Studies of species coexistence within communities and food webs depend on knowing how species use varying resources. Diet has been asserted as a partitioned resource and an important proxy for measuring ecological similarity between species. Diet, like any aspect of an organism's ecology, varies over space and time, which may diminish the generality of conclusions made about how species interact. Few studies have examined diet variation across two or more dimensions, but here we evaluate diet variation over space and time for four lizard species within the genus Ctenotus (Scincidae). Samples were collected at three field sites in the Great Victoria Desert of Western Australia over the course of 16 years. Diet varies widely over both space and time. However, changes in diet over time overwhelm variation over space at the scale of our study. Despite diet variation within species, distinct differences exist between species in fundamental and realized dietary niche space. Limited overlap between species in dietary niche space implies fundamental ecological differences between species that may not be overturned by environmental variation.

Queen Snakes (Regina septemvittata) are extreme dietary specialists, feeding nearly exclusively on freshly molted crayfish. To elucidate specific cues that mediate prey detection and foraging behavior in R. septemvittata, we examined the response of R. septemvittata and the dietary generalist Nerodia sipedon sipedon, to chemical compounds produced by crayfish during the molting cycle. Ingestively naive neonate snakes were presented with 20-hydroxyecdysone, ecdysone, methyl farnesoate, ponasterone A, xanthurenic acid, and distilled water. Their response was measured using a modification to the tongue-flick attack score. Regina septemvittata exhibited an elevated tongue-flicking response to ecdysone, whereas N. s. sipedon exhibited no differential responses to these same arthropod molting chemicals. In a second experiment, R. septemvittata showed a two-fold higher tongue-flicking response to intermolt crayfish extract that contained ecdysone than to intermolt crayfish extract alone, whereas N. s. sipedon demonstrated no differential response between these extracts. In a third experiment consisting of feeding trials, R. septemvittata was offered live intermolt crayfish with and without ecdysone. The presence of ecdysone increased the feeding scores of R. septemvittata. When ecdysone was present, crayfish were ingested in five of the seven trials, but when ecdysone was absent crayfish were not ingested in any trial. These results suggest that ecdysone may play a critical role in the interaction between R. septemvittata and their prey. With numerous stream contaminants known to imitate ecdysone and disrupt the arthropod molting cycle, this finding may have important implications for the conservation of R. septemvittata.

Recent literature on foraging in Hawksbill Sea Turtles in the Caribbean region concludes that prey selectivity is a combination of preference for certain prey species and their local abundance. In this study, prey selectivity patterns were measured in five juvenile Hawksbill Sea Turtle (Eretmochelys imbricata) aggregations in the Culebra Archipelago, Puerto Rico, and the hypothesis that juvenile Hawksbill Sea Turtles exhibit selectivity for certain prey items independent of their environmental availability was tested. Hawksbill Sea Turtles showed positive selection for the corallimorph Ricordea florida, which was rare in all four study sites, and for the alga Lobophora variegata, that was abundant in one site. Turtles exhibited low preference for the sponge Chondrilla nucula, the most common prey item in both diet samples and the environment at all study sites. Low preference for this sponge corresponds to its high availability in the environment. Turtles also exhibited low preference for the sponge Cinacyrella sp. and the branching anemone Lebrunia danae. That juvenile hawksbills exhibited strong positive selectivity for rare items indicates that diet selection is not necessarily related to the abundance of the items in the environment. In addition, spatial variability in diet composition among Hawksbill Sea Turtles in the Culebra Archipelago indicates plasticity in their foraging habits.

We describe the diet of a Liolaemus cuyanus population from the Monte of San Juan Province in Argentina. Diet composition, trophic niche breadth, age, sexual, and seasonal variation were analyzed. In addition, we investigated the relationship between L. cuyanus morphology and size of prey consumed. From the stomach contents of 105 lizards, we found that L. cuyanus is an omnivore, feeding mainly on ants, hemipterans, coleopterans (larvae and adults), and reproductive plant structures (seeds, fruits, and flowers) of the genera Lycium, Atriplex, Larrea, and Portulaca. We observed differences between juvenile and adult diets, probably associated with body- and head-size restrictions. Conversely, sexes did not differ in diet, in spite of head- and body-size sexual dimorphism. Seasonal variation in diet was observed in juveniles, whereas adults did not show substantial seasonal changes in the diet. Our findings show that L. cuyanus is opportunistic in diet and that diet appears to vary depending on age and morphology.

