Behavioral responses to plant toxins by two omnivorous lizard species

An ability to detect plant toxins and thereby avoid eating chemically defended plants would be very beneficial for omnivorous and herbivorous lizards. We studied the ability of the omnivorous Podarcis lilfordi to detect compounds belonging to three classes of common plant toxins, as well as responses indicating aversion. Solutions of the alkaloid quinine, saponin, and the phenolic coumarin, as well as distilled water (odorless control), were presented to lizards on cotton swabs. The lizards detected all three toxins as indicated by significantly decreased tongue-flick rates and tongue-flick attack scores in comparison with distilled water. Several other variables revealed aversion to saponin, including a low number of individuals that bit swabs, avoidance of swabs after tongue-flicking, performance after tongue-flicking the swab of repeated short-excursion tongue-flicks that were directed away from the swab and did not contact any substrate, failure to respond at all in the next trial, and wiping the snout on the floor of the terrarium. Reasons for apparent differences in tongue-flicking behavior between P. lilfordi and two other omnivorous lizard species are discussed. We also showed experimentally that saponin depresses the tongue-flick rate in the omnivorous Bonaire whiptail lizard, Cnemidophorus murinus. Tongue-flicking enables at least one lizard species to detect specific chemicals representing three major classes of plant toxins. It is hypothesized that this ability is a widespread adaptation to reduce ingestion of plant toxins.

Desert lizard reproduction: seasonal and annual variation in Urosaurus ornatus (Iguanidae)

The reproductive cycle and cycles in fat body and liver masses were examined in Urosaurus ornatus from central Arizona. Adult males underwent spermiogenesis from mid-April until late August. The cycle in testes mass was paralleled by cyclical activity in structure of the seminiferous tubules and epididymides. Mass of fat bodies and livers also fluctuated seasonally, showing a distinct increase with declining reproductivity. Yolk deposition in females occurred from May until late August with ovulation occurring from early June until early September. Breeding females comprised two groups: young females in their first breeding season and older females that were in at least their second breeding season. The younger (smaller) group had a mean clutch size of 6.0 and produced only one clutch, whereas the older (larger) group had a mean clutch size of 7.7 and at least a portion of these females produced more than one clutch. For the most part, older females began breeding earlier in the reproductive season than younger females. Females cycled fat body and liver masses with a distinct increase in organ size associated with declining reproductivity. Reproductive intensity varied during a given season but not annually, even though rainfall varied annually.

Food-chemical discrimination and correlated evolution between plant diet and plant-chemical discrimination in lacertiform lizards

Lizards use chemical cues to locate and identify prey and plant food, assess the nutritional quality of food, and detect plant toxins. Among insectivorous lizards, all actively foraging species studied respond strongly to prey chemicals sampled lingually, but ambush foragers do not. Much recent research has been devoted to assessing differential responses to food and nonfood chemicals (i.e., food-chemical discrimination) by omnivorous and herbivorous species and determining whether correlated evolution has occurred between plant diet and plant-chemical discrimination. We conducted experimental studies of food-chemical discrimination by two species of teiid lizards, the omnivorous Cnemidophorus murinus and the actively foraging insectivorous Ameiva ameiva. The omnivore distinguished both prey and plant chemicals from control substances. The insectivore exhibited prey-chemical, but not plant-chemical, discrimination, as indicated by tongue-flicking and biting. A comparative analysis using concentrated-changes tests showed that correlated evolution has occurred between plant consumption and plant-chemical discrimination in a major lizard taxon, Lacertiformes. These results extend and strengthen previous findings of similar correlated evolution to a new group and add to a growing database indicating that omnivorous lizards use chemical cues to assess both prey and plant foods.

Life at the interface: ecology of Prionodactylus oshaughnessyi in the western Amazon and comparisons with P. argulus and P. eigenmanni

The gymnophthalmid lizard Prionodactylus oshaughnessyi was studied at two Amazonian rain-forest sites. These lizards live at the interface of the terrestrial habitat and arboreal habitat, are active throughout the day at relatively low body temperatures, and maintain body temperatures (29.0 ± 0.34°C) slightly higher than ambient temperatures. Grasshoppers and crickets, roaches, insect larvae, and spiders dominate their carnivorous diet. Sexual size dimorphism is not apparent but differences in coloration and relative head size exist, with males having brighter and more vivid coloration and a relatively larger head. Differences in activity time, prey type, prey size, and microhabitat use exist between populations. A comparison of three species of Prionodactylus from Amazonian rain forest revealed some ecological similarity. However, differences in microhabitat use and diet exist. Differences in Baupläne were consistent with differences in microhabitat use. Dietary overlaps were relatively low; nevertheless, diets of the Prionodactylus species were more similar to each other than expected, based on a null model analysis in which a sampling of all diets was used for comparison.

