Microhabitat use and feeding habits of Crossodactylus bokermanni Caramaschi and Sazima, 1985 (Anura, Hylodidae) at a site in southeastern Brazil

Milena Wachlevski, Paulo H. C. Souza, Katia Kopp and Paula C. Eterovick

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Abstract: We studied a population of Crossodactylus bokermanni in a stream at the Reserva Particular do Patrimônio Natural, Santuário do Caraça, south-eastern Brazil, with respect to microhabitat use and diet. We characterized microhabitats based on substrate, distance to water and exposure level of the occupying  individual (exposed or sheltered), and adjacent aquatic microhabitats (evaluated as potential nesting sites based on observed nests), according to water current (absent, slow or fast), substrate and depth. Calling males, silent males, ovigerous females, nonovigerous females and juveniles showed spatial niche overlap higher than that

expected by chance, with calling males showing the strongest preference for microhabitats close to potential nesting sites (with intermediate depths, fast current and sandy bottom). Only 14 males out of 48 individuals examined for stomach contents had prey in their stomachs. The food items with the highest electivity values were Coleoptera and Diptera, but preys with both high and low mobility were exploited.

The role of body size on the outcome, escalation and duration of contests in the grey treefrog, Hyla versicolor

Michael S. Reichert and H. C Gerhardt

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Abstract: Aggressive interactions in animals are often resolved in favour of the individual with superior fighting ability, or resource-holding potential (RHP). A recent revival of studies of aggressive behaviour has focused on the assessment strategies used in animal contests. Strategies of dispute resolution through mutual or self-assessment of RHP differ in the predicted relationship between interaction duration and each competitor’s relative and absolute RHP. We studied potential components of RHP (mass, length, body condition) and their relationship to contest duration and the level of escalation in the grey treefrog, Hyla versicolor, using a novel method to stage aggressive interactions in the laboratory. Overall, large males were more likely to win than small males, but they only had an advantage in less escalated interactions and were not more successful in physical fights. There was limited evidence for an effect of body size on interaction duration or the level of escalation. Specifically, the body condition of both the smaller and larger contestant was weakly negatively related to the duration and level of escalation of contests. This relationship is the opposite of what would be expected under any assessment strategy. Given these data, coupled with the lack of relationships between other size measures and interaction duration, we conclude that assessment of body size does not occur in contests in H. versicolor. Other unmeasured components of RHP may play a role in determining interaction duration, and the relatively weak and ineffective fighting abilities of this species may limit the dominance of larger individuals. Relatively little is known about aggressive behaviour in frogs. Our method for staging aggressive interactions allows us to address predictions of game theory models in an important group for studies of animal communication.

Why be a cannibal? The benefits to cane toad, Rhinella marina [¼Bufo marinus], tadpoles of consuming conspecific eggs

Michael R. Crossland, Mark N. Hearnden, Ligia Pizzatto, Ross A. Alford and Richard Shine

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Abstract: Unlike many species that are ‘occasional’ cannibals, the tadpoles of cane toads specifically target conspecific eggs for consumption, ignoring the eggs of sympatric frog species (at least within the toads’ current invasive range in Australia). We tested three hypotheses as to the benefits of consuming conspecific eggs: transfer of toxins from eggs (which have high toxin content) to tadpoles (which have lower toxin content), nutritional input, and reduction of future competition. We found no evidence of toxin transfer, but eggs contained sufficient nutrition for cannibalistic tadpoles to develop through to metamorphosis, and egg consumption enhanced rates of tadpole growth and differentiation through reduction of subsequent competition from younger tadpoles. Features of the cane toads’ life history (e.g. synchronized deposition and development of all eggs within a clutch; delay between hatching and onset of feeding; short larval stage relative to interclutch interval of a given adult female) mean that the cannibals are unlikely to be close relatives of the younger conspecifics they consume (either as eggs or as metamorphs). Kin selection may thus favour rather than oppose cannibalism. The end result is that cannibalistic toad tadpoles benefit through nutrition and reduced future competition, with little collateral risk of eating their own siblings. Another potential cost of cannibalism (risk of disease transmission) may be minimal in this system, because the eggs are unlikely to contain pathogens (reflecting their brief embryonic periods and protective jelly layers). The combination of these forces has favoured the evolution of targeted cannibalism by cane toad tadpoles.

Calling activity of Crossodactylus gaudichaudii (Anura: Hylodidae) in an Atlantic Rainforest area at Ilha Grande, Rio de Janeiro, Brasil

Maurício Almeida-Gomes, Monique Van Sluys and Carlos F. D. Rocha

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Abstract: The calling activity in anuran amphibians can be influenced by several environmental variables that can affect such activity in different ways. In the present study we investigated the relationship of the daily calling activity of males of the diurnal frog Crossodactylus gaudichaudi with some environmental variables. The study was carried out between July 2003 and June 2005 in an area of Atlantic forest in Ilha Grande, an island located on the southern coast of the State of Rio de Janeiro. The observations were made in three fixed points in the forest, adjacent to streams, always from 05:00 to 19:00h, one day per month. We verified that the males of C. gaudichaudii have strictly diurnal calling activity, staying active during all months of the year. The highest counts of emitted calls were registered, in general, at the beginning and at the end of each day sampled. Air emperature, relative humidity and light intensity affected the daily rate of calling activity in different ways, with air temperature and light intensity seeming to be the factors that influence most importantly the activity of the species. The photoperiod seemed to be the main factor regulating the extension of the calling activity along the year in males of C. gaudichaudii.

The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana

Trenton W. J. Garner, Matthew W. Perkins, Purnima Govindarajulu, Daniele Seglie, Susan Walker, Andrew A. Cunningham and Matthew C. Fisher

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Abstract: Batrachochytrium dendrobatidis is the chytridiomycete fungus which has been implicated in global amphibian declines and numerous species extinctions. Here, we show that introduced North American bullfrogs (Rana catesbeiana) consistently carry this emerging pathogenic fungus. We detected infections by this fungus on introduced bullfrogs from seven of eight countries using both PCR and microscopic techniques. Only native bullfrogs from eastern Canada and introduced bullfrogs from Japan showed no sign of infection. The bullfrog is the most commonly farmed amphibian, and escapes and subsequent establishment of feral populations regularly occur. These factors taken together with our study suggest that the global threat of B. dendrobatidis disease transmission posed by bullfrogs is significant.

Fauna of Amphibians, Reptiles, and Mammals of the State of Rio de Janeiro, Southeastern Brazil

Carlos F. D. Rocha, Helena G. Bergallo, José P. Pombal Jr., Lena Geise, Monique Van Sluys, Ronaldo Fernandes e Ulisses Caramaschi.

