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The Doradidae fishes constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and the sister group to all other thorny catfishes, and it includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, and the use of complementary approaches, including genetic studies, is an important step to better characterize this diversity and the relationships among the species within the genus. Therefore, we conducted a comprehensive analysis using conventional cytogenetic techniques and physical mapping of three multigene families (18S and 5S ribosomal DNA [rDNA], U2 small nuclear DNA [snDNA]) and four microsatellite motifs, namely (AC)n, (AT)n, (GA)n, and (GATA)n, in two sympatric species from the Negro River: Acanthodoras cataphractus and Acanthodoras cf. polygrammus. We found significant differences in constitutive heterochromatin (CH) content, distribution of the microsatellite (AT)n, and the number of 5S rDNA and U2 snDNA sites. These differences may result from chromosome rearrangements and repetitive DNA dispersal mechanisms. Furthermore, the characterization of the diploid number (2n) of these Acanthodoras species enables us to propose 2n = 58 chromosomes as the plesiomorphic 2n state in Doradidae based on ancestral state reconstruction. Acanthodoradinae is the oldest lineage of the thorny catfishes, and knowledge about its cytogenetic patterns is crucial for disentangling the karyotype evolution of the whole group. Thus, this study contributes to the understanding of the mechanisms behind chromosome diversification of Doradidae and highlights the importance of Acanthodoradinae in the evolutionary history of thorny catfishes.

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Sympatric species may overlap in their use of habitat and dietary resources, which can increase competition. Comparing the ecological niches and quantifying the degree of niche overlap among these species can provide insights into the extent of resource overlap. This information can be used to guide multispecies management approaches tailored to protect priority habitats that offer the most resources for multiple species. Stable isotope analysis is a valuable tool used to investigate spatial and trophic niches, though few studies have employed this method for comparisons among sympatric marine turtle species. For this study, stable carbon, nitrogen, and sulfur isotope values from epidermis tissue were used to quantify isotopic overlap and compare isotopic niche size in loggerhead (Caretta caretta), green (Chelonia mydas), and Kemp's ridley (Lepidochelys kempii) turtles sampled from a shared foraging area located offshore of Crystal River, Florida, USA. Overall, the results revealed high degrees of isotopic overlap (>68%) among species, particularly between loggerhead and Kemp's ridley turtles (85 to 91%), which indicates there may be interspecific competition for resources. Samples from green turtles had the widest range of isotopic values, indicating they exhibit higher variability in diet and habitat type. Samples from loggerhead turtles had the most enriched mean δ34S, suggesting they may forage in slightly different micro-environments compared with the other species. Finally, samples from Kemp's ridley turtles exhibited the smallest niche size, which is indicative of a narrower use of resources. This is one of the first studies to investigate resource use in a multispecies foraging aggregation of marine turtles using three isotopic tracers. These findings provide a foundation for future research into the foraging ecology of sympatric marine turtle species and can be used to inform effective multispecies management efforts.

RESUMO

Basic and molecular cytogenetic techniques were carried out in 3 Neotropical region populations of catfishes, two of Trachelyopterus galeatus (one from the marshlands of Paraguay River basin and another from Lago Catalão, Amazon River basin) and one of Trachelyopterus porosus, a sympatric population to T. galeatus from the Amazon River basin. This study aimed to describe and understand the structure and evolution of Trachelyopterus B chromosomes, mainly through physical mapping of repetitive elements. A diploid number of 58 chromosomes was found for all individuals, as well as the presence of B chromosomes. For T. porosus this is the first report of a supernumerary. The sympatric species of T. galeatus and T. porosus from Amazon River had 1-3 B chromosomes and T. galeatus from Paraguay River had 1-2 B chromosomes, all of them showed intra- and interindividual numerical variation. Two females of T. porosus exhibited a new variant B chromosome (B2), previously not seen in Auchenipteridae, which might have originated from B1 chromosomes. All B chromosomes were entirely heterochromatic. In contrast to all complement A and B2 chromosomes, in which the telomeric sequences were found in the telomeric regions, B1 chromosomes of all populations were totally marked by (TTAGGG)n probes. (GATA)n sequence sites were found through all complement A chromosomes, but B1 and B2 chromosomes exhibited only a clustered block in one of the chromosome arms. The most frequent B chromosomes (B1) in all populations/species, including those previously studied in Auchenipteridae catfishes, share the following characteristics: totally heterochromatic, small, metacentric, with accumulation of repetitive (TTAGGG)n sequences, and a low number of (GATA)n copies, which might suggest a common ancient origin in Trachelyopterus species/populations.

