Despite a number of studies showing a negative relationship between age and telomere length, the universality of this pattern has been recently challenged, mainly in ectothermic animals exhibiting ...diverse effects of age on telomere shortening. However, data on ectotherms may be strongly affected by the thermal history of the individuals. We thus investigated the age-related changes in relative telomere length in the skin of a small but long-lived amphibian living naturally in a stable thermal environment over its entire life, allowing comparison with other homeothermic animals like birds and mammals. The present data showed a positive relation between telomere length and individual age, independent of sex and body size. A segmented analysis highlighted a breakpoint in the telomere length-age relationship, suggesting that telomere length reached a plateau at the age of 25 years. Further studies focusing on the biology of animals that live much longer than expected based on body mass will contribute to our better understanding of how ageing processes evolved and may also bring innovation for extending human health span.
Abstract
During recent years, the scientific interest in the work of Austrian biologist Paul Kammerer (1880‒1926) has risen again. This development can largely be attributed to advances in the fields ...of epigenetics and epigenetic inheritance, and it resulted in provocative discussions. This article contributes to enhancing the knowledge about Kammerer's publications in two respects. First, I provide a brief overview and contextualization of Kammerer's main works on phenotypic plasticity and its inheritance, some of which seem little known at present. Thereafter, to ensure an accurate transmission of the historical record, I comment on recently published suggestive information about what Kammerer did and wrote, chiefly referring to Kammerer's original writings on fire salamanders (Salamandra salamandra) and cave salamanders (Proteus anguinus). Although the exact contents of Kammerer's writings remain controversial and must be regarded with caution, his writings need to be treated objectively and accurately to avoid historical record distortion and to render the performance of adequate replications of his experiments possible.
The olm (Proteus anguinus), an endemic amphibian of the Dinarides' underground waters (Europe), is one of the world's most widely known subterranean species. Although various aspects of olm biology ...have been extensively studied, the data on their behavior in the wild remain scarce mostly due to inaccessibility of their natural habitat. Yet, olms also occur in several karstic springs during nighttime. These are easier to access and present an exciting opportunity to study olm behavior in nature. Here, we report on systematic observations of olms in one such spring in Slovenia, where we observed them for nine consecutive summer nights, coupling direct on-site observations with IR camera trap recordings. We used IR camera trap recordings to construct simple ethograms, as well as to quantify olm movement activity by video-tracking. Olms regularly occurred on the surface during the night, and dawn appeared to be a key stimulus for their retreat underground. They were constantly active, but rarely swam far from the spring. Despite the short-term nature of the study, we collected new occurrence and movement data, and at the same time tested the usability of IR cameras for surveying olm presence and behavior in nature. Experience gained through the study may prompt long-term and more complex behavioral studies using similar approaches.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Information on individual trophic specialization may be relevant to better understand the ecological adaptation of populations to their environment and the evolution of their realized trophic niche. ...In this study, we analysed the trophic specialization at the individual level in a population of the plethodontid Northwest Italian Cave Salamander (Speleomantes strinatii (Aellen, 1958)), a terrestrial generalist predator. Salamanders were sampled in northwestern Italy on the forest floor in autumn (n = 49) and spring (n = 47) along with their available prey. In autumn, when trophic resources showed a twofold reduction in abundance, the population trophic niche width (TNW = 2.58) was significantly broader than during spring (TNW = 2.25), and in both seasons, individual specialization (IS) was significantly higher than expected by chance (P = 0.001). There were no sexual or ontogenetic differences in IS within each season, but IS in autumn was significantly higher than in spring (IS = 0.34 and IS = 0.41, respectively; P = 0.01). These findings are in accordance with the niche variation hypothesis, which predicts a positive relationship between TNW and IS. Therefore, while the population became more generalist, individual salamanders shifted towards a more specialized diet by adapting their feeding behaviour to changes in prey availability.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lungless salamanders of the family Plethodontidae have historically been considered to be passive conformers to their surrounding thermal environment because there is no evidence that they ...thermoregulate behaviourally in the field. In contrast, plethodontids readily choose optimal temperatures when placed on experimental thermal gradients. It has been hypothesized that restriction to moist habitats prevents these salamanders from exploiting thermally diverse microhabitats in nature. We tested this hypothesis, as well as the hypothesis that response to temperature differs among plethodontid species, by investigating the thermal ecology of two species (Cave Salamander, Eurycea lucifuga Rafinesque, 1822, and Northern Slimy Salamander, Plethodon glutinosus (Green, 1818)) occupying twilight zones of six caves in northwestern Georgia. We recorded inside and outside temperatures, as well as the number of each species, for each of three seasons (summer, fall, spring) over 13 years. We also tested for differences in thermal preference along experimental gradients in the laboratory. We further generated environmental niche models (ENMs) to investigate the potential role of abiotic variables, including environmental temperature, in determining the geographic range of each species. We found that both species responded to cave temperature in such a way as to suggest that these salamanders thermoregulate behaviourally when given a diversity of thermal options within a relatively constant moisture regime. We also determined that E. lucifuga prefers lower temperatures than P. glutinosus. ENM analysis indicated that, while abiotic variables both strongly influence the ecological niche of both species, the range of E. lucifuga is strongly predicted by them. The geographic distribution of P. glutinosus is apparently heavily influenced by the presence of closely related, contiguous neighbors with similar niche requirements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
Cover illustration. Like most other cave animals, the Proteus anguinus anguinus (cave‐dwelling salamander) experiences periodically poor and discontinuous food supply and/or intermittent ...hypoxia that may occur for long periods in the subterranean environments. The salamander adjusts its metabolism and utilization of metabolic reserves to these fluctuating periods of food supply. In this issue of the Journal of Morphology, Mali and coauthors studied morphological and biochemical changes of liver tissue of the cave‐dwelling salamander during periods of food deprivation (pp 887–900). With a combination of qualitative morphological and quantitative biochemical data, the authors evaluate the adaptive capacity of the liver and the importance of the liver as an energy storing organ.