We studied dietary composition and seasonal dietary patterns of the Méxican Twelve-lined Whiptail (Aspidoscelis lineatissima) in Chamela, Jalisco, México. We removed stomach contents and identified them as to the order to which they belonged. We calculated an importance value, food niche breadth, and food niche overlap indexes. Termites were the most important prey item. They were consumed throughout the year, particularly during the dry season, suggesting that A. lineatissima is a facultative specialist during the driest period of the study. Other important food items were lepidopteran larvae, coleopterans (adults and larvae), hymenopterans, orthopterans, and arachnids. Dietary composition was similar between the sexes. However, we found dietary differences among lizard size classes and seasons, indicating opportunistic use of temporally abundant arthropods.

Snakes that exhibit caudal luring typically have a conspicuously colored tail tip. We conducted a field experiment to test the adaptive significance of tail color. A sample of 169 neonate Pigmy Rattlesnakes (Sistrurus miliarius) was treated by coloring their yellow tails with either black pigment similar to their cryptic body color or yellow ink as a procedural control. Snakes were released and recaptured over the next three months. Tail color manipulation did not significantly influence the proportion of snakes with palpable food. Also, the treatments did not affect growth in SVL or mass. These findings suggest that snakes with cryptic tails did not experience reduced prey capture. The presence of conspicuous tail coloration in this species may be explained by phylogenic inertia, selective benefits of small magnitude, or by habitat-related differences in prey composition or abundance.

The Blue-spotted Salamander (Ambystoma laterale) and the Jefferson Salamander (Ambystoma jeffersonianum) are both part of the Jefferson complex that also includes unisexuals of various ploidy levels and genome composition, referred to as genomotypes. Female unisexuals reproduce mainly through gynogenesis, but ploidy elevations, translocations, recombinations, intergenomic exchanges, and genome replacement also have been documented. The objective of this study was to obtain information on the geographical distribution of genomotypes and the distribution of genetic diversity in southern Québec, Canada. To do so, we examined populations of the Jefferson complex from five sites, including one site from a city and the other sites from protected areas. Genetic analysis using mitochondrial DNA and six microsatellite loci were performed. Results revealed that genomotype frequencies vary greatly, because some populations were mainly composed of A. laterale, whereas unisexuals were clearly predominant in other populations. Diploid, triploid, and putative tetraploid unisexuals were found in some of the populations. One of the populations analyzed seems to be composed only of LJ unisexual salamanders, raising questions about the mode of reproduction used in this population. Finally, the population located in an urban environment presents a low genetic diversity, and we propose hypotheses to explain this finding.

Optimizing conservation efforts requires distinguishing between rare and potentially endangered species (few extant individuals, functionally rare) and species that are difficult to find (operationally rare). Certain suites of life-history parameters such as slow growth, late maturity, low fecundity, and long interbreeding intervals are thought to be associated with functional rarity and with intrinsic vulnerability to population declines. We estimated life-history parameters by using capture-recapture data of one such elusive species, the Sharp-tailed Snake (Contia tenuis), from 1997 to 2005 in northern portions of its range in British Columbia, Canada. Body size ranged from 84 mm (smallest juvenile) to 323 mm (largest female). Mean snout–vent lengths were 212 ± 14 mm (mean ± SD) for adult males and 251 ± 28 mm for females. They were slow growing (adult growth rate, 4.3 ± 3.8 mm/yr), had extended time-to-sexual maturity (5–6 yr), and had small clutch size (3.6 ± 1.1 eggs). Estimated adult survival was 0.71 (95% confidence interval [CI]  =  0.59–0.81). Estimated population growth rate for one population over the 8-yr study period was 0.89 (95% CI  =  0.79–1.1). Compared with populations farther south and other similarly sized colubrid snakes, Sharp-tailed Snakes at our study site exhibited many “slow” life-history traits that could increase their vulnerability to population declines. Our analysis validated Sharp-tailed Snakes as a species of conservation concern in British Columbia with traits that could lead to functional rarity and highlighted research into mortality, migration, and recruitment patterns as key needs for conservation planning.