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Abstract: Tadpoles are able to perceive and discriminate signals from environment and they may use this ability in behaviors and ecological processes. Recognition mechanisms may be involved in schooling by means of attraction among individuals, characterizing a social process. By means of laboratory experiments the present study investigated the presence or absence of attraction to conspecifics in tadpoles of Rhinella icterica and R. ornata, two sympatric species from the Atlantic Forest of southeastern Brazil. We collected eggs of these two species in the field and reared them in laboratory according to two different methods (isolated or in groups of siblings). Tadpoles were submitted to experiments of choice between conspecifics, heterospecifics, and an empty compartment. Rhinella icterica tadpoles preferred to associate with conspecifics rather than R. ornata tadpoles, and we verified this is an innate behavior. Rhinella ornata tadpoles failed to discriminate between conspecifics and R. icterica tadpoles. When submitted to choice between a group of tadpoles of the other species and an empty compartment, R. icterica tadpoles presented random distribution, while R. ornata tadpoles preferred to associate with heterospecifics. Our results indicate R. icterica tadpoles have preference to associate with conspecifics, while R. ornata tadpoles may school indiscriminately. This study contributes for a better understanding of larval anuran social behavior.

Resumo: Os girinos são capazes de perceber e discriminar sinais do ambiente e podem usar essa capacidade em comportamentos e processos ecológicos. Mecanismos de reconhecimento podem estar envolvidos na agregação por meio da atração entre indivíduos, caracterizando um processo social. O presente estudo investigou, por meio de experimentos de laboratório, a presença ou ausência de atração por coespecíficos em girinos de Rhinella icterica e R. ornata, duas espécies simpátricas, da Mata Atlântica do sudeste do Brasil. Coletamos ovos dessas duas espécies no campo e os cultivamos em laboratório de acordo com dois métodos diferentes (isolados ou em grupo de irmãos). Os girinos foram submetidos a experimentos de escolha entre coespecíficos, heteroespecíficos e compartimento vazio. Girinos de Rhinella icterica preferiram associar-se a coespecíficos do que com girinos de R. ornata, e verificamos que este é um comportamento inato. Os girinos de Rhinella ornata não conseguiram discriminar entre coespecíficos e girinos de R. icterica. Quando submetidos à escolha entre um grupo de girinos da outra espécie e um compartimento vazio, os girinos de R. icterica apresentaram distribuição aleatória, enquanto os girinos de R. ornata preferiram associar-se a girinos heteroespecíficos. Nossos resultados indicam que girinos de R. icterica preferem associar-se a coespecíficos, enquanto girinos de R. ornata podem agregar-se indiscriminadamente. Este estudo contribui para uma melhor compreensão do comportamento social de larvas de anuros.

RESUMO

Abstract: The effect of the hydrological cycle on the abundance of adults and larvae of the weevils Cyrtobagous salviniae and Cyrtobagous singularis in the Pantanal was tested and related to the host-plant abundance, limnological variables, and hydrological connectivity of 10 "bays" (lakes and ponds) along the Cuiabá River. Adults and larvae of C. salviniae were more abundant than C. singularis, and larvae and adult abundance differed significantly both within and between the two species. Adults and larvae of both species were more abundant in connected bays, but only C. salviniae responded to both connectivity and hydrological cycle, with the highest abundances during the high-water and rising-water periods for adults and larvae, respectively. Abundance of C. singularis was negatively related to the predominance of C. salviniae, and populations of adults and larvae of both species were slightly and negatively related to the limnological variables and host-plant abundance. The results showed that the temporal variation in larval and adult abundance and dominance of C. salviniae is influenced by hydrological cycle and connectivity, but not by limnological variables and host-plant abundance.

Resumo: O efeito do ciclo hidrológico sobre a abundância de adultos e larvas dos curculionídeos Cyrtobagous salviniae e Cyrtobagous singularis do Pantanal foi testado e relacionado com a abundância das plantas hospedeiras, variáveis limnológicas e conectividade hidrológica de 10 baías do rio Cuiabá. Os adultos e larvas de C. salviniae foram mais abundantes do que C. singularis, e a abundância de larvas e adultos diferiu significativamente intra e interespecificamente. Adultos e larvas de ambas espécies foram mais abundantes em baías conectadas, mas apenas C. salviniae respondeu ao ciclo hidrológico, com a maior abundância de adultos durante o período de cheia, e maior abundância de larvas na enchente. A abundância de C. singularis foi relacionada negativamente com a predominância de C. salviniae, e a abundância de adultos e larvas de ambas espécies foi fraca e negativamente relacionada com as variáveis limnológicas e abundância das plantas hospedeiras. Os resultados demonstraram que a variação temporal na abundância de larvas e adultos e a dominância de C. salviniae foram influenciadas pela conectividade e ciclo hidrológico, mas não pelas variáveis limnológicas e abundância das macrófitas aquáticas.

