Anurans that breed in plant-held water bodies (phytotelmata) often have larvae with unique modifications for surviving in micro-aquatic environments. These larvae are exposed to severe abiotic conditions (e.g., food limitation, low dissolved oxygen levels, risk of desiccation), and multiple cohorts are frequently found in the same container. To test for cannibalism and interactions among cohorts in two phytotelm-dwelling anuran larvae (Mantidactylus bicalcaratus and M. punctatus) from Madagascar, I reared larvae in experimental microcosms. Larvae of both species had significantly faster growth rates in a high detritus treatment compared to the control (P < 0.0001). The experimental evidence also demonstrated that the larvae of these two species display no cannibalistic behavior, regardless of multiple cohorts, sibling relationships, density, or food and water levels. These data indicate that larvae of both species obtain most or all of their nutrition from eating detritus and the organisms associated with detritus. In M. punctatus, experiments with multiple cohorts indicate that competition for food is strongest within, not among, cohorts, and I found no evidence for a priority effect. Relatively low stage-specific mortality, along with a prolonged breeding season, philopatry, and a lack of predatory behavior, may explain why cannibalistic behavior has not evolved in these species.

The selection of an appropriate ambush site by a sit-and-wait predator is necessary for maintaining an adequate energy intake for survival and for future reproduction, especially when events are of long duration. We tested whether the snake Echis coloratus (Viperidae), a sit-and-wait predator, selects specific ambush sites in an oasis setting. We characterized the sites used by 22 individuals near a desert spring and compared them to randomly selected available sites. Ambush sites were not random; they were usually located <5 m from water on raised objects. Females, but not males, occurred more frequently under cover than expected by random choice. Field observations did not enable us to determine the cues that lead the snakes to locate their ambush. Thus, we used semi-natural enclosures to test the hypothesis that E. coloratus uses prey chemical cues when selecting its ambush sites. Most ambushes were located in sites with cover, whether the odor of gerbils was present or not. Even when odors from additional prey species were presented, there was no preference for sites with odor over control sites. The results suggest that E. coloratus at the oasis set ambushes in microhabitats that provide cover, high probability for encounters with prey, and, possibly, a physiologically convenient humid environment. The cues used by E. coloratus for predicting future prey availability seem to be the structure of the microhabitat rather than prey odor.

Variation among vertebrates in the response to alarm chemicals released from injured conspecifics and heterospecifics may be caused by differences in phylogeny and/or ecology. To investigate the relative importance of phylogeny and ecology in the evolution of alarm responses, we tested five species of plethodontid salamanders (genus Eurycea) for whether they avoid chemicals from injured conspecifics and congeners of sympatric and allopatric populations. We also examined whether different methods of data collection and analysis produce equivalent results. All methods indicate that E. guttolineata, E. multiplicata multiplicata, and E. quadridigitata do not avoid chemicals from injured conspecifics or congeners. Some methods indicate that E. longicauda melanopleura avoids alarm chemicals from conspecifics and sympatric E. lucifuga and that E. wilderae avoids alarm chemicals from conspecifics and allopatric E. m. multiplicata. However, other methods indicate that these species do not avoid chemicals from injured conspecifics. We conclude that (1) only some species may avoid areas with alarm chemicals, (2) ecological factors may be more important than phylogenetic affinities in determining responses to alarm chemicals, and (3) differences in methodology can lead to disparate conclusions about the response of a species to alarm chemicals.

Skeletochronology has been widely and successfully used to age temperate amphibians, enabling geographic comparisons of longevity and the age at maturity. To date, however, there have been very few similar studies conducted using skeletochronology in tropical or sub-tropical amphibians. In this study, we examined the applicability of skeletochronology for aging four sub-tropical anuran species (Litoria chloris, L. lesueuri, L. pearsoniana, and Mixophyes fleayi) that occur across a range of altitudes in southeast Queensland, Australia. We then used reliable estimates to examine altitudinal variation in longevity, age at maturity (AM), and potential reproductive lifespan (PRLS) for each species. Skeletochronology was successful in three of the four species. The age of L. lesueuri individuals from low altitude sites could not be reliably estimated due to extended activity seasons. On average, females were older than males in L. chloris, L. pearsoniana, and M. fleayi and were also older when breeding for the first time. There was, however, no significant difference in the PRLS between males and females within any of the three species. There were trends towards greater longevity and older AM in high altitude populations of all three species; however, there was no significant altitudinal variation in PRLS in any of the species. Our results suggest little intraspecific variation in the number of years that individuals of the four species are capable of breeding, regardless of gender, geographic location, longevity, and AM.

Pond-breeding amphibians frequently encounter roads during their movements across the landscape to reach their breeding, summering, or hibernation sites. Through night driving surveys conducted each summer from 1995–2002 on a 20-km stretch of secondary road within a national park of eastern Canada, I evaluated whether road traffic had cumulative effects on amphibian abundance over this period. I also investigated the effect of nightly variations in traffic intensity on the number of amphibians killed on the road. I recorded a total of 4643 amphibian crossing events during the 37 surveys. I did not detect any decreasing trend in abundance for amphibian roadside populations over the 8 years. The number of dead American toads (Bufo americanus) increased with increasing traffic intensity. The number of ranid frogs (Rana clamitans, R. pipiens, and R. sylvatica) dead on the road was greatest when many individuals were moving on the road and at moderate traffic intensities (approximately 10–18 vehicles/h). In contrast, spring peepers (Pseudacris crucifer) dead on the road increased with decreasing traffic intensity. The number of ambystomatid salamanders (Ambystoma laterale and A. maculatum) dead on the road, on the other hand, did not respond to traffic intensity. Nonetheless, results indicate that subtle variations in traffic intensity as those observed in this study (i.e., 5–26 vehicles/h) can increase mortality on the road for certain amphibian species. Future studies in landscape ecology should routinely consider measures associated with roads, such as the proximity and density of roads, when investigating amphibian abundance patterns in wetlands.