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Abstract: The Brazilian Atlantic Rain Forest is considered one of the ecossystems with highest biodiversity and rate of endemisms of the planet. In the latitudes of the State of Rio de Janeiro these characteristics are accentuated, defining the region as a relevant area in the “hot spot” Atlantic Rain Forest. In this study, we present the species of amphibians, reptiles, and mammals occurring in the political-geographical limits of the State of Rio de Janeiro, as a result of investigations in the literature, collections, and personal records of researchers. The occurrence of 478 species was registered, including 166 species of amphibians distributed in nine families, 127 species of reptiles in 21 families, and 185 species of mammals in 36 families. Among these, 35 amphibians, five reptiles, and three mammals were considered endemic to the State of Rio de Janeiro. The subspecies attributed to the fauna of the State are referred, as well as the introduced and the undescribed species. The high diversity found may be, in large part, explained by the characteristics of irregular relief and edaphic particularities of the region, which promote the occurrence of different habitats, such as lowland coastal forests, dense montane ombrophylle forests, highland open formations, coastal sandbanks, mangroves, rivers, rivulets, lakes, lagoons, and swamps, as well as coastal marine environments.

A New Species of Hylodes (Anura: Hylodidae) from the Brazilian Atlantic Forest

Rodrigo Lingnau, Clarissa Canedo e José P. Pombal Jr.

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Abstract: We describe a new species of Torrent Frog, genus Hylodes, from southern and southeastern Brazil. The new species is assigned to the Hylodes nasus species group and is characterized by large size, robust body, distinctly granular dorsolateral surfaces, absence of light dorsolateral stripes, moderate-sized fringe on the outer margin of toe V, and distinct advertisement call with long note duration. The new species is morphologically similar to Hylodes asper but is readily separated from that species by its distinct vocalization and by the shorter fringe on the outer side of toe V. Description of advertisement call and behavioral notes are provided.

Exotic species introductions into South America: an underestimated threat?

Jon Paul Rodríguez

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Abstract: Prior studies on the latitudinal extent and ecological impact of exotic plant species suggest that areas of high diversity, such as the Neotropics, may be relatively 'resistant' to invasions. To explore the generality of this assertion and assess the impact of alien species on continental tropical faunas, I compiled data for threatened Neotropical animals from the red data books of Bolivia, Brazil, Minas Gerais (a Brazilian state), Peru, and Venezuela. A total of 378 species (including both vertebrates and invertebrates) were considered. For each taxon, I recorded whether it is threatened by habitat conversion, overexploitation, and/or exotic species. As suggested by other researchers, exotic species introductions appear to be relatively unimportant in South America, threatening only 6% of animal taxa. However, many South American animals are themselves either recent invaders or survivors of the Great American Biotic Interchange (GABI) which began during the Pliocene. Here, I hypothesize that the GABI may have acted as an 'extinction filter', leaving faunal groups of mostly South American origin relatively more threatened by the current wave of exotic invaders than those with prominent North American representation. The data support this prediction. For taxa whose current diversity patterns were not strongly influenced by the GABI, exotic species are indeed an important threat. For example, alien invaders threaten 29% of continental fishes and 30% of amphibians, figures comparable to those recorded in temperate areas. As more information on these less-studied taxa becomes available, the magnitude of the threat posed by exotic species introductions will probably reveal itself to be large. Of critical importance is to assess the impact of invasions on biological realms that have only been recently exposed to alien taxa, such as the aquatic faunas of the numerous drainages that occur along the eastern and western slopes of the South American Andes. The results of these investigations provide predictions for similar research focussed on other continental tropical regions of the world.

Vast underestimation of Madagascar’s biodiversity evidenced by an integrative amphibian inventory

David R. Vieites, Katharina C. Wollenberg, Franco Andreone, Jörn Köhler, Frank Glaw and Miguel Vences

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Abstract: Amphibians are in decline worldwide. However, their patterns of diversity, especially in the tropics, are not well understood, mainly because of incomplete information on taxonomy and distribution. We assess morphological, bioacoustic, and genetic variation of Madagascar's amphibians, one of the first near-complete taxon samplings from a biodiversity hotspot. Based on DNA sequences of 2,850 specimens sampled from over 170 localities, our analyses reveal an extreme proportion of amphibian diversity, projecting an almost 2-fold increase in species numbers from the currently described 244 species to a minimum of 373 and up to 465. This diversity is widespread geographically and across most major phylogenetic lineages except in a few previously well-studied genera, and is not restricted to morphologically cryptic clades. We classify the genealogical lineages in confirmed and unconfirmed candidate species or deeply divergent conspecific lineages based on concordance of genetic divergences with other characters. This integrative approach may be widely applicable to improve estimates of organismal diversity. Our results suggest that in Madagascar the spatial pattern of amphibian richness and endemism must be revisited, and current habitat destruction may be affecting more species than previously thought, in amphibians as well as in other animal groups. This case study suggests that worldwide tropical amphibian diversity is probably underestimated at an unprecedented level and stresses the need for integrated taxonomic surveys as a basis for prioritizing conservation efforts within biodiversity hotspots.

Anuran Calling Survey Optimization: Developing and Testing Predictive Models of Anuran Calling Activity

Charlotte K. Steelman and Michael E. Dorcas

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Abstract: Amphibian populations, particularly anurans, are declining worldwide, and programs that use calling surveys have been established to monitor anuran populations. Models that describe the environment's influence on calling may be useful to increase detection allowing optimization of surveys. Using an automated recording system, we evaluated the calling activity of Pseudacris crucifer, Pseudacris feriarum, and Rana sphenocephala at an ephemeral wetland in the Piedmont of North Carolina. We used stepwise logistic regression to model environmental variables that significantly affected calling activity. Models revealed that, for P. crucifer, water and air temperature positively influenced calling, whereas day of year, barometric pressure, and light intensity negatively influenced calling. For P. feriarum, air temperature positively influenced calling, and day of year, relative humidity, wind speed, barometric pressure, and light intensity negatively influenced calling. Finally, air temperature positively influenced calling for R. sphenocephala, whereas water temperature, relative humidity, wind speed, and light intensity negatively influenced its calling. Using these results, we developed comprehensive as well as simpler, "user-friendly" models, predicting the best conditions under which to conduct anuran calling surveys. The user-friendly models were tested using previously collected data from calling surveys performed in the same region of North Carolina and found to accurately predict calling activity approximately 70% of the time. We discuss how weather forecast data may be applied to these models to determine the best times to conduct calling surveys and how models such as those developed in this study can be used to interpret data previously collected during amphibian calling surveys.

