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Temporal Fluctuations in Abundances of Anuran Amphibians in a Seasonal Amazonian Rainforest
Abstract
Anuran amphibians were sampled over a period of 6 yr at a site in seasonal lowland tropical rainforest in southern Amazonian Peru. Three sampling periods were at the beginning of the rainy seasons in 1986, 1989, and 1991; two were in the middle of the rainy seasons of 1986 and 1990, and one was in the dry season of 1989. Temperature and rainfall were recorded throughout all sampling periods. Sampling was done along a system of trails and in four series of quadrats. A total of 5236 individuals of 61 species of anurans was recorded during the sampling period. Analysis of the data on the 20 most abundant species reveals that anuran activity is closely correlated with the occurrence of peaks of heavy rainfall and not total rainfall during a sampling period. There is no compelling evidence for declines in anuran populations at this site. /// -- Se muestrearon los anfibios anuros en un sitio en el bosque lluvioso tropical estacional de tierras bajas en el sur del Perú amazónico a lo largo de un período de 6 años. Tres períodos de muestreo fueron en los comienzos de las estaciones de lluvia en 1986, 1989, y 1991; dos a mediados de las estaciones de lluvia en 1986 y 1990, y uno en la estación seca en 1989. Se registraron la temperatura y cantidad de lluvia a lo largo de todos los períodos de muestreo. El muestreo se realizó a lo largo de un sistema de trochas y en cuatro series de cuadrantes. Se registró un total de 5236 individuos de 61 especies de anuros durante el período de muestreado. El análisis de los datos de las 20 especies más abundantes revela que la actividad de los anuros está estrechamente correlacionada con la occurrencia de máximos de lluvia torrencial y no con la cantidad de lluvia durante un período de muestreo. No existe evidencia convincente de descensos en las poblaciones de anuros en este sitio.
... Este resultado se puede deber en gran medida a las altas precipitaciones durante los muestreos, superiores a los valores esperados. Las altas precipitaciones fueron una constante durante el muestreo y pueden también influir negativamente en la actividad de los animales (Toft, 1980;Allmon, 1991;Duellman, 1995;Inger, 2003;Ponssa, 2004;Watanabe et al. 2005). En la época de febrero disminuyó considerablemente la precipitación, pero no hubo diferencias en relación a las abundancias encontradas, y es posible que esta época más seca no fuera tan drástica como para afectar el comportamiento de actividad y abundancias de las poblaciones de anfibios o por el contrario tenga el mismo efecto negativo en las abundancias que las altas precipitaciones (Duellman, 1995). ...
... Las altas precipitaciones fueron una constante durante el muestreo y pueden también influir negativamente en la actividad de los animales (Toft, 1980;Allmon, 1991;Duellman, 1995;Inger, 2003;Ponssa, 2004;Watanabe et al. 2005). En la época de febrero disminuyó considerablemente la precipitación, pero no hubo diferencias en relación a las abundancias encontradas, y es posible que esta época más seca no fuera tan drástica como para afectar el comportamiento de actividad y abundancias de las poblaciones de anfibios o por el contrario tenga el mismo efecto negativo en las abundancias que las altas precipitaciones (Duellman, 1995). ...
Las características geográficas y ambientales de los Andes y la variación altitudinal han generado una amplia gama de hábitats y patrones ambientales que afectan la composición de las comunidades de anfibios. Las condiciones ambientales locales y la estructura vegetal influyen en la composición y la abundancia de anfibios. Adicionalmente, los gradientes ambientales y la geografía son determinantes en la estructura de los ensamblajes. Se analizó la composición y estructura del ensamblaje de anfibios en un rango altitudinal en la Reserva Río Blanco (Manizales, Colombia), entre los 2200 y 3600 m. de altura. Se realizaron 5 salidas de campo con una duración de 5 a 3 días por sitio. Se utilizaron muestreos por transectos y registro por encuentros visuales. Se encontró un total de 23 especies y 1012 individuos entre todas las especies. Teniendo en cuenta otros 3 registros adicionales, se obtuvo un total de 26 especies de anfibios. Con los estimadores de riqueza se alcanzó una buena efectividad del muestreo, el estimador ACE y Chao 1 estimaron entre 26 y 28 especies totales. Se encontró que la riqueza y la diversidad disminuyeron a medida que aumentó la altura. Se describen relaciones del recambio de especies entre los sitios de muestreo. No se encontró diferencia en las abundancias entre los diferentes meses de muestreo, sin embargo, las abundancias totales variaron entre las diferentes altitudes, además no se encontraron relaciones significativas entre la estructura del bosque y las abundancias. Los patrones de riqueza y diversidad encontrados para Río Blanco son considerados normales en comparación a los estudios de gradientes altitudinales con anfibios realizados en Colombia. La intervención del hábitat pudo haber influido en las abundancias y dominancias de algunas especies, también la mayoría de especies presentan alta especificidad de hábitats y de rangos altitudinales.
... The impact of environmental conditions on amphibian temporal diversity can be observed at two levels: the community level (through changes in species composition; Tonkin et al. 2017), and the population level (through effects on species activity; Segev et al. 2012). Most studies identified temperature (Bertoluci and Rodrigues 2002;Saenz et al. 2006;Schalk and Saenz 2016;Segev et al. 2012), rainfall (Duellman 1995;Bevier 1997;Gottsberger and Gruber 2004;Schalk and Saenz 2016) and humidity (Heinermann et al. 2015) as important drivers of amphibian species activity. Temporal activity may also be driven by intrinsic factors, with species exhibiting consistent peaks of activity between years (Duellman and Trueb 1994). ...
... We only found a slight seasonality in beta-diversity along streams. This weak seasonality contrasts with previous studies performed in tropical seasonal environments where clearer patterns of amphibian activity emerged (Duellman 1995;Marques et al. 2001;Bertoluci and Rodrigues 2002;Kupfer et al. 2005;Prado et al. 2005;Gardner et al. 2007;dos Santos et al. 2009;Lopez et al. 2011;da Vasconcelos et al. 2011;Segev et al. 2012;Schalk and Saenz 2016). Those studies were mostly performed in regions with marked seasonal precipitation. ...
Seasonality exerts strong pressures on biodiversity patterns. Yet, temporal beta-diversity is poorly studied in tropical systems, and the drivers of variability in amphibian activity and seasonality remain largely unknown. We quantified intra- and interannual variation in temporal beta-diversity relying on a nine-year, year-round survey (51 species, n > 23 000) performed in a protected area (Betampona, Madagascar). We assessed the dependence on climate of beta-diversity and abundance using a distance-based redundancy analysis and generalised linear mixed models, respectively. Despite the majority of species being preferentially active during one specific period, beta-diversity and abundance were more variable between years than within years. Temporal variation in beta-diversity was best explained by temperature (but climate accounted for only 2% of variation). Species abundance was best explained by temperature (for 32% of the tested species), monthly humidity (30%) and monthly rainfall (24%). We found no climatic dependence for 24% of the species. Our results suggest that studies focusing on species phenology can be misleading when based on single-year surveys even in seasonal systems. The high interannual variability in diversity may be due to an adaptive responses to an important regime of stochastic events. Given the direction of the relationships between weather and abundances, we predict that a large proportion of amphibians would suffer from climate change in Madagascar. We emphasise the need to account for multiple temporal scales in studies of tropical species composition and abundance to better understand species phenology and their response to climate change, and make targeted conservation actions more effective.
... While some anurans show long periods of calling activity and mating, known as prolonged breeders, others concentrate their reproduction during short time windows, even a few hours per year, and are known as explosive breeders [24]. In tropical regions, massive aggregations of explosive breeders generally involve multiple species simultaneously, leading to highly-diverse anuran communities [25][26][27][28]. Such phenomena typically occur in ephemeral ponds, which are sparsely distributed in tropical forests and are likely triggered under particular weather conditions. ...
... Yet, the structure and dynamics of these unique acoustic communities are still largely unknown probably because of their ephemeral nature, density and complexity. To our best knowledge, few studies have documented broad and generic patterns in explosive neotropical anurans, observing correlations between peaks of activity and the occurrence of heavy rainfall at the beginning of the rainy season [25,26,28], and only two studies have analysed their fine scale dynamics [23,27]. In the former study, the data collection was done by human calling surveys through a 4-month fieldwork in French Guiana. ...
Background:
Anurans largely rely on acoustic communication for sexual selection and reproduction. While multiple studies have focused on the calling activity patterns of prolonged breeding assemblages, species that concentrate their reproduction in short-time windows, explosive breeders, are still largely unknown, probably because of their ephemeral nature. In tropical regions, multiple species of explosive breeders may simultaneously aggregate leading to massive, mixed and dynamic choruses. To understand the environmental triggers, the phenology and composition of these choruses, we collected acoustic and environmental data at five ponds in French Guiana during a rainy season, assessing acoustic communities before and during explosive breeding events.
Results:
We detected in each pond two explosive breeding events, lasting between 24 and 70 h. The rainfall during the previous 48 h was the most important factor predicting the emergence of these events. During explosive breeding events, we identified a temporal factor that clearly distinguished pre- and mid-explosive communities. A common pool of explosive breeders co-occurred in most of the events, namely Chiasmocleis shudikarensis, Trachycephalus coriaceus and Ceratophrys cornuta. Nevertheless, the species composition was remarkably variable between ponds and for each pond between the first and the second events. The acoustic structure of explosive breeding communities had outlying levels of amplitude and unexpected low acoustic diversity, significantly lower than the communities preceding explosive breeding events.
Conclusions:
Explosive breeding communities were tightly linked with specific rainfall patterns. With climate change increasing rainfall variability in tropical regions, such communities may experience significant shifts in their timing, distribution and composition. In structurally similar habitats, located in the same region without obvious barriers, our results highlight the variation in composition across explosive breeding events. The characteristic acoustic structure of explosive breeding events stands out from the circadian acoustic environment being easily detected at long distance, probably reflecting behavioural singularities and conveying heterospecific information announcing the availability of short-lived breeding sites. Our data provides a baseline against which future changes, possibly linked to climate change, can be measured, contributing to a better understanding on the causes, patterns and consequences of these unique assemblages.
... The influence of environmental variables, such as rainfall, humidity, and temperature, on anuran reproduction is well known (Duellman, 1995;Brooke et al., 2000;Bertoluci and Rodrigues, 2002), although the extent and relative importance of specific factors are not clear in some cases (Boquimpani-Freitas et al., 2007). The breeding seasons of most anuran species in seasonal tropical environments are typically associated with the rainy season (Duellman, 1995;Bertoluci, 1998;Canelas and Bertoluci, 2007;Pirani et al., 2013). ...
... The influence of environmental variables, such as rainfall, humidity, and temperature, on anuran reproduction is well known (Duellman, 1995;Brooke et al., 2000;Bertoluci and Rodrigues, 2002), although the extent and relative importance of specific factors are not clear in some cases (Boquimpani-Freitas et al., 2007). The breeding seasons of most anuran species in seasonal tropical environments are typically associated with the rainy season (Duellman, 1995;Bertoluci, 1998;Canelas and Bertoluci, 2007;Pirani et al., 2013). There is usually a greater number of calling species during the rainy season since this behavior is strongly associated with reproduction (Bertoluci, 1998;Pirani et al., 2013). ...
