This letter reports synchronization phenomena and mathematical modeling on a frustrated system of living beings, or Japanese tree frogs (Hyla japonica). While an isolated male Japanese tree frog calls nearly periodically, he can hear sounds including calls of other males. Therefore, the spontaneous calling behavior of interacting males can be understood as a system of coupled oscillators. We co...

Anurans have been introduced in many parts of the world and often become invasive over large geographic areas. Although predation is involved declines invaded amphibian populations, there a lack quantitative assessments evaluating potential risk posed to native species. This particularly true for Pelophylax water frogs, which western Europe, but no studies date examined their on other amphibian...

Mature female leopard frogs, Rana pipiens, collected from several sites in Minnesota from 1967 through 1977, were examined for the presence of pigmented oocytes. An increase in the percent of mature females with pigmented oocytes was observed in the frogs captured in 1977 compared to those captured earlier. Coincident with the increase in prevalence of females with pigmented oocytes, there was ...

The terrestrial anuran Rana sylvatica tolerates extended periods of whole-body freezing during the winter. Freezing survival is facilitated by extensive glycogen hydrolysis and distribution of high concentrations of the cryoprotectant glucose into blood and all tissues. As glycogenesis is both an energy-expensive process and counter-productive to maintaining sustained high cryoprotectant levels...

The Pig Frog (Rana grylio) is an aquatic frog that is an abundant component of the Everglades ecosystem. South Floridians recreationally and commercially hunt pig frogs in marshes throughout Water Conservation Areas (WCA) and Big Cypress National Preserve (BCNP) in South Florida. Most of these areas are under fish consumption advisories because of high levels of methylmercury present in game fi...

The wood frog, Rana sylvatica, from Interior Alaska survives freezing at -16°C, a temperature 10-13°C below that tolerated by its southern conspecifics. We investigated the hepatic freezing response in this northern phenotype to determine if its profound freeze tolerance is associated with an enhanced glucosic cryoprotectant system. Alaskan frogs had a larger liver glycogen reserve that was mob...

We measured concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) in northern leopard frogs collected from the Green Bay ecosystem and explored the catalytic activity of hepatic cytochrome P450-associated monooxygenase (P450 enzyme) as a biomarker for exposure to aryl hydrocarbon receptor (AhR) agonists. The two ...

More than 90% of a breeding colony of clawed frogs (Xenopus tropicalis) imported to the United States from western Africa died in an epizootic of chlamydiosis. Chlamydial inclusions were observed by light and electron microscopy in the liver of an infected frog. Chlamydia pneumoniae was isolated in cell cultures from four frogs. A cutaneous infection by a chytridiomycete fungus observed in two ...

Ancestral frogs underwent anatomical shifts including elongation of the hindlimbs and pelvis and reduction of the tail and vertebral column that heralded the transition to jumping as a primary mode of locomotion. Jumping has been hypothesized to have evolved in a step-wise fashion with basal frogs taking-off with synchronous hindlimb extension and crash-landing on their bodies, and then their l...

We studied how Dendrobates pumilio frogs exit the canopy. They had been observed jumping and gliding to the ground, and we conjectured that they would have adapted to jump from the canopy to the ground as an energy-saving mechanism. We observed many frogs jumping and gliding from branches to the ground rather than crawling down the trunk, which may be an economic adaptation, but there were not ...