Conservation of Brazilian Amphibians

Débora L. Silvano and Magno V. Segalla

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Abstract: Brazil is the world leader in amphibian diversity, with 765 species, most of which have been described in the last 40 years. The Brazilian Official List of Threatened Species and the results of a workshop for the Global Amphibian Assessment indicate that 26 species are threatened. The majority of these occur in the Atlantic Forest, one of the world's biodiversity hotspots. The main threat to amphibians is the destruction of their habitats through deforestation, conversion into agricultural land, mining, wildfires, and infrastructure development and urbanization. In Brazil little is known about other causes of amphibian decline observed worldwide, such as pesticides, infectious diseases, climate change, invasive species, or wildlife trade. Brazilian conservation policies include such important legal instruments as the Official List of Threatened Species and the selection of priority areas for conservation measures in all of Brazil's major biomes. Although there is little information on geographic distributions and the natural history and ecology of the large majority of the currently recognized species, a number of important regional studies for amphibian conservation are under way. New species are discovered each year.

Taxocenose de anuros (Amphibia: Anura) em uma área de Floresta Ombrófila Densa no Sul do Brasil

Camila G. Armstrong e Carlos E. Conte

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Abstract: Assemblage of anurans (Amphibia, Anura) in a locality of dense Atlantic rain forest, Morretes, Paraná, Brazil. The species richness, habitat use and main environmental impacts on a taxocenose of anurans were determined during 19 months, in a region originally covered by dense Atlantic rain forest at Morretes municipality. Thirty-two species of anurans, belonging to ten families, were registered. In the local anuran fauna, 58% of these species were associated with open areas, and 42% of the species were associated to forests. Among all species, the most frequently observed reproductive mode was mode 1 eggs and exotrophic larvae in lentic water, mainly presented by the family Hylidae. The deforestation, which today has the major negative impact on this amphibian assemblage, is present in the region for at least 28 years. Environmental management programs are necessary to keep the diversity of anurans.

Patterns of advertisement call evolution in toads and chorus frogs

Reginald B. Cocroft and Michael J. Ryan

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Abstract: Patterns of evolution in the acoustic signals of two groups of anuran amphibians were examined. Call character matrices for clades ofBufo(Bufonidae) andPseudacris(Hylidae) were derived from analysis of tape-recorded calls, and these call characters were mapped onto phylogenetic trees based on morphological and biochemical data. It was found that the characters that make up a call evolve at different rates. In hylids, characters allied with the morphological aspects of sound production were more conservative than those based on the physiological or behavioural aspects of calling, while in bufonids divergence rates of these character types did not differ. Observed patterns of character change within sets of close relatives suggest a focus for process-oriented research by identifying the origin and direction of important changes in calling behaviour.

Anurofauna de remanescentes de floresta Atlântica do município de São José do Barreiro, estado de São Paulo, Brasil

Herbert Serafim, Susan Ienne, Paulo José P. Cicchi and Jorge Jim

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Abstract: The municipality of São José do Barreiro (SP) located in the Atlantic Forest Domain, at elevations between 480 and 2088 m above sea level, exhibit ample topografic and climatic complexity that result in the presence of severals phytophysionomies with High Mountain Grasslands, Seasonal Semideciduous Forest, Tropical Rainforest, and Araucaria Forest. The aim of this study was to verify the anuran species richness in two different forest habitats in this area, one in a Seasonal Semideciduous Forest and the other in a Tropical Rainforest. Animals were collected by active search from April 2004 to December 2006. In the studied period, we registered 35 anuran species in nine families. The anuran richness observed in the studied region is similar to other localities considered preserved, as the Estação Ecológica Juréia-Itatins (Peruíbe, SP) and Serra do Japi (Jundiaí-SP). The similarity in species composition among seven localities in Atlantic Forest in São Paulo state was associated to the vegetal types of the studied areas. The ample altitude variation, the presence of different types of vegetation, and the little knowledge of the local fauna in this region, make the surveys very important to support future studies on species conservation.

Anuros da Reserva Rio das Pedras, Mangaratiba, RJ, Brasil

Ana Maria T. Carvalho e Silva, Guilherme R. Silva and Sérgio P. Carvalho e Silva

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Abstract: A study of anuran fauna composition was made in an Atlantic Rainforest pocket, at the south of Rio de Janeiro State, municipality of Mangaratiba, from May 1997 to September 2006. Field work was carried out monthly during the first five years and for the next five years every two months, totalizing 82 field trips. Visits had a mean duration of two nights, with a group of four people. Visual and audio active searches were performed. Forty-one species, in twenty-one genera distributed in nine families, were accounted for: Amphignathodontidae (three), Brachycephalidae (six), Bufonidae (two), Centrolenidae (one), Cyclorhamphidae (two), Hylidae (21), Hylodidae (two), Leptodactylidae (three) and Microhylidae (one). The species were related to the many reproductive micro-habitats found at the Rio das Pedras Reserve. The geographical distribution and altitudinal variation of Gastrotheca albolineata were extended. The altitudinal variation of Proceratophrys appendiculata and Bokermannohyla circumdata were also extended. Scinax angrensis and Aplastodiscus eugenioi were included in the list of species from Rio de Janeiro State. The anuran fauna from Rio das Pedras Reserve represents 25% of all of Anuran species found in Rio de Janeiro State, including one species Endangered- EN and one Near Threatened - NT and another species with restricted distribution. The number of species was considered expressive when compared with other Atlantic Rainforest area of São Paulo State.

Global Change in Forests: Responses of Species, Communities, and Biomes

Andrew J. Hansen, Ronald P. Neilson, Virginia H. Dale, Curtis H. Flather, Louis R. Iverson, David J. Currie, Sarah Shafer, Rosamonde Cook and Patrick J. Bartlein

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Abstract: This article serves as a primer on forest biodiversity as a key component of global change. We first synthesize current knowledge of interactions among climate, land use, and biodiversity. We then summarize the results of new analyses on the potential effects of human-induced climate change on forest biodiversity. Our models project how possible future climates may modify the distributions of environments required by various species, communities, and biomes. Current knowledge, models, and funding did not allow these analyses to examine the population processes (e.g., dispersal, regeneration) that would mediate the responses of organisms to environmental change. It was also not possible to model the important effects of land use, natural disturbance, and other factors on the response of biodiversity to climate change. Despite these limitations, the analyses discussed herein are among the most comprehensive projections of climate change effects on forest biodiversity yet conducted. We conclude with discussions of limitations, research needs, and strategies for coping with potential future global change.

Shedding Light on Ultraviolet Radiation and Amphibian Embryos

Lawrence E. Licht

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Abstract: The hypothesis that increasing ultraviolet-B (UVB) radiation is a causal factor in the decline of amphibian populations has received considerable attention in the scientific and public media. To evaluate the validity of this hypothesis, it is necessary to examine the natural environmental factors and biological traits of amphibians that protect them from UVB radiation. A careful reading of the literature reveals that most published studies on the effects of ambient UVB radiation on amphibian embryos have found no increased mortality Those few reports that show harmful effects employ experimental methods that do not place enough importance on the natural abiotic and biotic factors that provide UVB protection. In the laboratory, amphibian embryos are resistant to doses of UVB radiation far higher than those they would normally receive from ambient sunlight. The jelly surrounding amphibian eggs absorbs UVB radiation, as revealed by spectral measurements of absorbance; after UVB exposure, embryos with their jelly capsules removed show significantly higher mortality than those with the jelly intact. In light of this and other factors mitigating UVB absorption, the hypothesis that ambient UVB radiation causes amphibian mortality and population declines is without support.

