Diversity of amphibians in rice fields from northeastern Argentina

Se registró y analizó la diversidad y riqueza de una comunidad de anfibios que habita campos de arroz en el nordeste de Ar.gentina. Las muestras fueron obtenidas en el período comprendido entre octubre 2001 y junio 2003. Se identificaron 26 especies habitando cinco microhábitats: campos de arroz, zanjas y caminos, vegetación natural, vegetación acuática y barrancas. La vegetación natural fue el microhábitat más diverso mientras que las barrancas presentaron la menor cantidad de especies. El modelo de rango abundancia serie logarítmica fue el de mejor ajuste para tres de los microhábitats analizados, otro se ajustó al modelo geométrico y el restante al modelo de varilla rota. Los datos sugieren que los cultivos de arroz del nordeste argentino, podrían albergar una fauna muy diversa si están sujetos a un manejo apropiado.Registrou-se e analisou-se a diversidade e riqueza de uma comunidade de anfíbios que habita campos de arroz no nordeste da Argentina. As amostras foram obtidas no período compreendido entre outubro de 2001 e junho de 2003. Identificaram-se 26 espécies habitando cinco microhábitats: campos de arroz, sulcos e caminhos, vegetação natural, vegetação aquática e barrancas. A vegetação natural foi o microhábitat mais diverso enquanto que as barrancas apresentaram a menor quantidade de espécies. O modelo de espécie-abundância de série logarítmica foi o de melhor ajuste para três dos microhábitats analisados, outro foi ajustou ao modelo geométrico e o último ao modelo de vara quebrada. Os dados sugerem que os cultivos de arroz do nordeste argentino poderiam abrigar uma fauna muito diversa se estão sujeitos a uma manipulação apropriada.The anuran biodiversity and richness of a frog community inhabiting rice fields in northeastern Argentina was surveyed and analyzed. The samples were taken between October 2001 and June 2003. Twenty six species of amphibians were identified in five microhabitats: rice fields per se, ditches and paths, natural vegetation, aquatic vegetation and gullies. The natural vegetation was the most diverse of the microhabitats, while gullies were the poorest in species. The amphibian species of three of the microhabitats adjusted to the logarithmic range-abundance model, one to the geometric and one to the broken stick model. The data suggest that rice cropping in northeastern Argentina, if properly managed, can support a diverse anuran fauna.Fil: Duré Pitteri, Marta Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Kehr, Arturo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Schaefer, Eduardo Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Marangoni, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentin

Variation in body size and metamorphic traits of Iberian spadefoot toads over a short geographic distance

Determinants of geographic variation in body size are often poorly understood, especially in organisms with complex life cycles. We examined patterns of adult body size and metamorphic traits variation in Iberian spadefoot toad (Pelobates cultripes) populations, which exhibit an extreme reduction in adult body size, 71.6% reduction in body mass, within just about 30 km at south-western Spain. We hypothesized that size at and time to metamorphosis would be predictive of the spatial pattern observed in adult body size. Larvae from eight populations were raised in a common garden experiment at two different larval densities that allow to differentiate whether population divergence was genetically based or was simply a reflection of environmental variation and, in addition, whether this population divergence was modulated by differing crowding larval environments. Larger adult size populations had higher larval growth rates, attaining larger sizes at metamorphosis, and exhibited higher survival than smaller-sized populations at both densities, although accentuated at a low larval density. These population differences appeared to be consistent once embryo size variation was controlled for, suggesting that this phenotypic divergence is not due to maternal effects. Our results suggest considerable genetic differentiation in metamorphic traits that parallels and may be a causal determinant of geographic variation in adult body size. © 2008 The Authors.Peer Reviewe

Life-History Traits of Three Syntopic Species of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus) from the Atlantic Forest of Argentina