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We describe four new Glaphyrosoma species: G. brevivaginalis n. sp., G. huasteca n. sp., G. paragracile n. sp. and G. unumtympana n. sp. We redescribe and provide new distributional data for G. gracile, G. mexicanum and G. stephanosoltis. The subfamily status to tribe Glaphyrosomatini is proposed and a key to identify the genera is provided. The key to Glaphyrosoma species is updated to include the species here described. Finally, we present karyotype data and drumming information for selected species.

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Speciation is a multifactorial process with factors acting at different scales of space and time. Trophic niche segregation has promoted the diversification of cichlids fishes in lentic (lacustrine) environments, whether this is also the case in lotic (riverine) systems remains unknown. Herichthys is the genus of cichlids with the most boreal distribution in the Americas comprising 12 currently recognized species, most micro-endemic and only two with a wide distribution. In the present work, we analyzed the stomach content and lower pharyngeal jaw morphologies of the species of the genus to evaluate the possible role of feeding ecology in the diversification of the group. Trophic strategies varied widely, including omnivores, piscivores, invertivores, molluskivores, detritivores, herbivores and algivores. Low values of Pianka's index of niche overlap were found in the sympatric micro-endemic species, while in the widely distributed species the indices ranged from low to very high. The analysis of lower pharyngeal jaw morphologies allowed discriminating a shape associated with piscivorous species from other foraging groups. The results of this study suggest that trophic niche segregation is a factor that could promotes diversification within the genus Herichthys although additional studies need to be performed to fully understand the speciation process in this group of Neotropical cichlid fishes.

La especiación es un proceso con múltiples factores que actúan a diferentes escalas de espacio y tiempo. La segregación de nichos tróficos es un proceso que ha promovido la diversificación en cíclidos en entornos lacustres, pero en el caso de los ríos no está claro. Herichthys es un género de cíclidos cuya distribución es la más boreal en América, el cual comprende 12 especies actualmente reconocidas, la mayoría microendémicas y solo dos con una amplia distribución. En el presente trabajo, se analizó el contenido estomacal y las morfologías de la mandíbula faríngea inferior de las especies del género para compararlas y evaluar su posible papel en la diversificación del grupo. La dieta en dichas especies es muy variada e incluyó tanto especies que pueden ser consideradas omnívoras como especialistas. Se encontraron valores bajos del índice de solapamiento alimentario (índice de Pianka) en las especies simpátricas microendémicas, mientras que en las especies ampliamente distribuidas el índice fue muy variable. El análisis de morfometría geométrica de la mandíbula faríngea inferior permite discriminar dos formas principales, una que incluye la especie piscívora y otra que incluye a los otros grupos alimentarios. Los resultados encontrados en este estudio sugieren que la segregación de nicho trófico es un factor que promueve claramente la diversificación dentro del género Herichthys, aunque se deben realizar estudios adicionales para comprender completamente el proceso de especiación en este grupo de peces neotropicales.

RESUMO

Thermal tolerances of organisms play a role in defining geographic ranges and occurrence of species. In Cuba, three sympatric species of Anolis lizards (Anolis allogus, Anolis homolechis and Anolis sagrei) inhabit different thermal microhabitats. A previous study found that these species showed distinct gene expression patterns in response to temperature stimuli, suggesting the genetically distinct thermal physiology among species. To investigate whether the Anolis species inhabiting locally distinct thermal habitats diverge their thermal tolerances, we first conducted behavioural experiments to analyse the temperatures at which the three Anolis species escape from heat source. Then, for each of the three species, we isolated cDNA encoding a putative molecular heat sensor, transient receptor potential ion channel ankyrin 1 (TRPA1), which has been suggested to play a role on eliciting behavioural responses to heat stimuli. We performed electrophysiological analysis to quantify activation temperature of Anolis TRPA1 to see whether the pattern of divergence in TRPA1 responses is congruent with that of divergence in behavioural responses. We found that temperatures triggering behavioural and TRPA1 responses were significantly lower for shade-dwelling species (A. allogus) than for sun-dwelling species (A. homolechis and A. sagrei). The ambient temperature of shade habitats where A. allogus occurs stays relatively cool compared to that of open habitats where A. homolechis and A. sagrei occur and bask. The high temperature thresholds of A. homolechis and A. sagrei may reflect their heat tolerances that would benefit these species to inhabit the open habitats.