Choruses are commonly observed phenomena in both terrestrial and aquatic environments and are the product of species vocalizing contemporaneously usually at dawn and dusk. This study analyzes the composition and temporal distribution of anuran choruses at a recently built artificial pond in Southeast Brazil. Data were collected using Passive Acoustic Monitoring devices set to record 24-hours per day, seven days a month, throughout an entire year (October 2016 to September 2017). A total of eight species participated in the studied choruses: Boana albopunctata , Boana faber , Boana lundii , Phyllomedusa burmeisteri , Physalaemus cuvieri , Rhinella ornata , Rhinella diptycha and Scinax aff. perereca . The number of species, call emission rate, temperature, and humidity were all higher before midnight and during the rainy season. The species differed significantly in mean call rate by hour at which they sang. Boana faber and B. albopunctata were the species with the greatest vocal activity in both seasons, and were predominantly responsible for initiating choruses in the rainy season, while R. diptycha and B. lundii initiated choruses in the dry season. Anuran choruses started around 18:30 h during the rainy season and varied according to the time of sunset, while they started later in the dry season and were not correlated with sunset time. There was a positive correlation between the number of species calling and the call emission rate per month in both seasons. The results show that the choruses were correlated with climatic factors and that the species distributed their vocalizations over time, thus reducing acoustic overlap.
... We also found in contrast to previous studies (Aichinger, 1987;Duellman, 1995), that the encounter rate of amphibians was higher during the dry than the wet season. However, this might relate to the fact that seasons were broken coarsely into 'wet' and 'dry' as oppose to multiple shorter periods as those by Duellman (1995) Additionally, survey sites in our study were located to avoided water bodies and situated in typical forest habitat, whereas Aichinger (1987) specifically targeted water habitat features. ...
... We also found in contrast to previous studies (Aichinger, 1987;Duellman, 1995), that the encounter rate of amphibians was higher during the dry than the wet season. However, this might relate to the fact that seasons were broken coarsely into 'wet' and 'dry' as oppose to multiple shorter periods as those by Duellman (1995) Additionally, survey sites in our study were located to avoided water bodies and situated in typical forest habitat, whereas Aichinger (1987) specifically targeted water habitat features. This potential difference in seasonality patterns of encounter rates between typical forest habitat and specific water habitat features requires further attention. ...
... Collecting was done both during day and at night; most specimens were collected from 2100 to 2400 hr. This yearly, monthly, and daily variation in the number of frogs collected reflects both variation in weather conditions (Duellman, 1995) and collecting effort. Frogs were collected by hand and preserved a few hours after capture-usually within 6 hr and rarely more than 12 hr later. ...
... The rank order of the 20 most abundant frogs appears in Duellman (1995); hylids make up 12 of the 20 most abundant species. Body size and natural history data on the species of frogs from Cuzco Amaz6nico is presented in Table 1. ...
... In general, Neotropical amphibians reproduce during the wet season (e.g. Zina et al. 2007;Prado et al. 2005;Bertoluci & Rodrigues 2002;Duellman 1995;Rossa-Feres & Jim 1994;Duellman & Trueb 1994). The occurrence of tadpoles in wet months supports the results previously found by Boquimpani-Freitas et al. (2002) that P. tupinamba reproduce during the wet season. ...
... Eterovick and Fernandes (2001) analyzed distribution of tadpoles in montane meadows located in Minas Gerais State, southeastern Brazil, and observed that Proceratophrys cururu reproduces during the rainy period and that their tadpoles were present mainly during this season. Rainfall affects the start and duration of the reproductive season of tropical anurans (see Zina et al. 2007;Prado et al. 2005;Bertoluci & Rodrigues 2002;Duellman 1995;Rossa-Feres & Jim 1994;Rico et al., 2004). Rainfall is one of the most important abiotic factors influencing the timing of anuran reproduction (Gottsberger & Gruber 2004), and consequently, the distribution pattern of larvae (Eterovick & Fernandes 2001;Fatorelli & Rocha 2008). ...
We present a description of the external morphology of the tadpoles of Proceratophrys tupinamba, and provide information on its temporal distribution and microhabitat use. Proceratophrys tupinamba differs from other larvae of species in the genus Proceratophrys described by the tooth row, which is similar to that of P. appendiculata. Comparing our description to the description of P. appendiculata, some differences are observed in the body proportion. Tadpoles were most abundant during the wet season (October-March), and it was positively related with average monthly rainfall. Tadpoles of P. tupinamba are benthonic and occur more often in lentic portions of the stream. They were found most frequently exposed on the sand, which also represented the most available microhabitat among those sampled in the stream studied.
... Climatic variability could have affected frogs at our study site, but there was little variability in temperature or rainfall recorded during the period of biodiversity collapse (Appendix S1 in Catenazzi et al. 2011). Moreover, organisms in the southwestern Amazon might be better able to alternate between dry and wet conditions than elsewhere in the basin (Duellman 1995) because the regional climate includes distinct rainy and dry periods that are more intense in montane areas in the eastern Andes such as our study site (Villar et al. 2009). Much of the basin-wide interannual rainfall variability associated with ENSO occurred during the 1970s, in 1983-1986, 1989, 1992-1995(Villar et al. 2009). ...
... Moreover, organisms in the southwestern Amazon might be better able to alternate between dry and wet conditions than elsewhere in the basin (Duellman 1995) because the regional climate includes distinct rainy and dry periods that are more intense in montane areas in the eastern Andes such as our study site (Villar et al. 2009). Much of the basin-wide interannual rainfall variability associated with ENSO occurred during the 1970s, in 1983-1986, 1989, 1992-1995(Villar et al. 2009). Recent variability in precipitation has not been large at high elevations in southern Peru (Salzmann et al. 2013). ...
Background/Question/Methods
Lowland tropical habitats are among the warmest environments on a warming planet. Many ectotherms found in such climates are living close to the upper limits of their thermal tolerances. As climate warms further, such organisms must respond physiologically or behaviorally to increasing temperatures or suffer local extirpations. Lowland tropical ectotherms would be particularly susceptible to increasing temperatures if they show limited or no capacity for physiological acclimation to warming. We estimated the field substrate temperatures and critical thermal maxima (“CTmax”) for an assemblage of lowland tropical frogs. We estimated critical thermal maxima by placing frogs in water baths and slowly increased water temperatures until individual frogs lost their righting reflex. Further, we tested three common species of frogs for acclimation capacity by holding frogs in stable, temperature-controlled environments at 20°C, 26°C, 28°C, 30°C, and estimated the CTmax every 5 days for 20 days.
Results/Conclusions
We estimated substrate temperatures and CTmax for 16 species of frogs from 8 families. Substrate temperatures varied widely among species, between 23-28°C. Critical thermal maxima ranged from 28°C to 38°C. We found strong phylogenetic signature to CTmax, with direct developing strabomantid and craugstorid frogs characterized by the lowest CTmax values. None of the three species we tested for acclimation response showed any increase in CTmax after 20 days. Our study indicates that many species of lowland tropical frogs currently exist very close to their thermal upper limits and that these species show no capacity for physiological acclimation to higher temperatures. We discuss the results of this study in relation to amphibian population declines, emerging infectious diseases, and lowland biotic attrition.
... Climatic variability could have affected frogs at our study site, but there was little variability in temperature or rainfall recorded during the period of biodiversity collapse (Appendix S1 in Catenazzi et al. 2011). Moreover, organisms in the southwestern Amazon might be better able to alternate between dry and wet conditions than elsewhere in the basin (Duellman 1995) because the regional climate includes distinct rainy and dry periods that are more intense in montane areas in the eastern Andes such as our study site (Villar et al. 2009). Much of the basin-wide interannual rainfall variability associated with ENSO occurred during the 1970s, in 1983-1986, 1989, 1992-1995(Villar et al. 2009). ...
... Moreover, organisms in the southwestern Amazon might be better able to alternate between dry and wet conditions than elsewhere in the basin (Duellman 1995) because the regional climate includes distinct rainy and dry periods that are more intense in montane areas in the eastern Andes such as our study site (Villar et al. 2009). Much of the basin-wide interannual rainfall variability associated with ENSO occurred during the 1970s, in 1983-1986, 1989, 1992-1995(Villar et al. 2009). Recent variability in precipitation has not been large at high elevations in southern Peru (Salzmann et al. 2013). ...
Background/Question/Methods Amphibians are declining worldwide, but declines are particularly dramatic in tropical mountains where high endemism and vulnerability to introduced disease is leading to catastrophic extinctions. One the most important aspects of climate change in tropical mountains is the increase in temperature, which in the tropical Andes is accelerating deglaciation and is projected to reach 27C by 2100. Models based on organismal physiology predict that tropical ectotherms will be severely impacted by climate warming. In order to better understand the potential effects of climate warming in montane frogs, we measured the tolerance to heat stress in 15 species along an elevational transect between 1200 and 3700 m in the eastern slopes of the Andes (Manu National Park, Peru). We used the loss of righting response to measure the critical thermal maximum of frogs in the species-rich family Strabomantidae.
Results/Conclusions We found that critical thermal maxima decreased with elevation across strabomantid frogs and within species, but not as steeply as ambient temperatures. Consequently, thermal tolerance (the difference between the critical thermal maximum and the maximum ambient temperature at the corresponding elevation) increased with elevation, indicating that frogs at lower elevations are more vulnerable to thermal stress under a global warming scenario than frogs at higher elevations. This finding is not consistent with the fact that most threatened frogs are found at higher elevations. Our results suggest that climate warming is not the main driver of amphibian declines, which disproportionally affect high-elevation taxa.
... The increase in anuran abundance with the onset of the rainy season is a common pattern (Duellman, 1995;Wells, 2007). The studied population of R. hoogmoedi follows this pattern, with higher abundance during the onset of the wet season, when the recruitment of new cohorts was observed. ...
... obs.). In general, species of the R. margaritifera complex tend to be amongst the most abundant leaf-litter anurans in the areas where they occur, particularly when excluding those with direct development (Duellman, 1995;Poulin et al., 2001;Ávila et al., 2010;May et al., 2010). ...
We studied the natural history of the leaf-litter toad, Rhinella hoogmoedi Caramaschi & Pombal, 2006, in a rain forest located in an altitudinal rocky remain within the Brazilian caatinga biome. Rhinella hoogmoedi was more abundant during the first half of the wet season, when recruitment of new cohorts was observed. Leaf litter was the most commonly used substrate and activity was mainly diurnal. There was a positive relation between maximum prey size (length/volume) and predator size; ants and mites were the predominant prey in adults and froglets, respectively. The following defensive strategies were registered: cryptic and polymorphic colour pattern, immobility, thanatosis, generation of distress calls and production of a foamy substance by the paratoid glands. The similarities in natural history aspects among members of the R. margaritifera species group indicate a case of ecological niche conservatism.
