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Over the past century, humans have cleared the Earth's forests at an alarming rate and intensity. The majority of global forest cover is categorized as secondary forest, and it is becoming increasingly important to consider secondary forests in addition to old-growth forest in conservation planning for biota. We reviewed the literature to synthesize information on amphibian and reptile communities during secondary forest succession. We summarized literature on mechanisms of community change during forest succession and conducted a meta-analysis to estimate effect sizes for species richness and abundance in human-modified landscapes (agriculture, pasture, and plantation) and old-growth forests compared to regenerating secondary forests. Studies reported strong support for differences in species composition among human-modified landscapes, secondary forest, and old-growth forest as well as species-specific responses to successional forest change. Secondary forest generally had higher species richness and ab...

The conspecific attraction hypothesis predicts that individuals are attracted to conspecifics because conspecifics may be cues to quality habitat and/or colonists may benefit from living in aggregations. Poison frogs (Dendrobatidae) are aposematic, territorial, and visually oriented—three characteristics which make dendrobatids an appropriate model to test for conspecific attraction. In this study, we tested this hypothesis using an extensive mark‐recapture dataset of the strawberry poison frog (Oophaga pumilio) from La Selva Biological Station, Costa Rica. Data were collected from replicate populations in a relatively homogenous Theobroma cacao plantation, which provided a unique opportunity to test how conspecifics influence the spatial ecology of migrants in a controlled habitat with homogenous structure. We predicted that (1) individuals entering a population would aggregate with resident adults, (2) migrants would share sites with residents at a greater frequency than expected by chance, and (3) migrant home ranges would have shorter nearest‐neighbor distances (NND) to residents than expected by chance. The results were consistent with these three predictions: Relative to random simulations, we observed significant aggregation, home‐range overlap, and NND distribution functions in four, five, and six, respectively, of the six migrant–resident groups analyzed. Conspecific attraction may benefit migrant O. pumilio by providing cues to suitable home sites and/or increasing the potential for social interactions with conspecifics; if true, these benefits should outweigh the negative effects of other factors associated with aggregation. The observed aggregation between migrant and resident O. pumilio is consistent with conspecific attraction in dendrobatid frogs, and our study provides rare support from a field setting that conspecific attraction may be a relevant mechanism for models of anuran spatial ecology.

Aim Habitat modification is causing widespread declines in biodiversity and the homogenization of biotas. Amphibians are especially threatened by habitat modification, yet we know little about why some species persist or thrive in the face of this threat whereas others decline. Our aim was to identify intrinsic factors that explain variation among amphibians in their sensitivity to habitat modification (SHM), factors that could help target groups of species for conservation. Location Global. Time period 1986–2015 Major taxon studied Amphibians. Methods We quantified SHM using species abundances in natural and altered habitats as reported in published field surveys. We first examined associations between local SHM and range-wide threatened status, population trends and invasiveness. We then evaluated the importance of intrinsic and extrinsic variables in explaining species SHM using multiple comparative methods. Our analyses included over 200 species that could be ranked with confidence from 47 studies across five continents. Results Amphibians species varied considerably in local SHM. High SHM was associated with elevated range-wide extinction risk and declining population trends. Species that were tolerant of habitat modification were most likely to be invasive outside their native range. Geographical range size was the most important intrinsic predictor and was negatively associated with SHM. Larval habitat was also an important predictor, but was tightly coupled with phylogenetic position. Main conclusions Narrowly distributed species whose larvae develop on land or in lotic habitats are most sensitive to habitat modification. However, other unmeasured, phylogenetically constrained traits could underlie the effect of larval habitat. Species range size is frequently correlated with global extinction risk in vertebrates, and our analysis extends this macroecological pattern to the sensitivity of amphibians to local habitat loss, a proximate driver of extinction. These general patterns of SHM should help identify those groups of amphibians most at risk in an era of rapid habitat loss and scarce conservation resources.

Conservation invokes a range of policy issues including questions of economics, recreation, public good, stewardship, and governance obligations. When U.S. legislators consider creating new National Park units, interrelated policy issues influence decisions about whether to support or oppose a new site. In this article, we explored the influence of electoral competition, political party in control, and presidential election year on the number of new National Park units created between 1934 and 2014. Electoral competition theory hypothesizes that as the congressional majority margin decreases (gets more competitive), politicians act in more strategic and less partisan ways. In this analysis, high electoral competition occurred if the party in power had less than a 55% majority; low electoral competition was defined as a 55% or more majority. Three conditions of political control were also examined: (a) Democrats controlled the Presidency and the House, (b) Republicans controlled the Presidency and the House, and (c) shared party control (one party controlled the Presidency and the other party controlled the House). The effect that presidential election years had on the number of new park units created was also considered. Results indicated that more park units were created during periods of low electoral competition ( M = 5.00) than high electoral competition ( M = 2.04), F (1, 79) = 7.24, p = .009, η = .084 (Hypothesis 1). In addition, there was evidence of partisanship (Hypothesis 2). When Democrats controlled both the Presidency and the House, an average of 5.55 new park units were created annually. When political control was shared, an average of 3.34 park units were created per year, and when Republicans were in control only one park unit on average was created annually, F (2, 78) = 3.54, p = .034, η = .289. More park units were created in presidential election years ( M = 5.02), than nonpresidential election years ( M = 2.06), F (1, 74) = 2.32, p = .024, η = .259 (Hypothesis 3). There was no evidence of interaction effects among the variables (contrary to Hypothesis 4). This research contributes to the existing literature on the development and growth of the National Park System by analyzing the role of electoral competition, political control, and presidential election years as they effect the creation of new National Park units. Subscribe to JPRA

