A previous discussion on this blog has raised the following question: in which situations is a lizard most likely to lose its tail? Common wisdom has it that tails are most frequently lost in the avoidance of predators, and observational evidence backs this up, at least in the case of anoles–no AA reader has observed tail loss in a male-male aggressive interaction. But what about other lizards?
In Sitana ponticeriana, an agamid lizard that I often post about on this blog, a couple of observations point to the likelihood of male-male competition as a driver of tail loss. Tail loss is not uncommon–in the locality I have sampled best, 13.5% of lizards have lost their tails. Males are about 1.7 times as likely to lose their tails as females (16.5% of males vs. 9.6% of females). Further, lizard predators aren’t too common in this locality–fewer than 30 individuals of potential lizard predator species were spotted or heard in over two months of sampling, and no predation attempts were observed.
But more excitingly, I had the chance to observe firsthand the loss of a tail during a male-male fight this summer! The resident lizard had lost much of his tail prior to the fight, a measly 5.4 cm remaining. The intruder, however, had an almost complete tail. Here is a rather blurred photo of the two males facing each other:
In his beautiful monograph on anoles of Guadeloupe (A. marmoratus ssp), Lazell (1964, 1972) showed the existence of a large variability of phenotypes and described six subspecies of Grande-Terre and Basse-Terre , i.e. A. m. inornatus, A. m. speciosus, A. m. setosus, A. m. girafus, A. m. alliaceus and A. m. marmoratus (see my previous post “The anoles of Guadeloupe“). However, as Lazell indicated Lazell in 1964, “there exists between two distinct populations occupying different geographic areas a zone in which “intergrade” individuals assure continuous gene flow betweens the two extremes.” In other words, the classical subspecies could be considered as extremes that would be relatively few relative to the entire population of Guadeloupe anoles.
Within the framework of a project funded by the National Park of Guadeloupe and the University of Lyon (France) and in collaboration with the DEAL of Guadeloupe, we have identified this year the population of anoles on Basse-Terre and Grande-Terre. 120 stations distributed over the entire territory were studied. 687 anoles were characterized and 260 genetic samples were taken. This study demonstrated the existence of extreme variability of phenotypes between stations and within each station, with a minority representation of the subspecies classically described in the literature. This variability is represented by the poster below. This result leads us therefore to question the relevance of currently distinguished A. marmoratus subspecies as well as on the work of the field experimenter. What should be the selection criterion to select an individual on a station? Should it be random regardless of the phenotype, or should we select the one that is closest to the referenced phenotype, although this phenotype is a minority within the population?
AA reader Angel Sosa sends the attached photo and writes: ‘During monitoring of amphibians and reptiles in Cerro Azul region of Alto Chagres, Panama, I photographed three moth flies on the back of Anolis lionotus. The moth flies had bellies full of blood, which is clearly seen in the photograph. It’s the first time I have seen this group of arthropods feeding on a reptile. This is an endemic area of leishmaniasis, but little is known of the ecology of parasites in reptiles and their medical importance.”
Adult male Anolis sagrei looking out over a pile of seaweed
Aloha, my name is Amber Wright and I’m a first-time poster here on Anole Annals. I did my dissertation on niche variation between native and introduced populations of brown anoles, with field sites in Hawaii, Florida, Little Cayman, and the Bahamas. I will be starting up a new lab at the University of Hawaii, Manoa in January 2014, so look forward to future posts on Anolis vs. Phelsuma, and get in touch if you’re interested in joining the lab!
As covered in previous posts on Anole Annals (e.g. 1, 2), our team has been studying the effects of seaweed subsidies on near-shore food webs in the Bahamas where Anolis sagrei is a key predator. While studies published to date have detailed the effects of seaweed on direct and indirect interactions among lizards, insects, and plants, our most recent paper focuses on how lizards are able to capitalize on seaweed-derived resources.