... There has always been a noticeable change in the anuran population between the rainy and dry seasons. Many authors (Duellman, 1995;Vonesh, 2001;Onadeko et al., 2013;Onadeko, 2015) have stated this fact due to the existence of available water during the wet season, which favours the species' prospering conditions. Apart from the reproductive potentials brought about by the wet season, it was discovered in this study that species developed temporal niches that aided in the acquisition of additional food. ...
Toads have relatively wide distribution, bimodal lifestyle, and ectothermic conditions with stable environmental temperatures. Currently, toads are among the world's most endangered animal groups. They are exhibiting a decline in their population as an indication of increased habitat loss, environmental pollution, global climate change, diseases, and Overharvesting. Land use coupled with indiscriminate usage of pesticides and fertilizers are the main drivers of habitat deterioration. The current study aimed to document the abundance, diversity, and distribution of toads for improved conservation plans and management policies. A total of Four (4) sampling sites were selected namely Bosso, Tunga, Chanchaga, and Gidan-Kwano covering Two (2) Local Government Areas in Minna. Data were gathered in both the rainy and dry seasons. Toad samples were collected for Twelve (12) months from 03 June 2020-29 May 2021 with the help of pond rangers at the study sites. Opportunistic observations, audio, and visual encounters were used to perform the survey. Temporal abundance of toads in the study areas showed that a mean total of 684.42 toads were sampled with Chanchaga having a total of 243.35 (35.55%) while Gidankwano, Bosso and Tunga ponds had a mean total of 170 (24.83%), 150 (21.91%) and 121.07 (17.68%) respectively. Toad species encountered at the sampling sites were Amietophrynus regularis, Sclerophrys regularis, and Amietophrynus gutturalis. Shannon's and Simpson's diversity index revealed that Chanchaga had the highest index value of 0.9841, while Tunga had the lowest diversity of 0.8244. This study improves knowledge of toad diversity and distribution in Minna, Niger State for improved conservation plans and management policies.
... The effects of environmental factors on the temporal pattern of breeding in temperate-zone explosive breeders have been well studied (reviewed in Miwa 2007). However, relatively few studies have documented general breeding patterns in explosive-breeding tropical anurans (Aichinger 1987;Duellman 1995;Bevier 1997;Prado et al. 2005), and even fewer have assessed the importance of multiple environmental factors on reproductive timing at finer scales and/or across multiple breeding seasons (but see Gottsberger and Gruber 2004;Schalk and Saenz 2016;Ulloa et al. 2019). ...
The influence of abiotic and biotic factors on the temporal pattern of calling and breeding for many temperate anurans is well understood. However, few studies have documented patterns of reproduction in explosive-breeding tropical frogs or incorporated multiple environmental factors in their analyses, especially across multiple breeding seasons. We combine long-term natural history observations and automated data collection methods with boosted regression tree (BRT) analysis to determine the phenology and determinants of explosive breeding in the gliding treefrog, Agalychnis spurrelli. We monitored breeding for a total of 418 days across three breeding seasons and determined the relative importance of several environmental factors on the probability of calling and breeding activity. Our study population of A. spurrelli on Costa Rica’s Osa Peninsula forms breeding aggregations up to 11 times per year during 1–2-day long explosive-breeding events, from late May to mid-September. Calling and breeding activity are strongly and positively related to accumulated rainfall during the previous 24 and 48–24 h before, particularly rainfall during the afternoon and evening. Day-of-year, days since breeding occurred, and lunar phase also influence reproductive activity. This study provides the first description and analysis of the phenology and factors that predict explosive breeding in A. spurrelli and illustrates the value of using automated data collection paired with BRTs for the analysis of complex ecological data.
La influencia de factores abióticos y bióticos en el patrón temporal de cantos y reproducción de muchos anuros de zonas templadas es bien conocida. Sin embargo, pocos estudios han documentado patrones de reproducción en ranas tropicales, que se reproducen de manera explosiva, o han incorporado múltiples factores ambientales en sus análisis, especialmente a lo largo de múltiples temporadas de reproducción. Combinamos observaciones de historia natural a largo plazo y métodos automatizados de recolectar datos con análisis de árboles de regresión y técnicas de remuestreo (‘boosted regression trees’, BRT) para determinar la fenología y los determinantes de la reproducción explosiva en la rana planeadora, Agalychnis spurrelli. Monitoreamos la reproducción durante un total de 418 días a través de tres temporadas de reproducción y determinamos la importancia relativa de varios factores ambientales en la probabilidad de cantos y reproducción. Nuestra población de estudio de A. spurrelli en la Península de Osa en Costa Rica forma agregaciones reproductivas hasta 11 veces por año, los eventos de reproducción explosiva tienen 1 a 2 días de duración, desde finales de mayo hasta mediados de septiembre. Los cantos y la reproducción están fuerte y positivamente relacionados con la acumulación de lluvia en las 24 y 48 a 24 horas anteriores, particularmente durante la tarde y la noche. El día del año, los días desde la última reproducción, y la fase lunar también influyen la reproducción. Este estudio es la primera descripción y análisis de la fenología y los factores que predicen la reproducción explosiva en A. spurrelli e ilustra el valor de utilizar la recolección de datos automatizada junto con BRT para el análisis de datos ecológicos complejos.
... En las áreas protegidas se reduce la influencia antrópica, pero, la estacionalidad ambiental, incide sobre la estructura de las comunidades ecológicas produciendo cambios temporales y de recursos de las especies (Wolda 1988, Allmond 1991, Duellman 1995, Duellman & Thomas 1996. ...
Con el objetivo de determinar la variación temporal de la herpetofauna en el Centro Ecológico Wetso, PILA, Bocas del Toro, se realizaron siete muestreos durante la estación lluviosa del 2019y la estación seca del 2021, en las poblaciones de anfibios y reptiles. Como resultado, se identificaron 47especies, de las cuales 25corresponden a anfibios agrupadas en un orden, 9familias,19géneros; otras22 especies corresponden a reptiles; incluyendo dos órdenes, 12familias y 17géneros. Para anfibios el índice de diversidad de Shannon Wiener alcanzó H’= 2.89y el índice de equitatividad (J’= 0.98), para los reptiles el índice de diversidad de Shannon Wiener alcanzó H’= 2.21y el índice de equitatividad (J’= 0.90). Las especie más abundante o común para anfibios fue O. pumilio con 14.56% y para los reptiles G. albogularis con 34.2%.La correlación entre riqueza y precipitación promedio diaria (mm), demostró que hay una relación directa entre la riqueza de la herpetofauna observada y la precipitación, con r= 0.70para anfibios, y r= -0.75 para reptiles. Con esta información se presentó un patrón estacional, siendo la estación lluviosa favorable para los anfibios y la estación seca favorable para los reptiles.
... This pattern could be related to the reproductive strategies displayed by the different species. Dryophytes eximius and Lithobates neovolcanicus are the most representative taxa of the dry season, primarily due to the presence of hatchlings and juveniles (Duellman andTrueb, 1994, Duellman, 1995;Cadena-Rico et al., 2020). The species least represented during the rain season was Spea multiplicata, which was observed only once, at the beginning of the rains (June). ...
We carried out this study in the lower basin of the Temascatio River,
Guanajuato, Mexico, in a seasonal tropical environment. We identified ecological aspects of the microhabitat use and composition of
nine species of anurans found in three types of vegetation, in both the dry and rainy seasons. We characterized five types of habitats (saxicolous, arboreal, terrestrial, aquatic and riparian). The tropical deciduous forest and subtropical scrubland had higher species
representation than oak forest. A significant change was observed, both by species and season, and in the use of microhabitats between the rainy and dry seasons. Niche overlap was related to the habits of the species; that is, the arboreal–terrestrial species (Dryophytes eximius, Anaxyrus compactilis, A. punctatus, D. arenicolor and Hipopachus variolosus) and the aquatic species (Lithobates
neovolcanicus and L. megapoda) presented the highest overlap values. The principal component analysis showed that the thermal
factor and vegetation explain the structure of the anuran community, but not microhabitat use. This work provides information on the
ecology of the anurans inhabiting in the LBTR and emits an alert signal for conservation of the species at site, since the EVS (Enviroment
Vulnerability Score) showed that A. punctatus, Spea multiplicata, H. variolosus and L. megapoda presented values of high vulnerability. Finally, when concluding that natural vegetation determines the presence and structure of the anuran community, local governments must prioritize the protection of this ecosystem
... This is especially true in tropical environments, and with cryptic species which can be hard to detect (Gotelli and Colwell 2001). Indeed, in tropical sites which have been surveyed over many years, new species are discovered which have either not been recorded before, or are new to science Schlüter et al. 2004;Duellman 1999;Duellman 1995). In Manu National Park, Peru, for example, 155 amphibian species have been recorded since 1960. ...
Global biodiversity is currently facing the sixth mass extinction, with extinction rates at least 100 times higher than background levels. The Amazon Basin has the richest amphibian fauna in South America, but there remain significant gaps in our knowledge of the drivers of diversity in this region and how amphibian assemblages are responding to environmental change. Surveys were conducted in the Pacaya-Samiria National Reserve (PSNR) in Amazonian Peru, with a view to (1) comparing assemblage structure on floating meadows and adjacent terrestrial habitats; (2) determining the predictors of diversity in these habitats; and (3) exploring the effects of disturbance and seasonal flooding on diversity measures. Eighty-one species of amphibians have been recorded in these habitats since 1996 representing 11 families and three orders. In 2012-2013 22 anuran species used the floating meadow habitat, of which 10 were floating meadow specialists. These specialists were predominantly hylids which breed on floating meadows all the year round. Floating meadows therefore host an assemblage of species which is different to that found in adjacent terrestrial areas which are subject to seasonal flooding. Floating meadows enhance the amphibian diversity of the region, and rafts of vegetation that break away and disperse frogs downstream may explain the wide distribution of hylids within the Amazon Basin. Fourteen different reproductive modes were represented within the 54 anuran species observed. The number of reproductive modes present was influenced by localised disturbance and seasonal flooding. Diversity increased in the low water period, with hylids breeding in temporary pools. When the forest is inundated most species disperse away from the flood waters. Disturbance, habitat change, emerging diseases and climate change would likely lead to changes in species composition and assemblage structure rather than wholescale extinctions. However, further studies are needed to evaluate long-term consequences of synergistic environmental change.