Land-cover and climate change are both expected to alter species distributions and contribute to future biodiversity loss. However, the combined effects of land-cover and climate change on assemblages, especially at the landscape scale, remain understudied. Lowland tropical amphibians may be particularly susceptible to changes in land cover and climate warming because many species have narrow thermal safety margins resulting from air and body temperatures that are close to their critical thermal maxima (CTmax ). We examined how changing thermal landscapes may alter the area of thermally suitable habitat (TSH) for tropical amphibians. We measured microclimates in 6 land-cover types and CTmax of 16 frog species in lowland northeastern Costa Rica. We used a biophysical model to estimate core body temperatures of frogs exposed to habitat-specific microclimates while accounting for evaporative cooling and behavior. Thermally suitable habitat area was estimated as the portion of the landscape where species CTmax exceeded their habitat-specific maximum body temperatures. We projected changes in TSH area 80 years into the future as a function of land-cover change only, climate change only, and combinations of land-cover and climate-change scenarios representing low and moderate rates of change. Projected decreases in TSH area ranged from 16% under low emissions and reduced forest loss to 30% under moderate emissions and business-as-usual land-cover change. Under a moderate emissions scenario (A1B), climate change alone contributed to 1.7- to 4.5-fold greater losses in TSH area than land-cover change only, suggesting that future decreases in TSH from climate change may outpace structural habitat loss. Forest-restricted species had lower mean CTmax than species that occurred in altered habitats, indicating that thermal tolerances will likely shape assemblages in changing thermal landscapes. In the face of ongoing land-cover and climate change, it will be critical to consider changing thermal landscapes in strategies to conserve ectotherm species.

Amphibian populations are declining globally, and multiple anthropogenic stressors, including contamination by pesticides and shifting climates, are driving these declines. Climate change may increase average temperatures or increase temperature variability, either of which may affect the susceptibility of nontarget organisms to contaminants. Eight-day ecotoxicological assays were conducted with red-eyed treefrog (Agalychnis callidryas) larvae to test for additive and interactive effects of exposure to the fungicide chlorothalonil, average temperature, and temperature variability on tadpole growth and survival. Egg masses were collected from seasonal ponds at La Selva Biological Station in Costa Rica, and tadpoles were exposed to a series of chlorothalonil concentrations across a range of ecologically relevant mean temperatures (23.4-27.3 °C) and daily temperature fluctuations (1.1-9.9 °C). Survival was measured each day, and tadpole growth was measured at the end of each trial. Concentrations of chlorothalonil ≥60 µg/L reduced survival, although survival was not affected by mean temperature or daily temperature range, and there were no synergistic interactions between chlorothalonil and temperature regime on survival. Chlorothalonil suppressed tadpole growth at relatively low concentrations (∼15 µg/L). There were impacts of both average temperature and daily temperature range on tadpole growth, although there were no synergistic interactions between temperature regimes and chlorothalonil. The results should inform efforts to manage ecosystems impacted by multiple large-scale anthropogenic stressors as well as methods for the design of ecologically appropriate toxicology trials. Environ Toxicol Chem 2016;35:2998-3004. © 2016 SETAC.

Central America hosts a diverse, unique, and imperiled amphibian fauna, and for decades Central America been a major epicenter of research into amphibian decline and conservation. In this critical and quantitative review, we synthesize current knowledge regarding amphibian decline and conservation in the seven countries that constitute Central America. There are 495 currently recognized amphibian species known from the region, distributed among the three extant orders, 16 families, and 69 genera—though description of new species continues to occur at a rapid pace. Central America's amphibian fauna is unique: 251 species are restricted to the region, and amphibian diversity varies among the major biogeographic provinces and climatic zones found in Central America. We use data generated by the International Union for the Conservation of Nature (IUCN) to evaluate trends in extinction risk among Central American amphibians. As of 2014, there are 207 amphibian species considered threatened by the IUCN, and thr...

Survey response format has been shown to influence norm prevalence (percentage reporting a norm) and the numerical value of the reported norm. This article summarizes an experiment where respondents were randomly assigned to one of two conditions. In the semi-open response format treatment, respondents (n = 817) “wrote in a number” for an acceptable number of visitor encounters. In the closed format treatment, individuals (n = 826) “circled a number” of acceptable encounters along a range of possible responses. Hypothesis 1 predicted that norm prevalence would be higher for the closed format than the semi-open. Hypothesis 2 predicted that the mean tolerance level would differ in the two treatments. Results supported hypothesis 1. The percent reporting a norm was statistically higher in the closed versus the semi-open treatment. Results failed to support hypothesis 2. The average tolerance levels for the closed and semi-open formats were statistically equivalent.

Most predictions of how populations and species of ectotherms will respond to global warming are based on estimates of the temperature at which organisms lose motor control (i.e., CTmax - the Critical Thermal Maximum). Here, we describe a non-lethal protocol and ethograms to estimate the relative tolerance of amphibians to increasing temperatures. These methods—suitable for field or laboratory conditions—are replicable, inexpensive and applicable to both post-metamorphic stages and organisms with direct development. We illustrate the use of this standardized protocol for four amphibians from a tropical cloud forest in Veracruz, Mexico with contrasting life histories: a lungless salamander (Aquiloeurycea cafetalera: Plethodontidae), a leaf-litter frog (Craugastor rhodopis: Craugastoridae), a semiaquatic frog (Lithobates berlandieri: Ranidae), and a tree frog (Rheohyla miotympanum: Hylidae). We identified four behavioral responses preceding CTmax for all amphibians included in this study: 1) Optimal Activity Range, 2) Supra-optimal Activity Range, 3) Heat Stress Range, and 4) Involuntary Movements Range. Additionally, we identified a fifth parameter associated with resilience to heat shock: 5) Recovery Stage after reaching CTmax. We conclude that the behavioral responses preceding the Critical Thermal Maximum are as informative as CTmax. Using behavioral responses to estimate thermal tolerance has the additional advantage of reducing the risk of injury or death of amphibians during physiological experiments.