Current methods for controlling the invasive Brown Treesnake (Boiga irregularis) on Guam include a modified minnow trap with a live mouse lure. We investigated the effects on capture success of augmenting these traps with scented guide ropes leading to trap entrances. Initial screening of scent preferences was based on time spent in scented and unscented arms of a Y-maze. Preferences of large and small snakes were scored for six different prey scents (live and carrion gecko, skink, and mouse). Large snakes spent more time in the maze arm scented with live gecko and carrion gecko, whereas small snakes spent more time in the arm scented with carrion mouse and carrion gecko. After the laboratory study, a pilot trapping session was conducted in the field using three treatments (live mouse-scented ropes, carrion gecko-scented ropes, and carrion mouse-scented ropes) and two controls (traps with unscented guide ropes and those with no ropes attached). Contrary to laboratory results, live mouse-scented ropes were most effective. We conducted a second trapping session using live mouse-scented ropes as well as the two controls used in the pilot study. For snakes of below-average to average condition, the number of captures for traps with live mouse-scented ropes was higher than for traps with no ropes. However, for snakes of above-average condition, there were no differences in capture rates between trap treatments. Overall, treatment effects were weaker than latent individual heterogeneity and the influence of snake body size, with large snakes trapped more readily.

Quantifying and comparing habitat selection of related, syntopic species may help elucidate how species partition resources and compete. The Florida Bog Frog (Lithobates okaloosae) is endemic to northwestern Florida and is syntopic with the more widely distributed Bronze Frog (Lithobates clamitans clamitans). Our objective was to determine whether these closely related frogs selected different microhabitat characteristics at male calling sites, which in turn may influence successful reproduction or survival. From 2006 to 2008, we quantified microhabitat characteristics of male calling sites used by both species on Eglin Air Force Base, Florida. We created a suite of a priori models and used paired logistic regression to assess each species' habitat selection. Further, we compared habitat characteristics from each species' most highly supported model to directly compare habitat use. Model selection indicated that calling sites for L. okaloosae were best described by habitat features related to microhabitat cover (i.e., submergent vegetation, emergent vegetation, woody debris, frog-level canopy cover, distance to cover), whereas L. c. clamitans selected sites based on features that may be favorable for female oviposition or egg development (i.e., depth, water movement, depth × water movement interaction). Further, L. c. clamitans selected sites with 3.7 times less submergent vegetation and 1.6 times greater water depths than L. okaloosae. At this scale, these ranids select microhabitat differently; however, there is overlap among some selected variables. The habitat characteristics used by L. okaloosae may be associated with fire in the uplands and occasionally in the wetlands.

Information on the habitat use and movement patterns of Arroyo Toads (Anaxyrus californicus) is limited. The temporal and spatial characteristics of terrestrial habitat use, especially as it relates to upland use in coastal areas of the species' range, are poorly understood. We present analyses of radiotelemetry data from 40 individual adult toads tracked at a single site in coastal southern California from March through November of 2004. We quantify adult Arroyo Toad habitat use and movements and interpret results in the context of their life history. We show concentrated activity by both male and female toads along stream terraces during and after breeding, and, although our fall sample size is low, the continued presence of adult toads in the floodplain through the late fall. Adult toads used open sandy flats with sparse vegetation. Home-range size and movement frequency varied as a function of body mass. Observed spatial patterns of movement and habitat use both during and outside of the breeding period as well as available climatological data suggest that overwintering of toads in floodplain habitats of near-coastal areas of southern California may be more common than previously considered. If adult toads are not migrating out of the floodplain at the close of the breeding season but instead overwinter on stream terraces in near-coastal areas, then current management practices that assume toad absence from floodplain habitats may be leaving adult toads over-wintering on stream terraces vulnerable to human disturbance during a time of year when Arroyo Toad mortality is potentially highest.

