We used radiotelemetry to investigate the movement patterns of nine Psammophylax rhombeatus rhombeatus during spring 2006 on the west coast of South Africa. Snakes were on average tracked for 28 days and relocated twice per day. For each snake we calculated vernal home range size using minimum convex polygons, and 50 and 95% isopleths. These data show that male snakes moved significantly greater distances, had larger home ranges (average MCP  =  2.219 ha for males and 0.619 ha for females), and were thus more active than female snakes. Telemetered female snakes displayed non-overlapping activity zones. Skaapstekers exhibited most activity from 0900–1700 h and in ambient temperatures greater than 19°C. Overall these movement patterns are consistent with reports of other active-foraging snakes in mating season; however, it is possible these characteristics vary across seasons and populations for this wide-ranging species. Conspecific interactions observed during the study also provide insight into the mating system of P. r. rhombeatus. This is the first radiotelemetry study on any psammophiid inhabiting Africa and demonstrates that while male and female psammophiids are physically monomorphic, they potentially occupy very different ecological roles.

Dewlap coloration of anoles is diverse and both carotenoid and pterin pigments play a role in generating this color variation. In the present study, we examined the carotenoid and pterin concentrations responsible for generating color variability in the proximal, central, and marginal dewlap sections in three subspecies of Anolis jubar of the Cuban southern coast (A. j. oriens, A. j. maisiensis, and A. j. albertschwartzi). With the exception of pterins—likely drosopterins—(entirely absent in A. j. albertschwartzi and in the scales proximal to the dewlap base in the three subspecies), the dewlap colors were produced by the combination of the two pigment classes. Carotenoid levels differed by section in A. j. oriens and A. j. maisiensis, being highest in the central section of dewlap. Anolis j. oriens had higher pterin concentration than A. j. maisiensis in both central and marginal sections. Carotenoid concentrations were significantly higher than pterin concentrations, excepting the central section of A. j. oriens, in which no significant differences were found between pigments. Our findings demonstrate subspecies-level variation in dewlap pigmentation in Cuban A. jubar and have implications for cellular mechanisms responsible for phenotypic variation.

The study of acoustic communication in lizards has been restricted and mainly focused on Gekkota. The rest of the lizards, Unidentata, are generally considered voiceless, although there are sparse reports on vocal sound production in members of different families. We analyzed the spectro-temporal characteristics of the distress calls emitted by the Unidentata lizard, Liolaemus chiliensis (the weeping lizard; Liolaemidae), the only species of this highly diverse genus (>220 species) that vocalizes. We also explored the relationships of the call characteristics with the sex and size of the individuals. The vocalizations of L. chiliensis are highly diverse and complex compared to any known call produced by Unidentata lizards. They exhibit pronounced frequency modulations, various nonlinear phenomena, and harmonics that extend into the ultrasonic range. Fundamental frequency and call duration are correlated with body size, and males emit louder but simpler calls (i.e., with less nonlinear phenomena) than females. Based on the characteristics of the vocalizations, we discuss their potential role for startling predators and/or alerting conspecifics to predation risk.

The genus Oreolalax is reported from Vietnam for the first time and a new species is described based on morphological differences, molecular divergence, and phylogenetic placement. Morphologically, the new species is distinguishable from its congeners on the basis of a combination of the following diagnostic characters: size small; tympanum hidden; toes with webbing at base; dorsum with distinct, round, spiny warts; flanks with white, spiny spots; belly and lower surface of limbs smooth, with dark marbling; interorbital region without dark triangular pattern; upper surface of thigh with dark bars; male with black spines present on margin of lower lip, spinal patches on chest small with fine spines, nuptial spines on fingers small, and without vocal sacs. In phylogenetic analyses, the new species is unambiguously nested within the genus Oreolalax.

