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Fil: Gomez, Valeria Isabel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Nordeste. Centro de Ecologia Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecologia Aplicada del Litoral; Argentina

Desiccation exposes tadpoles to a decrease in habitat size due to a reduction in water depth and surface area. We tested the effect of surface area and water depth on growth and development of tadpoles of Physalaemus albonotatus and whether habitat size effects are constant over the larval period. We performed a 2 × 2 factorial design: two water depths and two surface areas. We measured tadpoles at 15 and 30 days after starting the experiment, and recorded weight and time to metamorphosis. Our results indicate that habitat size influences the morphology, growth, and development of tadpoles and that the response changes during development. At 15 days, tadpoles reared in shallow water had reduced their morphological variables and developmental stage, whereas tadpoles reared in enclosures with different surface areas showed no differences. At 30 days, tadpoles reared in enclosures with small surface areas had increased their body length, body height, and developmental stage, whereas tadpoles reared in different water depths showed no differences. Tadpoles reared in small surface areas reached metamorphosis earlier than tadpoles reared in large surface areas. The results suggest that during ontogeny the surface area and water depth had different influence in the phenotypic plasticity of tadpoles. Fil: Gómez, Valeria Isabel. 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; Argentina Fil: 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; Argentina

Changes in environmental conditions can induce organisms to alter their morphology, behavior and life history. Predation is an important factor in many aquatic communities and can strongly select for anti-predator responses. In the present work, we examined the responses in morphology, growth rate and development rate of Elachistocleis bicolor tadpoles raised in the presence of chemical cues from two different predators: a water bug (Belostoma elongatum) and a fish (Moenkausia dichroura). The experiment was performed in microcosm conditions. The experimental design consisted of three treatments: chemical cues from fish, cues from water bugs and a control group. Each treatment was replicated 30 times. Each container held a single larva. The main results were: (1) there were significant differences in body depth between the predator treatments (fish vs. water bug) and between the control group and the water bug treatment, (2) there were significant differences in tail depth between predator treatments (fish vs. water bug) and between the control group and the fish treatment, (3) there were no significant differences in the growth rate and developmental rate among the treatments. Our results suggest that the presence of predaceous fish and water bugs cause different effects on tadpole morphology. In the presence of water bugs, tadpoles decreased body depth, whereas in the presence of fish tadpoles increased tail depth. These responses could be related to the way in which predators capture their prey. Predator chemical cues did not have any detectable effect on the growth rate and development rate of E. bicolor tadpoles. Fil: Gómez, Valeria Isabel. 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; Argentina Fil: 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; Argentina

Amphibians exhibit extreme plasticity in the timing of metamorphosis, and several species respond to water availability, accelerating metamorphosis when their ponds dry. We analyzed the plasticity of the developmental response to water volume in Rhinella schneideri tadpoles. We raised tadpoles in mesocosm. Covariation between body size atmetamorphosis and timing of development was positive. Nevertheless, the first approximately 53% of the metamorphoses finishing the cycle required between 34 and 56 days, and the covariation between body size at metamorphosis and timing of development was negative. For these tadpoles, the larval density and the presence of predators did not significantly affect their mass to metamorphosis. Nevertheless, predators affected time to metamorphosis. For the remainder of the tadpoles that reached metamorphosis at > 56 days, the relationship between body size at metamorphosis and timing of development was positive. For these tadpoles, larval density was important for mass at metamorphosis and presence of predators was also important for time to metamorphosis. Two dominant features were observed: (i) approximately 53% of metamorphs had morphological features similar to individuals developing in desiccating ponds, and (ii) the other individuals had morphological characteristics comparable to metamorphs developing in an unchanging environment. Fil: 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; Argentina Fil: Gómez, Valeria Isabel. 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; Argentina

Predation affect the behaviour of organisms, and the number of conspecifics can influence the perception of predation risk. Two main types of traits, morphological and behavioural, are involved in the induced defences of many organisms. Here, we examined the influence of chemical cues of the predators Belostoma elongatum (Hemiptera, Belostomatidae) and Moenkhausia dichroura (Characiformes, Characidae) on the morphology, growth, development and activity of Scinax nasicus larvae. Our main goal was to determine whether the investment in morphological or behavioural defences varied according to the number of conspecifics and to the chemical cues of predators. To this end, we performed two experiments under microcosm conditions. In experiment 1, we determined morphological defences in tadpoles by analyzing changes in morphology, growth rate and development rate, whereas in experiment 2, we determined behavioural defences by analyzing changes in the activity of tadpoles. The experimental design consisted of two tadpole densities, with and without chemical cues of predators. We found that: 1) larval morphology, growth and development were significantly affected by density; 2) the chemical cues of the predators did not influence the morphology, growth or development of tadpoles; 3) tadpoles at high densities were more active than those at low densities; 4) tadpoles decreased the activity in the presence of chemical cues of M. dichroura; and 5) tadpoles increased the activity in the presence of chemical cues of B. elongatum. Our results suggest that density is a determinant factor of tadpole morphology of and that Scinax nasicus larvae respond to predators with behavioural defences, which vary according to the type of predator. Fil: Gómez, Valeria Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina; Fil: Kehr, Arturo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Centro de Ecologia Aplicada del Litoral (i); Argentina

Morphological and developmental plasticity in larvae of Physalaemus santafecinus (Anura: Leiuperidae) in response to chemical cues of different predators. Many antipredator responses are mediated or induced by the ability of the prey to identify chemical cues of predators. The presence of chemicals produced by predators may alert tadpoles to the presence of the predators, and a heightened response to alarm cues or predator presence may increase the possibility of prey survival. We examined changes in morphology, and growth and development rates of Physalaemus santafecinus tadpoles reared in the presence of chemical cues of water beetles (Hydrophilidae) and a fish (Characidae). We recorded the time to metamorphosis, as well as weights of metamorphic individuals to determine if the larval stage is accelerated. The experiments were performed under microcosm conditions, with three treatments—chemical cues from fish, water beetles, and a control group. Each treatment was replicated 30 times. To obtain independent data from different variables, treatments were conducted on individual larvae in separate containers. The principal results were, as follow. (1) Larval morphology was significantly affected by the presence of a predator. (2) Control tadpoles were significantly larger than those subjected to the other two treatments (cues of water beetles and fish). (3) Growth and development rates did not differ significantly among any treatments. (4) Neither time to metamorphosis nor weights of metamorphs varied significantly among treatments. Our results suggest that tadpoles are able to perceive predators by chemical cues released in the water, and P. santafecinus tadpoles alter their morphology to chemical cues that indicate predation. However, chemical cues of predators had no detectable effect on growth rate and developmental rates of these tadpoles.