scholarly journals Exposure to Batrachochytrium dendrobatidis affects chemical defences in two anuran amphibians, Rana dalmatina and Bufo bufo

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
János Ujszegi ◽  
Krisztina Ludányi ◽  
Ágnes M. Móricz ◽  
Dániel Krüzselyi ◽  
László Drahos ◽  
...  
Keyword(s):  
Life History ◽  
Larval Stage ◽  
Life History Traits ◽  
Batrachochytrium Dendrobatidis ◽  
Biodiversity Loss ◽  
Bufo Bufo ◽  
Control Treatment ◽  
Population Declines ◽  
Chemical Defences ◽  
Rana Dalmatina

Abstract Background Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo). Results Exposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species. Conclusions The lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events.

scholarly journals Body size mediates latitudinal population differences in response to Bd infection in two amphibian species.

2021 ◽  
Author(s):  
Sara Meurling ◽  
Maria Cortazar-Chinarro ◽  
Mattias Siljestam ◽  
David Ahlen ◽  
Erik Agren ◽  
...  
Keyword(s):  
Body Size ◽  
Batrachochytrium Dendrobatidis ◽  
Geographical Origin ◽  
Bufo Bufo ◽  
Northern Region ◽  
Population Declines ◽  
Rana Arvalis ◽  
Amphibian Species ◽  
Survival Difference ◽  
Species Survival

Populations of the same species may differ in their sensitivity to pathogens but the factors behind this variation are poorly understood. Moreover, infections may cause sub-lethal fitness effects even in species resistant or tolerant to disease. The chytrid fungus Batrachochytrium dendrobatidis (Bd), is a generalist pathogen which has caused amphibian population declines worldwide. In many species, Bd infection causes the disease chytridiomycosis, often leading to high mortality. We investigated how geographical origin affects tolerance to Bd by exposing newly metamorphosed individuals of two North European amphibians (moor frog Rana arvalis, common toad Bufo bufo) from two latitudinal regions to two different BdGPL strains. Bd exposure strongly lowered survival in B. bufo, and in both species survival was lower in the northern region, this difference being much stronger in B. bufo. Northern individuals were smaller in both species, and the survival difference between the regions was size-mediated with smaller individuals being more sensitive to Bd. In both species, Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that even individuals surviving the infection may have reduced fitness mediated by smaller body size. Bd strain affected size-dependent mortality differently in the two regions. We discuss the possible mechanisms how body size and geographical origin can contribute to the present results.

scholarly journals Population declines of tuna and relatives depend on their speed of life

2015 ◽  
Vol 282 (1811) ◽  
pp. 20150322 ◽  
Author(s):  
M. J. Juan-Jordá ◽  
I. Mosqueira ◽  
J. Freire ◽  
N. K. Dulvy
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Traits ◽  
Population Level ◽  
Maximum Size ◽  
Latitudinal Gradients ◽  
Fishing Mortality ◽  
Population Declines ◽  
Wide Range ◽  
Exploitation Status

Larger-bodied species in a wide range of taxonomic groups including mammals, fishes and birds tend to decline more steeply and are at greater risk of extinction. Yet, the diversity in life histories is governed not only by body size, but also by time-related traits. A key question is whether this size-dependency of vulnerability also holds, not just locally, but globally across a wider range of environments. We test the relative importance of size- and time-related life-history traits and fishing mortality in determining population declines and current exploitation status in tunas and their relatives. We use high-quality datasets of half a century of population trajectories combined with population-level fishing mortalities and life-history traits. Time-related traits (e.g. growth rate), rather than size-related traits (e.g. maximum size), better explain the extent and rate of declines and current exploitation status across tuna assemblages, after controlling for fishing mortality. Consequently, there is strong geographical patterning in population declines, such that populations with slower life histories (found at higher cooler latitudes) have declined most and more steeply and have a higher probability of being overfished than populations with faster life histories (found at tropical latitudes). Hence, the strong, temperature-driven, latitudinal gradients in life-history traits may underlie the global patterning of population declines, fisheries collapses and local extinctions.

scholarly journals Recent demographic histories and genetic diversity across pinnipeds are shaped by anthropogenic interactions and mediated by ecology and life-history

2018 ◽  
Author(s):  
M.A. Stoffel ◽  
E. Humble ◽  
K. Acevedo-Whitehouse ◽  
B.L. Chilvers ◽  
B. Dickerson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Life History ◽  
Large Scale ◽  
Biodiversity Loss ◽  
Single Species ◽  
Population Viability ◽  
Breeding Habitat ◽  
Comparative Approach ◽  
Population Declines ◽  
Effective Population