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How animals achieve evolutionary adaptation to different thermal environments is an important issue for evolutionary biology as well as for biodiversity conservation in the context of recent global warming. In Cuba, three sympatric species of Anolis lizards (Anolis allogus, A. homolechis and A. sagrei) inhabit different thermal microhabitats, thereby providing an excellent opportunity to examine how they have adapted to different environmental temperatures. Here, we performed RNA-seq on the brain, liver and skin tissues from these three species to analyse their transcriptional responses at two different temperatures. In total, we identified 400, 816 and 781 differentially expressed genes (DEGs) between the two temperatures in A. allogus, A. homolechis and A. sagrei, respectively. Only 62 of these DEGs were shared across the three species, indicating that global transcriptional responses have diverged among these species. Gene ontology (GO) analysis showed that large numbers of ribosomal protein genes were DEGs in the warm-adapted A. homolechis, suggesting that the upregulation of protein synthesis is an important physiological mechanism in the adaptation of this species to hotter environments. GO analysis also showed that GO terms associated with circadian regulation were enriched in all three species. A gene associated with circadian regulation, Nr1d1, was detected as a DEG with opposite expression patterns between the cool-adapted A. allogus and the hot-adapted A. sagrei. Because the environmental temperature fluctuates more widely in open habitats than in forests throughout the day, the circadian thermoregulation could also be important for adaptation to distinct thermal habitats.

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Tadpoles of two sympatric anurans, Bufo gargarizans Cantor, 1842 and Rana zhenhaiensis Ye, Fei & Matsui, 1995, were used as model organisms to examine the effects of different levels of tail loss on swimming performance and survival. On average, B. gargarizans tadpoles were shorter and had smaller tails and body mass than R. zhenhaiensis. After 75% tail loss, the survival rate of experimental and control B. gargarizans tadpoles, and of experimental tadpoles of the two species, differed significantly; the number of tadpoles surviving a complete impairment of their swimming ability did not differ between B. gargarizans and R. zhenhaiensis. After 50% tail loss, the swimming performance (swimming speed, maximum distance and number of stops) of the two species was significantly affected. However, the adverse influence of tail loss on the swimming speed of B. gargarizans tadpoles was greater compared to R. zhenhaiensis tadpoles. Our data indicates that a 50% tail loss results in swimming costs for B. gargarizans and R. zhenhaiensis tadpoles, and that 75% tail loss decreases the survival rate of B. gargarizans tadpoles. Therefore, we conclude that tadpoles of different species and with the same degree of tail loss use distinctive strategies to improve individual fitness in the face of predator pressure.

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RESUMO

Tadpoles of two sympatric anurans, Bufo gargarizans Cantor, 1842 and Rana zhenhaiensis Ye, Fei & Matsui, 1995, were used as model organisms to examine the effects of different levels of tail loss on swimming performance and survival. On average, B. gargarizans tadpoles were shorter and had smaller tails and body mass than R. zhenhaiensis. After 75% tail loss, the survival rate of experimental and control B. gargarizans tadpoles, and of experimental tadpoles of the two species, differed significantly; the number of tadpoles surviving a complete impairment of their swimming ability did not differ between B. gargarizans and R. zhenhaiensis. After 50% tail loss, the swimming performance (swimming speed, maximum distance and number of stops) of the two species was significantly affected. However, the adverse influence of tail loss on the swimming speed of B. gargarizans tadpoles was greater compared to R. zhenhaiensis tadpoles. Our data indicates that a 50% tail loss results in swimming costs for B. gargarizans and R. zhenhaiensis tadpoles, and that 75% tail loss decreases the survival rate of B. gargarizans tadpoles. Therefore, we conclude that tadpoles of different species and with the same degree of tail loss use distinctive strategies to improve individual fitness in the face of predator pressure.(AU)

