Plant Selection and Seasonal Patterns of Vocal Activity in Two Populations of the Bromeligen Treefrog Scinax perpusillus (Anura, Hylidae)

Reproductive site selection in a bromeliad breeding treefrog suggests complex evolutionary trade-offs

Reproductive site selection is a key determinant of fitness in many taxa. However, if the site characteristics that enhance offspring survival are detrimental to the parent's survival or mating success, then complex evolutionary trade-offs occur. In the Brazilian Atlantic Forest, males of the treefrog species Aparasphenodon arapapa use the temporary water bodies in forest-floor bromeliads to court and mate. Males fit tightly into the plant with the head blocking the access and after mating, stay in the bromeliad with the offspring. Since evaporation of the temporary water body inside the bromeliad results in reproductive failure, we expected that males would simply choose the largest bromeliad tanks with the most water. We found that although this was generally true, males seemed to avoid both very large bromeliads and very high water volumes. Field observations suggested a trade-off mechanism for this pattern, whereby very large and water-filled tanks would reduce the male's ability to effectively seal the tank entrance, avoid predation, or call to mating females. Males also avoided bromeliads with leaf litter and preferred slightly inclined plants. Our results indicate that during reproductive site selection, this bromeliad-breeder needs to engage in complex trade-offs between selection pressures, balancing water requirements against the need for defense and potentially, the ability to attract a mate.

Jumping into a trap: high prevalence of chytrid fungus in the preferred microhabitats of a bromeliad-specialist frog

The chytrid fungus Batrachochytrium dendrobatidis (Bd) has been identified as a major threat to several amphibian populations in tropical forests. Amphibians that inhabit the phytotelmata (water tanks) of bromeliads may be especially at risk of Bd infection since the humid, environmentally buffered microhabitat that they prefer might also be favorable for Bd persistence on the host. To test this hypothesis, we sampled adults and tadpoles of the bromeligenous anuran Phyllodytes edelmoi (endemic to the northern Brazilian Atlantic Forest) from the bromeliad Portea leptantha for Bd, using qPCR. We also analyzed 8 bromeliad characteristics: water tank temperature and pH, canopy closure, tank diameter, number of leaves, bromeliad maximum column depth to store water, bromeliad relative volume, and season. Adult frogs preferentially selected bromeliads with a smaller diameter, more leaves and a relatively higher volume of water. We found that Bd was more prevalent in frogs inhabiting bromeliad phytotelmata with smaller diameters, suggesting that the behavioral preferences of P. edelmoi may be driving Bd infection patterns. Therefore, species such as P. edelmoi will be trapped by their own natural history traits.

Bromeliad selection by two salamander species in a harsh environment

Bromeliad phytotelmata are frequently used by several Neotropical amphibian taxa, possibly due to their high humidity, microclimatic stability, and role as a refuge from predators. Indeed, the ability of phytotelmata to buffer against adverse environmental conditions may be instrumental in allowing some amphibian species to survive during periods of environmental change or to colonize sub-optimal habitats. Association between bromeliad traits and salamanders has not been studied at a fine scale, despite the intimate association of many salamander species with bromeliads. Here, we identify microhabitat characteristics of epiphytic bromeliads used by two species of the Bolitoglossa morio group (B. morio and B. pacaya) in forest disturbed by volcanic activity in Guatemala. Specifically, we measured multiple variables for bromeliads (height and position in tree, phytotelma water temperature and pH, canopy cover, phytotelma size, leaf size, and tree diameter at breast height), as well as salamander size. We employed a DNA barcoding approach to identify salamanders. We found that B. morio and B. pacaya occurred in microsympatry in bromeliads and that phytotelmata size and temperature of bromeliad microhabitat were the most important factors associated with the presence of salamanders. Moreover, phytotelmata with higher pH contained larger salamanders, suggesting that larger salamanders or aggregated individuals might modify pH. These results show that bromeliad selection is nonrandom with respect to microhabitat characteristics, and provide insight into the relationship between salamanders and this unique arboreal environment.

Habitat selection by anurofauna community at rocky seashore in coastal Atlantic Forest, Southeastern Brazil

Rocky seashores are low granitic hills distributed along the southeastern Brazilian coast with xeric-like vegetation due to the shallow soil. Knowledge on amphibian communities and their reproductive patterns is especially reduced on this kind of environment. Herein, we present a framework of two years monitoring an amphibian community at a rocky seashore environment located at the protected area of Parque Estadual da Serra da Tiririca, municipality of Niterói, state of Rio de Janeiro, Brazil. We conducted diurnal and nocturnal searches for frogs in tank bromeliads, rocky surface and shrubby vegetation. Annual pattern of breeding activity of anurans was also estimated. Individuals of the most abundant tank-bromeliad, Alcantarea glaziouana were collected and measured according to several variables to understanding the selection of bromeliads by frogs. We checked the influence of the environmental conditions on amphibian abundance, association between the bromeliads measures, and the water storage in the tank. We recorded the species: Scinax aff. x-signatus; S. cuspidatus; S. littoreus; Thoropa miliaris and Gastrotheca sp. Bromeliads were the preferential habitat used by anurans. The nocturnal habit was predominant for all species and during diurnal searches, the specimens were found sheltered in bromeliads axils. The number of calling males as well as amphibian abundance was associated with the rainiest and warmest period of the year. The species S. littoreus was observed in breeding activity in the majority of sample period. Adult calling males of T. miliaris were observed especially in the rainy season. Rainfall and temperature combined are positively correlated to the total number of captured amphibians. However, individually, rainfall was not significantly correlated, while temperature was positively correlated with the amphibian abundance. Water storage capacity by bromeliads was correlated to characteristics and size of the plant. In the rainy season, the height of the plant and the diameter on top view were correlated with the occurrence of amphibians, while during the driest period there was no correlation among variables and the bromeliad usage by amphibians. Recorded species were strongly associated to the Atlantic Forest domain. Nevertheless, the occupation of rocky seashores by anurans may be more associated with the specialized reproductive modes presented by species, since there is no permanent water available in ponds or streams.