Habitat loss and degradation are primary threats to amphibians and reptiles, but the relative effects of common land uses on assemblages and the mechanisms that underlie faunal responses are poorly studied. We reviewed the effects of four prevalent types of habitat alteration (urbanization, agriculture, livestock grazing, and silviculture) on amphibian and reptile species richness and abundance by summarizing reported responses in the literature and by estimating effect sizes across studies for species richness in each land-use type. We then used a multinomial model to classify species as natural habitat specialists, generalists, and disturbed habitat specialists and examined variation in effect sizes for each land-use type according to habitat specialization categories. There were mixed conclusions from individual studies, some reporting negative, neutral, or positive effects of land use on species richness and total abundance. A large proportion of studies reported species-specific effects of individual species abundance. However, in our analysis of effect sizes, we found a general trend of negative effects of land use on species richness. We also demonstrate that habitat associations of common species and species turnover can explain variation in the effect of land use on herpetofauna. Our review highlights the pervasive negative effects of common land uses on amphibians and reptiles, the importance of identifying groups vulnerable to land-use change (e.g., forest-associated species) in conservation studies, and the potential influence of disturbance-associated species on whole assemblage analyses.

Agricultural expansion continues to drive forest loss in species-rich tropical systems and often disrupts movement and distributions of organisms. The ability of species to occupy and move through altered habitats likely depends on the level of contrast between natural forest and surrounding land uses. Connectivity models, such as circuit theory models, are widely used in conservation biology, and their primary input consists of resistance surfaces representing movement costs associated with landscape features. Cost values are most frequently determined by expert opinion, which may not capture relevant levels of contrast among features. We developed resistance surfaces using experiments that represent different local mechanisms hypothesized to affect connectivity for two Neotropical amphibian species. Response ratios were calculated to translate experimental results to cost values used in connectivity modeling. We used relative abundance data in three land-cover types to generate resistance surfaces for evaluating independent support of models derived from experiments. Finally, we analyzed agreement among movement pathways predicted for each species and among three commonly used connectivity measures: Euclidean, least cost, and resistance distances. Experiments showed that extreme microclimates associated with altered habitats significantly increased desiccation and mortality risk for both species. Resistances estimated from microclimate experiments were concordant with those from survey data for both species. For one focal species, resistance estimates derived from predator encounter rates were also highly correlated with abundance-derived resistances. There was generally low agreement among the three alternative distance measures, which underscores the importance of choosing connectivity models that are most appropriate for the study objectives. Overall, similarity among linkages modeled for each species was high, but decreased with declining forest cover. Our results highlight the value of experiments for drawing inferences about processes in resistance modeling, as well as the need to consider model differences and species-specific responses when developing strategies to maintain connectivity.

Regeneration of secondary forests on previously deforested or degraded land is one of the most dominant forms of land-use change in the tropics. However, the response of animal communities to forest regeneration is poorly understood. To evaluate support for thermal quality as a mechanism driving reptile species distributions during secondary forest succession, we measured operative temperatures and occupancy in three successional forest stages (pasture, secondary forest, and old growth forest) for two anole species common in the landscape (Norops humilis and Norops limifrons). We then measured thermal preference in laboratory experiments and used operative temperature and temperature preference measurements to determine how thermal quality of habitat changes over the course of secondary forest succession, and if occupancy varies as a function of thermal quality. We found that thermal quality was lowest in pasture habitat because of a large frequency of temperatures above the thermal preference range. However, in low thermal quality pasture sites, riparian habitats and remnant trees provided a thermal refuge for both lizard species. Our results support thermal quality as a mechanism for reptile species distributions in altered landscapes and highlight the importance of the maintenance of riparian corridors.

Amphibians are important components of ecosystems worldwide and are already being negatively affected by contemporary rapid changes in climate. Climate strongly affects the distribution, abundance, and ecology of amphibian species. Changes in climate will have impacts on amphibian biodiversity that are not uniform across the globe. We highlight geographic areas expected to have more climate change impacts to amphibians in order to target them for biological mitigation and conservation action. Although adaptation by amphibians to climate change is happening, it will generally be too slow to prevent many negative consequences that will likely happen in the next few decades. We review known and potential impacts of climate change on amphibians and make recommendations for research and conservation actions.

Conversion of forests to agriculture often fragments distributions of forest species and can disrupt gene flow. We examined effects of prevalent land uses on genetic connectivity of two amphibian species in northeastern Costa Rica. We incorporated data from field surveys and experiments to develop resistance surfaces that represent local mechanisms hypothesized to modify dispersal success of amphibians, such as habitat-specific predation and desiccation risk. Because time lags can exist between forest conversion and genetic responses, we evaluated landscape effects using land-cover data from different time periods. Populations of both species were structured at similar spatial scales but exhibited differing responses to landscape features. Litter frog population differentiation was significantly related to landscape resistances estimated from abundance and experiment data. Model support was highest for experiment-derived surfaces that represented responses to microclimate variation. Litter frog genetic variation was best explained by contemporary landscape configuration, indicating rapid population response to land-use change. Poison frog genetic structure was strongly associated with geographic isolation, which explained up to 45% of genetic variation, and long-standing barriers, such as rivers and mountains. However, there was also partial support for abundance- and microclimate response-derived resistances. Differences in species responses to landscape features may be explained by overriding effects of population size on patterns of differentiation for poison frogs, but not litter frogs. In addition, pastures are likely semi-permeable to poison frog gene flow because the species is known to use pastures when remnant vegetation is present, but litter frogs do not. Ongoing reforestation efforts will probably increase connectivity in the region by increasing tree cover and reducing area of pastures.