Captive breeding programs are an important tool for the conservation of endangered species. These programs are commonly managed using pedigrees containing information about the history of each ...individual's family, such as breeding pairs and parentage. However, there are some species that are kept in groups where it is hard to distinguish between particular individuals within the group, making it very difficult to record any information at an individual level. Currently, software and methods commonly used for registering and analyzing pedigrees to help manage populations at an individual level are not adequate for managing these group‐living species. Therefore, there is a need to further develop these tools and methodologies for pedigree analysis to better manage group‐living species. PMx is a program used for the management of ex situ populations in zoos and aquariums. We adapted the pedigree analysis method implemented in PMx to analyze pedigrees (records of descendant lineages) of group‐living species. In addition, we developed a group pedigree data entry sheet and group2PMx, a converter program that enables group datasets to be imported into PMx. We show how pedigree analysis of a group‐living species can be used for population management using the studbook of the endangered Texas blind cave salamander Eurycea rathbuni. Such analyses of the pedigree of groups can improve the management of group‐living species in ex situ breeding programs. Firstly, it enables better management decisions based on more accurate genetic measures between groups, allowing for greater control of inbreeding. Secondly, it can improve the conditions in which group‐living species are held by adapting husbandry practices to better reflect conditions of these species living in the wild. The use of the spreadsheet and group2PMx extends the application of PMx, allowing conservation managers and other institutions outside the zoo and aquarium community to easily import and analyze their pedigree data.
We developed tools and methodologies for pedigree analysis to better manage group‐living species and populations that are usually kept in groups. Such analyses of the pedigree of groups can improve the management of group‐living species in ex situ breeding programs.
Abstract
A review is given on several sensory systems that enable troglophile and troglobian urodele species to orient non-visually in their extreme hypogean habitat. A new sense was discovered ...allowing the animals to orient according to the Earth's magnetic field, which could serve as a basic and always available reference for general spatial orientation. Moreover, working with permanent magnetic field stimuli offers a very sensitive experimental method to discover the urodeles' thresholds for other sensory modalities such as light, sounds, and other stimuli, perhaps in competition or combination with the magnetic one. Proteus' audition as underwater hearing and light sensitivity due to its partly remaining sensory cells and/or skin sensitivity were studied. Excellent underwater hearing abilities had been demonstrated for Proteus with an acoustic behavioural method. The ability of sound pressure registration in Proteus is supposed to be attained by the tight anatomical junction between the ceiling of the oral cavity and the oval window. More generally, all non-visual sensory capabilities may facilitate certain behavioral strategies, compensating for missing visual orientation. Troglobians are more likely than others to own and regularly use the sensorial opportunities of a magnetic sense for spatial orientation. Compared to their epigean relatives, cave animals may have retained phylogenetically older sensorial properties, transformed or improved them, or finally acquired new ones which enabled them to successfully survive in dark habitats. Neighbor populations living on surface did not necessarily take advantage of these highly evolved sensory systems and orientation strategies of the troglobian species and may have lost them. E.g. Desmognathus ochrophaeus is partly adapted to cave life and exhibits good magnetic sensitivity, whereas, D. monticula and D. quadrimaculatus are epigean and, although living in rather dark places, did not demonstrate magnetic sensitivity when tested with our method.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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