RESUMO
The Antarctic environment has special characteristics that influence the local marine life. The benthic organisms, adapted to these extreme conditions of life, are subject nowadays to effects of climate change. Recently, the consequences of glacier retreat on these assemblages have been observed in many West Antarctic Peninsula (WAP) regions, including King George Island (KGI). This study described the spatial variation of the benthic macrofauna in different areas of the Martel Inlet (Admiralty Bay - KGI), at depths around 25-30 m. Sampling was done in January 2001 at ten stations classified in localities according to their proximity to ice-margin/coastline in marine-terminating glacier (MTG), terrestrial-terminating glacier (TTG) and ice-free area (IFA). The total density and the abundance of annelids, nematodes, peracarid crustaceans and bivalves were higher at IFA stations. The locality discrimination by taxa and species was independent of available environmental/sedimentary conditions or was the result of unmeasured variables or species life history processes not assessed herein. Considering that our findings were obtained 21 years ago, they will be especially useful for comparing future studies of benthic assemblage responses to the influence of climate change and continuous glacier retreats in the WAP region.
Assuntos
Ecossistema , Nematoides , Animais , Baías , Regiões Antárticas , Camada de GeloRESUMO
Agromyzidae (Insecta: Diptera) is a cosmopolitan family of acalyptrate flies, with almost 3,000 species worldwide distributed. Most species are leaf miners on a large number of plants. Among them, Liriomyza Mik, 1894 is a large genus of leaf-miner species that can cause significant damage to economically important crops and is considered agricultural pests, such as Liriomyza sativae Blanchard, 1938 and Liriomyza huidobrensis (Blanchard, 1926), which are herein investigated. The present study deals with the impact of climatic factors (temperature, humidity, and precipitation), seasonality, and parasitoid abundance on leaf-miner infestation during one year in five cultivated crops in Northeastern Brazil. Climatic factors for instance had different effects on L. sativae populations in melon and watermelon crops. Larval abundances were greater during the dry season for both species, L. sativae and L. huidobrensis, and abundance of adult parasitoids followed the increase of mining larvae.(AU)
Assuntos
Animais , Dípteros/crescimento & desenvolvimento , Dípteros/parasitologia , Efeitos do Clima , Estações do AnoRESUMO
Agromyzidae (Insecta: Diptera) is a cosmopolitan family of acalyptrate flies, with almost 3,000 species worldwide distributed. Most species are leaf miners on a large number of plants. Among them, Liriomyza Mik, 1894 is a large genus of leaf-miner species that can cause significant damage to economically important crops and is considered agricultural pests, such as Liriomyza sativae Blanchard, 1938 and Liriomyza huidobrensis (Blanchard, 1926), which are herein investigated. The present study deals with the impact of climatic factors (temperature, humidity, and precipitation), seasonality, and parasitoid abundance on leaf-miner infestation during one year in five cultivated crops in Northeastern Brazil. Climatic factors for instance had different effects on L. sativae populations in melon and watermelon crops. Larval abundances were greater during the dry season for both species, L. sativae and L. huidobrensis, and abundance of adult parasitoids followed the increase of mining larvae.
Assuntos
Animais , Dípteros/crescimento & desenvolvimento , Dípteros/parasitologia , Efeitos do Clima , Estações do AnoRESUMO
ABSTRACT Agromyzidae (Insecta: Diptera) is a cosmopolitan family of acalyptrate flies, with almost 3,000 species worldwide distributed. Most species are leaf miners on a large number of plants. Among them, Liriomyza Mik, 1894 is a large genus of leaf-miner species that can cause significant damage to economically important crops and is considered agricultural pests, such as Liriomyza sativae Blanchard, 1938 and Liriomyza huidobrensis (Blanchard, 1926), which are herein investigated. The present study deals with the impact of climatic factors (temperature, humidity, and precipitation), seasonality, and parasitoid abundance on leaf-miner infestation during one year in five cultivated crops in Northeastern Brazil. Climatic factors for instance had different effects on L. sativae populations in melon and watermelon crops. Larval abundances were greater during the dry season for both species, L. sativae and L. huidobrensis, and abundance of adult parasitoids followed the increase of mining larvae.