AbstractA central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and negatively impact population viability and adaptive potential. In an era of unprecedented biodiversity loss and climate change, understanding both the determinants and consequences of bottlenecks in wild populations is therefore an increasingly important challenge. However, as most studies have focused on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we used a comparative approach by integrating genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to elucidate the consequences of large-scale commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong genetic signatures of recent population declines, with estimated bottleneck effective population sizes reflecting just a few tens of surviving individuals in the most extreme cases. Bottleneck strength was strongly associated with both breeding habitat and mating system variation, and together with global abundance explained a large proportion of the variation in genetic diversity across species. Overall, there was no relationship between bottleneck intensity and IUCN status, although three of the four most heavily bottlenecked species are currently endangered. Our study reveals an unforeseen interplay between anthropogenic exploitation, ecology, life history and demographic declines, sheds new light on the determinants of genetic diversity, and is consistent with the notion that both genetic and demographic factors influence population viability.

scholarly journals Infectious disease threats to amphibian conservation

2018 ◽  
Vol 27 (Supplement) ◽  
pp. 81-90
Author(s):  
A.A. Cunningham
Keyword(s):  
Infectious Disease ◽  
Batrachochytrium Dendrobatidis ◽  
Biodiversity Loss ◽  
Amphibian Conservation ◽  
Disease Spread ◽  
Population Declines ◽  
Amphibian Species ◽  
Late 20Th Century ◽  
Amphibian Population ◽  
In The Wild

The unexplained decline of amphibian populations across the world was first recognised in the late 20th century. When investigated, most of these “enigmatic” declines have been shown to be due to one of two types of infectious disease: ranavirosis caused by infection with FV3-like ranavirus or with common midwife toad virus, or chytridiomycosis caused by infection with Batrachochytrium dendrobatidis or B. salamandrivorans. In all cases examined, infection has been via the human-mediated introduction of the pathogen to a species or population in which it has not naturally co-evolved. While ranaviruses and B. salamandrivorans have caused regionally localised amphibian population declines in Europe, the chytrid fungus, B. dendrobatidis, has caused catastrophic multi-species amphibian population declines and species extinctions globally. These diseases have already caused the loss of amphibian biodiversity, and over 40% of known amphibian species are threatened with extinction. If this biodiversity loss is to be halted, it is imperative that regulations are put in place – and enforced – to prevent the spread of known and yet-to-be discovered amphibian pathogens. Also, it is incumbent on those who keep or study amphibians to take measures to minimise the risk of disease spread, including from captive animals to those in the wild.

scholarly journals Life-history traits matter for dispersal into semi-open habitat corridors:

2019 ◽  
Vol 2 ◽  
Author(s):  
Estève Boutaud ◽  
Dorothea Nolte ◽  
Claudia Drees ◽  
Thorsten Assmann
Keyword(s):  
Life History ◽  
Body Size ◽  
Life History Traits ◽  
Small Body ◽  
Biodiversity Loss ◽  
Species Traits ◽  
Open Habitat ◽  
Habitat Specialisation ◽  
Generalized Linear Modelling ◽  
Dispersal Success

Biodiversity face ever-increasing threats from the consequences of various human activities Conservation corridors have long been considered a viable solution to help counteract biodiversity loss. However, corridors simultaneously increase fragmentation for non-target habitats. To overcome this challenge, semi-open habitats, which are a mixture of open and woodland habitats, have been proposed as they may enable simultaneous dispersal of both stenotopic open and woodland species. Despite the fact that they could be used by a great range of species, strong interspecific variability exists with regards to the number of individuals effectively recorded in such environment. Consequently, generalisation about their effectiveness remains difficult. Life-history traits such as body size, hibernation stage, trophic guild, and habitat specialisation could be successfully used to enhance prediction with regards to dispersal success. We used generalized linear modelling to study the relationship of ground beetles species traits and dispersal success into semi-open habitat in two regions of Germany. Our preliminary results indicate that larger species, as well as species overwintering as larvae, tend to be more successful when dispersing into semi-open habitat than smaller species or species overwintering as adult. In addition, species locally abundant are also recorded in higher number. In the light of these results, semi-open corridors do not appear to be the best strategy to increase connectivity for species with small body size or overwintering as adult. For such species, priority should be given to traditional corridors whenever possible. Source habitats need also attention as population size will strongly determine the usefulness of such corridors.

scholarly journals "Heat waves" experienced during larval life have species-specific consequences on life-history traits and sexual development in anuran amphibians

2021 ◽  
Author(s):  
Janos Ujszegi ◽  
Reka Bertalan ◽  
Nikolett Ujhegyi ◽  
Viktoria Verebelyi ◽  
Edina Nemeshazi ◽  
...  
Keyword(s):  
Life History ◽  
Larval Development ◽  
Body Mass ◽  
Sexual Development ◽  
Life History Traits ◽  
Heat Waves ◽  
Life Stage ◽  
Bufo Bufo ◽  
Negative Consequences ◽  
Cold Adapted

