The effects of fire, local environment and time on ant assemblages in fens and forests

We investigated the effects of the abiotic environment, plant community composition and disturbance by fire on ant assemblages in two distinct habitat types in the Siskiyou Mountains in northern California and southern Oregon, USA. Sampling over 2 years in burned and unburned Darlingtonia fens and their adjacent upland forests, we found that the effects of disturbance by fire depended on habitat type. In forests, fire intensity predicted richness in ant assemblages in both years after the fire, and plant community composition predicted richness 2 years after the fire. No factors were associated with richness in the species‐poor fen ant assemblages. Species‐specific responses to both habitat type and disturbance by fire were idiosyncratic. Assemblage composition depended on habitat type, but not disturbance by fire, and the composition of each assemblage between years was more dissimilar in burned than unburned sites.     

Bayesian inference in ecology

Bayesian inference is an important statistical tool that is increasingly being used by ecologists. In a Bayesian analysis, information available before a study is conducted is summarized in a quantitative model or hypothesis: the prior probability distribution. Bayes’ Theorem uses the prior probability distribution and the likelihood of the data to generate a posterior probability distribution. Posterior probability distributions are an epistemological alternative to P‐values and provide a direct measure of the degree of belief that can be placed on models, hypotheses, or parameter estimates. Moreover, Bayesian information‐theoretic methods provide robust measures of the probability of alternative models, and multiple models can be averaged into a single model that reflects uncertainty in model construction and selection. These methods are demonstrated through a simple worked example. Ecologists are using Bayesian inference in studies that range from predicting single‐species population dynamics to understanding ecosystem processes. Not all ecologists, however, appreciate the philosophical underpinnings of Bayesian inference. In particular, Bayesians and frequentists differ in their definition of probability and in their treatment of model parameters as random variables or estimates of true values. These assumptions must be addressed explicitly before deciding whether or not to use Bayesian methods to analyse ecological data.     

Diversity of rotifers from northeastern U.S.A. bogs with new species records for North America and New England

In order to assess the effects of pollution on recruitment of brown trout (Salmo trutta f. fario L.) exposure experiments with brown trout early life stages were performed in two differently contaminated small streams near Stuttgart, southwest Germany, and in a control situation in the laboratory. Pollution in the more polluted stream is mainly due to effluents of municipal sewage treatment plants and to the influx of surface waters from areas of intense agriculture activity. Additionally, the water carries high particle loads, especially after rainfall events. Water quality of the less polluted stream is occasionally influenced by agriculture activity in the vicinity. For the exposure of trout early life stages incubators were used, which allowed frequent examinations without serious disturbance of the exposed organisms and thus the development could be monitored over time. Compared to the less polluted stream and the control, in the more polluted stream high mortality rates, the lowest hatching success, and lowest values for growth occurred. In the less polluted stream, mortality rates were comparably low in prehatching stages, but high in hatchlings and juveniles due to heavy infestations with protozoic ectoparasites Chilodonella cyprini (Moroff, 1902) and Ichthyobodo necator (Henneguy, 1883). However, pollution-related effects were not detected in this stream. Differences in developmental rates between the different treatments were correlated with different water temperatures in the two streams and the control. For the more polluted stream, previous studies have indicated embryotoxic potentials mediated by pollutants. The present study indicates that in this steam, additionally, fine solids which infiltrate stream gravels may seriously affect development of brown trout early life stages.     

Assembly rules for New England ant assemblages

Community assembly rules specify patterns of species co-occurrence and morphology dictated by interspecific competition. We collected data on the occurrence of ground-foraging ant species in 22 ombrotrophic bogs and adjacent forest plots of New England to test two general assembly rules: reduced co-occurrence of species among communities, and even spacing of body sizes of species within communities. We used null models to generate random communities unstructured by competition and evaluated patterns at regional and local spatial scales. At the regional scale, species co-occurrence in forests, but not bogs, was less than expected by chance, whereas, at the local scale, co-occurrence in both habitats was not different from random. At the regional scale, spacing of body size distributions was random (in bogs) or aggregated (in forests). At the local scale, body size patterns were weakly segregated in bogs, but random or weakly aggregated in forests. In bogs, size ratio constancy was accompanied by greater generic diversity than expected. Although assembly rules were originally developed for vertebrate communities, they successfully explained some patterns in New England ant assemblages. However, the patterns were contingent on spatial scale, and were distinctly different for bog and forest communities, despite their close proximity and the presence of many shared species in both assemblages. The harsh physical conditions of bogs may act as a habitat filter that alters community assembly rules.     