Exploration of the Iwokrama Forest in central Guyana resulted in the collection of two caecilians from the Cowfly Camp locality along the Iwokrama Mountain Trail. One specimen represents a new form that we describe as a diminutive new species of Microcaecilia. The second is an Epicrionops niger, a poorly known species from northern South America. We compare the Iwokrama specimen with literature accounts of E. niger and with three additional specimens collected elsewhere in Guyana. We also discuss the current taxonomy and distribution of the caecilians known from Guyana.

Hypopygus benoneae, new species, is described from streams in the lower Rio Anapu, in the eastern portion of the Amazon basin, Brazil. The new species is diagnosed from all congeners by a unique set of characters, including the absence of the sixth infraorbital bone and 115–134 total anal-fin rays. Hypopygus benoneae, new species, is a member of a clade also comprising H. hoedemani, H. lepturus, and H. minissimus. The description of H. benoneae, new species, brings the number of species in Hypopygus to nine. A dichotomous key to the species of Hypopygus is provided.

Hypopygus benoneae, nova espécie, é descrita para igarapés do baixo Rio Anapu, na porção oriental da bacia Amazônica, Brasil. A nova espécie é diagnosticada de todos os congêneres por uma combinação única de caracteres, tais como a ausência do sexto osso infraorbital e o número total de raios da nadadeira anal 115–134. Hypopygus benoneae, nova espécie, é um membro do clado que também inclui H. hoedemani, H. lepturus, and H. minissimus. A descrição de H. benoneae, nova espécie, eleva o número de espécies em Hypopygus para nove. Uma chave dicotômica para as espécies de Hypopygus é fornecida.

Leporinus moralesi is a poorly known species from central Amazon basin, Brazil, which is redescribed based on examination of type specimens and additional material. The species is diagnosed by having a dark midlateral stripe running from the vertical through the dorsal fin to the end of the middle caudal-fin rays, 35 to 38 lateral-line scales, five scale rows between the dorsal fin and the lateral line, four or five scale rows between the lateral line and the pelvic fin, 16 scale rows around the caudal peduncle, three teeth on the premaxilla and four on the dentary. Leporinus uatumaensis, described from the Rio Uatumã, a tributary of the Rio Amazonas immediately downstream from Manaus, is a junior synonym of L. moralesi. A lectotype is designated herein for Leporinus muelleri ( = L. moralesi). In addition, a new species of Leporinus from the Rio Tapajós, Pará, Brazil, is described. The new species shares with Leporinus moralesi the presence of symphyseal tooth of the premaxilla with two cusps of similar size in all examined specimens, and middle caudal-fin rays dark, but differs by the dark midlateral stripe beginning at the snout to the end of the middle caudal-fin rays.

Leporinus moralesi é uma espécie pouco conhecida na Amazônia Central, Brasil, e que é aqui redescrita com base no exame dos exemplares da série tipo e de material adicional. A espécie é diagnosticada por ter uma listra escura da vertical que passa pela nadadeira dorsal à nadadeira caudal, estendida sobre os raios medianos da caudal, 35 a 38 escamas na linha lateral, cinco séries de escamas entre a nadadeira dorsal e a linha lateral, quatro ou cinco séries de escamas entre a linha lateral e a nadadeira pélvica, 16 séries de escamas ao redor do pedúnculo caudal, três dentes no pré-maxilar e quatro no dentário. Leporinus uatumaensis, descrita do Rio Uatumã, um tributário da margem esquerda do Rio Amazonas pouco a jusante de Manaus, é aqui considerada sinônimo júnior de L. moralesi. A série tipo de Leporinus muelleri (L. moralesi) foi examinada e um lectótipo é aqui designado. Além disso, uma espécie nova de Leporinus do Rio Tapajós, Pará, Brasil, é descrita. A espécie nova compartilha com Leporinus moralesi a presença de dente sinfisiano no pré-maxilar com duas cúspides de tamanho similar em todos os exemplares examinados, e os raios medianos da nadadeira caudal escuros, mas difere desta por ter uma listra escura da ponta do focinho até a nadadeira caudal.

