Correlated trait response: comparing amphibian defense strategies across a stress gradient

2009 ◽  
Vol 87 (1) ◽  
pp. 41-49 ◽  
Author(s):  
T. S. Garcia ◽  
D. J. Paoletti ◽  
A. R. Blaustein
Keyword(s):  
Multiple Stressors ◽  
Species Difference ◽  
Elevation Gradient ◽  
Stress Gradient ◽  
Ultraviolet B ◽  
Correlated Response ◽  
Body Color ◽  
Multiple Traits ◽  
Amphibian Species ◽  
Rana Aurora

Animals inhabiting complex environments often contend with multiple stressors that can select for conflicting responses. Individuals can mediate these conflicts by utilizing correlated responses across multiple traits. In aquatic habitats, larval amphibians often face conflicting, simultaneous pressures, such as ultraviolet-B (UV-B) radiation and predators. UV-B radiation and predation risk influence behavior and body color in many amphibian species, altering activity rates, refuge use, and coloration. When both UV-B and predators are present, individuals can avoid conflicts by coupling behavior with body color to form a correlated response. UV-B exposure rates vary along an elevation gradient, thus trait combinations may also vary. We quantified changes in activity rates and body color in two anuran species, the red-legged frog ( Rana aurora Baird and Girard, 1852) (low elevations) and the cascades frog ( Rana cascadae Slater, 1939) (high elevations), during exposure to predator chemical cues (rough-skinned newt, Taricha granulosa (Skilton, 1849)) and UV-B radiation. Rana aurora decreased activity in response to UV-B and became more cryptic over time, while R. cascadae coupled decreased activity rates in response to predators with dark body coloration to screen out UV-B. Both species responded with a correlated trait response, yet employed opposite strategies. This observed species difference may be reflective of differences in stress across habitats and availability of alternative defenses.

Human-provoked amphibian decline in central Italy and the efficacy of protected areas

2010 ◽  
Vol 37 (7) ◽  
pp. 547 ◽  
Author(s):  
Manuela D'Amen ◽  
Biancamaria Pietrangeli ◽  
Marco A. Bologna
Keyword(s):  
Protected Areas ◽  
Multiple Stressors ◽  
Population Decline ◽  
Central Italy ◽  
Negative Relationship ◽  
Climatic Conditions ◽  
Amphibian Declines ◽  
Additive Models ◽  
Management Approach ◽  
Amphibian Species

Context Today, more than 32% of amphibian species are threatened and more than 43% face a steep decline in numbers. Most species are being affected simultaneously by multiple stressors and habitat protection is often inadequate to prevent declines. Aims The main goal of the present research was to understand the consequences of alternative human land use in producing landscape disturbance for amphibians. At the same time, we also evaluated the effect of changing climatic conditions as additional potential drivers of population decline. Another goal was to determine whether and to what extent the existing nature reserves have been effective in protecting species in recent decades. Methods We used generalised additive models (GAMs) to investigate the association between the state (stable/decline) of amphibian populations in 5 × 5 km cells in central Italy and proxies of different typology of anthropogenic stressors, climatic variables and protection measures. Key results We found a significant association between anthropogenic landscape modifications and species decline. This negative relationship was revealed with agricultural predictors for the majority of the species, whereas urban fabrics had a slightly smaller impact. We found significant associations between amphibian declines and climatic variation, particularly the increasing number of dry days. Protected areas protected declines of two species only. Conclusions Our results showed that the status of amphibians in this region warrants greater attention than has been given previously. The detrimental effect of agricultural practices, combined with increasing aridity, makes amphibian populations particularly susceptible to extinction, and the conservation measures applied till now are inadequate for species protection in this region. Implications Our results should stimulate the implementation of environmental policies that focus not only on the protection of single habitats, but also on ensuring the environmental quality of the surrounding landscapes. Moreover, an adaptive management approach should be applied to take into account future modification of hydrology and climate.

