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The neuropeptide kisspeptin and its receptor are essential for activation of the hypothalamic-pituitary-gonadal (HPG) axis and regulating reproduction. While the role of kisspeptin in regulating the HPG axis in mammals has been well established, little is known about the functional ability of kisspeptins to activate the HPG axis and associated behavior in non-mammalian species. Here we experimentally examined the effects of kisspeptin on downstream release of testosterone and associated aggression and display behaviors in the side-blotched lizard (Uta stansburiana). We found that exogenous treatment with kisspeptin resulted in an increase in circulating testosterone levels, castration blocked the kisspeptin-induced increase in testosterone, and testosterone levels in kisspeptin-treated animals were positively related to frequency of aggressive behaviors. This evidence provides a clear link between kisspeptin, testosterone, and aggressive behavior in lizards. Thus, it is likely that kisspeptin plays an important role more broadly in non-mammalian systems in the regulation of reproductive physiology and related behaviors.

While the use of nanoparticles has dramatically increased in recent years, the ecological consequences are not well known. In particular, little research has been done to investigate the potentially detrimental effects of nanoparticles on amphibians, especially across all life-history stages of salamanders and newts (caudates). To address this dearth in knowledge, we examined the effects of zinc oxide (ZnO) nanoparticles on egg, larval, and adult Rough-skinned Newts (Taricha granulosa). Chronic toxicity was tested on eggs and larvae, and acute toxicity was tested on eggs, larvae, and adults. For eggs, chronic exposure to ZnO nanoparticles caused higher mortality at 10.0 and 100.0 mg L(-1) compared to 0.0, 0.1, and 1.0 mg L(-1) . When given an acute exposure (24 hr) to 10.0 mg L(-1) nanoparticles at a late developmental stage, larvae hatched 5 days early, at a decreased developmental stage, and smaller size compared to the control. Chronic and acute exposure of larvae increased mortality up to 75% at both 10.0 and 100.0 mg L(-1) and exhibited sublethal effects, most dramatically, severe gill degradation. These results suggest nanoparticles can have lethal and sublethal effects on all life stages of amphibians.

Amphibians are well known as osmotically sensitive organisms due to their highly permeable skin and eggs and, as such, biologists have mostly discounted their presence in saline environments. Yet, from the 1800s to the present day, scientists have repeatedly found amphibians living and breeding in a variety of saline coastal and inland habitats. Despite this plethora of observations, their presence in these habitats is still mostly ignored, and the last (and only) complete literature review documenting amphibians in brackish and saline habitats was completed over 50 yr ago. Here we provide a review of the literature of amphibians in saline waters and present data on 144 species, in 28 families, on every continent except Antarctica. In doing so, we make the case that salt tolerance in amphibians may not be as rare as generally assumed. Through classifying habitats and studies, we conclude that the abilities of dozens of species to locally adapt to coastal and inland saline habitats have been exte...

A variety of mechanisms are responsible for enabling an organism to escape a predatory attack, including behavioral changes, alterations in hormone levels, and production and/or secretion of toxins. However, these mechanisms are rarely studied in conjunction with each other. The Rough-skinned Newt ( Taricha granulosa ) is an ideal organism to examine the relationships between these mechanisms because its behavioral displays and toxin secretion during a predator attack are well documented and readily characterized. While we found no direct relationship between antipredator behavior and endogenous levels of corticosterone (CORT), antipredator behavior was inhibited when exogenous CORT and adrenocorticotropic hormone (ACTH) were administered, resulting in high circulating concentrations of CORT, indicating that CORT may play a role in mediating the behavior. There was no correlation between the animal’s toxicity and either CORT or behavior. The results of this study provide evidence that CORT plays an important, yet complex, role in the antipredator response of these amphibians.

To accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. Yet, for the most part, these critical data are missing. We examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the rough-skinned newt (Taricha granulosa) from different populations. We found that salinity and temperature significantly interacted to affect newt embryonic survival and development, with the negative effects of salinity most pronounced at temperature extremes. We also found significant variation among, and especially within, populations, with different females varying in the performance of their eggs at different salinity–temperature combinations, possibly providing the raw material for future natural selection. Our results highlight the complex nature of predicting responses to climate change in space and time, and provide critical data towards that aim.