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Between January 2007 and December 2010, the abundance of medium-sized mammals was studied, with special focus on the Molina's hog-nosed skunk, Conepatus chinga (Molina, 1782), at four locations in southern Brazil. In this study, transect line methodology was used to obtain data for Distance Analyses. Transects were traveled by car at night, searching with spotlights along the edges of secondary roads in agricultural landscapes. Along 1,811 km, we obtained 620 observations of 20 mammal species. The most common species was the exotic European hare, Lepus europaeus (Pallas, 1778); the highest abundance estimated for South America was observed in one of the study areas, where its density was estimated as 32 individuals/km². Carnivores were the most commonly recorded mammals, represented by 10 species and comprising 51% of all observations. Molina's hog-nosed skunk occurred in all study areas, but occurred in sufficient numbers to obtain density estimates in only two of the areas. We estimated 1.4 to 3.8 individuals/km², in the first density estimate made by the transect method for a member of Conepatus in the Neotropics. These values are similar to those estimated for North American species of Mephitidae. In Brazil, C. chinga is apparently more abundant in the Pampa biome than in the grasslands of the Atlantic Forest. For two other carnivores, Lycalopex gymnocercus (Fisher, 1814) and Cerdocyon thous (Linnaeus, 1766), we estimated preliminary densities that were similar to those previously cited for different regions.

Entre janeiro de 2007 e dezembro de 2010 a abundância de mamíferos de médio porte foi estudada, com especial ênfase no zorrilho Conepatus chinga (Molina, 1782) em quatro locais no sul do Brasil. Neste estudo, foi utilizada a metodologia de transectos lineares de forma a obter dados para análises de densidade com uso do software Distance. Os transectos foram percorridos de carro, à noite, procurando por animais na periferia de estradas secundárias, com o uso de holofotes de longo alcance. Em 1.811 km percorridos, foram obtidos 620 registros de 20 espécies de mamíferos. A espécie mais comum foi a lebre européia Lepus europaeus (Pallas, 1778), para a qual, em uma das áreas estudadas, foi obtida a maior estimativa de abundância já registrada para a América do Sul, com uma densidade estimada de 32 indivíduos por km². Carnivora foi a ordem mais comumente registrada, representada por 10 espécies que, juntas, compreenderam 51% de todas as visualizações. O zorrilho ocorreu em todas as áreas estudadas, embora só tenha sido registrado em número suficiente para a obtenção de estimativas de densidade em duas destas áreas. A densidade do zorrilho foi estimada em 1,4 a 3,8 indivíduos por km², sendo esta a primeira estimativa por transectos lineares do gênero Conepatus na região Neotropical. Estes valores são similares aos observados para mefitídeos norte-americanos. No Brasil, C. chinga é aparentemente mais abundante no Pampa do que nos campos de altitude da Mata Atlântica. Para outras duas espécies, Lycalopex gymnocercus (Fisher, 1814) e Cerdocyon thous (Linnaeus, 1766), foram feitas estimativas preliminares de densidade que apontaram valores semelhantes aos de outras regiões de ocorrência das espécies.

RESUMO

Between January 2007 and December 2010, the abundance of medium-sized mammals was studied, with special focus on the Molina's hog-nosed skunk, Conepatus chinga (Molina, 1782), at four locations in southern Brazil. In this study, transect line methodology was used to obtain data for Distance Analyses. Transects were traveled by car at night, searching with spotlights along the edges of secondary roads in agricultural landscapes. Along 1,811 km, we obtained 620 observations of 20 mammal species. The most common species was the exotic European hare, Lepus europaeus (Pallas, 1778); the highest abundance estimated for South America was observed in one of the study areas, where its density was estimated as 32 individuals/km². Carnivores were the most commonly recorded mammals, represented by 10 species and comprising 51% of all observations. Molina's hog-nosed skunk occurred in all study areas, but occurred in sufficient numbers to obtain density estimates in only two of the areas. We estimated 1.4 to 3.8 individuals/km², in the first density estimate made by the transect method for a member of Conepatus in the Neotropics. These values are similar to those estimated for North American species of Mephitidae. In Brazil, C. chinga is apparently more abundant in the Pampa biome than in the grasslands of the Atlantic Forest. For two other carnivores, Lycalopex gymnocercus (Fisher, 1814) and Cerdocyon thous (Linnaeus, 1766), we estimated preliminary densities that were similar to those previously cited for different regions.