Invasive fish frequently negatively affect amphibian populations around the world. In agricultural regions of the world, the effects of invasive fish on amphibians may coincide with pollution by agricultural fertilizers. We conducted a mesocosm experiment to examine the potential independent and interactive effects of introduced Western Mosquitofish (Gambusia affinis) and ammonium nitrate, an agricultural fertilizer, on Green Frog (Lithobates clamitans) tadpoles. Mosquitofish had a negative effect on the survivorship of Green Frog tadpoles. Green Frog tadpoles from mesocosms with mosquitofish were larger than tadpoles from mesocosms without mosquitofish, possibly due to a thinning effect that reduced intraspecific competition, as well as increased primary productivity. Ammonium nitrate additions did not affect survivorship in Green Frogs. However, Green Frog tadpoles in ammonium nitrate addition treatments were larger than those from treatments without ammonium nitrate addition, possibly due to increased phytoplankton abundance. In conclusion, mosquitofish and ammonium nitrate addition each had independent and additive effects on Green Frog tadpoles, but there was no evidence for significant interactions between these two stressors. Our results suggest that environmental stressors can have additive effects in some systems and that introduced fish predators may have greater impacts on amphibian populations than low level chemical contamination.

Elucidating the mechanisms that influence spatial distribution patterns is vital to understanding how populations persist. We examined distribution in one of the most common salamanders in southeastern Michigan, the Blue-spotted Salamander (Ambystoma laterale-jeffersonianum unisexual complex). Three major tree species dominate the sub-canopy in the study site and form monospecific patches, which may have an effect on the distribution of terrestrial phases of local amphibian species. To examine this, we tested whether adult salamanders are significantly associated negatively or positively with patches of particular tree species. We then examined two potential causal factors: habitat quality, using leaf litter macroinvertebrate biomass as a proxy, and behavioral site choice in the Blue-spotted Salamander. We found that this species is positively associated with patches of red maple and negatively associated with patches of black cherry. We also found that, when presented with a choice, salamanders choose red maple leaf litter over black cherry leaf litter. In the absence of differences in physical leaf litter characteristics between patches of red maple and black cherry, we suggest that the Blue-spotted Salamander may be utilizing chemical cues to select habitat. Our findings imply that salamander populations may be affected not only by habitat loss, but also by changes in forest composition. These results provide evidence for a more complex model than the traditional amphibian metapopulation concept, where even fully forested habitat may form a matrix of optimal and sub-optimal, or even intolerable, patches.

Among salamanders of the genus Desmognathus, the larger species tend to be more aquatic and the smaller more terrestrial. I studied life histories in assemblages of Desmognathus in the southern Blue Ridge Mountains of North Carolina at sites in the Cowee and southern Nantahala Mountains. Traits evaluated included mortality/survival, age at first reproduction, fecundity, and body size. The first three are direct fitness traits that enter into the characteristic equation, _x = αΣ^∞l_xm_xe^−rx  =  1.0. One assemblage (Wolf Creek), in the Cowee Mountains, comprises three species, from larger to smaller, D. quadramaculatus, D. monticola, and D. ocoee. A second assemblage (Coweeta Creek), in the Nantahala Mountains, also includes D. quadramaculatus, D. monticola, and D. ocoee, as well as the smaller D. aeneus and D. wrighti. I also studied three species only (D. ocoee, D. aeneus, D. wrighti) in an assemblage of six species (Nantahala River) in the Nantahala Mountains just west of Coweeta Creek. In these assemblages, age at first reproduction and fecundity are greater in the larger, more aquatic species. Instantaneous mortality rate is lower in the larger species; however, the latter have lower survival to first reproduction than the smaller species because developmental time to sexual maturation is lengthier than in the smaller species. Among species, it appears that size-mediated tradeoffs exist among age at sexual maturation, fecundity, and survival. The tradeoff relationships of life-history traits among species in both the Cowee and Nantahala assemblages may reflect fitness invariance or symmetry, perhaps stemming from design constraints in the genus Desmognathus. What remain unclear are factors contributing to the correlation between body size and the position of species along the stream-to-forest habitat gradient.