Amphibians, due to their highly permeable skin and egg membranes, are generally considered osmotically challenged animals and, thus, highly sensitive to brackish and saline environments (Shoemaker and Nagy 1977; Duellman and Trueb 1994). Due to their intolerance of salt water, amphibians have long been mostly discounted from occurring in areas directly influenced by the ocean (Darwin 1872), and notes of salamanders in these habitats are rare (Neill 1958). On 14 May 2012, we observed a larval Dicamptodon tenebrosus (Coastal Giant Salamander) in the tidal area of Hunter Creek, Curry County, Oregon (UTM Zone 10, 382898.3E, 4693923.4N, WGS84), 177 m from the Pacific Ocean. The animal was active, appeared in good body condition, and had a snout-vent length of 5.5 cm and a total length of 9.7 cm (Fig 1A). We found the salamander in a shallow sand and rock pool on the edge of the stream (,30 cm deep), with a salinity of 1.0 ppt. Freshwater is generally ,0.5 ppt; brackish water is 0.5 to 20 ppt; sea-water typically averages 35 ppt (Boaden and Seed 1985). We measured salinities of up to 1.4 ppt in this area on other days, and these concentrations have been found to be detrimental to caudate amphibian embryonic and larval survival and development (Hopkins and others 2013a, 2013b, 2014). The water temperature at the time of our observation was 14.26C. This area of the stream is devoid of riparian and aquatic vegetation, except for some algae growing on the rocks, and is essentially on a sandy and rocky beach (Fig. 1B, 1C). Affected dramatically by the tides, the water level of this habitat changes by almost 1.0 m between high and low tides (Fig. 1B, 1C). A dead sea-star (Forcipulatida, Pisaster spp.) was located a few meters away from the salamander. This habitat is also affected by coastal storm events, which sometimes lead to sea-water washing through this area (Fig. 1D). As we only found 1 individual D. tenebrosus in the tidal area of this stream, it is possible that these storm events may prevent a larger population from inhabiting this habitat due to temporarily increased salinity beyond this species’ tolerance level, or simply because the lack of vegetation and cover in this habitat renders it unsuitable. It is also possible that this individual may have been washed downstream due to spring flooding, and may be sensitive to increased salinity levels, as was found for Ambystoma gracile (Northwestern Salamander) in British Columbia, where larvae were found dead or dying in a tidal area with presumably increased salinity (Carl 1949). The D. tenebrosus that we found in the tidal area did not, however, appear to be dead or dying, and may have been more salt-tolerant than the individuals observed by Carl (1949). Ferguson (1956) also found 1 larval D. tenebrosus approximately 20 m from the edge of the high tide area of a coastal stream in Lincoln County, Oregon, but salinity was not measured. To the best of our knowledge, salinity tolerance in D. tenebrosus has not yet been experimentally determined, and more work clearly needs to be done to determine tidal habitat utilization and salt tolerance in this species. Although reports of salamanders in tidal habitats in the Pacific Northwest are rare, Ferguson (1956) found Taricha granulosa (Roughskinned Newts) in the tidal area of a stream in southern Oregon, and we also found a large breeding group (over 60 individuals) of this species in the same tidal area as the Dicamptodon we observed (Hopkins and Hopkins, pers. obs.). Batrachoseps relictus (Relictual Slender Salamanders) were reported on a beach in California (Moss Landing, Monterey County) under driftwood near the tide line (Licht and others 1975; B Bury, pers. comm.), as was B. pacificus (Channel Islands Slender Salamander) in the Channel Islands (Hansen and others 2005). Batrachoseps relictus was experimentally determined to be physiologically adapted to the increased salinity in this habitat (Licht and others 1975). GENERAL NOTES

Freshwater organisms are increasingly exposed to elevated salinity in their habitats, presenting physiological challenges to homeostasis. Amphibians are particularly vulnerable to osmotic stress and yet are often subject to high salinity in a variety of inland and coastal environments around the world. Here, we examine the physiological responses to elevated salinity of rough-skinned newts (Taricha granulosa) inhabiting a coastal stream on the Pacific coast of North America and compare the physiological responses to salinity stress of newts living in close proximity to the ocean with those of newts living farther upstream. Although elevated salinity significantly affected the osmotic (body weight, plasma osmolality), stress (corticosterone), and immune (bactericidal ability) responses of newts, animals found closer to the ocean were generally less reactive to salt stress than those found farther upstream. Our results provide possible evidence for some physiological tolerance in this species to elevated salinity in coastal environments. As freshwater environments become increasingly saline and more stressful, understanding the physiological tolerances of vulnerable groups such as amphibians will become increasingly important to our understanding of their abilities to respond, to adapt, and, ultimately, to survive.

The embryonic development and time to hatching of eggs can be highly adaptive in some species, and thus under selective pressure. In this study, we examined the underlying interfamily variation in hatching timing and embryonic development in a population of an oviparous amphibian, the rough-skinned newt (Taricha granulosa). We found significant, high variability in degree of embryonic development and hatching timing among eggs from different females. Patterns of variation were present regardless of temperature. We also could not explain the differences among families by morphological traits of the females or their eggs. This study suggests that the variation necessary for natural selection to act upon is present in the early life history of this amphibian.