Janthinobacterium lividum, a bacterium that inhibits the growth of the lethal amphibian pathogen Batrachochytrium dendrobatidis, has been found in myriad environments, including the skins of amphibians that resist the fungus. We present evidence that the gastrointestinal tract of Plethodon cinereus, the Eastern Red-backed Salamander, can serve as a reservoir for J. lividum. Two of six individuals collected from a natural environment harbored J. lividum in the gut tube. Violacein, whose intense violet color allows for rapid visual detection and chemical analysis, served as a first indicator for the presence of J. lividum. This secondary metabolite of J. lividum was confirmed through reverse-phase high performance liquid chromatography, UV-Vis analysis, and high-resolution mass spectrometry. The identity of J. lividum was confirmed by PCR amplification with J. lividum–specific primers of DNA extracted from the isolated bacteria. Because J. lividum survives in the digestive tract, it will likely be inoculated onto skin around the cloaca and into the soil and indirectly onto salamander skins. Thus, the gut may act as an important reservoir for this antifungal bacterium.

Although a keratinous rattle structure at the end of the tail is the defining trait of rattlesnakes, there is variation in the ability of rattles to produce sound. In previously reported cases of reduced rattle functionality, near complete loss of sound production occurs in adult snakes that do not retain loose interlocking rattle segments. Here we report for the first time a distinct phenomenon: the delay in development of a functional rattle among neonate and juvenile Ridge-nosed Rattlesnakes (Crotalus willardi) resulting from universal loss of the rattle button, normally the first loose segment retained in functional rattles. Loose segments added during subsequent sheds are retained at rates similar to two other rattlesnake species examined (based on data from over 1,000 wild-caught rattlesnakes) and presumably other rattlesnakes with sound-producing rattles. This pattern of delayed rattle development results in effectively silent cohorts for approximately the first year of life and provides further insight into the ecological context of rattle function and evolution.

In some salamander species, as well as various other vertebrates, iron-rich molecules are sequestered in the enamel and enameloid layers of the crowns of teeth. In adults, the presence of iron can be detected easily because the cusps are often tinted orange-brown. However, visual confirmation is not possible in embryos or larvae. Consequently, the ontogenetic stage during which iron is first deposited in teeth is not known. We used scanning electron microscopy and energy dispersive X-ray spectroscopy to examine the teeth of embryonic and larval Streamside Salamanders, Ambystoma barbouri, to determine the earliest developmental stage during which iron can be detected in teeth and to quantify the relative iron concentration along the length of the enamel cap. Iron was present in first-generation teeth of embryos when individuals were still acquiring nutrients from yolk, suggesting that yolk, rather than diet, was the source of iron deposited in early generation teeth of salamanders. Furthermore, as in adults of other species of salamanders, the concentration of iron decreased from the apex to midshaft to base of teeth in embryonic and larval A. barbouri.

An external fundamental system (EFS) is a form of bone microstructure present in the outermost cortex of long bones in animals that have attained skeletal maturity. It indicates an effective cessation of any significant periosteal growth (i.e., growth in circumference or girth). Although an EFS has been noted in several reptile taxa, the idea that reptiles grow continually throughout their lives remains popular. Examination of femoral bone microstructure from captive American Alligators (Alligator mississippiensis) reveals parallel-fibered tissue terminating periosteally in an EFS, thus confirming determinate growth in another reptile taxon. The results of this study have several important implications for both modern and fossil tetrapods: first, because many birds, nonavian dinosaurs, pterosaurs, and basal pseudosuchians all produce an EFS, it can be concluded that determinate growth is a shared characteristic of Archosauria; second, because the captive alligators were not senescent, an EFS should not be associated with “old age” when interpreting growth histories of extinct animals; third, if no EFS is present, this should not immediately suggest indeterminate growth but rather that skeletal maturity was not attained prior to death. In addition, this study highlights the need for more osteohistological studies to establish exactly how widespread determinate growth is within both extinct and extant members of Sauropsida, because this form of growth may be the rule rather than the exception.

