RESUMO
Hosts and parasites are in a perpetual co-evolutionary "arms race". Due to their short generation time and large reproductive output, parasites are commonly believed to be ahead in this race, although increasing evidence exists that parasites are not always ahead in the arms race - in part owing to evolutionary lineage and recent ecological history. We assess local adaptation of hosts and parasites, and determine whether adaptation was influenced by ecological or evolutionary history, using full reciprocal cross-infections of four Gyrodactylus ectoparasite populations and their four guppy (Poecilia reticulata) host populations in Trinidad. To consider effects of evolutionary lineage and recent ecology, these four populations were collected from two different river drainages (Marianne and Aripo) and two different predation environments (high and low). The highest infection levels were obtained when parasites from the Aripo lineage infected guppies from the Marianne lineage, indicating a higher infectivity, virulence and/or reproductive success of the Aripo parasites. Aripo lineage guppies were also better able to limit Gyrodactylus population growth than guppies from the Marianne River, indicating their strong "resistance" to Gyrodactylus regardless of the source of the parasite. Predation environment had no detectable influence on host-parasite population dynamics of sympatric or allopatric combinations. The much stronger effect of evolutionary lineage (i.e., river) than recent ecological history (i.e., predation) emphasises its importance in driving co-evolutionary dynamics, and should be explored further in future studies on local host-parasite adaptation.
Assuntos
Ectoparasitoses/veterinária , Doenças dos Peixes/parasitologia , Poecilia/parasitologia , Adaptação Fisiológica , Animais , Evolução Biológica , Ecossistema , Ectoparasitoses/epidemiologia , Ectoparasitoses/parasitologia , Doenças dos Peixes/epidemiologia , Predisposição Genética para Doença , Rios , Trinidad e TobagoRESUMO
There are many non-mutually exclusive mechanisms for exotic invasions but few studies have concurrently tested more than one hypothesis for the same species. Here, we tested the evolution of increased competitive ability (EICA) hypothesis in two common garden experiments in which Chromolaena odorata plants originating from native and nonnative ranges were grown in competition with natives from each range, and the novel weapons hypothesis in laboratory experiments with leachates from C. odorata. Compared with conspecifics originating from the native range, C. odorata plants from the nonnative range were stronger competitors at high nutrient concentrations in the nonnative range in China and experienced far more herbivore damage in the native range in Mexico. In both China and Mexico, C. odorata was more suppressed by species native to Mexico than by species native to China. Species native to China were much more inhibited by leaf extracts from C. odorata than species from Mexico, and this difference in allelopathic effects may provide a possible explanation for the biogeographic differences in competitive ability. Our results indicate that EICA, innate competitive advantages, and novel biochemical weapons may act in concert to promote invasion by C. odorata, and emphasize the importance of exploring multiple, non-mutually exclusive mechanisms for invasions.
Assuntos
Chromolaena/fisiologia , Espécies Introduzidas , Adaptação Fisiológica , China , Geografia , Herbivoria , México , Dinâmica Populacional , Estresse FisiológicoRESUMO
The removal of sulfate and organic matter was assessed in an ASBR, which treated wastewater containing 500 mg CODL(-1) (3 g CODL(-1)d(-1)) in 8h-cycles at 30 degrees C. The wastewater was enriched with sulfate at [COD/SO(4)(2-)] ratios of 1.34, 0.67 and 0.34 (8.8,4.5 and 2.2 gSO(4)(2-)L(-1)d(-1)). For each COD/[SO(4)(2-)] ratio fill times used were: 10 min (batch), 3 and 6h (fed-batch), achieving sulfate reduction of 30%, 72% and 72% (COD/[SO(4)(2-)] of 1.34); 25%, 58% and 55% (COD/[SO(4)(2-)] of 0.67) and 23%, 37% and 27% (COD/[SO(4)(2-)] of 0.34), respectively, and organic matter removal of 87%, 68% and 80% (COD/[SO(4)(2-)] of 1.34); 78%, 75% and 69% (COD/[SO(4)(2-)] of 0.67) and 85%, 84% and 83% (COD/[SO(4)(2-)] of 0.34), respectively. The results showed that fed-batch operation improved sulfate reduction, whereas organic matter removals were similar for batch and fed-batch operation. In addition, increase in sulfate loading in the fed-batch operation improved organic matter removal.
Assuntos
Reatores Biológicos , Compostos Orgânicos/isolamento & purificação , Sulfatos/análise , Anaerobiose , Biomassa , Sulfatos/isolamento & purificaçãoRESUMO
A mechanically stirred anaerobic sequencing batch reactor containing anaerobic biomass immobilized on polyurethane foam cubes, treating low-strength synthetic wastewater (500 mg COD L(-1)), was operated under different operational conditions to assess the removal of organic matter and sulfate. These conditions were related to fill time, defined by the following feed strategies: batch mode of 10 min, fed-batch mode of 3 h and fed-batch mode of 6 h, and COD/[SO(4)(2-)] ratios of 1.34, 0.67, and 0.34 defined by organic matter concentration of 500 mg COD L(-1) and sulfate concentrations of 373, 746, and 1,493 mg SO(4)(2-) L(-1) in the influent. Thus, nine assays were performed to investigate the influence of each of these parameters, as well as the interaction effect, on the performance of the system. The reactor operated with agitation of 400 rpm, total volume of 4.0 L, and treated 2.0 L synthetic wastewater in 8-h cycles at 30 +/- 1 degrees C. During all assays, the reactor showed operational stability in relation to the monitored variables such as COD, sulfate, sulfide, sulfite, volatile acids, bicarbonate alkalinity, and solids, thus demonstrating the potential to apply this technology to the combined removal of organic matter and sulfate. In general, the results showed that the 3-h fed-batch operation with a COD/[SO(4)(2-)] ratio of 0.34 presented the best conditions for organic matter removal (89%). The best efficiency for sulfate removal (71%) was accomplished during the assay with a COD/[SO(4)(2-)] ratio of 1.34 and a fill time of 6 h. It was also observed that as fill time and sulfate concentration in the influent increased, the ratio between removed sulfate load and removed organic load also increased. However, it should be pointed out that the aim of this study was not to optimize the removal of organic matter and sulfate, but rather to analyze the behavior of the reactor during the different feed strategies and applied COD/[SO(4)(2-)] ratios, and mainly to analyze the interaction effect, an aspect that has not yet been explored in the literature for batch reactors.
Assuntos
Bactérias Anaeróbias/crescimento & desenvolvimento , Bactérias Anaeróbias/metabolismo , Reatores Biológicos/microbiologia , Técnicas de Cultura de Células/métodos , Compostos Orgânicos/metabolismo , Oxigênio/metabolismo , Sulfatos/metabolismo , Biodegradação Ambiental , Compostos Orgânicos/isolamento & purificação , Sulfatos/isolamento & purificaçãoRESUMO
Material of 498 specimens of 23 species of Phoridae collected by a trapping method in Cuba in 1966 is quantitatively and qualitatively analysed. A review of faunistic data, chorology, seasonal incidence and food preference is given and possible importance of the main species, mostly of the genus Megaselia, as potential vectors and causative agents of myiasis, is discussed.
Assuntos
Dípteros , Animais , Cuba , Ecologia , Fezes , Feminino , Preferências Alimentares , Humanos , Masculino , Carne , Estações do AnoRESUMO
The material of 22302 flies of Anthomyiidae, Muscidae and Calliphoridae collected by trap-method in Cuba 1966 was qualitatively and quantitatively analysed. Relative density, seasonal incidence and food preference were ascertained in 20 species. In potential vectors of human diseases the ecological characters and classification of synanthropy are given.