Variovorax sp. strain WDL1, which mineralizes the phenylurea herbicide linuron, expresses a novel linuron-hydrolyzing enzyme, HylA, that converts linuron to 3,4-dichloroaniline (DCA). The enzyme is distinct from the linuron hydrolase LibA enzyme recently identified in other linuron-mineralizing Variovorax strains and from phenylurea-hydrolyzing enzymes (PuhA, PuhB) found in Gram-positive bacter...

Ecologists have often suggested that the presence of pathogens that differentially affect interacting species may affect the outcome of interactions, yet few experimental studies have documented pathogen-mediated interactions using a natural host–parasite system. We studied the effects of a pathogenic water mold, Saprolegnia ferax, on competitive interactions between the Cascades frog Rana casc...

Free-living animals and their larvae utilize light and gravity as cues to navigate in open space. Detection and response to these environmental stimuli are important for the dispersal and settlement of ascidian larvae. Two pigmented structures in the brain of the ascidian larva, the ocellus and the otolith, have been shown to function as the photoreceptive and gravity sensitive organs, respecti...

Andean hylid frogs of the genus Hyla are reviewed. Eight groups of Hyla recognized in the Andes are defined; the species in two of these groups are treated in detail. The large H. armata, characterized by hypertrophied forelimbs and clumps of nuptial spines on the prepoUex and humerus in males, and a stream-adapted tadpole with a LTRF up to 15/17, is the sole recognized species in the H. armata...

Understanding the role of competition in explaining phenotypic diversity is a challenging problem, given that the most divergent species may no longer compete today. However, convergent evolution of extreme body sizes across communities may offer evidence of past competition. For example, many treefrog assemblages around the world have convergently evolved species with very large and small body...

Congeners belonging to the genus Ciona have disparate distributions limited by temperature. Ciona intestinalis is more widespread with a cosmopolitan distribution ranging from tropical to sub-arctic zones, while Ciona savignyi is limited to temperate-latitudes of the northern Pacific Ocean. To compare the heat stress response between congeners, we quantified changes in protein expression using ...

How are ecologically diverse organisms added to local assemblages to create the community structure we see today? In general, within a given region or community, a given trait (character state) may either evolve in situ or be added through dispersal after having evolved elsewhere. Here, we develop simple metrics to quantify the relative importance of these processes and then apply them to a cas...

Aim Patterns of species richness are often closely linked with climate, but the specific mechanisms by which species’ climatic niches underlie large-scale richness patterns remain poorly understood. It has been hypothesized that reduced temperature seasonality in the tropics promotes the evolution of species with narrow temperature niche breadths, and that this hypothesis helps explain high tro...