We examined the systematics of two frequently confused Albertine Rift endemic treefrogs, Leptopelis karissimbensis and Leptopelis kivuensis. One mitochondrial (16S) and one nuclear (BDNF) gene were sequenced to demonstrate genetic differences between the two species. Although we did not find morphometric differences between the two taxa, several characters can be used to diagnose each species, including coloration (adult male throat), ventral pigmentation, presence/absence of a slight heel spur in large individuals, and male advertisement calls. The geographic distribution of each species is revised based on our new locality records and reconsideration of historical records from the literature. We recommend that L. karissimbensis be downgraded in conservation status to near threatened, because it does not meet the IUCN restricted geographic distribution criteria of an endangered species.

Agama cristata and Agama insularis are two poorly known West African species that are generally regarded either as dubious or synonyms. Agama cristata was described from a single specimen that was partially mutilated, thus preventing a precise count of midbody scale rows. There have been no further records for this species until it was considered as a senior synonym of A. insularis, a species that was until recently known only from Los Islands, off the coast of Guinea. A particularity of the type of A. cristata is the presence of two black spots on each side of the neck. During a field trip in southern Mali, I found a specimen with the same characteristics as the type of A. cristata. Further sampling provided 16 additional similar specimens. Comparison of pattern and meristic data indicates than A. cristata and A. insularis are two distinct species that can be distinguished easily both on pattern and midbody scale count, 71–90 for A. cristata versus 111–147 for A. insularis. Both species also differ by their geographic distribution and habitat.

Brachymeles bicolor (Gray 1845), from the Sierra Madre Mountain Range of Luzon Island, and Brachymeles pathfinderi Taylor 1925, from southern Mindanao Island, are among the most distinctive species in the genus, representing the largest species and one of only two known nonpentadactyl species with unequal digit numbers respectively. However, both species are inadequately diagnosed, based on a total of only five specimens. Here we provide brief taxonomic histories, discuss and clarify type localities, and redescribe each species using larger sample sizes and specimens well documented and collected during our recent biodiversity surveys. We include new information on morphological variation, distribution, ecology, and microhabitat.

Understanding the spatial ecology of species at risk is essential for conservation because this information forms the base from which management and recovery plans are delineated. We studied microhabitat selection and evaluated the effect of reproductive class on daily movement patterns, home ranges, and seasonal activity of Blanding's Turtles in the St. Lawrence Islands National Park, Ontario, Canada. We also consider the potential conservation/management ramifications of differences in habitat use between the reproductive classes. We monitored 38 Blanding's Turtles (20 males, 13 gravid females, and 5 nongravid females) from April 2008 to August 2009 via radiotelemetry. Reproductive class did not have a significant effect on the mean daily movement of turtles in May, July, and August. In June, however, gravid females moved significantly more (mean  =  400 ± 49 m per day) than males (mean  =  194 ± 22 m per day). Reproductive class also had a significant effect on turtle home-range size, although high individual variation was observed (range  =  1.6–40.6 ha). Gravid females had significantly larger home ranges (mean  =  20.3 ± 3.5 ha) did than both males (mean  =  8.2 ± 1.8 ha) and nongravid females (mean  =  7.3 ± 3.2 ha). At the microhabitat scale, Blanding's Turtles selected colder water with more submerged and floating vegetation and avoided open water. Our results highlight the importance of stratifying field observations and spatial data by reproductive class and time and including terrestrial habitat in home-range analyses of Blanding's Turtles.