New Amphibians and Global Conservation: A Boost in Species Discoveries in a Highly Endangered Vertebrate Group

Jörn Köhler, David R. Vieites, Ronald M. Bonett, Francisco H. García, Frank Glaw, Dirk Steinke and Miguel Vences

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Abstract: Amphibians are characterized both by a strongly increasing number of newly discovered species and by a high degree of decline. The observed increase in species numbers, over 25 percent in 11 years, is largely due to the intensified exploration of tropical areas and the application of more efficient techniques such as bioacoustics and molecular genetics, rather than to the elevation of subspecies to species rank or the distinction of species that were formerly considered synonymous. In the mantellid frogs of Madagascar, the many species newly described between 1992 and 2004 were as genetically divergent as those described in previous research periods, and most had not been collected previously, corroborating the lack of “taxonomic inflation” in this vertebrate class. Taxonomic exploration is still desperately needed to avoid misinterpretations in global conservation policy.

Challenges in Evaluating the Impact of the Trade in Amphibians and Reptiles on Wild Populations

Martin A. Schlaepfer, Craig Hoover and C. Kenneth Dodd Jr.

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Abstract: Amphibians and reptiles are taken from the wild and sold commercially as food, pets, and traditional medicines. The overcollecting of some species highlights the need to assess the trade and ensure that it is not contributing to declines in wild populations. Unlike most countries, the United States tracks the imports and exports of all amphibians and reptiles. Records from 1998 to 2002 reveal a US trade of several million wild-caught amphibians and reptiles each year, although many shipments are not recorded at the species level. The magnitude and content of the global commercial trade carries even greater unknowns. The absence of accurate trade and biological information for most species makes it difficult to establish whether current take levels are sustainable. The void of information also implies that population declines due to overcollecting could be going undetected. Policy changes to acquire baseline biological information and ensure a sustainable trade are urgently needed.

Habitat use by a tree frog species of Scinax (Amphibia, Hylidae) at an urban forest fragment from south-eastern Brazil

Conrado A. B. Galdino, Ronald R. Carvalho Jr., Mauren A. V. Noronha e Menezes and Luciana B. Nascimento

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Abstract: We studied the pattern of habitat use by the tree frog Scinax aff. perereca. Fieldworks were performed from August 1996 to August 1997 at Parque das Mangabeiras, Belo Horizonte, State of Minas Gerais, southeastern Brazil. Calling males were observed in September, October and December 1996, February to April and June 1997. Females were found only in October 1996. Specimens were found perched on vegetation, on the ground or on stones near waterfall. At Parque das Mangabeiras, S. aff. perereca occupied nine types of substrata. The most frequently used substrata were shrubs, stones at the stream edges, and fallen trunks. The pattern of spatial occupation varied among months. Males were found calling in aggregations on the vegetation and spatial niche breadth was related to species abundance.

The ecology of extinction: population fluctuation and decline in amphibians

David M. Green

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Abstract: Even among widespread species with high reproductive potentials and significant dispersal abilities, the probability of extinctions should be correlated both with population size variance and with the extent of population isolation. To address how variation in demographic characteristics and habitat requirements may reflect on the comparative risk of species decline, I examined 617 time series of population census data derived from 89 amphibian species using the normalized estimate of the realized rate of increase, DeltaN, and its variance. Amphibians are demonstrably in general decline and exhibit a great range of dispersal abilities, demographic characteristics, and population sizes. I compared species according to life-history characteristics and habitat use. Among the populations examined, census declines outnumbered increases yet the average magnitudes for both declines and increases were not demonstrably different, substantiating findings of amphibian decline. This gives no support for the idea that amphibian population sizes are dictated by regimes featuring relatively rare years of high recruitment offset by intervening years of gradual decline such that declines may outnumber increases without negative effect. For any given population size, those populations living in large streams or in ponds had significantly higher variance than did populations of completely terrestrial or other stream-dwelling amphibians. This could not be related to life-history complexity as all the stream-breeding species examined have larvae and all of the wholly terrestrial species have direct development without a larval stage. Variance in DeltaN was highest amongst the smallest populations in each comparison group. Estimated local extinction rates averaged 3.1% among pond-breeding frogs, 2.2% for pond-breeding salamanders, and negligible for both stream-breeding and terrestrial direct-developing species. Recoveries slightly exceeded extinctions among European pond-breeding frogs but not among North American pond-breeding frogs. Less common species had greater negative disparities between extinctions and recoveries. Species with highly fluctuating populations and high frequencies of local extinctions living in changeable environments, such pond- and torrent-breeding amphibians, may be especially susceptible to curtailment of dispersal and restriction of habitat.

Pond Permanence and the Effects of Exotic Vertebrates on Anurans

Michael J. Adams

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Abstract: In many permanent ponds throughout western North America, the introduction of a variety of exotic fish and bullfrogs (Rana catesbeiana) correlates with declines in native amphibians. Direct effects of exotics are suspected to be responsible for the rarity of some native amphibians and are one hypothesis to explain the prevalence of amphibian declines in western North America. However, the prediction that the permanent ponds occupied by exotics would be suitable for native amphibians if exotics were absent has not been tested. I used a series of enclosure experiments to test whether survival of northern red-legged frog (Rana aurora aurora) and Pacific treefrog (Hyla regilla) larvae is equal in permanent and temporary ponds in the Puget Lowlands, Washington State, USA. I also examined the direct effects of bullfrog larvae and sunfish. Survival of both species of native anuran larvae was generally lower in permanent ponds. Only one permanent pond out of six was an exception to this pattern and exhibited increased larval survival rates in the absence of direct effects by exotics. The presence of fish in enclosures reduced survival to near zero for both native species. An effect of bullfrog larvae on Pacific treefrog larval survival was not detected, but effects on red-legged frog larvae were mixed. A hypothesis that food limitation is responsible for the low survival of native larvae in some permanent ponds was not supported. My results confirm that direct negative effects of exotic vertebrates on native anurans occur but suggest that they may not be important to broad distribution patterns. Instead, habitat gradients or indirect effects of exotics appear to play major roles. I found support for the role of permanence as a structuring agent for pond communities in the Puget Lowlands, but neither permanence nor exotic vertebrates fully explained the observed variability in larval anuran survival.