The ability of prey to escape predation often lies in the occurrence and efficacy of their predator avoidance and antipredator behaviors, which are often coupled with specialized morphology. How the use and efficacy of these behaviors change throughout ontogeny may be indicative of the vulnerability and ecological roles these animals experience throughout their lives. We examined the antipredator behavior of a large dragonfly nymph, Anax junius, from a historically fishless pond where these animals have traditionally been classified as top predators. These dragonfly nymphs displayed a series of distinct aggressive antipredator behaviors when grasped that involved stabbing with lateral and posterior spines and seizing with labial hooks. Larger (older) nymphs displayed these aggressive behaviors significantly more than smaller (younger) animals in simulated predation trials. During encounters with live larval salamander predators (Ambystoma tigrinum), all large nymphs, but only 12.5% of small nymphs successfully escaped predation attempts by the amphibians through the use of antipredator behavior. Large nymphs were also significantly more active than smaller nymphs in the presence of salamander larvae. Despite often being considered top predators in fishless ponds, our study demonstrates that their true role is more complex, depending on ontogeny and body size, and that effective antipredator behavior is likely necessary for survival in these systems.

Distasteful, noxious, and toxic secretions from skin glands have been demonstrated to play important antipredatory roles in amphibians. Previous studies suggest that the Long-toed Salamander (Ambystoma macrodactylum), a widely distributed urodele found near the northern limit of its range in northern British Columbia, is distasteful to predators. The source of this distastefulness has not been exclusively identified. Our objectives were to isolate the skin secretions of the Long-toed Salamander through electrical stimulation of its granular glands and bioassay this secretion for antipredatory effects with crayfish. Previous studies suggested that proteins play an important role in these secretions; therefore, we tested for their presence and utility. The feeding response of crayfish to control food pellets was compared to pellets incorporating raw salamander skin secretions and to pellets incorporating boiled secretions. Significantly more crayfish consumed the control pellets than the raw skin secretion pellets, indicating unpalatability of these skin secretions. Thus, skin secretions appear to have an important antipredatory function. Skin secretions tested positive for presence of proteins, but the feeding response of crayfish to raw and boiled secretions was not significantly different, indicating that proteins were either only partially denatured by boiling, or are not exclusively responsible for the antipredatory nature of the secretions. A very low concentration of secretion was required to illicit a significant antifeedant response in crayfish, and we discuss the possible implications of this in relation to a proposed dual function of the Long-toed Salamander's granular glands in nutrient storage and the energetic requirements of an amphibian in its northern range.

We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt (Taricha granulosa). We assigned newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development.

The world is increasingly impacted by a variety of stressors that have the potential to differentially influence life history stages of organisms. Organisms have evolved to cope with some stressors, while with others they have little capacity. It is thus important to understand the effects of both developmental and evolutionary history on survival in stressful environments. We present evidence of the effects of both developmental and evolutionary history on survival of a freshwater vertebrate, the rough-skinned newt (Taricha granulosa) in an osmotically stressful environment. We compared the survival of larvae in either NaCl or MgCl2 that were exposed to salinity either as larvae only or as embryos as well. Embryonic exposure to salinity led to greater mortality of newt larvae than larval exposure alone, and this reduced survival probability was strongly linked to the carry-over effect of stunted embryonic growth in salts. Larval survival was also dependent on the type of salt (NaCl or MgCl2) the larvae were exposed to, and was lowest in MgCl2, a widely-used chemical deicer that, unlike NaCl, amphibian larvae do not have an evolutionary history of regulating at high levels. Both developmental and evolutionary history are critical factors in determining survival in this stressful environment, a pattern that may have widespread implications for the survival of animals increasingly impacted by substances with which they have little evolutionary history.

The application of millions of tons of road deicing salts every winter in North America presents significant survival challenges to amphibians inhabiting roadside habitats. While much is known of the effects of NaCl on anuran tadpoles, less is known of effects on amphibian eggs, or any caudate life stage. In addition, little is known of the effects of MgCl2, which is now the 2nd most commonly used road deicer. Most studies have considered amphibians to be helpless victims of deicing salts, and ignore the possibility of the evolution of local adaptation to this stressor. We attempt to address these knowledge gaps and explore this evolutionary potential by examining the effects of NaCl and MgCl2 on the survival and development of eggs from different female rough-skinned newts (Taricha granulosa) from the same population. We demonstrate that both salts, at environmentally relevant concentrations, severely affect the embryonic survival and development of this amphibian, but that the effects of the salt are dependent on the identity of the mother. This female × treatment interaction results in substantial variation in tolerance to road deicing salts among newt families, providing the raw material necessary for natural selection and the evolution of local adaptation in this amphibian.