... Existen diversos estudios a nivel mundial sobre monitoreo y abundancia de anuros (Duellman 1995, Knutson et al. 1999, Donnelly et al. 2001, Gutiérrez-Lamus et al. 2004, Parris 2004, Cortez-Fernandez 2006, Moreira et al. 2008, Cáceres-Andrade y Urbina-Cardona 2009, Bardier et al. 2014, entre otros) y algunos han analizado las variaciones de abundancia en ensambles de anuros en Argentina (Sánchez et al. 2007, Bionda et al. 2011a, López et al. 2011. Como complemento de las investigaciones previas, para contribuir a la implementación de medidas de conservación en el Área Protegida Parque Natural Valle Fértil, y ante la necesidad de evaluar la respuesta de los anuros Chaqueños a factores abióticos en un escenario de cambio climático, este estudio plantea como objetivos: 1-Conocer la estructura espacio-temporal de un ensamble de anuros del Chaco Serrano en el centro-oeste de Argentina, y 2-Comparar parámetros demográficos entre dos periodos de estacionalidad e identificar la influencia de factores climáticos sobre estos parámetros. ...
Abundance as a demographic parameter is an important part of population dynamics, allowing space-time comparisons and evaluating the health status of species. This work aimed to know the temporal structure of an anuran assembly from Chaco Serrano in central-western Argentina and to identify the influence of climatic factors on those parameters. 14 samplings were carried out from October 2012 to February 2015. Samplings were grouped into dry and rainy seasons. The abundance of each species was analyzed by: 1) mean abundances, with factorial analysis of variance and 2) proportions, as frequencies of occurrence, from Chisquare tests. Redundancy analysis was performed to relate abundance, seasons, and environmental variables. In both seasons Rhinella arenarum arenarum was the most abundant species, followed by Pleurodema tucumanum and Leptodactylus luctator. Significant differences were found in species abundance, between seasons, and between sexes, with significant interactions between these factors. In the dry season, R. arenarum arenarum and L. luctator showed differences in sex ratios, whereas in the rainy season only P. tucumanum exhibited different frequencies between males and females. The minimum temperature and the rainfall proved to be significant variables in P. tucumanum abundance. No climatic influences were found for the other species. The results of this research contribute to understanding the Chaco anuran assemblage structure, suggesting that populations fluctuate over time and it may depend, in some species, on abiotic factors such as temperature and rainfall.
... Most tropical anuran species reproduce during the rainy season, when choruses tend to be larger and more frequent (Bertoluci, 1998;Canelas & Bertoluci, 2007;Duellman, 1995). ...
Males of a wide variety of vertebrates aggregate in mixed-species choruses to attract females and signal territory occupancy. It is often assumed that species within these choruses co-signal, interact and compete for the acoustic space, although few studies have tested this assumption, particularly in tropical and highly diverse environments. Using a novel combination of passive acoustics and network analysis, we monitored calling activity of a tropical anuran assemblage for an entire year and examined the structure and dynamics of mixed-species choruses. Species composition was determined at 1-min resolution on 288 recording hours and then used to estimate a set of centrality metrics (degree, strength and eigenvector) that characterize the species roles within the acoustic network. The studied assemblage formed a dynamic network comprising eight species during the rainy season and four during the dry season. These species showed distinct roles within the network, ranging from central species (those co-signalling frequently and with many species) to peripheral species (those barely co-signalling and with few species). Our results shed light on the species interactions in acoustic communities and challenge the general assumption of an equal contribution of species to the mixed-species choruses. While in the rainy season the territorial frogs Boana albopunctata and B. faber exhibit the most prominent role within the network (with a higher degree, strength and eigenvector centrality), all of the species calling in the dry season co-signalled with equal number of species, with only another territorial species, B. lundii, showing a higher rate of co-signalling events (higher strength and eigenvector centrality). This suggests that territorial behaviour may favour increased calling activity and hence central roles in acoustic networks. These findings contribute to a better understanding of chorus dynamics in tropical assemblages and have crucial implications for the study of species interactions and the evolutionary hypotheses of acoustic divergence.
... Si bien en las últimas décadas han aumentado el número de investigaciones sobre anfibios en Perú (Catenazzi & von May, 2014), mucho del trabajo que se viene realizando está limitado a descripciones y revisiones taxonómicas que incrementan al conocimiento básico de la inmensa diversidad herpetológica distribuida a lo largo del territorio peruano. En la región de Tambopata se han realizado varias evaluaciones rápidas que describen brevemente la herpetofauna local (Duellman, 1995;Duellman & Salas, 1991;Rodríguez & Emmons, 1994;Salas, 1995;Sehgelmeble, 1997), y solo Doan & Arizábal (2008) han analizado la variación entre ensamblajes locales de anfibios y reptiles en la región. Pese a que dichos en taxonomía y sistemática, identificar patrones ecológicos y relacionarlos con los cambios estacionales y geográficos es la base para entender las transformaciones de las biotas y poder manejar los efectos ecosistémicos que derivan de ellas. ...
The conversion of Amazonian forests to agricultural lands has a negative impact on biota,
being anurans one of the most vulnerable groups in the face of changes in the environmental conditions of their habitats. Traditionally, the influence of this transformation on the anurofaunistic assemblages of agricultural and natural systems has been analyzed in terms of species richness and abundance (i.e. taxonomic diversity), without taking into account, in the face of the disturbance, how altered morphological, ecological and reproductive characteristics contain individuals and functional groups in the community (i.e. functional diversity). We aim to show the differences between anuran taxonomic diversity (TD) and functional diversity (FD) metrics in natural systems (primary forest) and agricultural lands (secondary forest and banana crops) at Kawsay Conservation Concession, in the southeastern Peruvian Amazon. Anurans were sampled in thirty 4 x 30 m transects per site, recording species´ richness and abundances, as well as ten functional features related to their biological and ecosystem roles. The decrease in functional richness in the secondary forest –linked to local traits reductions– shows differences in TD and FD trends, contrasting with the similarity between primary forests and secondary forests for the rest of the local diversity estimates. Likewise, in the banana crop the transformation of the forest has promoted a drastic loss of species and functional traits, resulting in the lowest levels of TD and FD. In summary, a triple loss of biodiversity (species, groups and functional characteristics) associated with agriculture in the Peruvian Amazon is reported for the first time, which can be partially masked by the richness and species turnover increase in secondary forests.
... In contrast, we did not find any association between temperature and number of males calling in N. grandisonae, despite this factor playing an important role in the reproductive phenology of many anurans (Saenz et al. 2006, Steen et al. 2013, Green 2016. Breeding activity patterns in tropical anurans is mainly related to rainfall (Crump 1974, Aichinger 1987, Duellman 1995, Gibbs and Breisch 2001, Wells 2007 Phenology and mortality of embryos of Nymphargus grandisonae (Reading 1998, Silva-Ximenez and Tozetti 2015, Plenderleith et al. 2017. We recaptured 19 of 31 males, but no females were recaptured. ...
Studies of phenology and natural history of anurans provide information useful for its conservation. This is particularly important in current scenarios of emergent diseases, high rates of deforestation, and climate change. We recorded the timing of breeding of the Glass Frog Nymphargus grandisonae and its relationship to precipitation and environmental temperature for four years in a population located in the Central Andes of Colombia, South America. In addition, we recorded the causes of mortality in egg clutches of this species. We quantified infestation by fly larvae and its impact on the survival of embryos. We found that the reproductive activity of N. grandisonae (number of males calling) was seasonal and occurred in months with highest precipitation. The main cause of embryo mortality in clutches was associated with the infestation by a spittlebug fly of the genus c.f. Cladochaeta (Drosophilidae). The survival of embryos in infested clutches was significantly lower than in those clutches not infested by fly larvae. Our results provide baseline data for the monitoring of anuran population dynamics in the Andean region using the glass frog N. grandisonae as a model system.
... https://doi.org/10.1101/2020 be particularly pronounced at lower latitudes because spatial heterogeneity in the timing of climatic seasonality is higher towards the tropics (Duellman, 1995;Martin et al., 2009). ...
The role of geographic barriers in promoting reproductive isolation across space is well understood. Isolation by the time of breeding, however, may also promote population divergence when populations reproduce asynchronically in space, even in the absence of geographic barriers. Few examples exist of divergence due to breeding allochrony, particularly in vertebrates. We tested whether in Neotropical frogs asynchrony in precipitation patterns promotes intraspecific genetic divergence, speciation, and regional accumulation of diversity. We assessed the relationship between spatial asynchrony in precipitation and genetic divergence controlling for ecological connectivity across 48 Neotropical frog species. In addition, we examined whether regions within which precipitation regimes are more asynchronous across space have higher species richness and have experienced greater speciation rates. Beyond a generalized expected effect of ecological connectivity on intraspecific genetic divergence, we found that asynchrony in precipitation is positively associated with genetic differentiation in 31% of the species tested, resulting in a significantly positive cross-species effect of asynchrony in precipitation on genetic divergence in a meta-analysis. However, the effect of asynchrony in precipitation on population divergence seems not to scale to macroevolutionary patterns because spatial asynchrony in precipitation was not associated with geographical patterns of species richness or speciation rates. Our results indicate that genetic divergence can be promoted by asynchronous breeding lag in the absence of geographic barriers in species where breeding is associated with water availability, but such effects may not be stable enough through time to influence macroevolutionary patterns.
... Así, al ser los reptiles en general, más susceptibles a los cambios en la temperatura y los anfibios hacia los cambios en la disponibilidad de agua (Pough et al. 1998), la ocurrencia y actividad de los anfibios de Chamela responden a la estacionalidad de las lluvias, mientras que los reptiles, al registrarse relativamente poca variación estacional en la temperatura máxima (al medio día: Bullock 1986) pueden ocurrir durante prácticamente todo el año (García 2003). El efecto de la estacionalidad en las lluvias sobre las fluctuaciones en las comunidades de anfibios ha sido documentado en otras áreas tropicales, en especial en aquellas regiones marcadamente estacionales (Toft & Duellman 1979, Duellman 1995, Duellman & Thomas 1996. En el caso de los reptiles, como se mencionó anteriormente el efecto de la estacionalidad a nivel de comunidad (diversidad y riqueza) es menor que en anfibios, sin embargo, a nivel de especie e individuos, la estacionalidad, a través de los cambios en la disponibilidad de recursos, precipitación, y cambios en la estructura de la vegetación entre otros, tiene un efecto muy importante en los niveles de actividad y reproducción (Beck & Lowe 1991, Lister & García 1992, García & Ceballos 1994, Ramírez-Bautista 20041994). ...