Entre janeiro de 2007 e dezembro de 2010 a abundância de mamíferos de médio porte foi estudada, com especial ênfase no zorrilho Conepatus chinga (Molina, 1782) em quatro locais no sul do Brasil. Neste estudo, foi utilizada a metodologia de transectos lineares de forma a obter dados para análises de densidade com uso do software Distance. Os transectos foram percorridos de carro, à noite, procurando por animais na periferia de estradas secundárias, com o uso de holofotes de longo alcance. Em 1.811 km percorridos, foram obtidos 620 registros de 20 espécies de mamíferos. A espécie mais comum foi a lebre européia Lepus europaeus (Pallas, 1778), para a qual, em uma das áreas estudadas, foi obtida a maior estimativa de abundância já registrada para a América do Sul, com uma densidade estimada de 32 indivíduos por km². Carnivora foi a ordem mais comumente registrada, representada por 10 espécies que, juntas, compreenderam 51% de todas as visualizações. O zorrilho ocorreu em todas as áreas estudadas, embora só tenha sido registrado em número suficiente para a obtenção de estimativas de densidade em duas destas áreas. A densidade do zorrilho foi estimada em 1,4 a 3,8 indivíduos por km², sendo esta a primeira estimativa por transectos lineares do gênero Conepatus na região Neotropical. Estes valores são similares aos observados para mefitídeos norte-americanos. No Brasil, C. chinga é aparentemente mais abundante no Pampa do que nos campos de altitude da Mata Atlântica. Para outras duas espécies, Lycalopex gymnocercus (Fisher, 1814) e Cerdocyon thous (Linnaeus, 1766), foram feitas estimativas preliminares de densidade que apontaram valores semelhantes aos de outras regiões de ocorrência das espécies.

RESUMO

This study aimed to analyze the seasonal variation in diet composition and foraging behavior of Tropidurus hispidus (Spix, 1825) and T. semitaeniatus (Spix, 1825), as well as measurement of the foraging intensity (number of moves, time spent stationary, distance traveled and number of attacks on prey items) in a caatinga patch on the state of Rio Grande do Norte, Brazil. Hymenoptera/Formicidae and Isoptera predominated in the diet of both species during the dry season. Opportunistic predation on lepidopteran larvae, coleopteran larvae and adults, and orthopteran nymphs and adults occurred in the wet season; however, hymenopterans/Formicidae were the most important prey items. The number of food items was similar between lizard species in both seasons; however the overlap for number of prey was smaller in the wet season. Preys ingested by T. hispidus during the wet season were also larger than those consumed by T. semitaeniatus. Seasonal comparisons of foraging intensity between the two species differed, mainly in the wet season, when T. hispidus exhibited less movement and fewer attacks on prey, and more time spent stationary if compared to T. semitaeniatus. Although both lizards are sit-and-wait foragers, T. semitaeniatus is more active than T. hispidus. The diet and foraging behavior of T. hispidus and T. semitaeniatus overlap under limiting conditions during the dry season, and are segregative factors that may contribute to the coexistence of these species in the wet season.

Este estudo objetivou analisar a variação sazonal na composição da dieta e no comportamento de forrageamento de Tropidurus hispidus (Spix, 1825) e T. semitaeniatus (Spix, 1825) e medir a intensidade de forrageamento (número de movimentos, tempo gasto parado, distância percorrida e número de ataques sobre itens-presa) destas espécies em uma área do bioma caatinga no estado do Rio Grande do Norte, Brasil. Hymenoptera/Formicidae e Isoptera predominaram na dieta de ambas as espécies durante a estação seca. A predação oportunística de larvas de Lepidoptera, larvas/adultos de Coleoptera e ninfas/adultos de Orthoptera ocorreu na estação chuvosa, contudo as formigas foram os itens-presa mais importantes. O número de itens alimentares foi similar entre as espécies de lagartos em ambas as estações; no entanto a sobreposição para o número de presas foi menor na estação chuvosa. As presas ingeridas durante a estação chuvosa por T. hispidus foram maiores do que aquelas de T. semitaeniatus. As comparações sazonais da intensidade de forrageamento entre as duas espécies mostraram diferenças, principalmente na estação chuvosa, quando T. hispidus apresentou menos movimentos e ataques sobre presas, e mais tempo gasto parado comparado a T. semitaeniatus. Embora ambos os lagartos sejam forrageadores senta-e-espera, T. semitaeniatus é mais ativo do que T. hispidus. A dieta e o comportamento de forrageamento de T. hispidus e T. semitaeniatus mostram sobreposição sob condições limitantes durante a estação seca, e são fatores segregativos que podem contribuir para a coexistência dessas espécies na estação chuvosa.

