Category: Natural History Observations Page 8 of 34

http://www.panoramio.com/photo/73496240

What do diseases like Ebola, Influenza, SARS, and Rabies have in common? Well, for one, they’re all viruses. Second, and more germane to this discussion, they’re all zoonoses–diseases that are usually harbored in non-human animal hosts but occasionally spill over into humans. Zoonoses are the subject of David Quammen’s excellent and aptly named new book, Spillover.

http://www.realscience.us/2012/07/30/ebola-virus-spreads-across-uganda/

Quammen is in peak form with Spillover: he tracks these diseases and the researchers who study them from goat farms in Holland to bat caves in Uganda to wild meat markets on the Chinese mainland near Hong Kong. The book reads like a thriller–where exactly is Ebola lurking?– but doesn’t need fictional plot twists to keep the pages turning. Quammen’s accurate, clear, and exiting descriptions of the epidemiology, ecology, and evolution of zoonotic diseases keeps the pages turning instead.

http://upload.wikimedia.org/wikipedia/commons/5/50/Lesser_short-nosed_fruit_bat_(Cynopterus_brachyotis).jpg

A central message of Spillover is that a “successful” zoonosis is the result of opportunity. That is to say,  the life history of many zoonotic agents does not require a pass through human populations; they will survive, reproduce, and spread just fine in their animal hosts. However, if a zoonotic disease happens to find itself in a human body, those viruses (or bacteria, or protozoans, etc.) that can survive will survive, reproduce, and possibly spread to other people. Thus, the story of zoonoses is the story of humans creating the opportunity for spillover by coming into contact with animal hosts. For example, HIV (human immunodeficiency virus) is closely related to SIV (simian immunodeficiency virus) and all evidence suggests that it spilled into human populations through the use of chimpanzees for food. Nipah, a neurological and respiratory disease in Malaysia, Singapore, and Bangladesh, likely spills over into human populations through contact with fruit bat feces, contact that is becoming more common as human cities, towns, and agricultural fields encroach on the tropical rainforests that the bats call home. In sum, close contact with wild animals greatly increases the chance of spillover.

Close contact with wild animals… Close contact… Hmmm, what is it we do again?…

Oh yeah… Uh oh! 

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Brown/Grey phase Anolis cuvieri, just awakened from a nap. Photo by Alejandro Sanchez.

Most arboreal anoles are green, and for a good reason: it’s hard to pick out a green lizard amidst green vegetation. Yet, some species are more subdued in their coloration, with browns or grays–e.g., Anolis luteogularis from Cuba or Anolis microtus from Costa Rica.

An interesting twist is provided by Cuvier’s anole, the crown-giant of Puerto Rico, in which a polymorphism exists in which most lizards are green, but some are brown-grey. We were reminded of this situation by Alejandro Sanchez, who sent the photo displayed above with the comment that it had been a long time since he’d seen one of these morphs. Contrast that with his spectacular photo of the more common green morph below.

Green Anolis cuvieri. Photo by Alejandro Sanchez.

Rivero in his epic Los Anfibios y Reptiles de Puerto Rico notes the polymorphism, but does not provide any explanation or discussion, and I am unaware of any other literature on this subject. Puerto Rican readers out there: what else do we know? Are they definitely different morphs? Someone once whispered in my ear he had seen brown ones turn green, but the only publication of which I’m aware to discuss this phenomenon, Rand and Andrews (1975), says they don’t. But that was based on a very small sample size. Does the gray/brown morph occur throughout the island? Any idea what it’s all about? Any difference in habitat use? As far as I’m aware, the adaptive significance of this polymorphism has never been studied.

When videotaping Sitana last year, I noticed an odd interaction between a male and female, wherein the female suddenly ran towards the male, and after he displayed a little bit at her, she sat on him. She remained there for a couple of minutes, and then ran away.