This study uses the American Alligator (Alligator mississippiensis) to assess the use of reproductive allometry as a tool to infer crocodilian population marginality based on conformation to advantageous life-history strategies. It is hypothesized that reproductive allometry, a morphometric relationship between mother's size and her reproductive output, varies intraspecifically between populations and that this variation reflects population marginality based on size, stress, temporal exploitation, habitat fragmentation, and/or the presence of social hierarchy. This hypothesis is tested using relative comparisons of allometric correlation between a marginal population inundated with saline storm surge from Hurricane Ike in southeastern Texas and a hypothesized unstressed core population in southeastern Louisiana. Heterophil to lymphocyte ratios fail to falsify the hypothesis of a saline stressor. The number of significant morphometric correlations between various parameters, degree of correlation (R²), and slope of correlation between mother and her respective nest and clutch varied greatly between study sites. Reproductive allometry, as a measure of relative population marginality, may provide a cost effective way to prioritize management with local support for crocodilian taxa.

Fish spines can impede predation by gape-limited predators by increasing the difficulty and danger of swallowing, but do predators avoid dangerous prey in favor of less dangerous species in a choice situation, i.e., Forbes' “dangerous prey” hypothesis? We tested this hypothesis by giving Largemouth bass Micropterus salmoides a choice of three species with different degrees of spination: Goldfish (Carassius auratus), Bluegill sunfish (Lepomis macrochirus), and Channel catfish (Ictalurus punctatus). We hypothesized that Largemouth bass predation would be greatest for Goldfish (relatively spineless), less for Bluegills (thin, flexible, and sharp dorsal and anal spines), and least for channel catfish (stout pectoral spines that can be abducted and locked, thus increasing the effective girth of the fish). Prey fish were presented in paired combinations (Experiment 1) or with the three species together (Experiment 2) to individual Largemouth bass in net pens. Fewer Channel catfish were consumed in both experiments, whereas Goldfish and Bluegill were consumed equally. Pectoral spines of channel catfish appeared to deter predation, but Bluegill spines did not afford greater protection compared to relatively spineless Goldfish.

Predation risk is an important contributor to community structure that varies in response to abiotic and biotic factors. In aquatic habitats, predation risk is often linked to hydroperiod as the latter directly influences predator identity within these ecosystems. For pond-breeding salamanders, intraguild predation (IGP) and cannibalism are prevalent interactions in larval communities, but the frequency of each type of agonistic interaction, as well as changes in their pervasiveness along hydroperiod gradients are not well understood. Size-structured populations of aquatic life stages (paedomorphic adults and overwintered larvae) of mole salamanders (Ambystoma talpoideum) have the potential to be dominant IG predators and cannibals in permanent ponds because of large size advantages over successive cohorts, but the species exists as only a single larval cohort in temporary ponds with reduced predatory abilities on guild members. Thus, both the potential for and intensity of predation by this species is linked to hydroperiod; yet, the predatory abilities of aquatic life stages of mole salamanders have not been evaluated. This study examined the extent to which larger size classes (paedomorphs and overwintered larvae) of mole salamanders preyed upon conspecifics and a congeneric competitor, the spotted salamander (Ambystoma maculatum). Predation trials occurred in indoor microcosms and were executed under two habitat treatments that included pseudo-natural conditions containing alternate prey and refugia, as well as simplified environments (no alternative food or cover). Embryos or hatchlings of mole and spotted salamanders were exposed either separately or concurrently to paedomorphic and overwintered larval mole salamanders in each habitat treatment. Additionally, overwintered larvae were offered as prey to paedomorphic adults. No significant differences in mortality were observed between habitat treatments (complex versus simple) for either embryo or hatchling predation experiments. Mortality of mole and spotted embryos did not differ when they were offered separately or together, but paedomorphs caused significantly higher mortality among mole embryos compared to spotted embryos. Hatchlings of both species were heavily preyed upon (nearly 100% in all trials), but overwintered larvae exhibited 100% survival with paedomorph predators, indicating size-thresholds of predation risk that were not species specific. Paedomorphs and overwintered larvae therefore are most likely generalist predators that feed equally and effectively on hatchlings of co-occurring species, but are more likely to consume egg masses that do not incur significant handling costs. When present, paedomorphs or overwintered larvae have the potential to alter population dynamics of both guild members and conspecifics by being dominant predators on early life stages. As the prevalence of overwintering and paedomorphosis varies along hydroperiod gradients, predation risk from this species is likely to occur discontinuously and thereby may be an important, yet variable, structuring force.