Amphibians from Atlantic Forests of South America are one of the most threatened vertebrates of the world, mainly due to the habitat loss and infectious diseases. With the goal to improve the knowledge of the lifehistory traits of the amphibian that inhabit these regions, and thus, to aid conservation and management-decision making, our main goals were to describe the reproductive activity pattern and analyze the interspecific variation in body size and the reproductive traits of three species of redbelly toads (Melanophryniscus) of the Atlantic Forest of Argentina. We also analyzed age structure, whether Sexual Size Dimorphism (SSD) exists, and if this dimorphismcould be explained by proximate mechanisms such as differences in growth patterns. The Melanophryniscus we studied bred during two or three consecutive days, in several explosive events that occurred between April 2009 and October 2012. These events were determined by a trade-off between the air and water temperature, and the level of the water bodies. We observed spatial segregation among the three species we studied when they reproduced synchronously and in sympatry and with the presence of multiple clutches. We found inter-specific differences inbody size. We recorded male-biased sex ratio and SSD in all three species of Melanophryniscus studied. We also found significant interspecific differences in age-related parameters following the differences in body size. Species were not sexually dimorphic by age. We also did not find covariation between body size and reproductive traits. These new insights allow us to predict the responses of Melanphryniscus we studied to the impact of the destruction of their habitat and global warming.Fil: Marangoni, Federico. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Baldo, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentin

Life-History Traits of Three Syntopic Species of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus) from the Atlantic Forest of Argentina

Amphibians from Atlantic Forests of South America are one of the most threatened vertebrates of the world, mainly due to the habitat loss and infectious diseases. With the goal to improve the knowledge of the lifehistory traits of the amphibian that inhabit these regions, and thus, to aid conservation and management-decision making, our main goals were to describe the reproductive activity pattern and analyze the interspecific variation in body size and the reproductive traits of three species of redbelly toads (Melanophryniscus) of the Atlantic Forest of Argentina. We also analyzed age structure, whether Sexual Size Dimorphism (SSD) exists, and if this dimorphismcould be explained by proximate mechanisms such as differences in growth patterns. The Melanophryniscus we studied bred during two or three consecutive days, in several explosive events that occurred between April 2009 and October 2012. These events were determined by a trade-off between the air and water temperature, and the level of the water bodies. We observed spatial segregation among the three species we studied when they reproduced synchronously and in sympatry and with the presence of multiple clutches. We found inter-specific differences inbody size. We recorded male-biased sex ratio and SSD in all three species of Melanophryniscus studied. We also found significant interspecific differences in age-related parameters following the differences in body size. Species were not sexually dimorphic by age. We also did not find covariation between body size and reproductive traits. These new insights allow us to predict the responses of Melanphryniscus we studied to the impact of the destruction of their habitat and global warming.Fil: Marangoni, Federico. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Baldo, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentin

Can age and growth patterns explain the geographical variation in the body size of two toad species?

Determining both the age structure and growth pattern allows to establish the causal factors, environmental and/or genetic, that eventually may be responsible for the observed pattern of divergence. We examined the variation in age structure and growth pattern across populations of two toad species, Pelobates cultripes and Epidalea calamita that exhibit a geographic variation in body size in southern Spain. For both species, populations differed in mean age but age structure did not correlate with body size variation across populations. Although the population with the youngest females found for E. calamita was the smallest in body size, the oldest males for both species were found in a small body size population. The growth pattern fit well to a von Bertalanffy growth model and interdemic divergence were found for both the asymptotic body size (Sm ) and the growth coefficients (k). As expected, Large-Bodied populations of both species attained higher Sm but, Small-Bodied population had higher, although non significantly different, k growth coefficients. Also, the Small-Bodied population attained sexual maturity sooner but had also high longevity. The observed pattern may reflect both environmental variations in resources availability affecting body size observed across populations, but also different growth and maturity pathways that may respond to contrasting selective pressures.Fil: Marangoni, Federico. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; ArgentinaFil: Tejedo, Miguel. Consejo Superior de Investigaciones Científicas; EspañaFil: Cogalniceanu, Dan. Universitatea Ovidius din Constanta; Rumani