The choice of bromeliads as a microhabitat by Scinax argyreornatus (Anura, Hylidae)

The association of anurans to bromeliads presents different degrees of interaction such as: eventual, obligatory and bromeligen. The frog species Scinax argyreornatus shows a regular association with these plants. The goal of this study is to characterise the degree of association between the frog S. argyreornatus to different species of bromeliads. We identified which species of bromeliad is regularly associated with S. argyreornatus and recognised which factors interfere with this association preference. We analysed the Concentration of Relative Dominance of frogs per bromeliad species. As possible criteria for frog association preference to different bromeliads species we established the analysis of leaves number, length and width, number of leaf axils, stored water in the axils, pH and relative humidity, among other organographic components. Our observations were analyzed by ANOVA followed by the Tukey test. We also evaluated the preference for association by the constancy of Bodenheimer. The correlation matrix indicated that the relative humidity is the factor responsible for the frog-bromeliads association, except for Aechmea sp.. However Aechmea sp. was the species with greater constancy of occupation followed by Quesnelia arvensis and Neoregelia johannis. According to our statistical results, Aechmea sp. and Q. arvensis are not different regarding organographic parameters, but differ from N. johannis. Our observations suggest that the bromeliads organographic structure and the relative humidity are key conditions which influence the preferences of S. argyreornatus to bromeliad species, while the other features showed no correlation.

Anurofauna da floresta de restinga do Parque Estadual da Ilha do Cardoso, Sudeste do Brasil: composição de espécies e uso de sítios reprodutivos

O Parque Estadual da Ilha do Cardoso é uma área de grande importância para a conservação, pois abriga diferentes ecossistemas costeiros, como manguezais, dunas, restingas e mata atlântica de encosta, que, historicamente, estiveram sob forte pressão antrópica. A identificação duvidosa e a descoberta de novas espécies da anurofauna em ambientes costeiros, evidencia a escassez de estudos nessas regiões. Inventariamos a anurofauna da floresta de restinga do Parque Estadual da Ilha do Cardoso entre outubro de 2005 e outubro de 2007, por meio de 25 viagens mensais de dois dias de duração. Foram utilizados dois métodos: procura visual ativa em uma parcela permanente de 10 ha e procura visual e auditiva em nove sítios de reprodução. A anurofauna da área de estudo é composta por 17 espécies pertencentes às famílias Bufonidae (2 espécies), Craugastoridae (1), Hylidae (10), Leiuperidae (1), Leptodactylidae (2) e Microhylidae (1). A riqueza estimada foi de 17,77-17,96, o que mostra que nosso esforço amostral foi suficiente para registrar praticamente toda a anurofauna presente nessa formação de restinga. Essa riqueza pode ser considerada elevada quando comparada à de outras áreas de restinga, principalmente aquelas dotadas de vegetação menos estruturada. O predomínio da família Hylidae é característico de todas as localidades da região neotropical. Nenhuma espécie acha-se incluída nas listas de espécies ameaçadas de extinção do estado de São Paulo e do Brasil, mas Aparasphenodon bokermanni é considerada pouco conhecida ("Data Deficient") pela IUCN, e outras três espécies (Dendrophryniscus leucomystax, Haddadus binotatus e Itapotihyla langsdorffii) apresentam populações em declínio. Essas informações revelam a importância da floresta de restinga da Ilha do Cardoso para a manutenção de populações de anuros. Uma análise de agrupamento de 14 espécies que utilizaram nove sítios reprodutivos evidenciou três grupos, sendo o hidroperíodo o principal fator na determinação das similaridades. Conclui-se que a preservação de corpos d'água com diferentes fisionomias é essencial para a conservação de populações viáveis de anuros.

Herpetofauna de serrapilheira da Reserva Florestal de Morro Grande, Cotia (SP)

Apresentamos uma lista comentada de anuros, lagartos e serpentes registrados na Reserva Florestal de Morro Grande, Cotia, São Paulo. Essa lista inclui 27 espécies de anuros, cinco de lagartos e três de serpentes, capturados principalmente em armadilhas de interceptação e queda, mas também em encontros ocasionais no campo. Dezoito espécies de anuros capturadas em armadilhas de interceptação e queda foram utilizadas para a comparação de seis áreas da Reserva, três situadas em áreas de vegetação predominantemente secundária e três em áreas de vegetação predominantemente madura. As análises indicam que existe diferença significativa entre esses ambientes. Nós também comparamos a similaridade entre a anurofauna da Reserva Florestal de Morro Grande à de outras seis localidades do estado de São Paulo. A anurofauna da Reserva é mais similar àquela encontrada em outras localidades do planalto Atlântico, que àquela de localidades da baixada litorânea. O pequeno número de espécies de répteis amostrados não permitiu realizar as mesmas análises feitas para os anuros. A baixa abundância desses animais na floresta tornou a comparação entre áreas problemática. Existe uma evidente falta de informações sobre a biologia, distribuição e conservação da herpetofauna brasileira que poder ser mitigada através de inventários e monitoramento da fauna. O conhecimento da história natural, resultantes desses esforços, podem trazer argumentos sólidos para um planejamento eficiente de medidas conservacionistas.