Complex phenotypes typically have a correspondingly multifaceted genetic component. However, the genotype-phenotype association between chemical defense and resistance is often simple: genetic changes in the binding site of a toxin alter how it affects its target. Some toxic organisms, such as poison frogs (Anura: Dendrobatidae), have defensive alkaloids that disrupt the function of ion channel...

We model Batrachochytrium dendrobatidis (Bd) infection rates in Jamaican frogs—one of the most threatened amphibian fauna in the world. The majority of species we surveyed were terrestrial direct-developing frogs or frogs that breed in tank bromeliads, rather than those that use permanent water bodies to breed. Thus, we were able to investigate the climatic correlates of Bd infection in a frog ...

The triazine herbicide atrazine has been hypothesized to disrupt sexual development in frogs by up-regulating aromatase activity, resulting in greater estradiol (E2) concentrations and causing feminization in males. The goal of this study was to collect native ranid frogs from atrazine-exposed ponds and determine whether relationships exist between measured atrazine concentrations and the gonad...

The formation of proper sensory afferent connections during development is essential for brain function. Activity-based competition is believed to drive ocular dominance columns (ODC) in mammals and in experimentally-generated three-eyed frogs. ODC formation is thus a compromise of activity differences between two eyes and similar molecular cues. To gauge the generality of graphical map formati...

A remarkable diversity of bioactive lipophilic alkaloids is present in the skin of poison frogs and toads worldwide. Originally discovered in neotropical dendrobatid frogs, these alkaloids are now known from mantellid frogs of Madagascar, certain myobatrachid frogs of Australia, and certain bufonid toads of South America. Presumably serving as a passive chemical defense, these alkaloids appear ...

Laser vibrometry was used to measure the vibration velocity at different points on the ossicular apparatus of the bullfrog Rana catesbeiana in response to free-field sound. The ascending process of the extrastapes, neglected in most accounts of frog middle ear mechanics, supports a rocking motion of the extrastapes and is critical to the normal function of the ossicular apparatus. The articulat...

In spring, the lowest temperature during freezing that can be survived by wood frogs (Rana sylvatica) from southern Ohio is approximately -3 degrees C. We investigated whether the thermal limit of freeze tolerance in these frogs is regulated by tissue levels of glucose, a putative cryoprotectant that is distributed to tissues during freezing. Frogs receiving exogenous glucose injections prior t...

Sharp-nosed African reed frogs, Hyperolius nasutus Gunther, are small (0.4 g) hyperoliids which have minimal rates of evaporative water loss (4.5 mg g-1 h-1; 0.3 mg cm-2 h-1) that are only 1/10 to 1/20 that of a typical frog, Hylaregilla, of comparable size (171 mg g-1 h-1, 4.8 mg cm-2 h-1). The surface-area-specific resistance to water flux of H. nasutus dorsal skin (96-257 sec cm-1) is simila...

Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs...

Diverse microbial assemblages inhabit amphibian skin and are known to differ among species; however, few studies have analysed these differences in systems that minimize confounding factors, such as season, location or host ecology. We used high-throughput amplicon sequencing to compare cutaneous microbiotas among two ranid frogs (Rana dalmatina, R. temporaria) and four salamandrid newts (Ichth...