scholarly journals Nematode Parasites of Anurans from Three Cocoa Farms in Ondo State, Nigeria

2019 ◽  
pp. 1-11
Author(s):  
M. O. Oniya ◽  
A. L. Adeyekun
Keyword(s):  
Standard Procedure ◽  
Habitat Destruction ◽  
Species Level ◽  
Ultraviolet B ◽  
Pesticide Use ◽  
Amphibian Species ◽  
Ultraviolet B Radiation ◽  
Nematode Parasites ◽  
Ondo State ◽  
Cosmocerca Ornata

The research was designed to investigate the parasitic fauna of Anurans from cocoa farms in Ondo state. Amphibians are one of the most threatened groups of vertebrates. Many reasons are attributed to the decline of amphibian species such as global warming, habitat destruction and modification, others include: exploitation, pesticide use, introduced species, ultraviolet-B radiation (UV-B), pollution, parasites and diseases. A total of 31 frogs from 4 genera, Hemisus, Ptychadena, Rana and Xenopus and 7 toads from 1 genus, Sclerophrys were examined. 9 frogs were collected from Oluwateru farm at Iwoye Village; 7 frogs were collected from Folorunso farm at Ako-Igbatoro and 15 frogs from Obodulu farm in Idanre. 5 toads were collected from Oluwateru farm at Iwoye Village and 2 toads from Obodulu farm in Idanre. In all cases collection was done between 20:00 hrs and 05:00 hrs. Collected specimens were transported in sealed but ventilated containers to the laboratory where identification was done to species level. The frogs were anaesthetized until death in absolute chloroform soaked in cotton wool placed inside kill-jar for 3 minutes in the laboratory.  The gastrointestinal tracts were cut open and the contents of the various sections were put into separate Petri dishes containing normal saline.  The skin and the bladder were observed directly under a dissecting microscope for the presence of cysts and monogeneans. The parasites were fixed and preserved in 70% alcohol following standard procedure. Parasites recovered from the gastrointestinal tracts of the anurans include Cosmocerca ornata, Deising, 1861, Cosmocerca cummutata, Diesing, 1851 Paracosmocerca mucronata, Kung and Wu, 1945, Ampliceacum africanum, Taylor, 1924, Gendria liberrei Bain and Philipon, 1969 and Chenospirura asturi Hsu, 1957 Others were Procamallus brevis Kung, 1948 and Camallanus dimitrovi   Durette- Desset and Batcharov, 1974. Some of the parasites are zoonotic while a few others are established parasites of African fishes and water Birds raising probable public health concerns from the findings. Further works aimed at unravelling the biodiversity of hosts and parasites in the lush ecosystem of Ondo state, as well as identification of organisms involved in the life cycle are noted.

Problems utilizing an enzyme sensitive site assay for photorepair of exogenous DNA with cell-free extracts made from amphibian embryos

2000 ◽  
Vol 78 (10) ◽  
pp. 1869-1872 ◽  
Author(s):  
M Alex Smith
Keyword(s):  
Ultraviolet B ◽  
Signal Loss ◽  
Amphibian Species ◽  
Exogenous Dna ◽  
Free Protein ◽  
Amphibian Embryos ◽  
Damage Repair ◽  
Sensitive Site ◽  
Nuclease Digestion ◽  
Proper Estimation

Attempts were made to assay the ultraviolet-B (UVB) damage repair ability of seven Ontario amphibian species using an enzyme sensitive site restriction-enzyme (ESS) assay. Cell-free protein extracts of amphibian eggs caused the degradation of even high (9 mg/mL) exogenous DNA concentrations. This type of signal loss is characteristic of nuclease digestion. High endogenous concentrations of amphibian nucleases appear to preclude the use of plasmid DNA-ESS assays to determine the UVB damage repair abilities of amphibian eggs. Proper estimation of amphibian ultraviolet damage repair characteristics, using any assay, is reliant upon the generation of cell-free protein extracts created from amphibian embryos covered in protective jelly. The process of releasing the embryo from the glycoprotein-carbohydrate jelly ("dejellying") is achieved by shaking the jelly mass in a solution of 2% L-cysteine. Equivalent exposure to 2% L-cysteine results in a radically different end product with different amphibian taxa. These previously unreported phenomena have important implications for the production, standardization, and reporting of amphibian photorepair data.