RESUMO

This study aimed to analyze the seasonal variation in diet composition and foraging behavior of Tropidurus hispidus (Spix, 1825) and T. semitaeniatus (Spix, 1825), as well as measurement of the foraging intensity (number of moves, time spent stationary, distance traveled and number of attacks on prey items) in a caatinga patch on the state of Rio Grande do Norte, Brazil. Hymenoptera/Formicidae and Isoptera predominated in the diet of both species during the dry season. Opportunistic predation on lepidopteran larvae, coleopteran larvae and adults, and orthopteran nymphs and adults occurred in the wet season; however, hymenopterans/Formicidae were the most important prey items. The number of food items was similar between lizard species in both seasons; however the overlap for number of prey was smaller in the wet season. Preys ingested by T. hispidus during the wet season were also larger than those consumed by T. semitaeniatus. Seasonal comparisons of foraging intensity between the two species differed, mainly in the wet season, when T. hispidus exhibited less movement and fewer attacks on prey, and more time spent stationary if compared to T. semitaeniatus. Although both lizards are sit-and-wait foragers, T. semitaeniatus is more active than T. hispidus. The diet and foraging behavior of T. hispidus and T. semitaeniatus overlap under limiting conditions during the dry season, and are segregative factors that may contribute to the coexistence of these species in the wet season.

Este estudo objetivou analisar a variação sazonal na composição da dieta e no comportamento de forrageamento de Tropidurus hispidus (Spix, 1825) e T. semitaeniatus (Spix, 1825) e medir a intensidade de forrageamento (número de movimentos, tempo gasto parado, distância percorrida e número de ataques sobre itens-presa) destas espécies em uma área do bioma caatinga no estado do Rio Grande do Norte, Brasil. Hymenoptera/Formicidae e Isoptera predominaram na dieta de ambas as espécies durante a estação seca. A predação oportunística de larvas de Lepidoptera, larvas/adultos de Coleoptera e ninfas/adultos de Orthoptera ocorreu na estação chuvosa, contudo as formigas foram os itens-presa mais importantes. O número de itens alimentares foi similar entre as espécies de lagartos em ambas as estações; no entanto a sobreposição para o número de presas foi menor na estação chuvosa. As presas ingeridas durante a estação chuvosa por T. hispidus foram maiores do que aquelas de T. semitaeniatus. As comparações sazonais da intensidade de forrageamento entre as duas espécies mostraram diferenças, principalmente na estação chuvosa, quando T. hispidus apresentou menos movimentos e ataques sobre presas, e mais tempo gasto parado comparado a T. semitaeniatus. Embora ambos os lagartos sejam forrageadores senta-e-espera, T. semitaeniatus é mais ativo do que T. hispidus. A dieta e o comportamento de forrageamento de T. hispidus e T. semitaeniatus mostram sobreposição sob condições limitantes durante a estação seca, e são fatores segregativos que podem contribuir para a coexistência dessas espécies na estação chuvosa.

RESUMO

We studied the feeding ecology of two Hylinae anurans (Hypsiboas raniceps and Scinax acuminatus), living sympatrically and syntopically in the Pantanal of Miranda, Mato Grosso do Sul State, Brazil. The two hylid species had similar relative mouth width but differed in body size. The diet of the two frog species were composed of arthropodan prey. Both species consumed 11 different prey types, of which seven were common among them. Hypsiboas raniceps had a larger niche breadth (B A = 0.64) than S. acuminatus (B A = 0.48). Trophic niche overlap among frog species was 60.7 percent. Our data are suggestive that although for many anurans the diet simply tend to reflect prey availability in the microhabitat, these two frog species, despite sharing similar microhabitat and period of activity (thus potentially exposed to a similar array of preys), tends to differ somewhat in diet (about 40 percent) which may result from some intrinsic ecological aspects to each of them (e.g. ecophysiology) and/or differences in body size.

Nós estudamos a ecologia trófica de duas espécies de anuros hilídeos (Hypsiboas raniceps e Scinax acuminatus), vivendo simpátrica e sintopicamente no Pantanal do Miranda, Mato Grosso do Sul, Brasil. As duas espécies possuíram largura da boca similar mas diferiram no tamanho do corpo. Ambas as espécies consumiram artrópodos, distribuídos em 11 diferentes tipos de presas das quais sete foram comuns entre elas. A amplitude do nicho trófico de H. raniceps (B A = 0,64) foi relativamente superior aquela de S. acuminatus (B A = 0,48). A sobreposição do nicho trófico entre as espécies foi de 60,7 por cento. Embora, para muitas espécies, a dieta tenda a refletir a disponibilidade de presas no microhabitat, nossos resultados sugerem que estas duas espécies de anuros, apesar de partilharem microhabitat e período de atividade (e, portanto, potencialmente estarem expostas ao mesmo universo de presas) tendem a diferir em algum grau nas suas dietas (cerca de 40 por cento) o que pode ser resultante de alguns aspectos ecológicos intrínsecos a cada uma delas (e.g. ecofisiologia) e/ou diferenças no tamanho corpóreo.

