61 resultados para habitat connectance

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


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Every year, autochthonous cases of Plasmodium vivax malaria occur in low-endemicity areas of Vale do Ribeira in the south-eastern part of the Atlantic Forest, state of São Paulo, where Anopheles cruzii and Anopheles bellator are considered the primary vectors. However, other species in the subgenus Nyssorhynchus of Anopheles (e.g., Anopheles marajoara) are abundant and may participate in the dynamics of malarial transmission in that region. The objectives of the present study were to assess the spatial distribution of An. cruzii, An. bellator and An. marajoara and to associate the presence of these species with malaria cases in the municipalities of the Vale do Ribeira. Potential habitat suitability modelling was applied to determine both the spatial distribution of An. cruzii, An. bellator and An. marajoara and to establish the density of each species. Poisson regression was utilized to associate malaria cases with estimated vector densities. As a result, An. cruzii was correlated with the forested slopes of the Serra do Mar, An. bellator with the coastal plain and An. marajoara with the deforested areas. Moreover, both An. marajoara and An. cruzii were positively associated with malaria cases. Considering that An. marajoara was demonstrated to be a primary vector of human Plasmodium in the rural areas of the state of Amapá, more attention should be given to the species in the deforested areas of the Atlantic Forest, where it might be a secondary vector.

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Post-settlement processes are a major focus in the study of the dynamics of marine populations and communities. Post-settlement movement of juveniles is an important, but often ignored, process which affects local predator-prey and competitive interactions. We used benthic suction sampling and pitfall traps to examine density and locomotory activity of Carcinus maenas juveniles in different intertidal habitat types in the Rio Mira Estuary, Portugal, to better understand intra-specific interactions in a system where density-dependent processes are known to regulate population dynamics. As expected, significantly higher densities of juvenile shore crabs were found from bare mud compared to densely vegetated habitats. At the time of sampling, small and intermediate stages together outnumbered by far the larger juveniles. Conversely, larger crabs were much more frequent than smaller ones in traps. A locomotory index (LI), i.e. the ratio between crab catch in pitfall traps and their density within their moving range, is proposed as a measure of movement. LI analyses indicated that: (1) movement is an order of magnitude higher in large than small juveniles and much higher in sparse than dense vegetation cover; (2) activity of small juveniles is mostly crepuscular, regardless of vegetation cover; and (3) movement of large juveniles is very limited in dense Zostera patches, but very high in sparsely vegetated areas, during the day and night. These results suggest that small juveniles are relatively protected under dense vegetation cover due to lower mobility of larger crabs, and provide evidence of temporal segregation of activity windows between juvenile crabs of different sizes, which may be a key mechanism to reduce cannibalism and therefore increase the carrying capacity of nursery habitats. (C) 2008 Elsevier Ltd. All rights reserved.

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In addition to feeding on carrion tissues and fluids, social wasps can also prey on immature and adult carrion flies, thereby reducing their populations and retarding the decomposition process of carcasses. In this study, we report on the occurrence and behavior of social wasps attracted to vertebrate carrion. The collections were made monthly from September 2006 to October 2007 in three environments (rural, urban, and forest) in six municipalities of southeast Brazil, using baited bottle traps. We collected Agelaia pallipes (Olivier, 1791) (n = 143), Agelaia vicina (Saussure, 1854) (n = 106), Agelaia multipicta (Haliday, 1836) (n = 18), and Polybia paulista Ihering, 1896 (n = 3). The wasps were observed feeding directly on the baits and preying on adult insects collected in the traps. Bait and habitat associations, temporal variability of social wasps, and possible forensic implications of their actions are discussed.

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We describe habitat and inter-populational call variation of the dendrobatid frog Ameerega flavopicta. Data were collected in the Brazilian states ofminas Gerais and Goias. Principal component analysis separated the Goias population from others because of its higher call rates and shorter calls. The Paranaiba Rivermay represent themajor geographic barrier. We recognize the cephalic amplexus as themain type for the species. Although habitat disturbances increased since 1990, we did not notice differences in the density of callingmales at Serra do Cipo. Ameerega flavopicta appears to be quite resistant to alterations in its natural habitats caused by human activities.