scholarly journals Temperature, desiccation, and species performance trends along an intertidal elevation gradient

2020 ◽  
Author(s):  
Lindsay K. Eckersley ◽  
Ricardo Augusto Scrosati
Keyword(s):  
Seawater Temperature ◽  
Elevation Gradient ◽  
Stress Gradient ◽  
Field Method ◽  
Daily Temperature ◽  
Growth Data ◽  
Desiccation Rate ◽  
High Zone ◽  
Species Performance ◽  
High Elevations

This study investigated the effects of intertidal elevation on ecologically relevant temperature traits and the intensity of organism desiccation during low tides on a subpolar NW Atlantic shore. The goal was to relate those descriptors of environmental stress to elevational changes in the growth of dominant sessile species (algae and mussels) that influence overall community structure. In-situ measurements taken at the low, middle, and high intertidal zones revealed that daily temperature maxima, daily temperature range, and desiccation rate increased significantly from low to high elevations. Conditions were especially stressful at the high zone, as the highest temperature (47 °C, recorded during aerial exposure at low tide) more than doubled seawater temperature and desiccation rate surpassed 90 %. Transplant experiments showed that seaweed (Ascophyllum nodosum) and mussel (Mytilus edulis) growth rate decreased dramatically from low to high elevations. Therefore, although subpolar shores are mostly known for their harsh winter conditions, the pronounced vertical stress gradient that characterizes the intertidal zone during ice-free months also plays a major role in determining spatial changes in benthic species performance. Our study also suggests that inferring stress differences between habitats based on growth data from transplanted specimens may be a useful field method to further develop stress ecological theory.

scholarly journals Positive genetic associations among fitness traits support evolvability of a reef-building coral under multiple stressors

2019 ◽  
Author(s):  
Rachel M. Wright ◽  
Hanaka Mera ◽  
Carly D. Kenkel ◽  
Maria Nayfa ◽  
Line K. Bay ◽  
...  
Keyword(s):  
Climate Change ◽  
Weight Gain ◽  
Genetic Variance ◽  
Multiple Stressors ◽  
Genetic Correlations ◽  
Genetic Associations ◽  
Multiple Traits ◽  
Physiological Indicators ◽  
Synergistic Interactions ◽  
Fitness Traits

AbstractClimate change threatens organisms in a variety of interactive ways that requires simultaneous adaptation of multiple traits. Predicting evolutionary responses requires an understanding of the potential for synergistic interactions among stressors and the genetic variance and covariance among fitness-related traits that may reinforce or constrain an adaptive response. Here we investigate the capacity of Acropora millepora, a reef-building coral, to adapt to multiple environmental stressors: rising sea surface temperature, ocean acidification, and increased prevalence of infectious diseases. We measured growth rates (weight gain), coral color (a proxy for Symbiodiniaceae density), and survival, in addition to nine physiological indicators of coral and algal health in 40 coral genets exposed to each of these three stressors singly and combined. Individual stressors resulted in predicted responses (e.g., corals developed lesions after bacterial challenge and bleached under thermal stress). However, corals did not suffer substantially more when all three stressors were combined. Nor were tradeoffs observed between tolerances to different stressors; instead, individuals performing well under one stressor also tended to perform well under every other stressor. An analysis of genetic correlations between traits revealed positive co-variances, suggesting that selection to multiple stressors will reinforce rather than constrain the simultaneous evolution of traits related to holobiont health (e.g., weight gain and algal density). These findings support the potential for rapid coral adaptation under climate change and emphasize the importance of accounting for corals’ adaptive capacity when predicting the future of coral reefs.