Multiple sclerosis: urinary amine measurement for orthomolecular diagnosis

Urinary amines from 53 people who have multiple sclerosis and 58 controls have been separated and measured quantitatively by means of low-resolution ion-exchange procedure. Dependences on multiple sclerosis and on sex have been detected. The multiple-sclerosis-dependent pattern has been tested for diagnostic value by means of the weighted non-correlation index method.     

The ecology of Belizean mangrove-root fouling communities: patterns of epibiont distribution and abundance,and effects on root growth

The aerial prop roots of the neotropical red mangrove,Rhizophora mangle L., begin growing well above highest high water (HHW) and often extend well below lowest low water (LLW) before rooting in the benthic substratum. In Belize, Central America, prop roots growing below LLW are colonized by diverse assemblages of organisms, including macroalgae, hydrozoans, ascidians, sponges, anemones, hard corals, and isopod crustaceans. Mangroves, root-fouling epibionts, root herbivores, and benthic predators engage in complex interactions that are major determinants of mangrove growth and production. Species richness of root epibionts increases with distance from the mainland and with proximity to the barrier reef. Species richness decreases with variability in water temperature and salinity. Ascidians and sponges transplanted from Lark Cay into the coastal Placencia Lagoon failed to survive, but anemones from Lark Cay survived in Placencia Lagoon. Reciprocal transplants survived off-shore. The gastropod predator,Melongena melongena L., present only in mainland estuaries, reduced local barnacle abundance and epibiont species richness in Placencia Lagoon. Isopod species richness also increases with distance from shore, but the number of roots bored by these species decreases. These isopods can reduce root relative growth rate (RGR_root) by 55%. On off-shore cays, sponges and ascidians ameliorate negative effects of isopods. In mainland estuaries where epibionts are less common, isopod damage to roots is more severe. Experimental studies in mangrove swamps throughout the world would clarify the importance of plant-animal interactions in these widespread tropical ecosystems.     

Substrate selectivity and sensitivity to inhibition by FK506 and cyclosporin A of calcineurin heterodimers composed of the alpha or beta catalytic subunit.

The calcineurin (CaN) alpha and beta catalytic subunit isoforms are coexpressed within almost all cell types. The enzymatic properties of CaN heterodimers comprised of the regulatory B subunit (CnB) with either the alpha or beta catalytic subunit were compared using in vitro phosphatase assays. CaN containing the alpha isoform (CnA alpha) has lower K(m) and higher V(max) values than CaN containing the beta isoform (CnA beta) toward the PO4-RII, PO4-DARPP-32(20-38) peptides, and p-nitrophenylphosphate (pNPP). CaN heterodimers containing the alpha or beta catalytic subunit isoform displayed identical calmodulin dissociation rates. Similar inhibition curves for each CaN heterodimer were obtained with the CaN autoinhibitory peptide (CaP) and cyclophilin A/cyclosporin A (CyPA/CsA) using each peptide substrate at K(m) concentrations, except for a five- to ninefold higher IC50 value measured for CaN containing the beta isoform with p-nitrophenylphosphate as substrate. No difference in stimulation of phosphatase activity toward p-nitrophenylphosphate by FKBP12/FK506 was observed. At low concentrations of FKBP12/FK506, CaN containing the alpha isoform is more sensitive to inhibition than CaN containing the beta isoform using the phosphopeptide substrates. Higher concentrations of FKBP12/FK506 are required for maximal inhibition of beta CaN using PO4-DARPP-32(20-38) as substrate. The functional differences conferred upon CaN by the alpha or beta catalytic subunit isoforms suggest that the alpha:beta and CaN:substrate ratios may determine the levels of CaN phosphatase activity toward specific substrates within tissues and specific cell types. These findings also indicate that the alpha and beta catalytic subunit isoforms give rise to substrate-dependent differences in sensitivity toward FKBP12/FK506.     

Ectopic pairing of chromosome regions containing chemically similar DNA

Using genetically controlled stocks ofDrosophila melanogaster we have compared the frequency of ectopic pairing in a line showing intense quinacrine fluorescence at two sites (81F and 83E) on chromosome 3 with one showing such fluorescence at only one of these sites (81F). The frequency of ectopic pairing is an order of magnitude greater in cells from the line showing intense fluorescence in both regions than in the line showing it in only one. These data indicate that ectopic pairing is dependent upon properties of discrete chromosome regions as small as individual bands. Since A: T-rich chromatin is known to fluoresce intensely after quinacrine staining, these data further suggest that ectopic pairing is dependent on similarities of the DNA of the discrete chromosome regions involved.