The Mississippi Silverside, Menidia audens, was first encountered in Kentucky Reservoir, the most downstream reservoir on the mainstem Tennessee River, in 1991. Over the next 19 years, it invaded all nine mainstem reservoirs, consisting of 1049 river km, and two tributary reservoirs, at an average rate of 55 km per year. This species was first encountered in Barkley Reservoir, the lowermost reservoir of the Cumberland River, in 1990, and has since established populations throughout at least 402 river km of the mainstem Cumberland River. Following the first record of M. audens in an unimpounded section of a Tennessee River tributary during 1998, 1048 sites were sampled throughout the Tennessee River system and this species was documented in only eight additional unimpounded tributaries, indicating aversion to lotic systems. Following the invasion of Tennessee River reservoirs by M. audens, mean abundance of the Brook Silverside, Labidesthes sicculus, linearly decreased with time. Electrofishing catch per unit effort (CPUE) data indicate that 14 years after sympatry with M. audens, L. sicculus were undetectable or occurred at extremely low densities in reservoirs. Reservoir populations of L. sicculus exhibited cyclic variation in abundance among years prior to the presence of M. audens. The observed range of electrofishing CPUE of L. sicculus before invasion by M. audens (n  =  3865) was significantly different (P < 0.001) than the observed range following the presence of M. audens (n  =  3975). After detection of M. audens, electrofishing CPUE of L. sicculus decreased and the range of variation from year to year diminished. Data from Cumberland River reservoirs showed similar patterns of displacement.

The nesting site selected by a female turtle influences the temperature and humidity of the incubating eggs, which affects the development, survival, and sex of the embryo and the subsequent developmental phases. The present study evaluated the effects of environmental variables on the duration of incubation, hatching success, and sex ratio of hatchlings of Podocnemis unifilis in an area of várzea swamp on the lower Amazon River in Brazil, during the 2007 and 2009 nesting seasons. Nests were located, marked, and monitored, and physical and environmental characteristics were measured. The temperature of the nests was measured, and hatchlings were collected to determine the sex ratio. The mean temperature, vegetation cover, and nesting date influenced the duration of the incubation period, and the grain size of the substrate influenced hatchling survival. The sex ratio differed between the years and was female-biased in 2007 and male-biased in 2009, emphasizing the need for further long-term studies of the reproductive cycle in chelonians.

Little is known about the freshwater fishes of western Ecuador despite serious environmental threats, including the creation of large artificial impoundments. Phenotypic and genetic divergence of populations of a large predatory fish, Hoplias microlepis, is examined in rivers and artificial impoundments of the Guayas River drainage in western Ecuador. Despite the recent formation of the impoundments (∼20 years prior to the sampling), H. microlepis in these habitats diverged morphologically from river populations. Impoundment fish tended to have larger eyes, longer dorsal and caudal fins, and thinner bodies than river fish. Classification rates for habitat of origin based on morphometric measures were relatively high (71.7–83.3%), and the magnitude of morphological divergence was substantial when contrasted with divergence from H. malabaricus, a congener from eastern Ecuador. Frequencies of mtDNA d-loop haplotypes differed significantly among samples. Genetic divergence between river samples implies that the genetic structure in the drainage predates the formation of the impoundments. The genetic analysis also indicates that the morphological divergence between fish in different habitat types is not likely due to shared ancestry. Genetic diversity tended to be higher in the river samples, and the percentage of private alleles was higher in the impoundment populations, which is consistent with rapid population expansion from a limited number of founders in impoundments.