Anolis cristatellus female sitting on male (photo by Kristin Winchell)

I had no idea what was happening–there were at least two more females in the vicinity, and I wondered if this sitting behaviour was an instance of female competition over the male. But I didn’t see the behaviour again, and thought no more of it until Kristin Winchell mentioned that she had seen similar behaviour in her captive Anolis cristatellus, being housed in male-female pairs for a common garden experiment. Moreover, she has noticed the same pairs repeatedly engaging in such interactions. Any thoughts on what might be going on?

Anolis cristatellus female sitting on male (photo by Kristin Winchell)

Photograph of Mantheyus phuwuanensis by S. Manthey from Ulrich Manthey’s book on agamids of SE Asia.

Posts about how other lizards have outdone anoles in one way or another are a common theme here on Anole Annals (e.g., 1, 2, 3, 4). Keeping this trend going, I wanted to share a photograph of a remarkable species of lizard found in northeastern Thailand and Laos. This photograph of Mantheyus phuwuanensis is by S. Manthey and appears in Ulrich Manthey’s book Agamid Lizards of Southern Asia: Draconinae 2 Leiolepidinae. Very little is known about this species. The photo caption in the book notes that this is a male display. The Reptile Database has a few references, but most are not readily accessible. The one paper I could get my hands on is Ananjeva and Stuart’s (2001) paper from the Russian Journal of Herpetology that moves this species from Ptyctolaemus to its own monotypic genus based on the presence of femoral pores and other traits. Ananjeva and Stuart (2001) don’t comment on the belly dewlap, but do note that the species lives along rock streams and that it spreads its ribs and becomes dorsoventrally flattened when handled, a “behavior that is almost certainly an adaptation for fitting into rock crevices.”

Literature Cited:
Ananjeva, N. B. and B. L. Stuart. 2001. The agamid lizard Ptyctolaemus phuwuanensis Manthey and Nabhitabhata, 1991 from Thailand and Laos represents a new genus. Russian Journal of Herpetology 8:165-170.

Anolis blanquillanus. Photo by Martin Dávila.

Anolis blanquillanus is a rare lizard that occurs on the flattened Blanquilla Island and on Los Hermanos archipelago (the Brother’s Archipelago), which comprises a series of seven islets or Morros that emerge abruptly from the sea.  These islands are ubiquitous in the Venezuelan Caribbean Sea and have never been connected to the mainland. A recent visit to Los Hermanos archipelago from 16-19th of August 2013, sponsored by the Laboratorio de Protección y Manejo de Cuencas at the Instituto Venezolano de Investigaciones Científicas (IVIC), allowed us to make some observations of this interesting lizard. Specifically, we had the opportunity to visit Morro Fondeadero (36 ha, 0.5 Km², 120 m of elevation), one of the seven Morros that make up Los Hermanos archipelago. This group of islands forms an arc to the southeast of Isla La Blanquilla and is located approximately 80 km NW of Isla de Margarita, 10 km SE of La Blanquilla, and 160 km N of the Venezuelan mainland (Puerto La Cruz).

Morro Pando seen from Morro Fondeadero. In the background is Morro grueso, behind this, El Rajao, one of the two Morochos (the Twins). Photo by Martin Davila.

One of the goals of this trip was to study the terrestrial herpetofauna, which is mainly composed of lizards, although marine turtles also inhabit the surrounding areas (but there are not nesting beaches). My personal goal was to collect an undescribed species of Gymnophthalmid lizard, observed more than 70 years ago in this archipelago by the Dutch naturalist P. Wagennar Hummelinck, but never collected until our recent survey work. Los Hermanos and La Blanquilla were surveyed by Hummelinck during the late 1930s, which resulted in the description of Anolis blanquillanus and Phyllodactylus rutteni. More recently, these islands are rarely visited, although on occasion fishermen climb to Morro Fondeadero mainly to make a prayer to the Virgen del Valle (the Valley Virgin) in order that she protect them during the time they are working on the sea.

During the five days we spent at Morro Fondeadero, we had the opportunity to take some data on Anolis blanquillanus, the most commonly observed reptile on the island. The vegetation in this Morro is composed of cactuses, some bushes and isolated trees (Ficus sp.). Temperatures can reach over 40ºC and the relief possesses much inclination. For this reason, we decided to sleep on a little less inclined rocky surface that would be a safer place to sleep, although not comfortable.