Assessing the value of secondary forest for amphibians: Eleutherodactylus frogs in a gradient of forest alteration

Gentile Francesco Ficetola, Dario Furlani, Giorgio Colombo and Fiorenza di Bernardi

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Abstract: Secondary forests constitute a growing portion of forested areas worldwide. They might have a substantial role for the conservation of biodiversity in tropical areas, but there is little information on their potential to support forest species and the recovery of faunal communities. We studied two forest frogs (Eleutherodactylus diastema and E. fitzingeri) in an area of Costa Rica composed of a mosaic of primary forest, young secondary forest and pasture, and we compared the density of calling males in areas with different forest alteration. Autoregressive models were used to compensate for potentially undesired effects of spatial autocorrelation and pseudoreplication. Both species were most abundant in riparian, primary forest. However, E. fitzingeri was also abundant in riparian secondary forests, and its density far from the river was similar in primary and secondary forest, suggesting that river proximity can influence the recovery of secondary forest for amphibians. Conversely, the density of E. diastema was similar in secondary forest and pasture, stressing interspecific differences for recovery rate. These frogs have a keystone role in nutrient cycling and food webs, and their prompt recovery might represent an important step for the functional recovery of forests. Nevertheless, the strong interspecific differences stress the complexity of these processes.

Deforestation and the Structure of Frog Communities in the Humedale Terraba-Sierpe, Costa Rica

Dario Furlani, Gentile Francesco Ficetola, Giorgio Colombo, Murat Ugurlucan and Fiorenza di Bernardi

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Abstract: Loss of tropical forests is a major cause of biodiversity loss worldwide. Although drastic modification of the habitat has been shown to negatively affect amphibians, we are far from a complete understanding of the response of amphibian communities to deforestation. We studied frog assemblages in a gradient of forest modification in a humid area of Costa Rica, where the primary forest has been partially converted into pasture. The study area is a mosaic of primary palm forest, abandoned pasture covered by secondary forest, and pasture. Species richness was assessed by randomized walk surveys and audio strip transects. We also measured ecological features to evaluate the relationship between landscape alteration and amphibian distribution. The study area hosted a large number of amphibian species. We focused our monitoring on six anurans: Leptodactylus labialis, Eleutherodactylus fitzingeri, E. diastema, Hyla rosenbergi, H. microcephale, and Cochranella granulosa. Three species (L. labialis, H. rosenbergi, and H. microcephala) were most abundant in pasture areas with livestock presence, while E. fitzingeri, E. diastema, and C. granulosa were associated with primary forest. Most of the variation in community structure was explained by the joint effect of forest alteration and presence of livestock. Whereas forest specialists suffer direct negative effect from deforestation, generalist species can take advantage of forest alteration and the presence of farm animals. Species that are able to take advantage of the new environmental characteristics associated with human modifications of landscapes will come to prevail in the new communities.

MORPHOLOGICAL DIVERSITY AND EVOLUTION OF EGG AND CLUTCH STRUCTURE IN AMPHIBIANS

Ronald Altig and Roy W. McDiarmid.

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Abstract: The first part of this synthesis summarizes the morphology of the jelly layers surrounding ail amphibian ovum. We propose a standard terminology and discuss the evolution of jelly layers. The second part reviews the morphological diversity and arrangement of deposited eggs-the ovipositional mode; we recognize 5 morphological classes including 14 modes. We discuss some of the oviductal, ovipositional, and postovipositional events that contribute to these morphologies. we have incorporated data from taxa from thronghout the world but recognize that other types will he discovered that may modify understanding of these modes. Finally, we discuss the evolutionary context of the diversity of clutch structure and present a first estimate of its evolution.

Impacto do desmatamento e formação de pastagens sobre a anurofauna de serapilheira em Rondônia

Paulo Sérgio Bernarde and Lílian Cristina Macedo

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Abstract: Abundance and diversity of leaf-litter frog species were studied in forest and pasture in Rondonia, Brazil. Also, the efficiency of use of pitfall traps was examined. Pitfall traps were established in three treatments: forest interior far 100 m) from water; forest interior near 100 m) water; pasture, far from water. Species richness was typical of the Amazon region, with a total of 1,324 individuals of 27 species in nine families: Aromobatidae (1 species), Brachycephalidae (2), Bufonidae (4), Cycloramphidae (1), Dendrobatidae (1), Hylidae (5), Leiuperidae (1), Leptodactylidae (7) e Microhylidae (5). Pitfall traps captured 57% of the species known for this location, capturing mainly terrestrial and fossorial species. The greatest richness and diversity of captures were during the rainy season in the forested sites. Forest converted to pasture affects several features of the habitat that reduce habitat quality with respect to these amphibians, including fewer places for reproduction, reduced food supply, loss of leaf-litter and soil compaction all with their influence on microclimate, as well as the arrival of other species more common in open areas.

Distribuição temporal e diversidade de modos reprodutivos de anfíbios anuros no Parque Nacional das Emas e entorno, estado de Goiás, Brasil

Katia Kopp, Luciana Signorelli e Rogério P. Bastos

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Abstract: The communities of anuran amphibians, especially in tropical regions, are directly influenced by environmental conditions, whfich play an important role in structuring and regulating communities. This study aimed to determine the diversity of reproductive modes, season of vocalization and to test correlation among climatic variables and richness, abundance of adult frogs and tadpoles, and activity of vocalization of males in 12 water bodies located in and around the Emas National Park, southwestern state of Goiás, Brazil. Sixteen samples were carried out between December 2005 and March 2008. A total of 25 species from five families were recorded: Bufonidae (one species), Hylidae (nine species), Leptodactylidae (eight species), Leiuperidae (six species) and Microhylidae (one species). Four patterns of reproductive activity were recognized among the species: continuous, intermediate, long and explosive. The richness of adult frogs, the abundance and activity of the calling males were positively related to air temperature, humidity and precipitation. The richness of tadpoles was positively related to precipitation and water temperature, but there was no relationship between the abundance of tadpoles with no descriptors of climate. Six reproductive modes were recorded, 56% of species had widespread aquatic reproductive modes (mode 1 and 4) and 44% deposit eggs in nests of foam (modes 11, 13, 30 and 32). The species recorded in this study showed a predominance of reproductive modes and general reproductive pattern typically associated with the warm and rainy period, as expected for tropical and seasonal regions. However, the temporal segregation between groups of species within the rainy season seems to facilitate the coexistence of generalist species typical of open and/or anthropogenic areas.

Reproductive modes and fecundity of an assemblage of anuran amphibians in the Atlantic rainforest, Brazil

Marília T. Hartmann, Paulo A. Hartmann and Célio F. B. Haddad

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Abstract: Reproductive modes and size-fecundity relationships are described for anurans from Picinguaba, a region of Atlantic rainforest on the northern coast of the state of São Paulo, Brazil. We observed 13 reproductive modes, confirming a high diversity of modes in the Atlantic rainforest. This diversity of reproductive modes reflects the successful use of diversified and humid microhabitats by anurans in this biome. We measured the snout-vent length of 715 specimens of 40 species of anurans. The size-fecundity relationship of 12 species was analyzed. Female snout-vent lengths explained between 57% and 81% of clutch size variation. Anurans with aquatic modes laid more eggs than those with terrestrial or arboreal modes. Larger eggs were deposited by species with specialized reproductive modes.