RESUMEN Se evaluó el efecto de la estacionalidad ambiental y la estructura de la vegetación en los patrones espacio-temporales de la comunidad (composición, diversidad, riqueza y abundancia relativa) de los anfibios y reptiles de la región de Chamela, Jalisco. Tres sitios fueron muestreados, mediante un diseño de bloque dentro de una matriz de vegetación de arroyo (VA) y bosque tropical caducifolio (BTC) utilizando tres técnicas complementarias de muestreo (trampeo; parcelas de búsqueda intensiva y transectos visuales) durante la época de secas y de lluvias. Se registraron 34 especies (25 de reptiles y nueve de anfibios). Las curvas de acumulación de especies y los índices predictores de riqueza, sugieren que el esfuerzo de muestreo fue el adecuado. Los valores más altos de riqueza, diversidad y abundancia se registraron en la VA. Se registraron mayores fluctuaciones estacionales en anfibios que en reptiles, y en el BTC que en la VA. Se documenta un recambio de especies, tanto espacial (matriz de vegetación VA-BTC) como temporal (estacional), más marcado en anfibios cuyo registro de individuos fue mínimo durante la época de secas y solo dentro de la VA. La VA es importante para el mantenimiento de la diversidad herpetofaunística, no sólo por su menor estacionalidad y mayor productividad, sino por su mayor complejidad estructural. Se encontró una mayor respuesta de los anfibios hacia los cambios en la estructura de la vegetación que los reptiles, los cuales estuvieron más ampliamente distribuidos espacial y temporalmente. Palabras clave: bosque tropical caducifolio; herpetofauna; estacionalidad ambiental; vegetación; estructura de la comunidad ABSTRACT The effect of effect of environmental seasonality and habitat structure on the spatial and temporal patterns of the reptile and amphibian communities in Chamela, Jalisco, Mexico was evaluated. Three complementary sampling techniques (plots, visual transects and sampling arrays with drift fences and pitfall traps) were used in three sites during the wet and dry seasons using a block design to sample the seasonally dry tropical forest (SDTF) and its adjacent arroyo forest (VA). Thirty-four species were recorded (25 of reptiles and 9 of amphibians). The species accumulation curves and richness predictors suggested sampling effort was appropriated. Highest values of species richness, diversity and relative abundance were recorded in the VA when compared with the SDTF. Seasonal fluctuations were marker in the amphibian community and in the SDTF than in reptiles and the VA respectively. There is a marked species turn over both spatially (along the VA and SDTF) and temporally (across the seasons) more Acta Zoológica Mexicana (n.s.) 24(2): 91-115 (2008)
... Other observers have recorded peaks in amphibian abundance during the wet season (Scott 1976;Allmon 1991;Vonesh 2001) and in particular during heavy rainfall (e.g. Duellman 1995). This is a phenomenon that is most probably related to the phenology of reproductive activity as well as environmental tolerances of individual species (Donnelly 1989b;Donnelly & Guyer 1994;Stewart 1995;Watling & Donnelly 2002). ...
Amphibians are declining globally from climate change, habitat destruction, pollution and disease. In tropical environments deciphering causes of decline is hampered by a lack of population data. In this study, climate, water quality and amphibian population was recorded at Caño Palma Biological Station in Costa Rica over 3 years. Population dynamics were recorded for 16 species of amphibian and the affects of flooding on them determined. Spearman Rank Correlation, Principal Component Analysis, Multiple Analysis of Variance and Linear Regression were used to investigate climate and flooding. Direct measurements of aqueous pH, conductivity, iron, nitrate, hardness, oxygen, carbon dioxide and salinity were made through periodic inundation. A mark-recapture program for 16 amphibian species collected population data from an area of Manicaria swamp forest and a breeding pond in lowland wet forest. Pollock Open Jolly-Seber and Petersen-Schnabel population models estimated amphibian abundance. Canonical Correspondence Analysis (CCA) was used to investigate relationships between climate, water quality and amphibian populations. Temperature and humidity remained stable. Rainfall data recorded up to 350mm in one 24 hour period. Flooding occurred annually and was governed by rainfall and spring river tides. Water quality of the environments changed little during flooding. CCA results suggested that amphibian abundance was not related to water quality. Salinity and conductivity levels increased but were not toxic. Amphibian populations fluctuated within and between years. Pollock Open Jolly-Seber estimates were completed for Chaunus marinus, Rana vaillanti and Oophaga pumilio. Petersen-Schnabel estimates were completed for Bufo coniferus, O. pumilio, Craugastor fitzingeri, Craugastor polyptychus and Leptodactylus melanonotus. All populations appeared unchanged across years. C. marinus, R. vaillanti, O. pumilio, B. coniferus, C. fitzingeri, C. polyptychus and L. melanonotus adapted to flooding by altering their preferred behaviour and microhabitat. Most amphibians suspended seasonal activity during flooding.
... In general, the reproductive activity of the temperate region anurans, are dependent upon a combination of rainfall and temperatures [7,17,[23][24][25]. However, limited knowledge is available for the amphibians inhabiting tropical regions [15,20,[26][27][28][29][30]. ...
Seasonality is represented as an initiation-termination-reinitiation of any physiological processes. Photoperiod is the most predictable environmental cue which organism use to time their daily physiology and seasonal functions. In natural light environmental conditions, day and night components change in terms of duration, intensity and spectrum of light available. In many vertebrate species, daytime light intensity and spectrum of light play a critical role in gonadal recrudescence-regression cycle. In tropical conditions, many amphibian species show a clear relationship between reproduction and seasonal distribution of rainfall. In temperate conditions, reproduction is usually centered during spring and summer seasons when environmental conditions are favorable. Poikilotherms are highly sensitive to change in environmental temperature and their physiology and metabolic activities depend on environmental temperature. How environmental factors (light and temperature) influence, the reproduction of terai tree frog (Polypedates teraiensis) is not known. We hypothesized that light acts as a proximate factor but the temperature is the ultimate factor for reproduction of terai tree frog. Three experiments were performed. In experiment one, we studied the annual reproductive cycle under natural environmental conditions. Beginning from the month of March till October 2016, we procured adult frogs (male and female) in the middle of each month. Monthly observations were recorded for body weight and gonadal weight and GSI was calculated. We found the annual change in body mass, gonadal weight and GSI in both male and female with high gonadal weight and GSI values from March to June. These results suggest that terai tree frog is seasonal breeders, and their breeding corresponds with long days. In experiment two we addressed the effects of light duration, light intensity and light spectrum on gonadal growth regression cycle. We observed that long days promote gonadal growth regression cycle. However, after achieving critical daylength there is no additive effect of light duration. Further, light intensity and spectrum have limited role in gonadal growth regression cycle of this species. In experiment three we tested the role of temperature on body weight and testicular growth under stimulatory photoperiod (12 L:12D). Group one was exposed to high temperature (34 ± 2 °C), while group two was exposed to low temperature (22 ± 2 °C). We found that low temperature promotes testicular recrudescence under laboratory conditions. Altogether our study suggests both photoperiod and temperature are involved in the regulation of seasonal breeding in tree frog. Findings from the above study could be used for captive breeding of amphibians and may be helpful in amphibian conservation programmes.
... Algunas de las especies de anfibios y reptiles de estos bosques se encuentran generalmente en bosques bajos de Amazonía, y algunas de ellas son encontradas con regularidad en bosques de áreas inundables tales como Ceratophrys cornuta, que generalmente es encontrada en épocas y lugares húmedos, (Duellman, 1995). ...
... As espécies de anuros que responderam positivamente às variações na temperatura média (Allobates gr. marchesianus, Hamptophryne boliviana, Boana geographica e Rhinella marina) possuem o período reprodutivo concentrado na estação chuvosa (Duellman, 1995;Menin et al., 2008;Venâncio et al., 2014). As demais espécies selecionadas também mostraram uma tendência de resposta positiva às variações na temperatura. ...
RESUMO Apesar da elevada riqueza de anfíbios e répteis conhecida para a porção Sul-Ocidental da Amazônia brasileira, o conhecimento sobre estes é pontual e poucos estudos avaliaram as variações temporais na ocorrência e abundância das espécies. Os objetivos deste estudo foram descrever as taxocenoses de anfíbios e répteis em uma localidade da Reserva Extrativista Chico Mendes, verificar quais variáveis climáticas influenciam as flutuações temporais na riqueza e abundância e identificar as principais espécies de anfíbios e répteis influenciadas por elas. A área de estudo está localizada na região do Seringal Etelvi, porção sudoeste da Reserva, município de Brasiléia, estado do Acre. A coleta de dados ocorreu entre outubro de 2011 e setembro de 2012, num total de 48 dias de amostragem, com os métodos de procura limitada por tempo e armadilhas de interceptação e queda. Foram registrados 978 espécimes de 31 espécies de anfíbios e 54 de répteis. Maior riqueza e abundância de anfíbios ocorreram durante o período chuvoso, sendo a abundância associada positivamente com a temperatura média. Apenas a abundância de répteis foi maior durante o período chuvoso. Porém, tanto riqueza quanto abundância mensais foram associadas positivamente com a temperatura média. Quatro anfíbios, Allobates gr. marchesianus, Hamptophryne boliviana (Parker, 1927), Hypsiboas geographicus (Spix, 1824) e Rhinella marina (Linnaeus, 1758), e dois répteis, Kentropyx pelviceps Cope, 1868 e Norops fuscoauratus (D’Orbigny, 1837), tiveram suas abundâncias mensais associadas positivamente com a temperatura média. O lagarto Dactyloa punctata (Daudin, 1802) teve a abundância mensal associada com a precipitação. Foi possível verificar o aumento da riqueza e abundância de anfíbios e répteis durante períodos em que a disponibilidade de recursos é favorável para muitas espécies. As espécies podem reagir de formas diferentes às variações climáticas, enquanto algumas são sensíveis às flutuações, outras parecem não responder facilmente ou não reduzir suas abundâncias em períodos potencialmente desfavoráveis.
... In Neotropical anurans, it has been documented that breeding activity increases with increased precipitation (e.g., Aichinger, 1987;Duellman, 1995;Bevier, 1997;Prado et al., 2005;Canelas and Bertoluci, 2007;Vockenhuber et al., 2008;Cabanzo-Olarte et al., 2013). However, the specific time of reproductive activity can vary among species because of interspecific competition or particular life history features (Duellman and Trueb, 1994;Wells, 2007). ...
Frogs of the family Centrolenidae have been a good model system in recent studies of evolutionary ecology, biogeography, and systematics; however, the taxonomic status of some species is still uncertain. Knowing aspects about the natural history of such species can offer diagnostic characters useful for species delimitation and hence, baseline data for understanding the biology of the family Centrolenidae.
We describe the advertisement call and aspects of the breeding biology of “Centrolene” quindianum, a threatened species endemic
to the Andes of Colombia whose taxonomic status and phylogenetic relationships require clarification. Between July–December 2015, we
performed weekly fieldtrips to monitor the breeding activity of this species in a population located in department of Quindío, western slope of the Central Andes of Colombia. The advertisement call of “C.” quindianum consist of two types of calls. The most frequently emitted call is composed of two notes with amplitude modulation and a dominant frequency of 4,678.1 ± 156.0 Hz; the other type of call is composed of 3–5 notes with high amplitude modulation and a dominant frequency of 4,568.5 ± 61.4 Hz. Calling activity and oviposition was recorded in months with higher precipitation and lower temperature. Clutches contained 26 eggs on average, and the substrate for oviposition was mostly moss-covered tree branches. Egg yolk was usually yellow, although some eggs were green. In addition, we recorded an attempt of amplexus displacement and egg attendance by a female immediately following oviposition.