The threatened Bog Turtle (Glyptemys muhlenbergii) is considered among the most sedentary of turtles, yet with population sizes generally below 50 individuals, gene flow among populations is clearly necessary to maintain healthy levels of genetic diversity. Therefore, designing effective reserve networks for this species will require clarification of the rates of among-population gene flow over several spatial scales. We obtained genetic samples from a complex of 11 Bog Turtle populations within the Berkshire-Taconic region of Massachusetts and New York, and all individuals (n  =  234) were genotyped across 15 microsatellite loci. Average multi-generation dispersal rates were inferred from population-level differences in allele frequencies using an approximate-likelihood approach, and recent dispersal rates were inferred using genetic assignment algorithms. Over small geographic distances (average inter-fen distance of ca. 1 km), among-population dispersal rates historically averaged between 0.25 and 0.5 effective migrants per population per year (ca. 1% of each population dispersing each year), and these dispersal rates appear to have persisted in recent decades. Over larger geographic distances (≥10 km), we infer that Bog Turtle populations in the Berkshire-Taconic region have experienced low rates of gene flow among populations according to a “stepping-stone” model. We conclude that (1) Bog Turtle populations with nearest-neighbor distances of <2 km should be managed as inter-connected demographic units, (2) dispersal movements among adjacent populations may enhance regional population stability, and (3) gene flow over larger spatial and temporal scales probably requires dispersal among “stepping stone” habitats that may not harbor viable populations. Regional conservation planning for these and other small-bodied, endangered turtles should focus on establishing and maintaining networks of loosely connected population complexes to mimic historical connectivity patterns.

Steroid hormones play a critical role in the regulation of reproductive behavior of many amphibians. Changes in the plasma concentration of steroid hormones (testosterone, estradiol, and progesterone) in relation to sexual behavior of males and females were studied in a natural population of the toad (Bufo melanostictus) during the breeding season. Changes in plasma sex steroids were positively correlated with the sexual behavior of male and female toads. Plasma testosterone was low in calling males but reached a peak during amplexus before declining in the spawning and post-spawning males. Plasma estradiol and progesterone increased with the onset of sexual behavior in solitary females ready to breed, reaching a peak during spawning before declining in post-spawning females. The study reveals that B. melanostictus belongs to the type of ‘associated reproductive pattern’ in which plasma steroid hormone concentration is highly correlated with the sexual behavior of male and female toads.

Despite having relatively little dimorphism in external morphology, male and female Ambystoma maculatum have substantial differences in both short-term (e.g., resting metabolic rate) and long term (e.g., growth rate) physiological processes. In this study, I investigated differences in the mass of reproductive (gonads and proximal reproductive tract) and somatic (liver and heart) organs, and in hematological parameters related to oxygen carrying capacity (erythrocyte count, hematocrit, and hemoglobin concentration) and osmotic balance (plasma osmolality) between males and females before and after breeding. Pre-breeding females had substantially larger ovaries and oviducts compared to post-breeding females, whereas males had similar reproductive organ masses before and after breeding. Females had smaller livers than males, but similar heart masses. Males had similar erythrocyte counts to females, but higher hematocrits, hemoglobin concentrations, and plasma osmolalities. The internal anatomical and physiological differences between males and females suggest greater investment in gametogenesis in females and higher performance in aquatic environments in males. These findings highlight the importance of physiological dimorphisms in organisms where there is little apparent difference in external morphology between the sexes.