Life-cycle polyphenism has been hypothesized to facilitate ecological speciation in salamanders. A recent study demonstrated that the Eastern Newt (Notophthalmus viridescens) subspecies genetically differ in expression of life-cycle polyphenism. However, we currently lack direct evidence that the life-history divergence among the newt subspecies is associated with the suggested ecological parameters, namely availability of wetlands and suitable terrestrial habitats. To test such associations, we examined life-history traits of two subspecies, Notophthalmus viridescens viridescens and Notophthalmus viridescens dorsalis, across the subspecies boundary, which corresponds with changes in those ecological parameters between the Piedmont Plateau and the Coastal Plain. We reared larval newts derived from the two focal subspecies across the contact zone in outdoor mesocosms under two different hydroperiod treatments (three-month drying and permanent water). We found striking genetically based differences in life-history traits. The vast majority of larval N. v. viridescens metamorphosed to terrestrial juveniles (efts) regardless of pond hydroperiod treatments. In contrast, only a small portion of larval N. v. dorsalis (<30%) metamorphosed to efts under either hydroperiod treatment, whereas more than 70% of its larvae became aquatic metamorphic or paedomorphic adults under permanent water conditions. Notophthalmus viridescens viridescens also metamorphosed to efts at a smaller body size and over a shorter larval period than N. v. dorsalis. The pattern of the life-history change was closely related to the environmental change across the subspecies boundary. The present study provides direct evidence of divergent selection associated with the ecological parameters driving the life-history divergence among the newt subspecies.

A parasitological survey was carried out to determine the relationships between the helminth fauna and biological traits of the hosts in three Algerian populations of Podarcis lizards belonging to two different evolutionary lineages. Size, sex, and locality of collection, as well as the infracommunities and component communities, were analyzed. Very low values of parasite infection parameters and diversity were found in all three populations. This is in accordance with the feeding habits of these lizard hosts, which only eat animal prey and no plant matter. Spauligodon saxicolae (Nematoda: Pharyngodonidae), a specialist in lizards, is reported here for the first time in Africa. This nematode was the dominant parasite species for the three populations of lizards regardless their phylogenetic lineage, size, sex, and environmental conditions.

We predicted that the probability of egg occurrence of salamander Salamandrina perspicillata depended on stream features and predation by native crayfish Austropotamobius fulcisianus and the introduced trout Salmo trutta. We assessed the presence of S. perspicillata at 54 sites within a natural reserve of southern Tuscany, Italy. Generalized linear models with binomial errors were constructed using egg presence/absence and altitude, stream mean size and slope, electrical conductivity, water pH and temperature, and a predation factor, defined according to the presence/absence of crayfish and trout. Some competing models also included an autocovariate term, which estimated how much the response variable at any one sampling point reflected response values at surrounding points. The resulting models were compared using Akaike's information criterion. Model selection led to a subset of 14 models with ΔAIC_c < 7 (i.e., models ranging from substantial support to considerably less support), and all but one of these included an effect of predation. Models with the autocovariate term had considerably more support than those without the term. According to multimodel inference, the presence of trout and crayfish reduced the probability of egg occurrence from a mean level of 0.90 (SE limits: 0.98–0.55) to 0.12 (SE limits: 0.34–0.04). The presence of crayfish alone had no detectable effects (SE limits: 0.86–0.39). The results suggest that introduced trout have a detrimental effect on the reproductive output of S. perspicillata and confirm the fundamental importance of distinguishing the roles of endogenous and exogenous forces that act on population distribution.

Clay models have been used to investigate the relative antipredator effectiveness of cryptic and of aposematic coloration in litter frogs, but such studies do not account for possible differences in prey escape behavior. We examined the escape behaviors of two litter frogs, the cryptic Craugastor bransfordii and the brightly colored and toxic Oophaga pumilio, in response to a human predator. For all individuals, we measured the distance between the frog and the observer at the instant of flight and the distance between frog's initial and final positions in the field. The cryptic C. bransfordii had a shorter flight initiation distance than did nonvocalizing individuals of the brightly colored O. pumilio. In addition, we noted that vocalizing O. pumilio males had a shorter flight initiation distance than did either nonvocalizing male or female O. pumilio. These findings demonstrate that a cryptic and an aposematic litter frog differ in their escape response to a predator. These results also suggest that, at least in male O. pumilio, a trade-off may exist between predator avoidance and reproductive success via territorial defense and mate attraction.