Human activities often replace native forests with warmer, modified habitats that represent novel thermal environments for biodiversity. Reducing biodiversity loss hinges upon identifying which species are most sensitive to the environmental conditions that result from habitat modification. Drawing on case studies and a meta-analysis, we examined whether observed and modelled thermal traits, including heat tolerances, variation in body temperatures, and evaporative water loss, explained variation in sensitivity of ectotherms to habitat modification. Low heat tolerances of lizards and amphibians and high evaporative water loss of amphibians were associated with increased sensitivity to habitat modification, often explaining more variation than non-thermal traits. Heat tolerances alone explained 24-66% (mean = 38%) of the variation in species responses, and these trends were largely consistent across geographic locations and spatial scales. As habitat modification alters local microclimates, the thermal biology of species will likely play a key role in the reassembly of terrestrial communities.

Loss of biodiversity within relatively pristine protected areas presents a major challenge for conservation. At La Selva Biological Station in the lowlands of Costa Rica, amphibians, reptiles, and understory birds have all declined over the past four decades, yet the factors contributing to these declines remain unclear. Here, we conduct two tests of the hypothesis that faunal declines are linked to shifting dynamics of leaf litter, a critical microhabitat for amphibians and reptiles and a major component of forest carbon cycles. First, we conduct a 16-month manipulation of leaf litter and measure response by terrestrial amphibians and reptiles. Second, we synthesize three year-long datasets collected over four decades to evaluate potential multi-decade change in standing litter depth. We show that litter depth regulates density of amphibians and reptiles, and that the strongest response to manipulations is in species that decline most rapidly based on long-term data. Our synthesis of litter depth data su...

Amphibian populations are declining worldwide, particularly in tropical regions where amphibian diversity is highest. Pollutants, including agricultural pesticides, have been identified as a potential contributor to decline, yet toxicological studies of tropical amphibians are very rare. The present study assesses toxic effects on amphibians of 10 commonly used commercial pesticides in tropical agriculture using 2 approaches. First, the authors conducted 8-d toxicity assays with formulations of each pesticide using individually reared red-eyed tree frog (Agalychnis callidryas) tadpoles. Second, they conducted a review of available data for the lethal concentration to kill 50% of test animals from the US Environmental Protection Agency's ECOTOX database to allow comparison with their findings. Lethal concentration estimates from the assays ranged over several orders of magnitude. The nematicides terbufos and ethoprophos and the fungicide chlorothalonil were very highly toxic, with evident effects within an order of magnitude of environmental concentrations. Acute toxicity assays and meta-analysis show that nematicides and fungicides are generally more toxic than herbicides yet receive far less research attention than less toxic herbicides. Given that the tropics have a high diversity of amphibians, the findings emphasize the need for research into the effects of commonly used pesticides in tropical countries and should help guide future ecotoxicological research in tropical regions.

Recreationists who encounter more people than their normative tolerance for seeing others usually feel more crowded than those encountering fewer than their norm. This research note extends this ob...

Different human land uses are not uniform in their ecological effects on remnant faunas. Explicitly recognizing the relative habitat value of prevalent land uses in comparison to forest will help improve conservation theory and practice in human-modified landscapes. To better understand how common land uses influence habitat quality and buffer forest fragments in tropical landscapes, we characterized reptile and amphibian assemblages across forest-pasture and forest-peach palm (palmito) ecotones in northeastern Costa Rica. We found that forest remnants contained significantly greater overall richness and abundance of reptiles and amphibians than either palmito or pasture; palmito supported greater species richness and abundance of herpetofauna than pastures. Assemblages of reptiles and amphibians in palmito also exhibited greater similarity to those found in forests than did assemblages in pasture, particularly for reptiles. Species exhibited distinctive responses to forest-land use ecotones, with some species reaching their highest abundances in non-forest habitat. Our results show that two important land uses in Costa Rica differ in their capacity to buffer forest patches and promote landscape connectivity for reptile and amphibian populations. Understanding these differences is crucial for identifying matrix environments that can complement the natural forest habitats of sensitive reptile and amphibian species.

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.

Peccaries are known to shape vegetation structure and create important breeding habitat for some pond-breeding amphibians in Neotropical forests. Because peccaries are also important agents of disturbance and microhabitat variation in the litter, peccary loss could have important consequences for litter amphibians and reptiles that depend entirely upon the litter for shelter, foraging and reproduction sites, and thermoregulation. However, very little is known about the effects of peccaries or their loss on litter amphibians and reptiles. We experimentally reduced peccary density in 20 × 50 m fenced exclusion plots (n = 5). We compared standing litter structure and amphibian and reptile abundance where peccaries were excluded to paired, open-forest control plots that had natural peccary densities. We encountered 16% more amphibian and reptile individuals in open control plots, and we encountered more juveniles of the most common anuran species in control plots than on peccary exclusions. Control plots had more compacted litter than peccary exclusion plots, indicating that peccaries alter the physical structure of the standing leaf litter in a way that promotes greater recruitment of juvenile anurans. Our results demonstrate that peccaries should be viewed not just as seed predators or ecosystem engineers for palms and pond-breeding amphibians, but also as important agents that affect leaf litter structure and abundance of terrestrial amphibians and reptiles. Peccary extirpation from overhunting or habitat degradation could have unexpected negative consequences for litter amphibians and reptiles, a diverse group already severely threatened by habitat loss, climate change, disease, and other anthropogenic effects worldwide.