Age, body size and growth pattern of Argenteohyla siemersi pederseni (Anura: Hylidae) in northeastern Argentina

In this study we analysed the body size, age structure, age at maturity, longevity and growth pattern of Argenteohyla siemersi pederseni in north-eastern Argentina using skeletochronological methods. Body size was sexually dimorphic; females were significantly larger and heavier than males, regardless of age. As A. s. pederseni is an explosive breeder with only one reproductive episode per year, we assumed that each Line of Arrested Growth (LAG) observed was equivalent to one period of decreasing growth, LAGs reflecting a direct estimation of individual age. The minimum number of LAGs counted was two for males and three for females, but there was no sexual difference in longevity. The von Bertalanffy's growth coefficients (K) were higher in males than in females for both size and body mass. Females had a lower growth rate than males, took longer to reach the minimum maturation size, and were older and larger at reproduction.Fil: Cajade, Rodrigo. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas Naturales y Agrimensura. Departamento de Biología. Laboratorio de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marangoni, Federico. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gangenova, Elena. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Can neutral genetic differentiation explain geographical variation in body size of the natterjack toad, Epidalea calamita?

Population genetic studies are crucial for evolutionary biologists because the population is the basic substrate on which evolution is forged. However little empirical evidence has been able to demonstrate the role that isolation and gene flow play in maintaining differentiation in populations at short geographic scales. Epidalea calamita exhibits a steep variation in body size and reproductive traits in southwestern Spain, associated with changes in the geological substrate. This implies a decrease of 70.9% of body mass and 28.5% in snout-vent length, on a micro-geographic scale of only 60 km. Previous results from both metamorphic and juvenile common garden experiments showed that genetic differentiation may be a causal determinant of geographic variation in adult. This study tested whether neutral genetic differentiation can explain the geographical variation in the body size observed in E. calamita. It was addressed analyzing the level of genetic structuring and gene flow among populations along the cline, comparing the genetic diversity between and within populations, as well as between ecological environments. The study showed that the geographic variation in body size observed in E. calamita has evolved in absence of geographic isolation, with moderate gene flow connecting the populations. Thus, neutral genetic differentiation cannot explain the geographical variation observed. Future studies are needed on the interaction between the genetic component with the environmental factors and will be necessary to analyze the contribution of the maternal effects in the origin and evolution of the geographical variation in the body size observed in E. calamita from southern Spain

Extreme reduction in body size and reproductive output associated with sandy substrates in two anuran species

Geographic variation in body size and reproductive traits has been reported in a wide range of organisms, including amphibians. Most studies have focused on latitudinal and/or altitudinal variation where differences in temperature and duration of the growing season are the main causes for population divergence. We describe a steep variation in body size and reproductive traits in two anuran species in southwestern Spain, associated with changes in the geological substrate. Pelobates cultripes and Bufo calamita (= Epidalea calamita) drastically reduced their size (a 71.6% and 76.1% reduction in body mass for P. cultripes and B. calamita, respectively) in just about 60 km. This extreme size reduction was more pronounced at the boundary between two different geological substrates (hercinic and sandy soil). Mean clutch mass, egg size, and clutch size were all smaller in B. calamita populations in the sandy environment. Likewise, clutch mass and egg size were both smaller in sandy P. cultripes populations. We observed a negative correlation between size-adjusted fecundity and egg size for both species, suggesting the existence of a reproductive trade-off that could explain the differences in reproductive allocation between populations and species. In P. cultripes, small-bodied populations had relatively higher fecundities and smaller eggs than large-bodied ones, whereas in B. calamita populations from the sandy area we found both populations with high fecundity and small eggs, and populations with low fecundity and large eggs. Common environmental effects associated with the sandy substrate produce a similar reduction in size in both toad species. © 2008 Koninklijke Brill NV, Leiden.Peer Reviewe

Predation of Dermatonotus muelleri (Boettger 1885) by Lepidobatrachus llanensis Reig and Cei 1963