Assuntos

RESUMO

We studied the feeding ecology of two Hylinae anurans (Hypsiboas raniceps and Scinax acuminatus), living sympatrically and syntopically in the Pantanal of Miranda, Mato Grosso do Sul State, Brazil. The two hylid species had similar relative mouth width but differed in body size. The diet of the two frog species were composed of arthropodan prey. Both species consumed 11 different prey types, of which seven were common among them. Hypsiboas raniceps had a larger niche breadth (B A = 0.64) than S. acuminatus (B A = 0.48). Trophic niche overlap among frog species was 60.7 %. Our data are suggestive that although for many anurans the diet simply tend to reflect prey availability in the microhabitat, these two frog species, despite sharing similar microhabitat and period of activity (thus potentially exposed to a similar array of preys), tends to differ somewhat in diet (about 40%) which may result from some intrinsic ecological aspects to each of them (e.g. ecophysiology) and/or differences in body size.

Nós estudamos a ecologia trófica de duas espécies de anuros hilídeos (Hypsiboas raniceps e Scinax acuminatus), vivendo simpátrica e sintopicamente no Pantanal do Miranda, Mato Grosso do Sul, Brasil. As duas espécies possuíram largura da boca similar mas diferiram no tamanho do corpo. Ambas as espécies consumiram artrópodos, distribuídos em 11 diferentes tipos de presas das quais sete foram comuns entre elas. A amplitude do nicho trófico de H. raniceps (B A = 0,64) foi relativamente superior aquela de S. acuminatus (B A = 0,48). A sobreposição do nicho trófico entre as espécies foi de 60,7 %. Embora, para muitas espécies, a dieta tenda a refletir a disponibilidade de presas no microhabitat, nossos resultados sugerem que estas duas espécies de anuros, apesar de partilharem microhabitat e período de atividade (e, portanto, potencialmente estarem expostas ao mesmo universo de presas) tendem a diferir em algum grau nas suas dietas (cerca de 40%) o que pode ser resultante de alguns aspectos ecológicos intrínsecos a cada uma delas (e.g. ecofisiologia) e/ou diferenças no tamanho corpóreo.

RESUMO

Climate, altitude and vegetation are usually considered as limiting factors in plant and animal distribution. Among vertebrates, climate and vegetation have consistently been considered as major determinants of geographical distributions. Here we analyzed the role of climate and the vegetation in limiting the geographical range of Atlantic Forest species of Drymophila Swainson, 1824 and assessed the performance of discriminant analysis to model the distribution of sympatric taxa. From each empirical point (locality) we recorded the values for nine climatic variables and the type of vegetation. The climatic data were obtained from a climate database elaborated by the Laboratório de Vertebrados and vegetation data from the ecoregions digital map of Latin America. The overlap of the climatic distribution map with the ecoregion map suggested that both factors are important in limiting the geographical range of Drymophila species. The discriminant approach, as applied here, was not satisfactory when compared with similar analysis carried out on parapatric species.

RESUMO

Climate, altitude and vegetation are usually considered as limiting factors in plant and animal distribution. Among vertebrates, climate and vegetation have consistently been considered as major determinants of geographical distributions. Here we analyzed the role of climate and the vegetation in limiting the geographical range of Atlantic Forest species of Drymophila Swainson, 1824 and assessed the performance of discriminant analysis to model the distribution of sympatric taxa. From each empirical point (locality) we recorded the values for nine climatic variables and the type of vegetation. The climatic data were obtained from a climate database elaborated by the Laboratório de Vertebrados and vegetation data from the ecoregions digital map of Latin America. The overlap of the climatic distribution map with the ecoregion map suggested that both factors are important in limiting the geographical range of Drymophila species. The discriminant approach, as applied here, was not satisfactory when compared with similar analysis carried out on parapatric species.

RESUMO

Climate, altitude and vegetation are usually considered as limiting factors in plant and animal distribution. Among vertebrates, climate and vegetation have consistently been considered as major determinants of geographical distributions. Here we analyzed the role of climate and the vegetation in limiting the geographical range of Atlantic Forest species of Drymophila Swainson, 1824 and assessed the performance of discriminant analysis to model the distribution of sympatric taxa. From each empirical point (locality) we recorded the values for nine climatic variables and the type of vegetation. The climatic data were obtained from a climate database elaborated by the Laboratório de Vertebrados and vegetation data from the ecoregions digital map of Latin America. The overlap of the climatic distribution map with the ecoregion map suggested that both factors are important in limiting the geographical range of Drymophila species. The discriminant approach, as applied here, was not satisfactory when compared with similar analysis carried out on parapatric species.