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Although most raptor species are found mainly in the tropics, information on their home range and spatial requirements in the Neotropics is still scarce. In this study, we used radio telemetry to evaluate the home range and the habitat use and selection of five Roadside hawks, Rupornis magnirostris (Gmelin, 1788) in a heterogeneous landscape in southeastern Brazil. The average home range size calculated using the adaptive kernel method (95% isopleth) was 126.1ha (47.4-266.7ha), but using the minimum convex polygon method (95% isopleth) it was 143.54ha (32.6-382.3ha). The roadside hawk explored a wide variety of habitats, most of them opportunistically, as suggested in the literature. Despite this, habitat quality could influence home range size and promote habitat selection. The observation of habitat use as expected, as well as the relatively small home range size, could be related to the generalist/opportunistic behaviour of the roadside hawk.

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Most amphibian species have biphasic life histories and undergo an ontogenetic shift from aquatic to terrestrial habitats. In deforested landscapes, streams and forest fragments are frequently disjunct, jeopardizing the life cycle of forest-associated amphibians with aquatic larvae. We tested the impact of habitat split-defined as human-induced disconnection between habitats used by different life-history stages of a species-on four forest-associated amphibian species in a severely fragmented landscape of the Brazilian Atlantic Forest. We surveyed amphibians in forest fragments with and without streams (referred to as wet and dry fragments, respectively), including the adjacent grass-field matrix. Our comparison of capture rates in dry fragments and nearby streams in the matrix allowed us to evaluate the number of individuals that engaged in high-risk migrations through nonforested habitats. Adult amphibians moved from dry fragments to matrix streams at the beginning of the rainy season, reproduced, and returned at the end of the breeding period. Juveniles of the year moved to dry fragments along with adults. These risky reproductive migrations through nonforested habitats that expose individuals to dehydration, predation, and other hazards may cause population declines in dry fragments. Indeed, capture rates were significantly lower in dry fragments compared with wet fragments. Declining amphibians would strongly benefit from investments in the conservation and restoration of riparian vegetation and corridors linking breeding and nonbreeding areas.

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Tropical rainforests are becoming increasingly fragmented and understanding the genetic consequences of fragmentation is crucial for conservation of their flora and fauna. We examined populations of the toad Rhinella ornata, a species endemic to Atlantic Coastal Forest in Brazil, and compared genetic diversity among small and medium forest fragments that were either isolated or connected to large forest areas by corridors. Genetic differentiation, as measured by F(ST), was not related to geographic distance among study sites and the size of the fragments did not significantly alter patterns of genetic connectivity. However, population genetic diversity was positively related to fragment size, thus haplotype diversity was lowest in the smallest fragments, likely due to decreases in population sizes. Spatial analyses of genetic discontinuities among groups of populations showed a higher proportion of barriers to gene flow among small and medium fragments than between populations in continuous forest. Our results underscore that even species with relatively high dispersal capacities may, over time, suffer the negative genetic effects of fragmentation, possibly leading to reduced fitness of population and cases of localized extinction. (C) 2008 Elsevier Ltd. All rights reserved.

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We investigate local lizard richness and distribution in central Brazilian Cerrado, harbouring one of the least studied herpetofaunas in the Neotropical region. Our results are based on standardized samplings at 10 localities, involving 2917 captures of 57 lizard species in 10 families. Local richness values exceeded most presented in earlier studies and varied from 13 to 28 species, with modal values between 19 and 28 species. Most of the Cerrado lizard fauna is composed of habitat-specialists with patchy distributions in the mosaic of grasslands, savannas and forests, resulting in habitat-structured lizard assemblages. Faunal overlap between open and forested habitats is limited, and forested and open areas may act as mutual barriers to lizard distribution. Habitat use is influenced by niche conservatism in deep lineages, with iguanians and gekkotans showing higher use of forested habitats, whereas autarchoglossans are richer and more abundant in open habitats. Contrary to trends observed in Cerrado birds and large mammals, lizard richness is significantly higher in open, interfluvial habitats that dominate the Cerrado landscape. Between-localities variation in lizard richness seems tied to geographical distance, landscape history and phylogenetic constraints, factors operating in other well-studied lizard faunas in open environments. Higher richness in dominant, open interfluvial habitats may be recurrent in Squamata and other small-bodied vertebrates, posing a threat to conservation as these habitats are most vulnerable to the fast, widespread and ongoing process of habitat destruction in central Brazil.