... Mientras que si enfocamos nuestros esfuerzos sobre una o más especies en particular, se debe conocer o tener alguna evidencia parcial de si son diurnas, nocturnas o crepusculares, para realizar así las búsquedas en el momento apropiado. Algunas especies están presentes en una localidad a lo largo del año, especialmente en climas no estacionales (ingeR 2003), pero la gran mayoría de las especies presentan mayor actividad y/o abundancia en determinadas temporadas o meses del año asociados con los patrones de precipitación y temperatura (Allmon 1991, ARzABe 1999, duellmAn 1995, 2005, ingeR 2003, toFt 1980, toFt et al. 1985, wAtAnABe et al. 2005), generalmente por hacerse más conspicuos durante su actividad reproductiva (machos vocalizando en coros o de manera individual). Un patrón semejante ocurre con los individuos premetamórficos (lAJmAnoVich 2000, wild 1996). ...
Como ha sido ampliamente divulgado en las revistas científicas y medios de comunicación del orbe, los anfibios enfrentan, en la actualidad, una grave amenaza para su conservación. Esta crisis mundial es el
resultado de una sinergia de muchas amenazas que están conspirando contra la supervivencia de uno de los grupos de vertebrados de una forma nunca observada en tiempos modernos. Con este conjunto de situaciones negativas como la creciente pérdida de hábitat, el inclemente uso de pesticidas, el aumento de la radiación ultravioleta, y la peligrosa expansión y patogenicidad de la chitridomicosis, los anfibios en general y muy seguramente otros grupos de especies de nuestra rica biodiversidad tendrán que enfrentar un futuro sombrío.
La buena noticia, si hay alguna, es que aún podemos hacer algo, pero requerimos dedicar esfuerzos a adquirir información reciente sobre la situación de conservación de las poblaciones, hacerles seguimiento y obtener de esta manera elementos de juicio para adelantar acciones novedosas y creativas que contrarresten esta crisis de conservación. Igualmente es importante resaltar que la investigación in situ y el trabajo mancomunado de muchos actores debe ser un componente central y clave para desarrollar este nuevo conocimiento. El reto es enorme, máxime si reconocemos y comprendemos que el estar en el epicentro de la biodiversidad convierte a los cinco países andinos en un escenario de máxima vulnerabilidad, pues los impactos de esa aún incomprendida sinergia de amenazas creciente, pueden ser desastrosos sobre nuestros recursos dado que siempre tendremos mucho que perder, pero también mucho que ganar en la medida que establezcamos un frente común para contenerlos. Al igual que el estatus de conservación de las especies de anfibios en
los Andes tropicales, nuestro conocimiento sobre la historia natural, niveles poblacionales y usos benéficos está en peligro. Y aunque los científicos lleven muchos años trabajando para incrementar el conocimiento sobre la diversidad de especies y se hayan adelantado los pasos necesarios para identificar algunas de las causas más importantes de la disminución de sus poblaciones, la realidad es que hay aún un enorme desconocimiento sobre aspectos relevantes de la historia natural en general y sobre la identidad de muchas de las especies que habitan en diversas regiones inexploradas o exploradas parcialmente. Todo ello conduce a pensar que el gran número de especies deficientes de datos (DD), casi amenazadas (NT) listadas en la última evaluación global de anfibios de 2004 según los criterios de UICN, pueden modificar sustancialmente e incrementar el número de especies en los niveles de amenaza(CR, EN, VU) que surjan de próximas evaluaciones a nivel nacional o global y probablemente, en la medida que conozcamos más sobre la situación real, se incrementen también tristemente en la categoría de extinta (EX). Esta situación nos señala que las exploraciones de campo deben ser una prioridad para la investigación en el futuro y dentro de ellas las que contribuyan a implementar actividades de monitoreo de las especies identificadas como amenazadas y los inventarios de sitios inexplorados. Con esta gran preocupación en mente este manual recoge la experiencia
de varios investigadores quienes han dedicado buena parte de su vida profesional al desarrollo de técnicas de seguimiento y a la ardua tarea de ponerlas en prueba por largos periodos para ver sus bondades en los resultados generados. De la misma manera estas experiencias se han puesto en práctica en los tres cursos de campo sobre inventario y monitoreo de anfibios desarrollados por la Iniciativa Atelopus de Conservación Internacional y la Iniciativa Darwin en Perú, Venezuela y Bolivia. El resultado final de este proceso de
depuración es el producto que hoy se presenta a la comunidad académica y en general a todos aquellos interesados en los anfibios. Igualmente este manual representa una pequeña pero estratégica parte del esfuerzo global para enfrentar las disminuciones y extinciones como se menciona en el Plan para la Conservación de los Anfibios (ACAP), documento desarrollado durante la Cumbre de la Conservación de los Anfibios que se reunió en Washington, D.C. en septiembre de 2005, y que es la guía para las acciones de conservación de los anfibios que se implementen, a nivel global, durante los próximos años. Esperamos que al promover la investigación con iniciativas como ésta, podamos incrementar nuestro conocimiento
... Calling density showed a strong relationship to relative humidity, with the number of calling males increasing in a linear fashion with increasing humidity; this is consistent with previous research on O. pumilio (Prö hl, 1997 ). Indeed, temperature and humidity are well known to affect breeding efforts in amphibians (Aichinger, 1987; Duellman, 1995; Bandoni de Oliviera and Navas, 2004; Poelman and Dicke, 2007). Humidity appears to be the most predictive variable for the number of frogs calling at any given time. ...
Call surveys offer a valuable method to monitor anuran populations attributable to their temporal breeding habits and close association with water. Many temperate locations have adopted citizen science programs to monitor local anuran populations using call surveys and road transects. These surveys, however, are not commonly conducted in the tropics. I tested use of call surveys for estimating population density of a small terrestrial poison frog, Oophaga pumilio, in six different populations in Bocas del Toro, Panama. By conducting three-minute call surveys, and searching for all individual frogs in a 10 m radius of the survey point, I directly compared the number of calling males to the observed number of frogs in a given area. I found call density to be a poor predictor of population density. Despite there being differences in population densities, the lack of a relationship between the number of calls and population density highlights the limited use for call surveys for terrestrial, territorial species. Although call surveys may be useful in some taxa for general abundance estimates, this study clearly demonstrates a startling deficiency of call surveys for anuran monitoring and highlights the need for species-specific analysis to further explore the utility of this method.
... Así, al ser los reptiles en general, más susceptibles a los cambios en la temperatura y los anfibios hacia los cambios en la disponibilidad de agua (Pough et al. 1998), la ocurrencia y actividad de los anfibios de Chamela responden a la estacionalidad de las lluvias, mientras que los reptiles, al registrarse relativamente poca variación estacional en la temperatura máxima (al medio día: Bullock 1986) pueden ocurrir durante prácticamente todo el año (García 2003). El efecto de la estacionalidad en las lluvias sobre las fluctuaciones en las comunidades de anfibios ha sido documentado en otras áreas tropicales, en especial en aquellas regiones marcadamente estacionales (Toft & Duellman 1979, Duellman 1995, Duellman & Thomas 1996. En el caso de los reptiles, como se mencionó anteriormente el efecto de la estacionalidad a nivel de comunidad (diversidad y riqueza) es menor que en anfibios, sin embargo, a nivel de especie e individuos, la estacionalidad, a través de los cambios en la disponibilidad de recursos, precipitación, y cambios en la estructura de la vegetación entre otros, tiene un efecto muy importante en los niveles de actividad y reproducción (Beck & Lowe 1991, Lister & García 1992, García & Ceballos 1994, Ramírez-Bautista 20041994). ...
... The assumption when sampling for amphibians is that transects or plots should be established away from trails or trail systems, as these habitats could affect the abundance and richness of amphibian species (Cole and Landres 1995). The use of trails for sampling amphibians has not been thoroughly tested, but this technique has been used frequently to sample for amphibian disease, richness, and ecology in temperate and tropical regions (e.g., Duellman 1995;Smith et al. 2009; Barquero et al. 2010). Furthermore, two studies have found higher relative abundance of amphibians in habitats directly adjacent to trails compared to areas away from trails (Davis 2007;von May and Donnelly 2009). ...
The conservation and management of wildlife species is contingent on estimating distribution and abundance. Sampling of wildlife requires repeated visits to accurately determine species occurrence and to quantify abundance across temporal and spatial scales. The use of trails to sample wildlife populations is increasing and offers opportunities to potentially sample more frequently, with increased ease of access, and less disturbance to habitats, which can be important in sensitive natural areas. We examined capture data of terrestrial salamanders within Great Smoky Mountains National Park to determine if detection and abundance estimates from trail and non-trail transects were significantly different. Across two, 3-week periods during June and July 2012, we sampled 195 transects (70 along trails and 125 within non-trail habitat) on multiple occasions. We found that most microhabitat variables associated with salamander detection and abundance did not differ between trail and non-trail transects. Further, our models indicate detection and abundance of terrestrial salamanders were not significantly different on trail and non-trail transects. These results suggest trails can be used to accurately estimate abundance of terrestrial salamanders and may reduce the need to sample for plethodontid salamanders in sensitive habitat.
... Highest values of tadpole density were recorded during the second sampling year, and we found a negative relationship between density and rainfall values in that year (Fig. 2). Climatic variations, mainly in rainfall, are an important cause of anuran population fluctuations (e.g., Duellman, 1995;Stewart, 1995). Some studies in tropical forest streams show higher tadpole densities in the rainy season (Fatorelli et al., 2010;Almeida-Gomes et al., 2012), suggesting that rainfall is one of the local factors regulating tadpole communities. ...
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... Considerably more juveniles, adults, and total individuals were captured during the wet season at all sites (Fig. 3). These results agree with several other studies that concluded that anuran encounters and diversity are greater during the wet season in South America (Toft, 1980a;Aichinger, 1987;Moreira and Lima, 1991;Duellman, 1995). We also found distinct seasonal patterns of leaf litter depth (Fig. 8). ...
We examined patterns of community structure and microhabitat requirements of Pristimantis frogs at sites of high geographic proximity in the Tambopata region of southeastern Peru. Herpetofaunal surveys were conducted at five sites encompassing approximately 131 square km of Tambopata Province, including EcoAmazonia (EA), Reserva Amazonica (RA), Explorer's Inn (EI), Sachavacayoc Centre (SC), and Tambopata Research Center (TRC). In addition to sampling and identifying all species of Pristimantis captured, environmental variables, including substrate, perch height, leaf litter depth, tree cover, and time of day, were collected and analyzed. Total frog encounters, species richness, diversity, and community similarity differed significantly among sites. Generally, similarity, richness, and diversity were not closely related to geographic proximity, but total abundance was. More individuals were captured at SC and TRC, whereas more total species were captured at TRC and El. Diversity was the highest at TRC, followed by RA, El, EA, and SC. Encounters of P. toftae and P. peruvianus also differed significantly among sites, with one species rarely encountered where the other was prevalent. Generally, more individuals of Pristimantis were captured during the wet season at all five sites. Significantly more individuals were captured during the night than the day. Significantly more individuals as well as species were captured on leaves and the ground versus all other substrate types, with more on leaves at night and on the ground during the day. Significantly more adults were captured higher off the ground than juveniles, with males found higher than females. There was no significant relationship between frog encounters and leaf litter or tree cover. Pristimantis peruvianus was shown to exhibit differences In microhabitat usage from P. toftae. We conclude that many factors contribute to the observed differences in diversity among the sites, requiring future studies that will also examine other environmental variables such as forest type, soil characteristics, and prey availability.
