Convergent evolution is characterized by the independent evolution of similar phenotypes within similar selective environments. Previous work on Trinidadian killifish, Rivulus hartii, demonstrated repeatable life-history differences across communities that differ in predation intensity. These studies were performed in rivers located on the south slope of Trinidad's Northern Range Mountains. The...

BACKGROUND Environmental exposure may play an important role in the incidences of neural tube defects (NTD) of birth defects. Their influence on NTD may likely be non-linear; few studies have considered spatial autocorrelation of residuals in the estimation of NTD risk. We aimed to develop a spatial model based on generalized additive model (GAM) plus cokriging to examine and model the expected...

We determined levels of hepatic cytochrome P4501A (CYP1A) mRNA, hepatic DNA adducts, and fluorescent aromatic compounds (FACs) in bile, a measure of exposure to polyaromatic hydrocarbons, in Atlantic tomcod from six river systems ranging from highly polluted to relatively pristine on the northeast North American coast (the Hudson River, New York; the St. Lawrence River, Quebec; the Miramichi Ri...

Although picophytoplankton (PP) (0.2-2 µm) are ubiquitous in lakes and oceans, their importance in rivers has rarely been studied. We examined PP assemblages during the ice-free period in five rivers of a temperate region varying in trophic state (9-107 µg/L total phosphorus) and water discharge (1-87 m3/s). In these rivers, PP abundance reached concentrations as high as those observed in lakes...

Genetic variation within species--a priority for biodiversity conservation--is influenced by natural selection, demography, and stochastic events such as genetic drift. We evaluated the role of these factors in 14 codistributed species of reptiles and amphibians on the Indonesian island of Halmahera by testing whether their molecular variation was correlated with geographic distance, ecology, r...

A method for the analysis of 10 perfluorinated compounds (PFCs) in whole fish homogenate is presented and applied to 60 fish samples collected from the Ohio, Missouri, and upper Mississippi Rivers in 2005. Method accuracy ranged between 86 and 125% with limits of quantitation between 0.2 and 10 ng/g wet weight. Intra- and inter-batch precision was generally +/-20%. Perfluorooctane sulfonate (PF...

The management of urban water resources plays an important role for developing countries. The Tietê and Pinheiros Rivers (São Paulo, Brazil) are affected by domestic and industrial effluents and by the diffuse pollution. This research aimed to quantify 134 variables in the water of Tietê and Pinheiros Rivers (approximately 7,200 and 6,600 analyses, respectively) from August 2007 to December 200...

A new species of Pseudancistrus is described from the Tapajós Basin, and assigned to the P. barbatus group by having hypertrophied odontodes along the snout and lacking evertible cheek plates. The new species is distinguished from other species in that group (P. barbatus, P. corantijniensis, P. depressus and P. nigrescens) by its pattern of spots, length and color of snout odontodes, greater he...

The Weber Problem for a given nite set of existing facilities Ex = fEx 1 ; Ex 2 ; : : : ; Ex M g IR 2 with positive weights w m (m = 1; : : : ; M) is to nd a new facility X such that P M m=1 w m d(X; Ex m) is minimized for some distance function d. A variation of this problem is obtained if the existing facilities are situated on two sides of a linear barrier. Such barriers like rivers, highway...

Stable nitrogen isotopes were used to assess the effects of wastewater treatment plant (WWTP) upgrades on the utilisation of sewage-N by estuarine biota in Moreton Bay, Australia. We measured delta(15)N of filamentous algae, mangrove leaves and shore crabs at the Brisbane and Logan Rivers before and after scheduled WWTP upgrades, and at two reference rivers where WWTPs had been upgraded >4 year...