Extreme temperatures during heat waves can induce mass-mortality events, but can also exert sublethal negative effects by compromising life-history traits and derailing sexual development. Ectothermic animals may, however, also benefit from increased temperatures via enhanced physiological performance and the suppression of cold-adapted pathogens. Therefore, it is crucial to address how the intensity and timing of naturally occurring or human-induced heat waves affect life-history traits and sexual development in amphibians, to predict future effects of climate change and to minimise risks arising from the application of elevated temperature in disease mitigation. We raised agile frog (Rana dalmatina) and common toad (Bufo bufo) tadpoles at 19 °C and exposed them to a simulated heat wave of 28 or 30 °C for six days during one of three ontogenetic periods (early, mid or late larval development). In agile frogs, exposure to 30 °C during early larval development increased mortality. Regardless of timing, all heat-treatments delayed metamorphosis, and exposure to 30 °C decreased body mass at metamorphosis. Furthermore, exposure to 30 °C during any period and to 28 °C late in development caused female-to-male sex reversal, skewing sex ratios strongly towards males. In common toads, high temperature only slightly decreased survival and did not influence phenotypic sex ratio, while it reduced metamorph mass and length of larval development. Juvenile body mass measured two months after metamorphosis was not adversely affected by temperature treatments in either species. Our results indicate that heat waves may have devastating effects on amphibian populations, and the severity of these negative consequences, and sensitivity can vary greatly between species and with the timing and intensity of heat. Finally, thermal treatments against cold-adapted pathogens have to be executed with caution, taking into account the thermo-sensitivity of the species and the life stage of animals to be treated.

Effects of the disinfectant Virkon S on early life-stages of the moor frog (Rana arvalis)

2012 ◽  
Vol 33 (3-4) ◽  
pp. 349-353 ◽  
Author(s):  
Sandra Hangartner ◽  
Anssi Laurila
Keyword(s):  
Early Life ◽  
Batrachochytrium Dendrobatidis ◽  
Emerging Diseases ◽  
Control Treatment ◽  
Life Stages ◽  
Population Declines ◽  
Early Life Stages ◽  
Negative Effects ◽  
Rana Arvalis ◽  
Moor Frog

Emerging diseases, such as the chytrid fungus Batrachochytrium dendrobatidis, contribute to global population declines of amphibians. Virkon S is one of the most commonly used disinfectants to reduce risk of spreading such pathogens. Virkon S is classified as harmful to aquatic organisms, but until today no negative effects on tadpoles have been reported. We studied the effects of three concentrations of Virkon S on early life-stages (embryos and hatchlings) of the moor frog Rana arvalis. Overall, Virkon S had no significant effects. However, hatching success was highest in the control treatment, suggesting that Virkon S may have weak negative effects on amphibian embryos. We suggest that further studies are needed to assess the negative effect of Virkon S on amphibians, and recommend that Virkon S is used with care and a minimized run-off into natural wetlands.

scholarly journals Effects of predator cues carry over from egg and larval stage to adult life-history traits in a damselfly

2020 ◽  
Vol 39 (4) ◽  
pp. 804-811
Author(s):  
Szymon Sniegula ◽  
Mateusz Raczyński ◽  
Maria J. Golab ◽  
Frank Johansson
Keyword(s):  
Life History ◽  
Larval Stage ◽  
Life History Traits ◽  
Adult Life ◽  
Predator Cues ◽  
Carry Over

scholarly journals Life history mediates the trade-offs among different components of demographic resilience

2021 ◽  
Author(s):  
Pol Capdevila ◽  
Iain Stott ◽  
James Cant ◽  
Maria Beger ◽  
Gwilym Rowlands ◽  
...  
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Natural Populations ◽  
Biodiversity Loss ◽  
Reproductive Capacity ◽  
Trade Offs ◽  
Recovery Times ◽  
History Of ◽  
Highly Correlated

Accelerating rates of biodiversity loss underscore the need to understand how species achieve resilience, their ability to resist and recover from a/biotic disturbances. Yet, the factors determining the resilience of species remain poorly understood, due to disagreements on its definition and the lack of large-scale analyses. Here, we investigate how the life history of 785 natural populations of animals and plants predict their intrinsic ability to be resilient. We show that demographic resilience can be achieved through different combinations of compensation, resistance, and recovery after a disturbance. We demonstrate that these resilience components are highly correlated with life history traits related to the species' pace of life and reproductive strategy. Species with longer generation times require longer recovery times post-disturbance, while those with greater reproductive capacity have greater resistance and compensation. Our findings highlight the key role of life history traits to understand species resilience, improving our ability to predict how natural populations cope with disturbance regimes.

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