scholarly journals Shifts in temperature influence howBatrachochytrium dendrobatidisinfects amphibian larvae

2017 ◽  
Author(s):  
Paul W. Bradley ◽  
Michael D. Brawner ◽  
Thomas R. Raffel ◽  
Jason R. Rohr ◽  
Deanna H. Olson ◽  
...  
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Temperature Shift ◽  
Amphibian Species ◽  
Change Models ◽  
Rana Aurora ◽  
Amphibian Larvae ◽  
Western Toads ◽  
Anaxyrus Boreas ◽  
Potential Shifts ◽  
Increased Susceptibility

AbstractMany climate change models predict increases in mean temperature, and increases in frequency and magnitude of temperature fluctuations. These potential shifts may impact ectotherms in several ways, including how they are affected by disease. Shifts in temperature may especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites may acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungusBatrachochytrium dendrobatidis(Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before Bd exposure alter susceptibility to Bd in the larval stage of two amphibian species – western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15° C) temperature in comparison to constant warm (20° C) temperature. Additionally, both species experienced an increase in Bd infection abundance when shifted to 20° C from 15° C, compared to a constant 20° C but they experienced a decrease in Bd when shifted to 15° C from 20° C, compared to a constant 15° C. These results are in contrast to prior studies of adult amphibians that found increased susceptibility to Bd infection after a temperature shift in either direction, highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis.

Hatching success and larval survival of the frogs Hyla regilla and Rana aurora under ambient and artificially enhanced solar ultraviolet radiation

1997 ◽  
Vol 75 (7) ◽  
pp. 1081-1088 ◽  
Author(s):  
Kristiina Ovaska ◽  
Theodore M. Davis ◽  
Iñigo Novales Flamarique
Keyword(s):  
Hatching Success ◽  
Larval Survival ◽  
Ultraviolet B ◽  
Experimental Conditions ◽  
Solar Ultraviolet Radiation ◽  
Hyla Regilla ◽  
Rana Aurora ◽  
Solar Uv ◽  
And Control ◽  
Solar Ultraviolet

The aquatic stages of amphibians may be sensitive to increased levels of solar ultraviolet B radiation (UV-B, 280–320 nm) that have been observed at higher latitudes over the past several decades, but the effects on most species are unknown. We exposed eggs and larvae of Hyla regilla and Rana aurora to three experimental treatments: (1) solar UV < 450 nm blocked (control), (2) ambient solar UV, and (3) solar UV-B enhanced 15 and 30% above ambient levels at midday to simulate conditions predicted for the next decades at midlatitudes. The rearing containers were covered with acrylic filters to provide the desired radiation regimes. Hatching success of H. regilla did not differ among the treatments and was 87.7, 71.8, and 87.1% in April 1995 and 94.0, 85.1, and 97.4% in May 1995 for the control, ambient, and enhanced UV-B treatments, respectively. In contrast, hatching success of R. aurora in the enhanced UV-B treatment (56.0%) was lower than in the ambient UV (89.8%) and control (81.0%) treatments. Larval survival over the first 2 months of development was reduced to 18.4% for H. regilla and 2.6% for R. aurora in the enhanced UV-B treatment compared with the ambient UV and control treatments. We conclude that ambient UV levels at the study site did not affect the embryonic or early larval survival of either of the species tested under the experimental conditions, but both species are potentially vulnerable to increases in solar UV-B.