Escolha de áreas prioritárias de conservação de anfíbios anuros do Cerrado através de um modelo de populações centrais-periféricas

Gabriela C. C. Padua, Miriam P. Pinto and José A. F. Diniz-Filho.

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Abstract: H a b i t a t  l o s s  causes great threats to biological diversity, and one of the alternatives to protect biodiversity is reserve planning using optimization tools to establish conservation priority areas. In this study, a simulated annealing algorithm was used to analyze the influence of  species distribution margins on selection of areas in Cerrado, for 131 anurans species. For this purpose, we used two databases: one containing the original species distribution, and another with the periphery of distributions excluded. Networks selected using the original distributions contained 17 cells, whereas networks found with the reduced distributions were larger, with 22 cells. The irreplaceable cells were the same in all networks, and new regions of replaceable cells in the margins of the biome arise when distributions without peripheral areas were considered.

Anurans of the Serra do Caraça, southeastern Brazil: species composition and phenological patterns of calling activity

Marco A. S. Canelas e Jaime Bertoluci

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Abstract: Annual patterns of calling and breeding activity of 38 anuran species were studied at Serra do Caraça, an 11,233 ha reserve located in a contact zone between Cerrado and Atlantic forest at the southern Espinhaço range, southeastern Brazil. Five patterns were evident: (1) species that call year-round or nearly year-round with larger aggregations generally observed in the rainy months, (2) species with opportunistic calling activity associated with rainfall during the wettest months of the year, (3) winter species, (4) explosive breeders with intense calling activity triggered by heavy rains during the rainy season or only in the beginning of the rainy season, and (5) summer species with variable breeding seasons. Both the monthly number of species with calling males and the monthly number of species that showed the maximum class of calling males were positively correlated with both mean monthly temperature and monthly precipitation.

Species richness, relative abundance, and habitat of reproduction of terrestrial frogs in the Triângulo Mineiro region, Cerrado biome, southeastern Brazil

Ariovaldo A. Giaretta, Marcelo Menin, Kátia G. Facure, Marcelo N. C. Kokubum e Júlio C. Oliveira Filho

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Abstract: Based on field observations and pitfall sampling, we determined the species richness, relative abundance, and reproductive habitat of terrestrial frogs in three municipalities in the Triângulo Mineiro region, south Cerrado biome, in southeastern Brazil. We found thirty-two species of terrestrial frogs, belonging to the families Brachycephalidae, Bufonidae, Cycloramphidae, Dendrobatidae, Leiuperidae, Leptodactylidae and Microhylidae. Most of the species were found in open areas and reproduced in human-generated environments, such as artificial lakes (10 species) and ponds (14 species). Dominance was high, with Physalaemus cuvieri Fitzinger, 1826 (Leiuperidae) representing 48% of sampled frogs. A larger number of individuals was captured in the wet season, when most of the species were reproducing. Compared to other areas of Cerrado biome, the Triângulo Mineiro sites presented a larger number of species, which may be attributed to the larger sampled area and greater sampling effort, lower altitude and presence of human generated habitats. The richness of terrestrial frogs was also larger than that in some forested localities in southeastern Brazil, indicating that the number of species cannot be explained only by precipitation and type of vegetation cover. The greater abundance of individuals during the wet season may be related to a greater movement of adults to breeding sites and to juvenile recruitment/dispersion. The heterogeneity of environments in the Cerrado biome, including its several isolated highlands, contributes to its high (local and regional) diversity of frogs.

Feeding habits of six anuran (Amphibia: Anura) species in a rainforest fragment in Northeastern Brazil

Ednilza M. Santos, Argus V. Almeida and Simão D. Vasconcelos.

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Abstract: Although Brazil encompasses one of the most abundant anuran faunas in the world, quantitative information on anuran ecology and diet are limited, especially in the Northeastern region. We analyzed the diet of six species: Hyla albomarginata, Hyla cf. branneri, Hyla minuta, Phyllomedusa aff. hypochondrialis (Hylidae), Leptodactylus natalensis, and Physalaemus cuvieri (Leptodactylidae) in a temporary pond in a rainforest remnant in Pernambuco, between 1999-2000. We analyzed diet composition, degree of food preference, and seasonal variations in diet. Leptodactylus natalensis and P. cuvieri showed higher diet diversity, whereas H. minuta consumed fewer food items. Insecta, Arachnida, and plants were preferential items for most species. Acari were consumed by all species; Hymenoptera, Odonata, and Coleoptera were also often consumed. A slight increase in diet diversity occurred in the rainy season. The species showed a generalist feeding behaviour, although P. cuvieri consumed Formicidae as major prey item.

ATIVIDADE REPRODUTIVA DE PHYSALAEMUS SIGNIFER (ANURA, LEPTODACTYLIDAE) EM AMBIENTE TEMPORÁRIO

Henrique Wogel, Patrícia A. Abrunhosa and José P. Pombal Jr.

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Abstract: The breeding activity of Physalaemus signifer (Girard, 1853) was monitored from July 1999 to July 2000 in a temporary pond in Palmital, Municipality of Saquarema, State of Rio de Janeiro, Atlantic Rain Forest, Brazil. Males were sexually actives only in four nights, arriving at the pond on the early rainy season. Males in amplexus were larger and spent more nights in the reproductive aggregation than solitary ones. The number of nights was correlated with the mass of the males. Males adopted satellite behavior as alternative tactic for mate acquisition. Changes between calling and satellite tactics were observed in different nights. Calling males were not larger and heavier than satellite ones. Satellite behavior seemed to be related with the order of arrival on the pond. Size and mass of males did not influence the results of fights. Resident males won the majority of agonistics combats. Three types of vocalizations are described: advertisement, territorial, and encounter calls.