Conversion of natural habitats to anthropogenic land uses is a primary cause of amphibian declines in species-rich tropical regions. However, agricultural lands are frequently used by a subset of forest-associated species, and the habitat value of a given land use is likely modified by the presence and characteristics of remnant trees. Here we used mark–recapture methods to examine abundances and movement probability of the poison frog, Oophaga pumilio, at individual trees in forest-fragment edges and adjacent pastures in north-eastern Costa Rica. One hundred and forty-seven trees were surveyed at three replicate sites that each included a forest fragment and adjacent pasture. Trees were sampled at distances of ≤30 m into forest and ≤150 m into pastures for Oophaga pumilio, and local environmental characteristics were measured at each tree. We also measured indices of physical condition (size and endurance) of frogs captured in forest edges and in nearby pastures. Analyses of 167 marked individuals showed no difference in per-tree abundances or sex ratios between pasture and forest edges. We found significant interactions between habitat type and leaf-litter cover, tree dbh and number of logs, indicating greater influence of local variables on abundances in pastures. Movement among trees was infrequent and not predicted by sex, size, habitat type or environmental variables. While results of endurance tests did not differ for individuals from the two habitats, frogs captured in pastures were, on average, larger than frogs captured in forest edges. These data indicate that remnant trees are important habitat features for O. pumilio in pastures and corroborate research in other systems that suggests that large relictual trees should be retained to maximize the potential for altered landscapes to provide habitat for native species.

We undertake a directed content analysis of Canadian tax jurisprudence to analyze procedural, interpersonal, and informational fairness, and their respective criteria, in the tax context. To facilitate our analysis, we apply Colquitt's (2001) theoretical framework of fairness. Consistent with this framework, we find 198 cases that contain procedural fairness, 34 cases that contain interpersonal fairness, and 37 cases that contain informational fairness. Furthermore, we identify seven criteria of procedural tax fairness (accuracy, bias, consistency, compatibility, correctibility, representativeness, voice), three criteria of interpersonal tax fairness (respect, propriety, timeliness), and four criteria of informational tax fairness (justification, truthfulness, full disclosure, taxpayer technical competence). Implications for taxpayers, tax authorities, and tax researchers are discussed.

Amphibian populations are globally threatened by emerging infectious diseases, and 2 pathogens in particular are recognized as major threats: the amphibian chytrid fungus Batra- chochytrium dendrobatidis (Bd) and ranaviruses. Here, we evaluated the prevalence of infection by Bd and ranavirus in an assemblage of frogs from a lowland wet forest in Costa Rica. We found an overall prevalence of 21.3% for Bd and 16.6% for ranavirus, and detected both pathogens widely among our 20 sampled species. We found a positive association between ranavirus and Bd infection in one of our 4 most commonly sampled species. We also found a positive but non-significant asso- ciation be tween infection by ranavirus and infection by Bd among species overall. Our study is among the first detailed evaluations of ranavirus prevalence in the American tropics, and to our knowledge is the first to detect a positive association between Bd and ranavirus in any species. Considerable research attention has focused on the ecology of Bd in tropical regions, yet we argue that greater research focus is necessary to understand the ecology and conservation impact of ranaviruses on amphibian populations already decimated by the emergence of Bd.

Herein we describe a new species of toad (genus Incilius) from Cerro Bollo in western Panama. The new species is unusual among toads in being earless, having sexual dichromatism, hands and feet with webbed digits that lack tubercles, and hypertrophied testes. The type locality of the new species is separated from the type locality of its congener, I. peripatetes, by ∼100 kilometers.

© 2016 John Wiley & Sons Ltd/CNRS. The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused the greatest known wildlife pandemic, infecting over 500 amphibian species. It remains unclear why some host species decline from disease-related mortality whereas others persist. We introduce a conceptual model that predicts that infection risk in ectotherms will decrease as the difference between host and pathogen environmental tolerances (i.e. tolerance mismatch) increases. We test this prediction using both local-scale data from Costa Rica and global analyses of over 11 000 Bd infection assays. We find that infection prevalence decreases with increasing thermal tolerance mismatch and with increasing host tolerance of habitat modification. The relationship between environmental tolerance mismatches and Bd infection prevalence is generalisable across multiple amphibian families and spatial scales, and the magnitude of the tolerance mismatch effect depends on environmental context. These findings may help explain patterns of amphibian declines driven by a global wildlife pandemic.

Management of communities in fragmented systems requires application of models for predicting and understanding patterns of diversity at relevant scales. Metacommunity models may help explain patterns of beta-diversity, but more empirical investigations are needed to determine the generality of these models and the importance of matrix identity as a mediator of metacommunity processes. We studied patterns of beta diversity among cypress domes in a landscape composed of two different matrix types within Big Cypress National Preserve to determine whether community composition differed by matrix type and to evaluate predictions of metacommunity models. We sampled fully-aquatic vertebrates in 16 cypress domes. A causal modeling framework was used to assess the relative importance of space and environmental variables measured in the domes and in the nearby matrix in explaining variation in community similarities. Our results show that community composition was influenced by matrix type, which violates the common metacommunity assumption that matrix identity has negligible effect on patch patterns. We found different drivers of beta-diversity patterns between matrix types; similarities among dome communities within cypress-prairie matrix were influenced by local environmental conditions and matrix characteristics, while communities in pine-rockland domes were most influenced by conditions in the matrix. Our results have implications for use of metacommunity models in conservation planning and we suggest that future research should focus on the importance of matrix identity and complexity in mediating community patterns in patchy landscapes.

Aposematic organisms are not predicted to show high levels of warning signal diversity because they are expected to be under stabilizing selection to decrease costs of ‘educating’ predators about their unpalatability. However, systematic changes in warning signals (polytypism) can be expected if they represent adaptations to local predators. The aposematic strawberry poison frog (Oophaga pumilio) is red throughout its mainland distribution in Costa Rica and Panama, but displays high levels of warning signal diversity in the Bocas del Toro Archipelago of Panama. Both coloration and spot pattern vary in a polytypic sense. Sexual selection contributes to maintaining the polytypism, but little work has investigated the potential influence of predation. We used unspotted models of O. pumilio to determine if predation might help explain the color polytypism on Isla Colon in the Bocas del Toro Archipelago of Panama. We tested whether attack rates differed among the red mainland morph, green/yellow Isla Colon morph, and the brown control. We found that frog color significantly predicted being attacked. The local green Isla Colon models were attacked more than foreign red or brown models. No difference in attack rate existed between red and brown control models. Our results suggest that the red mainland morph possesses a more effective warning signal, even when it is not the local morph. Honest signaling of unpalatability, neophobia, and the use of search images by local predators are potential explanations. Similarity of the brown model to other local poison frogs might explain the lower attack rate compared to previous work. The attack rate was lower on Isla Colon compared to mainland Costa Rica, which supports the hypothesis that less overall predation in the Bocas del Toro Archipelago may contribute to the overall warning signal diversity in O. pumilio there by relaxing selection for aposematic traits.

