ABSTRACT
In the present study we report a spatial autocorrelation analysis of molecular data obtained for Arapaima gigas, and the implication of this study for conservation and management. Arapaima is an important, but critically over-exploited giant food fish of the Amazonian várzea. Analysis of 14 variable microsatellite loci and 2,347 bp of mtDNA from 126 individuals sampled in seven localities within the Amazon basin suggests that Arapaima forms a continuous population with extensive genetic exchange among localities. Weak effect of isolation-by-distance is observed in microsatellite data, but not in mtDNA data. Spatial autocorrelation analysis of genetic and geographic data suggests that genetic exchange is significantly restricted at distances greater than 2,500 km. We recommend implementing a source-sink metapopulation management and conservation model by proposing replicate high quality várzea reserves in the upper, central, and lower Amazon basin. This conservation strategy would: 1) preserve all of the current genetic diversity of Arapaima; 2) create a set of reserves to supply immigrants for locally depleted populations; 3) preserve core várzea areas in the Amazon basin on which many other species depend. We stress that conservation strategies should not only preserve current genetic diversity, but also the evolutionary processes which have generated the observed patterns.
No presente estudo, é descrita uma análise de autocorrelação espacial de dados moleculares obtidos para Arapaima gigas e a implicação deste estudo para sua conservação e manejo. Arapaima é uma espécie de peixe gigante da várzea Amazônica de grande importância econômica, e criticamente sobre-explorada. A análise de 14 locos microssatélites e de 2.347 pb do DNAmt de 126 indivíduos amostrados em sete localidades na bacia Amazônica sugere que Arapaima forma uma população contínua com grande fluxo genético entre localidades. Um pequeno efeito de isolamento por distância é observado através dos dados de microssatélites, mas não através dos dados de DNAmt. A análise de autocorrelação espacial de dados genéticos e geográficos sugere que o fluxo gênico é significativamente restrito em distâncias maiores que 2.500 km. É recomendada a implementação de um modelo de manejo e conservação de metapopulação no padrão doador-receptor, replicando as reservas de várzea na bacia Amazônica superior, central e inferior. Esta estratégia de conservação iria: 1) preservar toda a atual diversidade genética da Arapaima; 2) criar um conjunto de reservas para fornecer imigrantes para populações locais reduzidas; 3) preservar áreas centrais de várzea na bacia Amazônica das quais diversas outras espécies dependem. Estratégias de conservação não deveriam somente preservar a atual diversidade genética, mas também os processos evolutivos que têm gerado os padrões observados.
Subject(s)
Animals , Conservation of Natural Resources/methods , Ecosystem , Fishes/genetics , Genetic Variation , Brazil , DNA, Mitochondrial/genetics , Geography , Microsatellite Repeats/geneticsABSTRACT
The isozyme distribution of cichlid lactate dehydrogenase (LDH) is related to species environmental preferences. Cichlasoma amazonarum. occurs in different environments and presents LDH tissue distribution patterns that correlate with oxygen tension at the capture location. Cichlasoma amazonarum was exposed to long term severe hypoxia (51 days at 36.4 +/- 5.9 mmHg), tissue LDH isozyme distribution was analyzed by electrophoresis and enzyme activities were measured by monitoring the oxidation of NADH as pyruvate was reduced to lactate. The exposure of Cichlasoma amazonarum to long-term severe hypoxia resulted in changes in the tissue distribution of LDH isozymes. The major changes in response to hypoxia occurred in heart, liver and brain: isozyme A4 was activated in heart and brain, whereas isozyme B4 was activated in liver. The most significant quantitative change occurred in brain LDH of hypoxia-exposed animals which adopted muscle type kinetics, reflecting a new LDH isozyme distribution. LDH activity was significantly reduced (P<0.05) in animals exposed to hypoxia (N = 8), suggesting an overall LDH suppression. Pyruvate inhibition decreased in all hypoxia-exposed tissues. Thus, the ability of Cichlasoma amazonarum to regulate LDH tissue expression according to oxygen availability allows the animal to survive chronic hypoxic environments. This phenotypic plasticity may occur in other hypoxia-tolerant fish species.
Subject(s)
Animals , Hypoxia/metabolism , L-Lactate Dehydrogenase/metabolism , Perches/metabolism , Analysis of Variance , Cerebrum/enzymology , Electrophoresis , Liver/enzymology , L-Lactate Dehydrogenase/metabolism , Muscle, Skeletal/enzymology , Myocardium/enzymologyABSTRACT
1. The effects of different thermal regimens on qualitative and quantitative characteristics of leucocytes were evaluated in two fish species of the Amazon region. 2. The proportion of circulating types of leucocytes changed significantly in Colossoma macropomum (tambaqui) but not in Hoplosternum littorale (tamoatá) exposed for four-week terms to 20, 25, 30, 35, and 40 degrees C. 3. The proportion of circulating lymphocytes decreased significantly in tambaquis exposed to 30, 35, and 40 degrees C. No changes in lymphocyte proportions were observed in tamoatás. 4. Neutrophils were almost absent in tambaquis, except in animals exposed to 40 degrees C. No significant changes in circulating neutrophils were observed in tamoatás. 5. The circulating leucocytes of Colossoma macropomum and Hoplosternum littorale are affected in different ways by temperature changes, suggesting species-specific adjustments to this parameter.