RELACIONAMENTO ENTRE ANFÍBIOS ANUROS E BROMÉLIAS DA RESTINGA DE REGÊNCIA, LINHARES, ESPÍRITO SANTO, BRASIL

José Alberto P. Schineider and Rogério L. Teixeira

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Abstract: Some anuran amphibians use the bromeliads during the entire life cycle and others only as diurnal shelter. At the sandy coastal plain of Linhares, State of Espírito Santo, Southeastern Brazil, 676 bromeliads were examined, of which 303 of Aechmea blanchetiana (Baker) L. B. Smith., 1955, 287 of Aechmea nudicaulis (L.) Griseb., 1864, and 86 of Vrisea procera (Mart. Ex Schult. f.) Wittm, 1891. The morphometric and physical-chemical analysis of different bromeliads evidenced variations among plants. During the period sampled, six anuran species were found inside the plant axils. The hylid frog Phyllodytes luteolus (Wied, 1824) was the most abundant species (260 specimens). Its abundance was higher in the epiphyte bromeliad Vrisea procera. Phyllodytes luteolus had higher occurrences in bromeliads located at a transitional area between open and under the shrub vegetation. Specimens of Scinax alterus (Lutz, B., 1973) and Aparasphenodon brunoi Miranda-Ribeiro, 1920, were more frequent mainly in transitional areas; Bufo granulosus Spix, 1824 occurred in open and transitional areas, whereas Gastrotheca fissipis (Boulenger, 1888) and Leptodactylus fuscus (Schneider, 1799) were found only in bromeliads located in open areas.

Sinalização visual e Biologia Reprodutiva de Dendropsophus werneri (Anura: Hylidae) em área de Mata Atlântica no Estado do Paraná, Brasil

Daniele B. Miranda, Michel V. Garey, Emygdio L. A. Monteiro-Filho and Marília T. Hartmann

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Abstract: We studied the reproductive biology and visual signaling of Dendropsophus werneri, whose distribution is limited to the Atlantic Rain Forest. The fieldwork was carried out in the Estação 2 do IAPAR, municipality of Morretes, state of Paraná, Brazil, from August 2006 to March 2007. Additional information on reproduction was gathered in the Reserva Natural Salto Morato, municipality of Guaraqueçaba, state of Paraná, Brazil, from September 2006 to March 2007. Males were smaller than females. Males called throughout all the study period in Morretes, but were active only during three months in Guaraqueçaba; males called from low vegetation along the edge of temporary ponds in open areas. The visual signaling was observed in two contexts: (1) aggressive behaviors between two males and (2) during the reproduction, by amplectant males. In the territorial behavior, males exhibited both aggressive and mixed calls, visual signaling as well as physical combats. We also recorded satellite behavior in four males. The mean egg number per clutch was 244 ± 32 eggs, varying between 188 and 310 eggs. We observed two reproductive modes: Mode 1 and Mode 24. In the present study, Dendropsophus werneri showed elaborated social interactions involving visual signaling, territorial behavior, mating bahavior with tactile stimuli, and two different reproductive modes, demonstrating its complex reproductive biology.

A preliminary list of the Herpetofauna from termite mounds of the cerrado in the Upper Tocantins river valley

Lorena A. Moreira, Danté B. Fenolio, Hélder L. R. Silva and Nelson J. Silva Jr.

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Abstract: Termite mounds are known to offer refuge and microhabitats to a great variety of invertebrates and vertebrates. In the valley of the upper Tocantins River, within areas of influence of hydroelectric power plants 4,000 termite mounds were surveyed to evaluate the diversity of amphibians and reptiles using these environments. Surveys in termite mounds from two other areas (Corumbá River and Araguaia River basins) were used for comparative purposes. The results for termitaria in the upper Tocantins river valley revealed nine families, 13 genera, and 25 species of amphibians, and 16 families, 32 genera, and 47 species of squamate reptiles. Compared to a general herpetofaunal list of the region, the data indicate that between 30.6% and 56.8% of the species use termitaria.

Temporada e turno de vocalização de LeptodactyLus nataLensis Lutz, 1930 (Amphibia, Anura) na mata atlântica de Pernambuco, Brasil

Fabiana O. Amorim, Karin E. von Schmaltz-Peixoto, Luciana C. S. S. Araújo and Ednilza M. dos Santos

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Abstract: Vocalizations of a population of Leptodactylus natalensis were monitored in a temporary pond from November 2002 to October 2004. This pond is located in a fragment of Atlantic rainforest belonging to the private Ecologic Refuge Charles Darwin, in the city of Igarassu, state of Pernambuco, Brazil. Individuals were active during most of the studied months, with peaks of activity during dry season. Vocal activity was recorded both in day and nighttime. There was a significant negative effect of temperature on vocal activity. The number of individuals vocalizing was not affected significantly by rainfall, but it was by the number of females on the environment. A great plasticity of vocal activities of L. natalensis was verified, both in season and turn.

ESTRATÉGIAS E MODOS REPRODUTIVOS DE ANUROS (AMPHIBIA) EM UMA POÇA PERMANENTE NA SERRA DE PARANAPIACABA, SUDESTE DO BRASIL

José P. Pombal Jr. and Célio F. B. Haddad

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Abstract: southeastern Brazil. This study describes the temporal patterns, behavioral strategies, reproductive modes, and fecundity of an anuran assemblage in a permanent pond in Serra de Paranapiacaba, municipality of Ribeirão Branco, south of São Paulo State (approximately 24º13'S; 48º46'W; ca. 800m above sea level). Field work was carried out between January and December 1993, totaling 40 nights of observation. Seven preliminary visits were made before this period and seven additional ones after December 1993. Naturalistic observations usually began before sunset and were concluded around 24:0001:00h. On three occasions the observations lasted the entire night. The commonest reproductive strategy among males of different species was that performed by calling male, but the satellite behavior was observed in some species. The calling temporal pattern was prolonged for the species of the assemblage; however, some species called only occasionally. Six different reproductive modes were observed in the pond or on its margins. The SVL of females of different species was positively correlated with egg clutch volume, irrespective of the reproductive mode. The SVL of females was also positively correlated with the number of eggs per clutch, although the correlation is stronger for species with a generalized reproductive mode. However, for species with specialized reproductive mode the number of eggs per clutch was not correlated with the SVL of females. A significant and positive correlation between female SVL and egg diameter was also detected for species with generalized reproductive mode. On the other hand, for species with specialized reproductive mode, female's SVL and egg diameter were negatively correlated. Terrestrial reproductive modes are possibly restricted to small-sized species. Large eggs may face problems of gas exchange due to their longer development period and lower surface/volume ratio.

Notas Sobre Predação em uma Taxocenose de Anfíbios Anuros no Sudeste do Brasil

José P. Pombal Jr.

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Abstract: Anuran amphibians are preyer by all vertebrate groups and several invertebrates. However, predation studies on amphibians are still occasional and anecdotic. Herein, informations on predation of an anuran assemblage of southeastern Brazil are provided. Invertebrates (spiders and water bugs), the frog Leptodactylus cf. ocellatus, and five snake species (four Colubridae and one Viperidae) preyer on small individuals or small anuran species.