... Such monitoring needs to be established as a long-term measure, based on a sufficient ecological and phenological knowledge of the species concerned (e.g. Skelly et al. 2003;Duellman 1995), and should be based on species that are easily seen and identified, and continuously active. At Andasibe, and probably at similar sites of mid-altitude rainforest in central eastern Madagascar, according to our results this applies to Boophis viridis, B. pyrrhus, Aglyptodactylus madagascariensis (only in the warm/rainy season) and Mantidactylus grandidieri (only if calm sections of streams are included in the monitoring transects). ...
Madagascar hosts a high diversity of amphibians estimated at over 500 species, nearly all of them endemic. Surprisingly few data are available on the activity cycles of this fauna, despite its importance for ecological, evolutionary and conservation research. Here we report the results of a year-round survey of amphibians along a transect bordering the Analamazaotra forest near Andasibe in central eastern Madagascar. During 120 transect walks evenly spaced through the year, a total of 2530 individuals of 40 species of anurans was observed. Abundance was higher during the warm/rainy season (December to April) and peaked in February. Of the five climatic predictors measured, only mean temperature and relative humidity showed high importance values, and multi-model averages indicate that these two variables have a strong effect on amphibian abundance along the transect. Species richness showed no evident peak during the study period and was best explained by a model including average temperature and rainfall. Canonical correspondence analysis indicates that Boophis sibilans, B. tephraeomystax, B. boehmei and Plethodontohyla notosticta were more frequently encountered along the transect on cold and humid days while Plethodontohyla mihanika, Gephyromantis boulengeri and Spinomantis aglavei were distinctly more abundant on cold and dry days, and Paradoxophyla palmata on warm and dry days. The results of our study flag a number of species as suitable candidates for future monitoring initiatives and suggest that a simple combination of visual and acoustic surveys can estimate amphibian activity with high sample sizes in Madagascar’s rainforests.
... The wet spring and summer provided favorable conditions for amphibian activity and reproduction. Studies have shown that annual variation in amphibian reproduction is great and that apparent population sizes fluctuate widely from year to year (Pechmann et al., 1991;Duellman 1995 (Samson and Knopf, 1994). Other studies of long-term changes in the central United States have detected major changes in herpetofaunal communities (Ludwig et al., 1992;Lannoo et al., 1994), and loss of habitat has been cited as a major factor for the observed changes. ...
To assess changes in the herpetofauna in the northern Flint Hills of Kansas, we conducted a survey on the Fort Riley Military Reservation (Riley and Geary counties) in 1993 and compared our results with those of C. E. Burt and other early collectors. Of 46 species reported before 1930, 37 were found in 1993. Four species recorded before 1930 and not found in 1993 (Bufo cognatus, Carphophis vermis, Thamnophis radix and Crotalus horridus) are known or believed to persist in Riley and Geary counties. Four other species (Heterodon platirhinos, Nerodia erythrogaster, N. rhombifer and Regina grahamii) have not been reported in over 50 yr and may be extirpated locally. Two additional species (Spea bombifrons and Trachemys scripta) found in 1993 were not reported by early collectors. Changes in relative abundance of species from pre-1930 to 1993 were few, and there was no evidence of decline in amphibian populations. With the exception of declines in species dependent on rare habitats located in the floodplain of major rivers, the herpetological assemblage in the Fort Riley area has changed little during the past 70-100 yr. We attribute this stability to land uses that have maintained large tracts of native vegetation.
... Thus far, there is no evidence that amphibian abundances in undisturbed lowland rain forest in the Amazon basin have declined (Duellman, 1995;von May et al., 2009). In contrast, Catenazzi et al. (2011) have documented the decadal collapse of montane forest anuran assemblages along a steep elevational gradient on the eastern slopes of the Andes in Manu National Park. ...
Peru hosts a rich amphibian fauna with approximately 571 species described to date. Many of these species have been formally described only recently, and many more remain to be discovered and recognized. Despite the increase in the number of known species, some reports indicate recent, and in some cases enigmatic, loss of species richness at several sites in the Peruvian Andes. Similar population declines have been observed in neighboring Andean countries. The pathogenic fungus Batrachochytrium dendrobatidis is associated with some of these declines, and we include a timeline of records of this pathogen in Peruvian amphibians. However, the paucity of standardized, long-term surveys limits our ability to understand the causes of declines and to assess the conservation status of Peruvian amphibians. Here we provide updated information on the conservation status of amphibians in Peru, and we discuss the possible causes of the observed declines. Furthermore, we discuss present and future threats to amphibian biodiversity, and we outline actions needed to promote the survival of this globally endangered group. We include a list of candidate sites for long-term surveys.
... Besides insects, the only other animal prey items that the woolly monkeys consumed were tree frogs and, very rarely, snakes (Di Fiore, 1997). The limited data that exist regarding seasonal changes in herpetofaunal density in lowland neotropical forests suggest that abundance is correlated with periods of heavy rainfall (Duellman, 1995). Moreover, Rodriguez and Cadle (1990) noted that breeding activity of neotropical anurans typically increases with the start of the rainy season. ...
We investigated the time allocation decisions of lowland woolly monkeys (Lagothrix lagotricha poeppigii) in a terra firma forest in eastern Ecuador where they occur sympatrically with 9 other primate species. Woolly monkeys spent considerable amounts of time searching for and attempting to procure animal prey—roughly as much time as they spent consuming plant material: ripe fruits, leaves, and flowers. The amount of time spent foraging for animal prey is positively related to the habitat-wide availability of ripe fruits (the predominant component of the woolly monkey diet), and negatively related to both ambient temperature and the abundance of potential prey items in the habitat. Time spent resting showed exactly the opposite pattern with respect to these ecological variables. These results suggest that woolly monkeys follow an energy-maximizing strategy of food acquisition during times of fruit abundance—focusing on animal foods and perhaps laying down fat reserves to utilize when ecological conditions worsen—and follow an energy-minimizing strategy when fruit resources are scarce. Such a strong and seasonal commitment to animal prey foraging is unique among the ateline primates and is not ubiquitous even among lowland woolly monkeys. We suggest that this foraging strategy, and the greater intragroup cohesion that characterizes some populations of Lagothrix, are both opportunistic responses to regional differences in habitat quality. Identifying and accounting for such intraspecific variation should be a goal of any analysis of comparative socioecology.
... Leiuperidae and Leptodactylidae species deposited their eggs in foam nests on the water surface (except the Pseudopaludicola genus that deposits its eggs directly into lentic environment), in underground burrows or in depressions made by males, protecting them from desiccation (DUELLMAN; TRUEB, 1994;PRADO;UETANABARO;HADDAD., 2005), this is a common strategy in species that inhabit dry environments with open vegetation types and availability of water restricted to short periods of the year (CARDOSO; ARZABE, 1993;DUELLMAN, 1995;ARZABE, 1999). ...
In this work we aim to increase knowledge about biodiversity in the Parnaíba Delta River through
characterization of anuran fauna of Ilha do Caju, municipality of Araioses, Maranhão state. We
recorded nine species belonging to three families: Leiuperidae, Leptodactylidae and Hylidae. In
addition to biogeographical and historical factors, environmental conditions and irregular rainfall
distribution, seem to contribute to the low species richness of amphibians in this island that have
a predominance of species that build foam nests (Leiuperidae and Leptodactylidae). Ilha do Caju
is considered as a natural laboratory that allows obtaining information for planning and evaluating
the status of conservation and preservation of regional biodiversity, helping to support future studies
in the Parnaíba Delta River region.
... The increase in rainfall during some months affects the annual activity of some anuran species (e.g. Donnelly and Guyer 1994;Duellman 1995;Hatano et al. 2002;Fatorelli et al. 2010). ...
We studied the temporal distribution of tadpoles of Crossodactylus gaudichaudii, and their relationship with rainfall, in a Brazilian Atlantic Rainforest area. There is no previous information about the population dynamics of tadpoles from this species. We sampled 60 m along streams between May 2002 and April 2005. Tadpoles in initial stages of development (up to stage 25) were present in all months of the year and represented 80.4% of those sampled. This indicates a continuous recruitment of new individuals in the aquatic environment. Tadpoles in final stages of development (stages 42–46) represented only 5% of those sampled, which may be the result of higher mortality in the early development stages. Body length of tadpoles varied among developmental stages and between seasons. Tadpole density was higher in the rainy season than in the dry season, and was significantly related to rainfall in the area.
Background
Dispersal limitations vary among species within the same region. For some species, geographic distance is the primary constraint, while for others, environmental factors such as climate and vegetation patterns play a larger role. These landscape-driven effects are shaped by species-specific ecological traits. Despite being conceptually intuitive, landscape genetics hypotheses—such as Isolation by Distance and Isolation by Environment—remain largely underexplored in tropical regions. We conducted a comparative landscape genetics study to assess the influence of geographic and environmental landscape features on genetic differentiation in two ecologically distinct anurans species: Dendropsophus oliveirai , a diminutive treefrog that uses ponds for reproduction and larval development, and Physalaemus cuvieri , a terrestrial frog that breeds in both ponds and rain pools, depositing eggs in foam nests where embryos develop. These species co-occur in highland forest enclaves within a dry vegetation matrix across the Borborema Plateau, northeastern Brazil.
Methods
We sampled individuals of both species in seven highland forest enclaves to assess phylogeographic patterns and genetic variation along the steep NE-SW climatic and vegetation gradient characterizing the plateau. Additionally, we collected geographic, climatic, and vegetation data for each site. We analyzed the relationships between geographic distance, environmental variation, climatic variation, and mtDNA genetic differentiation in both species using Mantel tests and Structural Equation Modeling.
Results
We found lower genetic differentiation in P. cuvieri , which was primarily associated with the geographic distance among enclaves, with only weak influence of environmental variation among sampling sites. Conversely, higher genetic differentiation was detected among geographic populations of D. oliveirai , mainly driven by a combination of geographic distance, environmental heterogeneity, and past climatic variation.
Conclusions
The contrasting genetic structures of the two species likely result from differences in their ability to traverse dry lowland areas between mesic highland forests, with Isolation by Distance and Isolation by Environment affecting each species differently. These findings suggest that both selective and neutral mechanisms contribute to genetic variation. Our study highlights that highland forests in northeastern Brazil may harbor genetically distinct anuran populations, where gene flow is constrained not only by geographic distance but also by environmental factors, especially in diminutive species with specific reproductive needs.