To briefly summarize the most relevant previously reported lizard results (Spiller et al. 2010), when we added seaweed to experimental plots we found that lizards switched from foraging on terrestrial prey to consuming seaweed detritivores, and that lizard density increased by about 60%. We saw an initial increase in density within the first three months, suggesting that lizards quickly moved into plots to take advantage of the seaweed. However, peak lizard abundance was observed a full year after the initial subsidy, which suggested that a lagged reproductive response could also be contributing to the overall increase in lizards.
We analyzed mark-recapture data from close to 500 individuals over the 20-month experiment to try and figure out how lizards could be turning resource input into reproductive output. We found that subsidized lizards did not survive better or have better body condition than unsubsidized lizards, but they did grow 30% faster.
A 30% faster growth rate may not seem like much of an advantage, but achieving reproductive size sooner could be a big deal in light of some key aspects of anole life history. While A. sagrei can reproduce over much of the year, there is a period of reproductive quiescence during the winter. Having a breeding season coupled with the fact that anoles can reproduce continuously (about an egg a week for A. sagrei) means that when you reach maturity during the breeding season constrains how many eggs you can produce.
We fit a model of individual growth to the mark-recapture data to quantify this effect, and proposed the following scenario shown in Figure 3 from the paper below. Lizards hatching very early in the season reach reproductive size before or near the start of their first breeding opportunity regardless of whether seaweed is present; the difference therefore lays in the lizards that hatch late. Late-hatching lizards without access to seaweed do not reach reproductive size in time to lay any eggs and must survive until the next breeding season to reproduce. Subsidized lizards that hatch late are able to catch up a bit, hitting reproductive size in time to take advantage of at least half of their first breeding season. Averaging egg production over all possible hatch-dates in a year, these growth differences translate into subsidized females laying an average of 16 eggs vs unsubsidized females laying an average of 8 eggs in year one. That’s a doubling in fecundity due to seaweed addition.
Model-estimated growth and reproductive phenology for females born during the study period. This scenario assumes a size at hatching of snout–vent length = 16.5 mm, a one-month incubation time, and that the peak egg-laying period is from May to September (shaded boxes). The dotted line indicates minimum reproductive size (snout–vent length = 34 mm). Growth trajectories follow lizards hatching early (June) and late (October) in the breeding season. Symbols (triangles and circles) mark when lizards reach minimum reproductive size depending on hatch date and whether seaweed was added (solid lines) or removed (dashed lines).
A view of our hotel from the parking lot, right in front of the spot where the brown anole was lounging.
On our recent trip to Mexico, we had been warned that brown anoles were spreading beyond the coast, and sure enough, we found ’em. The photo above is a female A. sagrei we spotted in the parking lot of our point five-star hotel located in downtown Chinantla, Veracruz, Mexico. The photo ain’t pretty, but the ID is unmistakeable: them’s Cuban emigres, doing just fine in the Mexican heartland.
We actually found brown anoles at two spots in Chinantla. The other was a small, bright green pained shack near the intersection of the highway and the main road through town. A bunch of female and juveniles brown anoles were running up and down the walls of the shack, easily seen from the side of the road. You can’t miss it, not only due to its bright color, but also because of the transit police standing in front, randomly waving over cars–especially those driven by oddly-attired biologists–and then finding problems with their registration or what-not. In fact, you’ll have plenty of time to watch the anoles as the officers explain at great length why they will have to impound the car, even though it is a rental and you are five hours from Veracruz, where your flight leaves the next morning, because the car’s tax certificate for 2013 is not plastered to the back window. You’ll probably be distracted by your colleague on her cell-phone berating the rental car office, but stay focused, even when–finally–the police officers realize (as the rental car people predicted) that it is possible to pay the registration tax, on the spot, in cash, and without being given a receipt. Any way, that’s where to look for brown anoles in Chinantla.