During the first day, after we found the place for our provisional camp, we opened a small trail in search for the summit to verify vegetation data we had obtained using satellite images. On this trail we saw the first individual of A. blanquillanus; after that first encounter, many additional juveniles and adults appeared before our eyes, including males fighting! Some individuals were very curious, approaching us very close, head bobbing and displaying their dewlaps.

Female A. blanquillanus. Photo by Martin Dávila.

To my surprise, all individuals observed were in good condition in spite of the very dry habitat resulting from the particularly long and dry season. I observed some individuals jumping from their perch trying to catch insects. Also I had the opportunity to see a big male swallowing a small fruit of Ficus sp. One individual that we collected defecated digested fruit of Ficus sp. while it was in the bag. Also, I was surprised with how two males were fighting only approximately two meters away from us without caring much for our presence. Anolis blanquillanus, along with Gonatodes naufragus, Phyllodatylus rutteni and Iguana iguana, are the only species (all natives) that have colonized Morro Fondeadero. Interestingly, species such as Cnemidophorus leucopsammus, the most common lizard in La Blanquilla, is absent, although Hummelinck reported the species there. Nine of us worked intensively during the day for four days, and no Cnemidophorus were observed, nor were P. rutteni (also observed by Hummelinck in 1940). Our findings suggest that it is unlikely C. leucopsammus ever existed there; however, it might exist in low densities, or it might have been extirpated by exotic species, such as domestic rats (Rattus rattus) that are very common on the island.

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With regard to the recent discussion of the black spots on the side of A. allisoni:

We saw a bunch of sarcophagid flesh fly larvae infections in canopy-dwelling Puerto Rican A. evermanni. These evermanni were sluggish and often had brown spots either on the shoulder or just dorsal and anterior to the rear legs. I captured some of these lizards and held them in captivity as the flies emerged and the flies emerged in the spots.

Now, our thinking was that the evermanni — a morphologically unspotted lizard — had these spots as a result of the fly larvae damaging the tissue from inside the body cavity. On the evermanni with fly infestations, the soon-to-be-exit holes looked like the “shoulder” spots shown  here on these lizards and on many other anole species.

In contrast, the Puerto Rican spotted A. stratulus had a much reduced frequency of sarcophagid infestation compared to evermanni living in the same canopy habitat and location. These spots often fooled me into thinking that stratulus individuals had been infected, but they were actually just spotted in the shoulder and anteriorly dorsal to the rear leg, where the flies would leave exit holes on evermanni.

One hypothesis is that perhaps morphological spots on spotted lizards fool female flies looking to larviposit on lizards into “thinking” that the lizard is already infected. An infected lizard, when it has visible spots, will soon die, too soon for a flesh fly female’s larvae to survive to the pupal stage, if the female were to larviposit on this dying lizard

I always wanted to do an experiment with the flesh flies and the evermanni and a sharpie, but ….

[Editor’s note: sarcophagid fly effect on anoles has been previously discussed in on AA]

When I arrived at the University of Florida this summer, I was struck by the bustling sidewalks – bustling not with students, but with brown/festive/Cuban anoles. They were everywhere! But now that it’s cool out (not cold, lets say below 70 degrees to be generous), they are essentially gone. Where I could once count ten anoles sitting on a single bench, it would now take some effort to find this many in a reasonable amount of time.  Where did they go?

Today, while cleaning up piles of leaves from the yard, I was surprised to find a fairly large collection of A. sagrei under my leaf piles. One pile had as many as four under it (lizards that were not shoveled up inadvertently before realizing my cache) and every pile had at least a few. These individuals were almost certainly below their thermal optima as my son had no problem scooping up three at once and proudly displaying them for a photo op. Is it possible that the lizards found these piles warmer than those found elsewhere, attracted to the heat of the composting leaves? Maybe they were just there to stay out of yesterday’s rain and had not yet ventured out. I would be curious to hear if anyone else ever observed something like this?