Context Within the same geographical area, geographical distance is the most important landscape feature limiting dispersal in some species, whereas for others environmental variation, such as climate and vegetation patterns, may curtail dispersal. Such landscape effects are usually determined by the ecological traits of the species. Although very intuitive, landscape hypotheses remain poorly investigated in tropical regions. Objectives We developed a comparative landscape genetic study evaluating the association and importance of geographic and environmental landscape features on the genetic differentiation in two ecologically differing anurans, the treefrog Dendropsophus oliveirai (a reproductive habitat specialist) and the chorus frog Physalaemus cuvieri (a reproductive habitat generalist), in highland forests inserted in a dry vegetation matrix in Northeastern Brazil. Methods We applied Mantel tests and Structural Equation Modeling to assess associations between geographic distance and environmental factors on mitochondrial genetic variation of the two study species. Results We found lower genetic differentiation in P. cuvieiri , mainly associated with geographic distance along a latitudinal gradient and weakly influenced by environmental variation among highland forests. Conversely, the higher genetic differentiation in D. oliveirai was associated with a combination of geographic distance along a longitudinal gradient, environmental variation, and past climatic variation. Conclusions Idiosyncrasies in the genetic structure and associations with landscape features in the two species may have resulted from different abilities to cross the dry lowland among the mesic highland forests. Our findings also suggest selective and neutral evolutionary mechanisms conducive to intraspecific genetic variation in the study area.
Este Manual de Campo ha sido el producto de un esfuerzo colectivo, que ha involucrado profesionales de diferentes instituciones y países de los Andes tropicales y de especialistas de otros países en América y Europa. Su conocimiento, experiencia extensiva y compromiso en la conservación de los anfibios han sido claves para el desarrollo del mismo. Este compendio de experiencias llega en un momento en que los esfuerzos para la conservación de los anfibios son tan altamente necesarios como
críticos y urgen el incremento del trabajo de campo que permita disminuir los vacíos de conocimiento colectivo acerca de los anfibios andinos.
Este manual se desarrolló con estas prioridades en mente, ya que ha sido escrito como herramienta de apoyo para los biólogos especialistas o para aquellas personas profesionales o en curso de serlo, interesados en los anfibios, con el objeto de facilitarles la estructuración de proyectos de investigación en los Andes tropicales.
“Técnicas de inventario y monitoreo para los anfibios de la región tropical andina”
recoge el deseo de los autores de los capítulos en ofrecer el estado del arte sobre el conocimiento de los mecanismos, prácticas y metodologías sobre el inventario y monitoreo de los anfibios con la esperanza de motivar el reclutamiento de nuevos investigadores que, a través de su propia iniciativa o de los cursos que hasta ahora
han venido siendo adelantados por la Iniciativa Atelopus, puedan ampliar su formación académica en beneficio de la conservación de nuestra herencia natural.
We report temporal variation and an “outbreak” of frog predation by moustached tamarins, Saguinus mystax, in north-eastern Peruvian Amazonia. Frog predation rates were generally very low, but strongly increased in October 2015. Other high rates, identified by outlier analyses, were also observed in September–November of other years. Over all study years, predation rates in this 3-month period were significantly higher than those in the remainder of the year, suggesting a seasonal pattern of frog predation by tamarins. Reduced fruit availability or increased frog abundance or a combination of both may be responsible for both the seasonal pattern and the specific “outbreak” of frog predation.
Water snakes of the genus Helicops have different uses of food resources that can facilitate species coexistence. To assess diet and foraging habitat of water snakes in eastern Brazilian Amazonia, we used prey consumed by Helicops angulatus, Helicops hagmanni, and Helicops polylepis deposited in scientific collections to analyze variations in composition, breadth, and niche overlap on a regional scale. Among these prey, we used fish (main item) to calculate ecomorphological attributes that might indicate fish habitat and, consequently, the foraging habitat used by snakes. Our analyses indicate these three snake species have similar diet compositions but differ in the proportion in which each item is consumed. Helicops angulatus had the most generalized diet and H. hagmanni had the most specialized diet. Food niche overlap among the three species was moderate. All three species forage in the medium and upper strata of the water column in the lentic zone; however, H. polylepis feeds on prey with varied morphological features that may indicate foraging in many types of environments. The snakes have similar diets and foraging habitats; however, they use food items and space in different proportions.
Abstract. Very little is known on the ecological attributes of neotropical salamanders. The aim of this study was to evaluate the effect of two abiotic factors on the temporal and spatial abundance of B. paraensis. Data were collected during four periods, in 23 plots of 250 m² distributed randomly in Gunma ecological Park, in the brazilian state of Pará. In each plot, temperature and relative humidity of the air were measured during searches, and abundance of salamanders was determined by active nocturnal searches. the abundance of salamanders varied significantly during the course of the year. the highest abundance (0‑18) was recorded in the mid wet season, followed by the late wet season (0‑7), early dry season (0‑9), and late dry season (0‑6). Spatial abundance of salamanders was influenced by climatic conditions only in the late dry season. temporal and spatial variation in the abundance of the salamanders is associated with relative humidity, which was highest in the mid wet season, and lowest in the late dry season, affecting their activity and consequently their detectability during the searches.
Forested landscapes are often dissected by an extensive network of primary and secondary logging roads, which may constitute a relatively permanent change in habitat structure for surrounding wildlife populations. We collected data on eight species of amphibians in central Maine (USA) in an effort to better understand the influence of logging roads on their movements and roadside habitat use in a forested landscape. The effects of a wide (12 m), heavily used logging road were compared to those of a narrower (5 m), less used forest track. Generally, anuran habitat use and movements were unaffected by even the larger road. In contrast, salamander abundance (i.e., Ambystoma sp., Plethodon cinereus, and Notopthalmus viridescens) was 2.3 times higher at forest control sites than at roadside sites. Furthermore, captures in roadside traps (road crossings) were only 25.9% of similarly oriented captures in paired forested controls, suggesting that the larger road significantly inhibited movement by salamanders. The importance of barrier effects from the larger road also varied depending upon the specific type of movement being made, with a greater proportion of natal dispersal movements taking place across roads (22.1%) than either migratory movements (17.0%) or home-range movements (9.2%). Forest roads apparently can serve as a partial filter to the movements of some amphibian species.
Quantitative and qualitative samples of amphibian and lizard faunas were taken from forest litter in Costa Rica and compared with similar samples collected in Borneo, the Philippines, and Panama. Animal abundance is about ten times greater in Costa Rican lowland wet forest than in Borneo. Radically different routes and rates of energy flow are postulated to account for the difference. In a series of upland (1010-1425 m) samples in the Philippines, the number of litter lizards and frogs increases with elevation. A single upland (1200 m) Costa Rican sample contains about three times as many animals per 100 m2 as two lowland sites. This increase with altitude correlates well with hypotheses that overall tropical forest productivity is greatest at intermediate elevations. Herpetofaunal densities are greater in wet areas compared to dry sites and flat terrain compared to slopes. These observations are linked to the greater variation and lesser total litter fall in dry sites and/or slopes. The number of species of amphibians and lizards regularly inhabiting the litter is similar in all wet lowland forests studied. Increasing elevation and decreasing rainfall correlate with faunas having fewer species. The former is seen as the result of the differential ability of lowland species to invade uplands, and the latter as a decrease in the kind and duration of frog-spawning sites. Reduced equitability with increasing elevation is principally due to the much greater proportional increase of the commonest species. In the evolution of American and Bornean-Philippine wet lowland faunas, frogs with direct development (Eleutherodactylus) have radiated in the former in the same fashion that skinks have in the latter.
Reports of declining amphibian populations in many parts of the world are numerous, but supporting long-term census data are generally unavailable. Census data from 1979 to 1990 for three salamander species and one frog species at a breeding pond in South Carolina showed fluctuations of substantial magnitude in both the size of breeding populations and in recruitment of juveniles. Breeding population sizes exhibited no overall trend in three species and increased in the fourth. Recent droughts account satisfactorily for an increase in recruitment failures. These data illustrate that to distinguish between natural population fluctuations and declines with anthropogenic causes may require long-term studies.
Analysis of a 35 year data base on frogs from species assemblages in southeastern Brazil, suggests three kinds of species changes: the appearance of Hyla albopunctata at Boraceia; the possible extinction of Fritziana ohausi at Boraceia when the bamboo species in which Fritziana reproduces flowered and died; and population reductions and extinctions of a number of species at several localities in southeastern Brazil in 1979. We argue that the cause of this latter event was most likely due to unusually heavy frosts. The unusual event in 1979 had differential effects on the species which resulted in both short-term ecological changes within the assemblages effected and potential long-term evolutionary effects on the assemblages and individual species involved.
This paper documents changes in the size of a breeding population of Yosemite toads, Bufo canorus, over 20 years at Tioga Pass, California. Surveys of B. canorus numbers in breeding aggregations were made yearly from 1971 to 1982, and less systematic observations were made from 1983 to 1991. Six other populations in the eastern Sierra Nevada were surveyed occasionally from 1973 to 1990. The total number of marked males entering the largest breeding pools at Tioga Pass declined nine-fold from 1974 to 1982. The mean number of toads found in daily searches during breeding also dropped over the 20 year study. Similar declines occurred at smaller breeding sites throughout Tioga Pass Meadow and at the six other populations. In 1990 we found evidence for continued reproduction by B. canorus at all but one location (Sylvester Meadow), although reproduction was minimal at Tioga Pass. No single source of mortality was responsible for all the declines. We interpret the decline in our study populations as caused primarily by drought, disease, and predation. Spring snow depths in 1976, 1977 and 1987-1991 were below the 62 year average, resulting in low tadpole survival. The death of adults from disease at Tioga Pass, and from predation at another site (Mildred Lake) also contributed to the declines. Although habitat destruction and localized human activities were not major factors, some natural variables responsible for the declines may have had anthropogenic components.
Rana muscosa is one of several high-elevation amphibians that have recently disappeared from seemingly pristine sites. The present study documents an event of mass mortality among larval and metamorphosed R. muscosa in a lake in Kings Canyon National Park, California, and the ultimate extinction of the population. In 1979 metamorphosed individuals declined from ca. 800 individuals in early summer to nearly zero in late summer. During this time many carcasses were collected, individuals showed symptoms of red-leg disease, and blood from an affected individual contained the bacterial pathogen characteristic of this disease, Aeromonas hydrophila. Also during the summer of 1979, nearly all of the approximately 1100 tadpoles began metamorphosis, but all metamorphosing individuals were consumed by Brewer's blackbirds (Euphagus cyanocephalus). This population of R. muscosa continued to exist until at least 1983, but was extinct by 1989. Recolonization of the site will probably never occur because streams connecting to extant populations of R. muscosa now contain introduced fishes.
Article de synthese sur le premier Congres Mondial d'Herpetologie (Canterbury, U.K., Septembre 1989) concernant le declin de nombreuses especes d'amphibiens de par le monde. Plusieurs exemples, discussion sur les causes possibles et les strategies a suivre