Ambient Ultraviolet B Radiation and Prevalence of Infection by Batrachochytrium dendrobatidis in Two Amphibian Species

2011 ◽  
Vol 25 (5) ◽  
pp. 975-982 ◽  
Author(s):  
MANUEL E. ORTIZ-SANTALIESTRA ◽  
MATTHEW C. FISHER ◽  
SAIOA FERNÁNDEZ-BEASKOETXEA ◽  
MARÍA J. FERNÁNDEZ-BENÉITEZ ◽  
JAIME BOSCH
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Ultraviolet B ◽  
Amphibian Species ◽  
Ultraviolet B Radiation

Photolyase activity of the embryo and the ultraviolet absorbance of embryo jelly for several Ontario amphibian species

2002 ◽  
Vol 80 (6) ◽  
pp. 1109-1116 ◽  
Author(s):  
M Alex Smith ◽  
Michael Berrill ◽  
Carolyn M Kapron
Keyword(s):  
Ultraviolet B ◽  
Cyclobutane Pyrimidine Dimers ◽  
Amphibian Species ◽  
South Central ◽  
Pyrimidine Dimers ◽  
In Vitro Measurements ◽  
Primary Form

Organisms whose eggs develop at or near the interface between air and water may be particularly vulnerable to damage from ultraviolet radiation. The primary form of ultraviolet B (UV-B) radiation damage to biological systems is the formation of cyclobutane pyrimidine dimers (CBPDs) in DNA. The most common method of repairing this damage is photoenzymatic repair via photolyase, whose actions are specific to CBPDs. We utilized a bacterial-transformation assay to estimate the level of photolyase activity of various tissue types in seven species of amphibians collected in south-central Ontario. In this assay, the photolyase activity of a species is measured as the rate of CBPD removal from UV-B-damaged plasmid DNA by cell-free extracts created from the tissue of the species in question. The depth of oviposition and the UV-B absorbance of the embryo jelly, two variables that alter an embryo's in situ exposure to UV-B radiation, were measured to determine whether the level of photolyase activity was correlated with expected UV-B exposure. In vitro measurements of photolyase activity for the seven species were significantly different (F[6] = 10.31, p < 0.0001) and tended to be positively correlated with expected in vivo exposure to UV-B radiation.

scholarly journals External morphological anomalies of the amphibians of the Kharkiv region

2020 ◽  
Keyword(s):  
Steppe Zone ◽  
Body Color ◽  
Amphibian Species ◽  
Partial Frequency ◽  
Morphological Abnormalities ◽  
Lissotriton Vulgaris ◽  
National University ◽  
Bombina Bombina ◽  
New Type

In Ukraine, amphibian anomalies have not been sufficiently studied. The most studied regions are Kyiv region and the steppe zone of Ukraine. In the Kharkiv region, studies of external anomalies of amphibians have not been conducted before. In 2016 we have begun to study this problem. The purpose of this study is to examine the variety of external anomalies of amphibians in the Kharkiv region. The material is sampling amphibians from the stock collections of the Museum of Nature of V.N.Karazin Kharkiv National University and sampling live amphibians from different localities of the Kharkiv region, explored in the period from 2016 to 2018. Anomalies were determined visually, according to the classification of V.L.Vershinin and O.D.Nekrasova. For each the amphibian species frequency of malformed animals Pas (the proportion of abnormal individuals from all individuals in the sample) and partial frequency of abnormalities Ap (the proportion of individuals in the sample having this anomaly) were determined. As a result 17 variants of morphological abnormalities were identified: brachydactyly, oligodactyly, ectromelia, polyphalangy, finger thickening, rotation, syndactyly, shizodactyly, ectrodactyly, skin web and growth on the foot, thaumelia, hemimelia, lack of a swimming membrane, anophthalmia, brachycephaly and pattern abnormal. The most widespread anomaly encountered in the surveyed amphibians is brachydactyly (accounting for almost half of the reported cases of morphological abnormalities). This limb anomaly is the least harmful, so individuals with such abnormalities are usually quite viable. Amphibian anomalies are evenly distributed among samples: the highest occurrence of individuals with anomalies was recorded in Lissotriton vulgaris, in other samplings of frog (except Bufotes viridis and Bombina bombina), the occurrence of individuals with anomalies did not exceed five percent. A new type of body color anomaly in this year's Bufotes viridis was also identified and described.

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