Estruturação espacial e temporal de uma comunidade de anuros (Amphibia) na Serra do Cipo, Minas Gerais

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

An anuran community was studied from August 1996 to July 1997, in a 1200 m high rocky field site at the Serra do Cipó, including a stream, a puddle and a swamp. Spatial and temporal distributions of the species were studied, and features useful to distinguish them were looked for. Factors possibly responsible for community structure were listed and examined based on field observations. Fourteen anuran species were registered in the study site: Hyla alvarengai, H. saxicola, Phyllomedusa megacephala, Scinax duartei, Leptodactylus cunicularius, L. furnarius, L. jolyi, L. labyrinthicus, L. syphax, Odontophrynus americanus, Physalaemus cuvieri, Proceratophrys cururu, Pseudopaludicola mineira, and Thoropa megatympanum. Tadpoles differed in microhabitat use specially concerning position in water column, occurrence period and water flow. Aquatic vegetation, depth, and habitat used were of secondary importance for species differentiation. Meanwhile, some dimensions of many species niches showed superposition. Males calling sites were distinguished specially concerning habitat used, even though activity period was also important for species differentiation. Most species started reproductive activities as soon as it started raining, in an opportunistic way. This behavior can be advantageous in temporary environments. Developmental periods were estimated for some species, and they were short in general, as expected for species from temporary environments. Scinax duartei tadpoles developed to froglets in 5 months, the longest period registered. Their larval behavior may help avoiding predation during this period, when they remain sheltered among aquatic vegetation and move little. The most important tadpole predators registered in the study site were belostomatids and odonate nymphs. Their abundance peaks occurred after those of tadpoles, as predicted for predator-prey populations with interconnected cycles. Mortality rates were high for tadpoles, and predation was their most likely cause. Competitive interactions could not be detected in the anuran community. Partial niche superposition in tadpoles and adult males calling sites may suggest that competition is not an important force structuring this community. The successful development of Odontophrynus americanus in the three habitats studied is also indicative of the absence of food lirnitations in any of them, even though differences in plankton concentrations have been registered. The anurans showed morphological, physiological, and behavioral features likely to improve their success in the rocky field environment. Examples of these are the foam nests of many leptodactylids, the nests built in vegetation by Phyllomedusa megacephala, resistance to high temperatures in Leptodactylus cunicularius, L. furnarius, and Physalaemus cuvieri tadpoles, ability to climb rocks in Thoropa megatympanum tadpoles, the resting behavior of Hyla alvarengai and H. saxicola. Stochastic colonization and extinction events seem common in the Serra do Cipó, depending on habitats natural conditions and anurans resistance to them and to tadpole predators

ASSUNTO(S)

reprodução anuro anfibio girino

ACESSO AO ARTIGO

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