As part of its ongoing studies of Central and South American anoles, Team Mainland—fresh off successful field work in Colombia and Venezuela earlier this year, traveled to the Veracruz, Mexico to sample that state’s anole fauna. Joined by Anne-Claire Fabre, Victor Jiménez, and Ramón Martínez, Team Mainland worked at the fabled Estación de Biología Tropical Los Tuxtlas, home to eight or nine (depending on which paper you read) species of anoles. The goal of the trip was to characterize the ecology, behavior, and morphology of the species residing at the station. Although all anoles are interesting in their own right, as we know, not all anoles are created equal. And, indeed, there was one special species we had our heart set on seeing: the large aquatic anole, Anolis barkeri.
Anolis barkeri. Photo by J. Losos
Anolis barkeri. Photo by Victor Jimenez.
And lo and behold, we saw them! Aided by Bob Powell’s advice to visit his old field site, a lovely stream located several kilometers from the station, we spent several days observing the antics of these gorgeous anoles, the largest of the mainland aquatics. And by antics, I mean primarily sitting around doing nothing, though they did flash their gorgeous red dewlaps occasionally (alas, not caught by camera, but several times on video—stay tuned once they get processed). Actually, they were sometimes quite active, running rapidly from one place to another. Like other mainland aquatics, these guys hang out right next to streams, and when threatened will sometimes jump in. They don’t go swimming away, though, at least not in our observations (which agree with others); rather, they immediately go to the nearest water-land interface and hang out, hoping they have not been detected.
Our trip occurred in early August, at the end of both the reproductive and dry seasons. We were told that it had been a particularly dry dry season, which may explain some of the observations. For example, A lemurins is supposed to be very common, but we didn’t see a one. Also, males of two other common species, A. sericeus and A. rodriguezi, were few and far between. This was surprising, but perhaps these—like many mainland species—are primarily annual, that is, with a lifespan averaging less than a year. Perhaps the males, spent by their exertion, are all dead, explaining why we saw so few of them. That was a classic hypothesis borne of field observations, but the Malice of Nature did not intervene to refute it. A number of people suggested that A. barkeri is only found in shaded streams; in the open, it is pushed out by basilisks. “Find a basilisk,” we were told, “and you won’t find A. barkeri.” For the record, we did find several small basilisks along the stream, though only in open, sunny spots in the otherwise well-shaded watercourse. The A. barkeri were found on logs and rocks, always near the water. They didn’t impress me as brilliant swimmers, but could immediately climb onto rocks—very good graspers, with long arms and sharp claws.
I was particularly curious to learn more about A. sericeus.
We hear a lot about invasive anoles–A. sagrei and others–showing up all over the place: Singapore, Taiwan, you name it. But how do they get there? I was recently reminded of an article by Gad Perry and colleagues in the journal Iguana (now Reptiles and Amphibians: Conservation and Natural History–a quarterly journal available online and worth a look). Perry et al. examined a barge delivering a large number of potted plants to the small island of Guana in the British Virgin Islands. The plants came initially from Florida, but had been sitting in a nursery on a nearby island for at least ten days. What would they contain?
To find out, the investigators laboriously inspected the plants, all 220+ of them, one by one. And sure enough, there were stowaways: six juvenile Puerto Rican crested anoles (A. cristatellus); a dwarf gecko, Sphaerodactylus macrolepis; also, an immature spider, three snails and nests of the red fire ant. In addition, the barge carrying the cargo contained two other lizards, Ameiva exsul.
And remember, this is one just one shipment. Now, in this case, all of the lizards were natives, as were most of the invertebrates. But imagine all of the plants being shipped out from Florida, containing brown anoles, Cuban treefrogs, and who knows what else? My prediction: it’s just a matter of time before brown anoles are everywhere in the urban tropical world.