Conversion of forests to agricultural land or pastures is occurring at a rapid rate in many tropical regions. Amphibians may be particularly susceptible to changes in landscape composition and connectivity because of their physiological characteristics and complex life cycles. We experimentally assessed landscape resistance for the dart-poison frog Oophaga pumilio associated with two prevalent land-cover types, secondary forests and pastures, in the northeastern lowlands of Costa Rica. We measured recapture rates of individuals displaced into forests and into pastures, the effects of microclimate on the movement performance of individuals, and the influence of land-cover type and displacement distance on orientation ability of O. pumilio. Results showed a significant interaction between displacement distance and land-cover type indicating greater resistance to movement experienced by individuals displaced into pastures compared with frogs displaced into forests. Microclimatic conditions in pastures had a detrimental effect on the movement performance of O. pumilio and initial orientation was both distance and habitat dependent. Understanding the magnitude of resistance presented by different land-uses to amphibian dispersal is important for the development of successful conservation strategies in human-altered landscapes.

The emerging infectious disease chytridiomycosis, caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in widespread population declines, extirpations, and extinctions of amphibians throughout the world. In the Neotropics, most amphibian declines have occurred in cool mid- to high-elevation sites (> 400 m asl), and it is hypothesized that high temperatures limit the growth of Bd in lowland tropical sites, despite few data available on the distribution of Bd in lowland forests. Here, we report the results of a 12-mo pathogen surveillance program for three common species of frogs at a warm lowland site in northeastern Costa Rica. We combine standard non-invasive skin swabbing techniques with a quantitative polymerase chain reaction assay to analyze the infection prevalence and Bd load across a 1-yr period. Our data indicate an overall Bd infection rate of 6.1 percent, but prevalence varies from 400 m msnm). Se supone que temperaturas elevadas limitan el crecimiento en llanuras tropicales, aunque disponemos de poca informacion sobre la distribucion de Bd en partes bajas. Aqui reportamos los resultados de un programa de monitoreo de 12 meses para cuantificar la infeccion por Bd en 3 especies comunes de ranas de la Estacion Biologica La Selva, en el noreste de Costa Rica. Usamos los metodos de frotado de piel de ranas con reaccion en cadena de la polimerasa cuantitativa (qPCR) para cuantificar la prevalencia e intensidad de infeccion por Bd. Nuestros datos indican una prevalencia de infeccion de 6.1%, con valores de prevalencia

Herein we review what is known about the chemical ecology of poison frogs with a focus on dendrobatid poison frogs. While five anuran families are known to have an alkaloid-derived chemical defense, the dendrobatids have been studied in greatest detail and provides chemical ecologists with a complex model system for understanding how chemical defenses operate in real time and may have evolved through evolutionary time. We describe the diversity of alkaloid defenses known from frogs, alkaloid sequestration, biosynthesis and modification, and we review what is known concerning arthropod sources for alkaloids. There is variation in nearly every attribute of the system and we try to describe some of the challenges associated with unraveling the complexities of this model system.

Warning signals of aposematic organisms often include patterns that contrast with background coloration, though controversy exists over their importance. Many dendrobatids have contrasting colors, but no work has established whether these are anti-predator components of the warning signal. We used 840 clay frog models to test whether a black spotted pattern on the red dorsum of the poison frog Oophaga pumilio (= Dendrobates pumilio) from Costa Rica enhances the aposematic signal. Model type, patterned or not patterned, did not predict predation. However, we did find evidence that background (i.e., contrast between an aposematic organism and its environment) influenced a predator's attack decision because models on white paper (higher contrast) were attacked significantly less than models on leaf litter (lower contrast). Our results indicate that the pattern of Costa Rican O. pumilio does not influence predation. Our results also support the hypothesis that novel backgrounds evoke a neophobic reaction and ...

1. Altered global climates in the 21st century pose serious threats for biological systems and practical actions are needed to mount a response for species at risk. 2. We identify management actions from across the world and from diverse disciplines that are applicable to minimizing loss of amphibian biodiversity under climate change. Actions were grouped under three thematic areas of intervention: (i) installation of microclimate and microhabitat refuges; (ii) enhancement and restoration of breeding sites; and (iii) manipulation of hydroperiod or water levels at breeding sites. 3. Synthesis and applications. There are currently few meaningful management actions that will tangibly impact the pervasive threat of climate change on amphibians. A host of potentially useful but poorly tested actions could be incorporated into local or regional management plans, programmes and activities for amphibians. Examples include: installation of irrigation sprayers to manipulate water potentials at breeding sites; retention or supplementation of natural and artificial shelters (e.g. logs, cover boards) to reduce desiccation and thermal stress; manipulation of canopy cover over ponds to reduce water temperature; and, creation of hydrologoically diverse wetland habitats capable of supporting larval development under variable rainfall regimes. We encourage researchers and managers to design, test and scale up new initiatives to respond to this emerging crisis. © 2011 The Authors. Journal of Applied Ecology

Aim Connectivity is a key determinant of the distribution and abundance of organisms and is greatly influenced by anthropogenic landscape modification, yet we lack a synthetic perspective on the magnitude and extent of matrix effects on connectivity. We synthesize results from published studies to understand the importance of matrix effects on fragmented animal populations. Location Global. Methods We conduct a meta-analysis of 283 fragmented populations representing 184 terrestrial animal taxa to determine the strength of matrix composition effects on the occurrence and abundance of animals in fragmented habitat. Results Studies that use data on matrix composition report greater effects on abundance and occupancy of fragmented populations than studies that define connectivity without regard to the surrounding matrix (i.e. ‘binary’ studies that describe only characteristics of patch habitat). Main conclusions Our findings underscore that conservation strategies must consider the importance of matrix habitat, have important implications for metapopulation and metacommunity paradigms, and provide direct large-scale, multi-taxa evidence that matrix habitat is an important driver of ecological dynamics in heterogeneous landscapes.