On 7 December 2013, we performed an intensive night survey between the localities Fuerte Esperanza and Misión Nueva Pompeya, in the Chaco Province, northern Argentina. The night was preceded by a heavy storm, creating a multitude of temporary ponds. The environmental conditions triggered the explosive reproduction in D. muelleri: vocalizing adult males were heard in addition to observations of pairs in amplexus inside water bodies and the presence of females on land which were headed to the breeding ponds. At 00.48 hours, we witnessed an adult D. muelleri being preyed upon by an adult Lepidobatrachus llanensis Reig and Cei 1963 on the side of a dirt-road segment (Ruta Provincial no. 61) (25°0?8.52?S, 61°30?50.25?W).Fil: Stanescu, Florina. University Constanţa; RumaniaFil: Marangoni, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Reinko, Ivana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentin

Body Size, Age and Growth Pattern of the most represented anurans in Inselbergs of northeastern Argentina

The decline of biodiversity is an urgent concern that raises significant alarm today. Severalspecies vanish without their biology being understood, or sometimes, even without awarenessof their existence. Due to the significance that the Inselbergs has to biodiversity and nature, asthey have been recognized as genuine evolutionary laboratories, they present a unique opportunity to enhance our understanding of biologically unexplored species. Our study presentsthe first information regarding the body size, age and growth pattern of Scinax fuscovarius,Odontophrynus asper, and Melanophryniscus atroluteus, the three most frequently encounteredanuran species in the Inselbergs outcrops of northeastern Argentina. We have demonstratedthat the variations in body size cannot be attributed to the effect of the specific hill where thespecies inhabit. We discovered that sexual dimorphism in age and the analyzed morphologicalvariables is expressed differently in the three examined species. We also demonstrated that theobserved differences in body size between populations of M. atroluteus of Inselbergs and theAtlantic Forest of Argentina can be attributed to differences in age at sexual maturity and growthpatterns. However, we believe that other proximate mechanisms should be taken into account,such as the effects of the environment and inter- and intra-specific competition experiencedduring the larval stages, for a better understanding of the population differences in adult bodysize and age. Our findings will assist in the evaluation of species management and conservationstrategies within their habitat.El declive de la biodiversidad es una preocupación urgente que suscita gran alarma hoy en día. Varias especies desaparecen sin que se comprenda su biología o, a veces, incluso sin que se sepa de su existencia. Debido a la importancia que los Inselbergs tienen para la biodiversidad y la naturaleza, ya que han sido reconocidas como auténticos laboratorios evolutivos, presentan una oportunidad única para mejorar nuestra comprensión de especies biológicamente inexploradas. Nuestro estudio presenta la primera información relativa al tamaño corporal, edad y patrón de crecimiento de Scinax fuscovarius, Odontophrynus asper, and Melanophryniscus atroluteus, las tres especies de anuros más frecuentemente encontradas en los afloramientos de los Inselbergs del noreste de Argentina. Hemos demostrado que las variaciones en el tamaño corporal no pueden atribuirse al efecto del cerro específico donde habitan las especies. Descubrimos que el dimorfismo sexual en edad y en las variables morfológicas analizadas se expresa de manera diferente en las tres especies examinadas. También demostramos que las diferencias observadas en el tamaño corporal entre las poblaciones de M. atroluteus de los Inselbergs y del Bosque Atlántico de Argentina pueden atribuirse a diferencias en la edad a la madurez sexual y en los patrones de crecimiento. Sin embargo, creemos que deben tenerse en cuenta otros mecanismos próximos, como los efectos del ambiente y la competencia inter e intraespecífica experimentada durante las fases larvarias, para comprender mejor las diferencias poblacionales en el tamaño corporal y la edad de los adultos. Nuestros hallazgos ayudarán a evaluar las estrategias de gestión y conservación de las especies dentro de su hábitat.Fil: Piñeiro, Jose Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología. Laboratorio de Herpetología; ArgentinaFil: Cajade, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología. Laboratorio de Herpetología; ArgentinaFil: Marangoni, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Departamento de Biología; Argentin