Following previous threads documenting nectivory in various Anolis (1, 2, 3), here is another account recently observed in south Florida, from Florida International University’s palm botanist Scott Zona in Miami:
This American green anole was methodically going along an inflorescence of one of the palms (Ptychosperma macarthurii) in my back yard licking the nectar droplet from the tip of each pistillode. This palm is an exotic ornamental from New Guinea and northern Australia but is widely cultivated around the world. It is monoecious (male and female flowers on the same inflorescence) but strongly dichogamous (separation in time). The male flowers open first. The lizard was lapping up a droplet of nectar that is excreted by the long, slender pistillode (sterile pistil) in each male flower. I watched him for several minutes (and have lots more photos). The lizard was very methodical about going to every flower, climbing to another branch, and then exhibiting the same feeding behavior. It is unlikely that the lizard would be a pollinator, because of the strong dichogamy; however, female flowers also secrete nectar, so if the same anole were to find another inflorescence in the female phase, it could affect pollination.
American green anole (Anolis carolinensis) feeding on the nectar of a palm inflorescence in south Florida
Nectivory in anoles has been well summarised in a previous post, in which Ambika Kamath noted that they had observed a a female licking palm flowers in south Florida but regrettably never got a picture – well it may have been a year and 3 months, but here’s one!
With the wealth of introduced anoles in south Florida, I wonder if this feeding behaviour has been observed in other species but not yet documented – the ecologically similar A. porcatus and A. chlorocyanus seem likely candidates…
If anyone would like more information on this, or has a keen interest in palms, please feel free to email Scott directly.
Recently, Bryan Falk wrote an interesting report on how nematode parasites are passed from one anole to another by sexual contact. He summarized a fascinating paper by Langford et al. in the Journal of Parasitology that convincingly demonstrated this phenomenon. In reading that paper, I found one idea they suggested in the Discussion to be particularly intriguing. I’ll let them describe it:
“Our finding that C. penneri” (the nematode parasite) “is transmitted by copulation has some interesting implications for the host’s reproductive and behavioral biology. Anolis sagrei reproduces in a female-defense polygyny, wherein large males (e.g., SVL = 50 mm) establish and maintain territories containing multiple, relatively small females (Schoener and Schoener, 1980). In Anolis mating systems, young males are generally thought to have little mating success because they are excluded from females by large territorial males (Losos, 2009). In contrast, our parasitological results suggest that small male lizards are copulating with mature females and becoming infected with a sexually transmitted parasite. Thus, our results provide some support for the female mimicry hypothesis (Orrell and Jenssen, 2003) and/or the ‘‘dear enemy’’ phenomenon (Paterson, 2002) in anoles. This insight into A. sagrei reproduction should encourage anologists to reconsider the role of covert and satellite males in anole mating systems where C. penneri infects small male lizards. In conclusion, the major contribution of our study is the establishment of copulation as the route of transmission for C. penneri between lizards and the discovery of both ecological and physiological host specificity in these worms.This study also provides insight into the host’s biology, specifically support for the female mimicry hypothesis in anoles proposed by Orrell and Jenssen (2003).”
I queried Gabriel Langford, “just how small are these infected males?” He responded: “We sampled an evenly distributed group of females and males that ranged from a few days old to large (male SVL 68mm) adults. If memory serves (I’m on my tablet, no data in front of me), at least 35 of the 87 males fell into the range of 34-50 mm. Also, we had several males just above (infected) and below (uninfected) the 34 mm cut-off, which allowed us to be fairly confident about this number in A. sagrei.”
These results suggest that even quite small males may be mating, even though they are far too small to hold a territory. The idea that “sneaker” males may exist in anole populations has been suggested before, but not demonstrated. The occurrence of such matings has all kinds of interesting implications for anole sexual selection and evolution.
Anolis gundlachi 10 seconds later. Photo by Alejandro Sanchez.
West Indian photographer and natural historian extraordinaire Father Alejandro Sanchez sent in these photos, commenting “I took these two pics less than 10 seconds apart from each other – the time it took for me to modify the flash’s settings. Yet the lizard noticeably changed color patters in such a short time, surely for being scared by my proximity. Anolis gundlachi is one of my favorites.”