The nature of chemical defenses in poison frogs has been explored in a variety of species, and most studies focus on the types of chemical defenses and their sources. The defensive compounds of frogs are stored in dermal granular glands that have been described for several species that are chemically protected from predators and/or microorganisms. Gland ultrastructure is known for some species of dendrobatoid frogs, but the relationship between body size and chemical defense has heretofore not been explored. It might be expected that the capacity for defensive protection increases as a function of body size, especially given the fact that juvenile poison frogs are known to have smaller quantities of alkaloids than adults. We examined poison glands histologically in a sample of the poison frog Oophaga pumilio to determine if the physical basis of the defensive system changes as a function of body size. We measured average gland size, estimated the number of glands, and calculated the density and percentage of skin area occupied by glands in a patch of dorsal skin for 25 individuals. For males and females, the size, number and percentage of skin area occupied by poison glands increased allometrically as a function of body size, whereas poison gland density decreased with body size. Adults have a larger capacity to store alkaloids and more of their dorsal skin is associated with poison glands as compared with juveniles, which may translate into greater protection from predators in adults and could explain why adults are more apparent (active above the leaf litter) than juveniles at our study site in north-eastern Costa Rica. Furthermore, juveniles and subadults may benefit from automimicry because they resemble adults in appearance.

The potential effect of forest type on the structuring of animal communities in western Amazonia remains poorly understood. In this study, we tested the hypothesis that amphibian species richness, composition and abundance differ across forest types in the lowland rain forest of south-eastern Peru. By using 320 individual transects, we compared the amphibian assemblages across four major forest types (floodplain, terra firme, bamboo and palm swamp) at each of four sites separated by 3.5–105 km. We identified 1967 individuals of 65 species in 11 families and found that a large proportion of the amphibian diversity in this region is attributed to habitat-related beta diversity. Overall, we found that forest type is more important than site in predicting both species composition and abundance. We also found that, when analyses are conducted separately for each forest type and include species abundance data, similarity between assemblages decreases with increasing geographic distance. In contrast to studies that considered species presence/absence but ignored species abundances, our results highlight the importance of including abundance data in the assessment of animal diversity patterns in western Amazonia. We conclude that evaluating community structure across forest types can improve our understanding of diversity patterns in this region.

Nested species subsets are a common pattern of community assembly characteristic of many types of fragmented landscapes and insular systems. Here we describe nested subset patterns of amphibian and reptile occupancy on 23 forest islands in north-eastern Bolivia. We used observed occupancy patterns to differentiate five distributional guilds: widespread species, rare species, poor colonizers, area-sensitive species and supertramps. Amphibian occurrences were nested along a forest island isolation gradient, and when species from each of the distribution classes were removed from subsequent analyses of nestedness, we found that dispersal-limited poor colonizers were responsible for the association between nestedness and isolation. Amphibians associated with the grassland matrix at the study site showed a nested pattern linked with area, although this pattern did not scale up to all amphibians and could not be unequivocally attributed to any of the distributional guilds we recognized. There were no strong associations between two biological characteristics, body size and relative abundance in the matrix, and the likelihood of occupancy along either forest island area or isolation gradients. The relative importance of isolation in shaping nested patterns of amphibians on these forest islands may be a result of either (1) the greater range in isolation values included in this study compared with many others; (2) the long time since isolation in this landscape, manifesting a footprint of isolation not apparent in more recently fragmented patches; (3) the relatively homogeneous grassland matrix surrounding forest islands that likely provides little refuge for animals moving among forest islands.

The selection of a sampling protocol is critical to study amphibian and reptile communities and in many instances researchers have combined the use of visual encounter surveys (VES) conducted on trails and off trails. The effect of human-made trails on relative abundance estimates of amphibians and reptiles has been assessed in a few temperate locations, but data are lacking for tropical sites. Our study was designed to address this issue by comparing abundance estimates of frogs and lizards on and off trails in a lowland rainforest in south-eastern Peru. We used nocturnal VES to sample frogs and lizards along transects established on trails and off trails in two different forest types. We found that the observed relative abundance estimates of frogs and lizards were affected by the location of transects (on trail vs. off trail) and the type of forest (floodplain forest vs. terra firme forest). We also found an interaction between the two main effects, indicating that the effect of transect location with respect to trails varies as a function of habitat. Observed frog abundances were higher on trails than off trails, indicating that studies that include VES on trails will bias relative abundance estimates in contrast to studies that include only VES off trails. We suggest that transects should be established only off trails, especially for monitoring studies because trail use by humans can have a strong influence on observed animal abundance.

We describe the advertisement calls of four species of glassfrogs (Centrolenidae) of the genus Nymphargus, Rulyrana and Centrolene known to occur in the upper Manu National Park, on the eastern slopes of the Andes in southern Peru. Glassfrogs inhabit a harsh acoustic environment, because they call and reproduce along noisy mountain streams and rivers. We found extensive variation in the structure, temporal and spectral characteristics of the recorded calls. Although sample sizes were small, our data indicate that intraspecific variation is small. Interspecific variation in calls involved temporal as well as spectral traits. We observed two divergent call structures from a hypothetical simple model of the advertisement call. This simple model consists of a well-pulsed and moderate-frequency modulated call, such as the call emitted by N. pluvialis. The two divergent modifications encountered in our study included the further simplification of the call structure, such as the loss of amplitude and frequency m...

