976 resultados para Neotropical fishes
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The rare Neotropical ant subfamily Leptanilloidinae is revised and its internal phylogeny and biogeography discussed. A new genus, Asphinctanilloides gen.n., including three new species, A, amazona, A. anae and A. manauara, and three new species of Leptanilloides, L. improvisa, L. legionaria and L. sculpturata are described. The only previously known species of the subfamily, L. biconstricta Mann (1923), is redescribed, and the larva of L, legionaria sp.n, is described. Keys to the genera and the species, and a phylogeny of the group are provided. Emphasis has been placed on the study of abdominal and sting characters.
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The distribution, activity, diet, and reproduction of an undescribed catfish species of the genus Trichomycterus (Trichomycteridae) were studied in the Morro do Diabo State Park, an important conservation area in the Rio Paranapanema basin, State of São Paulo, southeastern Brazil. Trichomycterus sp. is a rheophilic species occurring solely in the riffle areas of the streams and hunts mostly immature aquatic insects during the day by picking them from the substrate. The population has a balanced sex ratio, but females were uncommon in the smallest and largest size classes suggesting that females demonstrate a more accelerated growth pattern. Presence of mature individuals throughout the year represents an opportunistic reproductive tactic for fishes living in fast flowing waters, where the clutches could be shifted by the current, but the high incidence of mature individuals in the wet season may be related to optimal environmental conditions for juveniles during that period. Because of the restriction of Trichomycterus sp. to riffle environments, the conservation of this species depends on the maintenance of the original characteristics of these headwaters. That demands protecting the riparian vegetation and consequently the stream from excessive siltation resulting from runoff and erosion.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We observed individuals of Odontostilbe pequira, a small characid, approaching and biting individuals of larger-bodied fishes of other species. This observation was made in two clear water headwater streams of the Cuiaba basin, Paraguay River system, located in Nobres, Mato Grosso State, Brazil, which led us to investigate the behavioral interactions of these fish. We characterized behavioral interactions between species by direct underwater observations using snorkelling and video recordings. Additionally, we proceeded diet analyses of O. pequira, obtaining intestinal coefficient and the index of alimentary importance. During underwater observations we checked the relative frequency of attacks by O. pequira on larger fish species. Odontostilbe pequira attacked individually or in large groups, and the anostomid Leporinus friderici was the preferred target prey species, while Prochilodus lineatus was apparently avoided. Our study sustains that O. pequira is omnivorous, with a diet that varies seasonally. It feeds mainly on plants, but also on animal prey, including the scales of small fishes, and, possibly, the mucus and epidermis of larger fish species. We suggest the term "mutilating predation" to describe the latter relationship.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Sexual selection is a crucial element to understand behavioral evolution. Teleost fish have been considered as good models for research on sexual selection in the last decades due to their variety of sexual behavior. Female fish can choose males based on body and behavioral traits, such as body size, body color, ornaments, territorial quality, nest size and courtship behavior. Choices are based upon several types of sensorial inputs, such as visual, chemical, sonorous and electrical signals. Intrasexual selection also acts on females because they can mate with a dominant individual in male-male competitions. For both approaches, there is an expectation regarding the benefits of sexual selection by means of female choice. However, in several cases females do not choose the dominant male. In this mini-review, we present and discuss both intersexual and intrasexual mechanisms of sexual selection in fish and point out that females do not always choose a male for mating.