The adaptive significance of a complex caudal adaptation in the tropical gekkonid lizard Lygodactylus klugei

The tail of the Brazilian gekkonid lizard, Lygodactylus klugei, exhibits a suite of characteristics associated with both tail retention and tail loss adaptations. Tails are specialized for locomotion, possess specialized cutaneous glands, and are high in lipid and energy content. Tail loss in a natural population, however, is high and presumably associated with escape from predation via tail autotomy. The importance of the presence of a complete tail both functionally and for future predator escape is reflected by rapid regeneration of a tail complete with specialized functionally important structures.

WE, Perera A, Pérez-Mellado V. Escaping predators on vertical surfaces: Lacerta perspicillata in limestone quarries of Lithaca

Escape behavior of the Mediterranean lizard Lacerta perspicillata was studied experimentally in a limestone quarry at Lithica on the island of Menorca, Balearic Islands, Spain. These lizards are exposed to avian predators while active on vertical rock faces. Simulated kestrel attacks using a cardboard model elicited escape responses from nearly all lizards approached. Methods of escape included entering a crevice, retreating over or around an edge, running behind a shrub growing against the rock surface, running behind a shrub and dropping to the ground ("bush to ground"), and retreating under or behind a rock isolated from a rock face. Most lizards fled directly to the closest available refuge or to alternative refuges only slightly farther away. Nevertheless, lizards that initially perched near crevices more frequently fled to other types of refuge than lizards that were initially near other refuges. The latter usually fled to the closest refuge. Lizards predominantly fled parallel to the ground or directly toward it (down) into a refuge regardless of the direction of attack (above, below, straight on). Direction of attack affected the type of refuge used. Lizards approached from above were more likely to flee to bush-ground or crevices than those approached from below or the same height. Straight-line retreat directly to a refuge appears to be the most viable escape strategy for these lizards when faced with attacks by avian predators, but the direction of attack may influence decisions based on risk.

NEW SPECIES OF RHABDIAS (NEMATODA: RHABDIASIDAE) AND OTHER HELMINTHS FROM NOROPS CAPITO (SAURIA: POLYCHROTIDAE) FROM NICARAGUA

Rhabdias nicaraguensis n. sp. (Rhabditida: Rhabditidae) from the lungs of Norops capito (Sauria: Polychrotidae) is described and illustrated. Rhabdias nicaraguensis n. sp. represents the 54th species assigned to the genus and the 12th from the Neotropical realm. Of the 12 Neotropical Rhabdias species, nicaraguensis is most similar to tobagoensis and vellardi. These 3 species have equatorial placement of the vulva, inflated cuticle, and 6 small circumoral lips. Rhabdias nicaraguensis is easily separated from R. tobagoensis by the shape of the buccal cavity and from R. vellardi by body size and shape of the tail. Rhabdias nicaraguensis differs from both species by host preference, the amount of inflated cuticle covering the body, and the phasmids situated posterior to the midpoint of the tail.

New species of Oswaldocruzia (Nematoda: Molineidae) in Ameiva festiva (Squamata: Teiidae) from Nicaragua

Oswaldocruzia nicaraguensis n. sp. (Strongylida: Molineidae) from the intestines of Ameiva festiva (Sauria: Teiidae) is described and illustrated. Oswaldocruzia nicaraguensis represents the 78th species assigned to the genus and is most similar to the Caribbean species of the genus by possessing spicules in which each of the 3 divisions terminates in numerous fine points. Of the 8 species assigned to this group, O. nicaraguensis is most similar to Oswaldocruzia moraveci; of the 8 species, only O. moraveci and O. nicaraguensis possess a type II bursa and lack cervical alae. It is separated from O. moraveci by the position of the tips of ribs 5-6; close together in O. nicaraguensis, well separated in O. moraveci.