This paper explores the relationship between tax-induced dividend clientele theory and the recent changes to the taxation of income trusts in Canada. On October 31, 2006, the Canadian government announced the Tax Fairness Plan (TFP) calling for the elimination of the considerable tax advantage enjoyed by income trusts. Generally, distributions from income trusts are now taxed at rates comparable to those imposed on corporate dividends. We examine market reaction to the TFP to address three issues: first, whether the valuation effect of a dividend tax increase is consistent with the traditional or the new view of dividend taxation; secondly, whether the market reaction to tax increases has a differential impact on firm value that is related to the tax preferences of taxable, tax-exempt, and foreign investor tax clienteles; and thirdly, whether firms change their dividend policies in response to the preference of institutional investors (tax-based dividend policy effect) or whether institutional investors are sorting themselves across firms based on their dividend policies (investor sorting effect). Our results provide strong evidence as follows. First, the valuation effect in reaction to the TFP announcement is consistent with the traditional view of dividend taxation – i.e. that taxes on dividends reduce the net return to investors, increase the firm's cost of capital and lower the firm's ability to access capital markets, thereby discouraging investment and savings. Secondly, we saw that trusts with a larger percentage of their units held by tax-exempt, low-tax, and foreign investors had a higher decline in value when compared with trusts held mostly by ordinary taxable investors. These results support dividend tax clientele theory. Finally, we observed changes in institutional investor clienteles consistent with the investor sorting effect.

Habitat selection in amphibians has typically been investigated using species that breed in medium-sized to large bodies of water. So far, few studies have focused on tropical, phytotelm-breeding species. We examined habitat selection in the context of reproductive resource use by Ranitomeya biolat (Morales, 1992), a poison frog that uses bamboo internodes as breeding sites. We conducted field observations and experiments using bamboo and PVC sections to test the effect of physical and biotic factors on tadpole deposition. Our field observations indicated that water volume, as well as internode length, height, and angle, may be important for tadpole deposition. We predicted that adult R. biolat would deposit tadpoles in pools that are close to the ground, pools with high water volume, pools contained in long structures, and pools without conspecific tadpoles or heterospecific predators. Our experiments demonstrated that water volume and the length of the structure containing the pool affect the pattern of tadpole deposition. Tadpoles were also deposited more frequently in experimental pools containing no other tadpoles or no predators. Our results support the prediction that phytotelm-breeding species, to maximize their reproductive success, should deposit their tadpoles in pools with water volumes that maximize nutrient content and that present no competitors or predators.

The spread of invasive exotic vegetation is a serious threat to native habitats in South Florida. The exotic Australian pine proliferates in coastal areas forming monocultures. They fall over easily during strong winds, making nesting habitat inaccessible to sea turtles. The objective of this study was to determine if removing the standing pines would alter hatchling sex ratios of sea turtles because nest temperatures could increase in the absence of shade provided by the exotic pine species. A total of 274 Hobo temperature data loggers were deployed in sea turtle nests on Keewaydin Island, Collier County, Florida, during the 2001, 2002, 2004, 2005, and 2006 nesting seasons to monitor the effect of Australian pine removal on incubation temperatures. The results indicated that shading from the pines did not affect incubation temperatures differently than native vegetation. Therefore, removing the pines did not alter hatchling sex ratios. During the study, southwest Florida was affected by several ...

We quantified patterns of species richness and species composition of frogs and reptiles (lizards and snakes) among three habitats (continuous forest, forest islands, and a seasonally flooded savannah) and between forest island size and isolation classes in a floristic transition zone in northeastern Santa Cruz Department, Bolivia. Species richness was similar across macrohabitats, as was faunal composition of forested habitats, although savannah harbored a distinct herpetofauna. On forest islands, richness and composition of forest frogs was largely related to isolation, whereas reptiles were affected by both isolation and habitat. The observation that isolation rather than area was the primary driver of distribution patterns on forest islands stands in contrast to many studies, and may be a function of (1) the greater range in forest island isolation values compared to area or (2) the long history of isolation in this landscape.

We explored how the common vampire bat Desmodus rotundus is able to survive on hyper-arid rocky islands along the Peruvian coast in the absence of plants and terrestrial mammals. We used carbon and nitrogen stable isotope analyses on D. rotundus hairs and feces to assess the pri- mary source of food, and compared our results with field observations near D. rotundus colonies. Data from stable isotope analyses were consistent with field observations, indicating that D. rotundus feeds on the South American sea lion Otaria flavescens, and occupies the third trophic level in a chain linking anchovies Engraulis ringens, O. flavescens, D. rotundus and a hippoboscid fly, Trichobius parasiticus. Our report demonstrates the importance of marine-derived resources for D. rotundus along the Peruvian coast.

Auyantepui is an immense sandstone table mountain in the Venezuelan Guayana. This mesa did not appear on aviation maps and was unknown to the literate world prior to the late 1930s. It was explored from the air by Jimmy Angel, a bush pilot and colorful soldier of fortune for whom the world's highest waterfall is named (Angel Falls at the northern end of Auyantepui). About the same time, in 1937, Captain Felix Cardona Puig and Gustavo Heny discovered an access crack in the sandstone, allowing ascent onto the southern end of the mesa. The first scientific exploration followed immediately—the 1937–1938 Phelps Venezuelan Expedition of the American Museum of Natural History made the first zoological and general botanical collections. Today, no tepui other than the “Lost World” of Cerro Roraima is better known to the general public. The summit of Auyantepui has a known fauna of 24 species of amphibians and reptiles, including species added by the Robert G. Goelet American Museum–Terramar Expedition in ...