We completed a 3-yr demographic study of the rare Florida scrub lizard, Sceloporus woodi Stejneger, in a small habitat fragment. Censuses were conducted at 2–7 d intervals, with all hatchlings marked and monitored for survival. Field and laboratory observations were used to estimate fecundity. Survival and fecundity data were combined to estimate population growth rate. Sensitivity of the population growth rate to changes in survival and fecundity was examined by both retrospective and prospective analyses.

 Survival rates of cohorts declined throughout the study. The decline in survival rates resulted principally from the low survival rates of reproductive females and resulted, in turn, in a negative population growth rate. Subsequent visits to the study site indicated that the population did not decline to extinction, but the factors that affected survival rates are not known. We present some evidence for the potential importance of predation by snakes.

Caudal growth is examined in the phrynosomatid Callisaurus draconoides ventralis and the agamid Calotes versicolor, both from a segmental point of view and from that of the entire tail. Growth of the entire tail relative to snout–vent length follows negative allometry in the former species and positive allometry in the latter. Despite this result, patterns of segmental growth are differential along the length of the tail in both species and follow a similar pattern in each. In both C. d. ventralis and C. versicolor, proximal caudal vertebrae grow with positive allometry, followed by an extensive transitional region of approximate isometry, and a distal region of highly negative allometry. The region of positive allometry is more pronounced in C. versicolor, resulting in overall positive allometry, whereas the negatively allometric region is highly pronounced in C. d. ventralis, resulting in negative allometry of the entire tail. Differential regional growth of the tail is similar to previous findings for the polychrotid Anolis grahami, suggesting limited influence of ecological and functional aspects such as caudal autotomy, bipedalism, and arboreality on segmental tail growth. Although rates of growth of the entire tail are highly variable in iguanian lizards, differential patterns of segmental tail growth appear to be conserved and are very similar among the three species.

Morphological variation in the abdominal skeleton of Tropiduridae was examined from radiographs and cleared-and-stained specimens of 61 species. Based on the numbers of xiphisternal and postxiphisternal inscriptional ribs, as well as the presence of inscriptional ribs articulating ventromedially, seven patterns of rib attachment are described. The distribution of these patterns among the species studied reveals intra- and interspecific variation, which indicates that the abdominal skeleton of lizards is a good source of fixed and polymorphic characters for phylogenetic analyses.

Proposed definitions of the states of the pectoral girdle architecture in anurans—viz., arcifery, firmisterny, arciferofirmisterny, and “almost arcifery” are evaluated with respect to their consistency with the most recent morphological observations. All previous definitions of the states of pectoral girdle architecture are invalid and new ones are proposed; the associated terminology of these definitions is formally defined.

Abstract: We describe a new species of riparian Litoria from the Cloudy Mountains of southeastern Papua New Guinea. The new species is a member of the Litoria nigropunctata species group and differs from other members of that group in its combination of small size, blunt snout, head wider than long, no vomerine teeth, fingers one-third webbed, red iris, and several aspects of color pattern. The new species is among the smallest members of its genus in New Guinea and apparently can be distinguished readily from all other Papuan (New Guinea and surrounding islands) Litoria by its iris color alone. The sole female has many small, white ova, but exact reproductive mode for the species remains uncertain.

A new species of Eleutherodactylus is described from the lowlands of northwestern Ecuador. The new species is a small frog (snout–vent length <23 mm) characterized by: expanded and spadate disc cover on some fingers (usually III and IV) and most toes (usually III–V); bifid palmar tubercle; and brown dorsum with dark brown W-shaped scapular mark. A detailed osteological description of the new species is provided. Some of the osteological characters include relatively large nasals, small sphenethmoid, eight procoelous presacral vertebrae, manus with six carpal elements, and pes with four tarsal elements. A small portion of the frontoparietal fontanelle is exposed between the frontoparietals. Although the new species is small, there is no loss of skull bones and phalangeal elements.

Principal components analysis of 24 morphological and color-pattern characters scored for 634 specimens reveals four distinct, geographic groups within Phrynosoma coronatum. The four groups can be diagnosed on the basis of color pattern characters, but there are nearly discrete differences in morphological characters as well. Morphological evidence of hybridization has been detected between two groups. The four morphological groups are likely genetic entities given the close correspondence between the morphological patterns in Phrynosoma and genetic units detected in Urosaurus. Therefore, the four groups of coast horned lizards are treated as separate species. Latinized names (blainvillii, cerroense, coronatum) are available for three of the four taxa. The subspecies frontale and schmidti cannot be adequately distinguished by the multivariate analysis and are placed in the synonymy of P. blainvillii. In addition, a new species, Phrynosoma wigginsi, is described from the eastern side of the Sierra de Guadalupe and Sierra de La Giganta in the central Gulf Coast region of the peninsula of Baja California. Diversification in Phrynosoma has occurred via allopatric speciation and the geographic juxtaposition of these morphological groups provides additional evidence for two ancient transpeninsular seaways.