take credit for the initial sighting. The group of students of UPR-Humacao saw the male jump to the tree where the female was and almost immediately copulation started. In all it lasted about 15 minutes. The separation was very abrupt (possibly caused by the group of people under the tree, taking pictures). At that point the male jumped to another branch and ran down low enough for me to be able to shake it down and capture it. At that time, the male still had his hemipenis everted.”

Monkeys Eat Anoles

Capuchin monkey eating a basilisk. Photo by Andrew G.

Capuchin monkeys may look cute, but in reality they’re cold-blooded killers. A recent paper in Herpetology Notes reports on a golden-bellied capuchin (different species than the one pictured above and below) that ate a Polychrus marmoratus, an Anolis ortonii, and an Enyalius catenatus.

Monkey predation on anoles has been documented previously. This paper cites a case of a capuchin eating an A. cupreus, and primatologist Betsy Mitchell recorded one eating an anole–perhaps A. frenatus–in her thesis (which I don’t have in front of me). We also reported on another capuchin species eating a Polychrus in a previous post. A quick google found an undocumented report of rhesus macaques eating A. carolinensis in Florida. Anyone know of any other reports?

And, finally, for your delectation, a video of a capuchin eating an iguana:

Knight Anoles Spreading through Florida

An iguanito. Photo from the Coastal Star.

A nice article in the Coastal Star just reported on the spread of knight anoles through Florida. The article contains numerous nuggets, such as quotes from the Florida Fish and Wildlife Commission stating that they’re worried about bigger things (e.g., pythons, tegus), that they’re locally called “iguanitos,” and that iguanas are rebounding from freeze-caused mortality in the recent past and are mainly a problem for pooping by people’s pools.