Utilização de Habitats Reprodutivos e Micro-Habitats de Vocalização em uma Taxocenose de Anuros (Amphibia) da Mata Atlântica do Sudeste do Brasil

Jaime Bertoluci and Miguel Trefaut Rodrigues

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 Abstract: Breeding and calling site utilization were studied for an anuran community of the Parque Estadual Intervales, an Atlantic Rainforest reserve located in Southeastern Brazil (24°12'-24°25'S, 48°03'-48°30'W). Field work was carried out between April 1990 and March 1991. Forty-seven species from four families were recorded in the study site: Bufonidae (4), Hylidae (24), Leptodactylidae (18), and Microhylidae (1). We were able to obtain data on breeding habitat and microhabitat distribution for 26 species by monitoring six breeding sites year-round on a monthly basis. The number of species in the sites varied from 7 to 22. Species were classified as habitat generalists and specialists based on breeding site utilization. Most species showed preferences for certain calling sites. For some species calling site specificity seemed to depend on the density of the male aggregations rather than on the species composition of the assemblages.

Abiotic Correlates of Anuran Calling Phenology: The Importance of Rain, Temperature, and Season

Daniel Saenz, Lee A. Fitzgerald, Kristen A. Baum and Richard N. Conner

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Abstract: We surveyed anuran calls nightly at eight ponds in eastern Texas from 1 January 2001 through 31 December 2002. Air temperatures and daily rainfall also were recorded for each of the sites. Eastern Texas contains a diverse temperate anuran fauna and a climate that provides a range of conditions for anuran reproduction. During our study, we measured air temperatures that fluctuated seasonally with extremes from 0 to 29 C at 2100 h. We found rainfall to be generally abundant with occasional flooding events, however, prolonged periods of no precipitation were also observed. Given the level of anuran diversity and the amount of seasonal variation in temperature and rainfall in our temperate climate we expected to find a variety of breeding strategies. Results from our analyses did indeed suggest five basic breeding strategies based on anuran calling: (1) breeding within a predictable season (summer) independent of local weather patterns; (2) breeding opportunistically within a predictable season (summer) dependent on local rainfall; (3) breeding opportunistically within a predictable season (winter) dependent on local temperature; (4) breeding opportunistically dependent on local flood level rainfall events; (5) breeding opportunistically year round dependent on local temperature in the winter and local rainfall in the summer.

Comparison of Methods for Monitoring Reptiles and Amphibians in Upland Forests of the Ouachita Mountains

Doyle L. Crosswhite, Stanley F. Fox and Ronald E. Thill

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Abstract: We compared drift fence arrays (employing pitfalls and double-ended funnel traps), double-ended funnel traps without drift fences, and time-constrained searching as methods for capturing reptiles and amphibians in upland forests of the Ouachita Mountains, Arkansas. Taxonomic groups (anurans, salamanders, and squamates) were appraised for heterogeneity of susceptibility to capture among different methods. Also, capture success for types of funnel traps were compared across different size classes of squamates. We sampled a total of 91 days during six trapping periods over the spring and summer months of 1993 and 1994. Eight-hundred eighty-six individuals representing 38 species of reptiles and amphibians were captured. Standardizing captures by common unit effort (captures/trap-day or captures/person-day) shows that time-constrained searching was overall the most efficient, followed by drift fence arrays, then stand-alone funnel traps. However, more herps can be captured by trapping (especially when associated with drift fences) than searching, because of personnel limitations. Pitfall traps more effectively captured most anurans, salamanders, lizards, and small snakes, while double-ended funnel traps effectively captured most large squamates. Funnel traps made of aluminum window screen were significantly better for catching small squamates than funnel traps made of hardware cloth because small individuals could pass through the larger mesh of the latter.

Metapopulation Dynamics and Amphibian Conservation

David M. Marsh and Peter C. Trenham

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Abstract: In many respects, amphibian spatial dynamics resemble classical metapopulation models, in which subpopulations in breeding ponds blink in and out of existence and extinction and colonization rates are functions of pond spatial arrangement. This "ponds-as-patches" view of amphibian spatial dynamics is useful in several respects. First, it highlights the importance of regional and landscape processes in determining local patterns of abundance. Second, it offers a straightforward, pond-based approach to monitoring and managing amphibian populations. For many species, however, the ponds-as-patches view may be an over-simplification and metapopulation structure may be more apparent than real. Changes in distribution may be caused by processes other than extinction and recolonization, and most extinctions probably result from deterministic factors, not stochastic processes. In addition, the effects of pond isolation appear to be important primarily in disturbed environments, and in many cases these isolation effects may be better explained by the distribution of terrestrial habitats than by the distribution of breeding ponds. These complications have important implications for both researchers and managers. For researchers, future efforts need to determine the mechanisms underlying patterns of abundance and distributional change and patterns in amphibian populations. For managers, effective conservation strategies must successfully balance metapopulation considerations with careful attention to local habitat quality. Furthermore, translocations and active management may be indispensable tools for conserving amphibians in landscapes containing multiple breeding ponds.

Sexual Selection and Signal Evolution: The Ghost of Biases Past

Michael J. Ryan and A. Stanley Rand

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Abstract: The evolution of female mating preferences is an important key to understanding the evolution of signal diversity. Several hypotheses for preference evolution invoke different processes but all can produce the same end results: thus comparisons of extant traits and preferences within and among populations have made little progress in discriminating among competing hypotheses. Some of these hypotheses, however, do make different predictions as to the historical sequence of trait-preference evolution, and thus can be discriminated with appropriate phylogenetic analyses. We explore this approach in an analysis of the evolution of calls and call preferences in a monophyletic group of frogs, the Physalaemus pustulosus species group. In this clade there are pre-existing preferences for four call traits. These data reject hypotheses that invoke coevolution (good genes, runaway sexual selection) and females evolving preferences to choose males providing better resources, and instead support the hypothesis of sensory exploitation that suggests that males evolve traits that match pre-existing biases in the female's sensory system. We suggest that some of the difficulty in understanding preference evolution might derive from defining a preference only by those extant stimuli that elicit the preference. Our results suggest that preferences might be more general, and that signal diversity might arise from alternative means for eliciting the same preference. Furthermore, we discuss some difficulties with utilizing both population-based comparisons and phylogenetic approaches and suggest that the greatest progress will be made by addressing the problem of preference evolution at several levels of analysis.

Paedophryne amauensis

The Journal of Environment (source BBC Brazil) reported on 12/1/12 an article about the discovery of "possible" world's smallest frog, Paedophryne amauensis (photo). The new specie was found in Papua New Guinea. The snout-vent lenght is on average 7,7 mm. These small frogs live in the litter covering the soil. The article that involves the description of this specie was published in the journal PloS One and can be downloaded free here.

There are some disagreement about whether this species is the smallest frog in the world and perhaps the world's smallest vertebrate. However, this discussion adds little scientific knowledge. The most important is to discover new species and continue assembling the puzzle ecosystem.

Follow the link to full report: http://jornalmeioambiente.com/materia/1603/cientistas-encontram-menor-ra-do-mundo-em-papua-nova-guine