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Habitat use affects food intake, reproductive fitness and body temperature control in reptiles. Habitat use depends on both the characteristics of the animal and the environmental heterogeneity. In this study we investigated habitat use in a population of the South-American rattlesnake, Crotalus durissus, in a cerrado (the Brazilian savanna) remnant, in south-eastern Brazil. In general, snakes appeared to be thermal generalists. However, they showed substrate temperature preferences in the rainy season, when they selected colder substrates during the day and warmer substrates at night. Individuals were predominantly active on the surface and more frequently found under bushes. Furthermore, in general, the principal component analysis results indicate that rattlesnakes are generalists regarding the microhabitat variables examined in this study. These habitat characteristics, associated with a low thermal selectivity, indicate that rattlesnakes are able to colonize deforested areas where shade occurrence and vegetation cover are similar to those in the cerrado.

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Fecundity and oocyte development in Salminus hilarii female brood stock were analyzed with the aim of investigating the impact of migration impediment on oogenesis. Histological analyses of the ovaries were performed in adult females caught in two different environments-the TietA(a) River (natural) and captivity-and the gonadossomatic index, oocyte diameter and fecundity determined. Five germ cell development stages (oogonium, perinucleolar, cortical alveoli, vitellogenic, ripe) and two other structures (postovulatory follicles and atretic oocytes) were observed in females caught in the river. Captive animals lacked the ripe oocytes and postovulatory follicles and had a relatively higher number of atretic oocytes. Females in captivity are known to produce larger oocytes, and they release fewer eggs in each spawn (absolute fecundity) when compared with animals that are able to migrate. Our results suggest that the TietA(a) River is undergoing alterations which are being reflected in the reproductive performance of S. hilarii, mainly due to the presence of atretic oocytes in females caught in the river. The lack of postovulatory follicles and ripe oocytes in captive animals reveals that migratory impediment negatively impacts final oocyte maturation. However, the stage of maturation reached is adequate for ovulation induction with hormone manipulation.

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O trabalho apresenta o estudo taxonômico das espécies do gênero Nectandra no Mato Grosso do Sul, Brasil. Baseados na análise morfológica dos espécimes coletados em diferentes regiões do Estado são confirmados oito espécies de Nectandra: N. amazonum Nees, N. cissiflora Nees, N. cuspidata Nees, N. falcifolia (Nees) J.A. Castigl. ex Mart. Crov. & Piccinini, N. gardneri Meisn., N. hihua (Ruiz & Pav.) Rohwer, N. megapotamica (Spreng.) Mez e N. psammophila Nees. É fornecida uma chave de identificação para as espécies e apresentados descrições morfológicas, dados de distribuição geográfica, habitat, aspectos fenológicos, comentários taxonômicos e ilustrações para cada espécie.

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Trichomycterus dali, new species, is described from flooded limestone caves in Serra da Bodoquena karst area, State of Mato Grosso do Sul, Central Brazil. The new species is diagnosed by a unique character in the genus, the presence of conspicuous, ridge-like adipose folds lining dorsally throughout the body. Trichomycterus dali can be further distinguished readily from epigean congeners by the reduction of eyes and skin pigmentation (except for T. gorgona), and from remaining congeners (i.e., all hypogean plus T. gorgona) by the total loss of eyes, not visible externally (except for T. sandovali and T. spelaeus). Other diagnostic features includes very long barbels, especially the nasal (99.3-143.5% HL) and the maxillary (97.0-131.3% HL), pectoral-fin ray count reaching I,9 and a unique cranial fontanel with a conspicuous constriction on the meeting point of supraoccipital and the two frontal bones. The troglobitic status of the species is suggested by the presence of troglomorphisms on an advanced degree, especially the reduction of skin pigmentation, the total loss of eyes and the enlarged barbels. In addition, the presence of a well developed adipose fold in adults may indicate a distinctive adaptation acquired by neoteny to withstand the food scarce conditions of its hypogean habitat.