RESUMO
The sibling species of Capitella capitata are globally known for their tolerance to disturbed habitats and the C. capitata complex is often used as an ecological indicator. A recent re-description proposed that C. capitata, originally described in Greenland is restricted to the Artic and Subarctic regions. Given their ecological relevance, we conducted a morphological and molecular analyses based on mtDNA sequences to investigate the diversity and distribution of the C. capitata complex along the Brazilian coast. Our morphological and molecular data were congruent and revealed the existence of four new species distinct from C. capitata, collected from the type locality. This study is the first characterization of the biodiversity and distribution of Capitella species made along the Brazilian coast and yielded a set of morphological characters corroborated by the mtDNA sequences for species identification. Our results increase the biodiversity of the genus along the Brazilian coast by describing four new species (Capitella aracaensis sp. n., Capitella biota sp. n., Capitella neoaciculata sp. n. and Capitella nonatoi sp. n.). One species was collected from only one sampling site, while the others are distributed along the coast.
Assuntos
Anelídeos/classificação , Animais , Anelídeos/anatomia & histologia , Anelídeos/genética , Brasil , DNA Mitocondrial/genética , Especificidade da EspécieRESUMO
Perhaps the most widely used quantitative approach in metacommunity ecology is the estimation of the importance of local environment vs. spatial structuring using the variation partitioning framework. Contrary to metapopulation models, however, current empirical studies of metacommunity structure using variation partitioning assume a space-for-dispersal substitution due to the lack of analytical frameworks that incorporate patch connectivity predictors of dispersal dynamics. Here, a method is presented that allows estimating the relative importance of environment, spatial variation and patch connectivity in driving community composition variation within metacommunities. The proposed approach is illustrated by a study designed to understand the factors driving the structure of a soft-bottom marine polychaete metacommunity. Using a standard variation partitioning scheme (i.e. where only environmental and spatial predictors are used), only about 13% of the variation in metacommunity structure was explained. With the connectivity set of predictors, the total amount of explained variation increased up to 51% of the variation. These results highlight the importance of considering predictors of patch connectivity rather than just spatial predictors. Given that information on connectivity can be estimated by commonly available data on species distributions for a number of taxa, the framework presented here can be readily applied to past studies as well, facilitating a more robust evaluation of the factors contributing to metacommunity structure.
Assuntos
Biota , Ecologia/métodos , Meio Ambiente , Poliquetos/fisiologia , Animais , Brasil , Biologia Marinha/métodos , Modelos BiológicosRESUMO
Populations of Ocyurus chrysurus were compared genetically and morphometrically along the West Atlantic coast to test the null hypothesis of population homogeneity in the area. Brazilian populations were found to be differentiated in shape (canonical variates analysis; F[48,515] = 10.84, p < 0.0001). Analyses of mitochondrial DNA sequences (663 bp of the control region) did not show any differences between Brazilian populations but could detect differences between Brazilian and Caribbean (Belize) populations. The samples from Pernambuco differed significantly from the other Brazilian populations in allozyme frequencies (11 loci; F ST = 0.167; p < 0.05), but this may have resulted from the small number of samples analysed for that population. Sequence variation of Belize samples departed from neutral expectations (Fu's FS = -8.88; p < 0.001). A mismatch distribution analysis points to an ancient population expansion in that area. We conclude that the genetic data do not allow the rejection of the null hypothesis of panmixia for Brazilian yellowtail snapper populations which should be treated as a single genetic stock, with a latitudinal gradient on their morphology which probably results from phenotypic plasticity. On the other hand, there is a severe restriction to gene flow between O. chrysurus populations from the Caribbean and from the southwestern Atlantic.