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Ituglanis mambai, new species, is described from a cave in the Mambaí karst area, State of Goiás, Central Brazil. The new species distinguishes from epigean and cave congeners by the combination of the following characteristics: posterior supraoccipital fontanel absent; pectoral-fin rays usually i,7; six pleural ribs; total vertebrae 37-38 behind Weberian apparatus; shorter predorsal length (65.1-70.8% SL); shorter caudal peduncle length (8.4-11.9% SL); shorter dorsal-fin base length (7.7-11.3% SL); wider interobital width (29.2-36.5% HL); larger mouth width (43.4-64.0% HL); intermediate between epigean and other cave Ituglanis species as regards to both eyes (diameter varying from 0.5 to1.0 mm in adults, 7.8-10.1 % HL) and pigmentation, composed by irregular light brown spots along the body. The latter indicate the troglobitic status for I. mambai. In addition, this species has the maxillae with a discrete medial-posterior projection; fronto-lacrimal one half-length of the maxillae and pointed backwards; posterior process of palatine half its length, with a tenuous medial concavity; 14 dorsal and 12 ventral procurrent rays. In the natural habitat, I. mambai displayed cryptobiotic habits, trying to hide in the graveled bottom or under boulders when disturbed, apparently showing a negative response to light. It was observed a preference to slow-moving waters. Recent flood marks were observed in the stream conduit in March/April 2007 (end of the rainy season) when less individuals were observed on 300 m of the subterranean stream compared to September 2004 (end of the dry season).

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After an ichthyofaunistic survey conducted in May 2007 on surface (epigean) water bodies of Cordisburgo karst area, State of Minas Gerais, 13 species were recorded, mostly characiforms; in addition three non-troglomorphic (normally eyed and pigmented) and one troglomorphic catfish (siluriforms) species were recorded in two caves surveyed at different occasions, totaling 17 fish species for the area. All the nominal species herein reported for Cordisburgo area have been previously reported for the Rio das Velhas basin. None of the species observed in caves were found in epigean habitats and vice-versa. The four cave species are distributed throughout subterranean stream reaches, with individuals at different size/age classes. This, associated to the lack of conspicuous morphological differences in relation to epigean congeners, indicate that Trichomycterus brasiliensis, Gymnotus cf. carapo and Pimelodella cf. vittata are troglophiles (species encompassing individuals able to live and complete their life cycle either in the surface or in the subterranean environment) in the Morena Cave; the latter forms a large population and may be at the beginning of a differentiation process due to isolation in the subterranean habitat, as indicated by a slight reduction in eye size. Topographic isolation may be the cause for the incipient, but unmistakable troglomorphism of the Rhamdiopsis population found in the Salitre Cave, allowing for its classification as troglobite (exclusively subterranean species). The Cordisburgo area is subject to significant anthropic pressure, mainly represented by deforestation for agriculture, cattle raising and timbering. Tourism is an additional important threat for cave communities, calling for urgent protection measures.

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O presente artigo aborda os métodos construtivos empregados pelos imigrantes japoneses que vieram, em 1918, para a cidade de Registro, na região do Vale do Ribeira do Iguape, no estado de São Paulo. A vinda dessa nova frente de imigração foi incentivada pelo Governo do Estado, com o propósito de promover o processo de colonização, bem como de estimular o desenvolvimento econômico do Vale do Ribeira do Iguape por meio da expansão da cultura do café para a região. As características dessa frente de imigração são muito diferenciadas em relação às demais, tendo em vista que os que dela faziam parte chegaram ao Brasil como proprietários de terras e com apoio financeiro e logístico oferecido por uma empresa particular japonesa, responsável por gerenciar o empreendimento. Esses imigrantes, portanto, contaram com auxílio de uma complexa infra-estrutura, cujo objetivo era viabilizar a sua missão de desenvolvimento da região. Mesmo tendo essa particularidade lhes proporcionado a liberdade de recriar sua cultura em solo brasileiro, a realidade do novo habitat forçou-os a reinterpretar seus hábitos culturais ante as novas circunstâncias físicas, econômicas e sociais encontradas. A fim de entender esse processo de adaptação, foi realizado um estudo dos métodos construtivos empregados em suas edificações, baseado nos conhecimentos desses imigrantes sobre sua arquitetura tradicional. Essa análise permitiu examinar o longo processo de sincretismo entre a cultura oriental e o conhecimento construtivo vernáculo dos habitantes do Vale do Ribeira do Iguape.