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1.
Starvation hardiness as preadaptation for life in subterranean habitats
Peter Kozel, Tone Novak, Franc Janžekovič, Saška Lipovšek Delakorda, 2023, original scientific article

Abstract: Most subterranean habitats, especially caves, are considered extreme environments, mainly because of the limited and erratic food supply and constant darkness. In temperate regions, many climatic conditions, such as temperature and air humidity, are periodically less adverse or even more favourable in caves than the harsh seasonal weather on the surface. Accordingly, many animal species search for hibernacula in caves. These overwintering, non-specialized subterranean species (nontroglobionts) show various modes of dormancy and ongoing development. Since they do not feed, they all undergo periodic starvation, a preadaptation, which might evolve in permanent starvation hardiness, such as found in most specialized subterranean species (troglobionts). To this end, we performed a comparative analysis of energy-supplying compounds in eleven most common terrestrial non-troglobiont species during winter in central European caves. We found highly heterogeneous responses to starvation, which are rather consistent with the degree of energetic adaptation to the habitat than to overwintering mode. The consumption of energy-supplying compounds was strongly higher taxa-dependant; glycogen is the main energy store in gastropods, lipids in insects, and arachnids rely on both reserve compounds. We assume that permanent starvation hardiness in specialized subterranean species might evolved in many different ways as shown in this study.
Keywords: subterranean habitats, caves, starvation hardiness
Published in DKUM: 08.12.2023; Views: 209; Downloads: 19
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2.
Mitigating the conflict between pitfall-trap sampling and conservation of terrestrial subterranean communities in caves
Peter Kozel, Tanja Pipan, Nina Šajna, Slavko Polak, Tone Novak, 2017, original scientific article

Abstract: Subterranean habitats are known for their rich endemic fauna and high vulnerability to disturbance. Many methods and techniques are used to sample the biodiversity of terrestrial invertebrate fauna in caves, among which pitfall trapping remains one of the most frequently used and effective ones. However, this method has turned out to be harmful to subterranean communities if applied inappropriately. Traditionally, pitfall traps have been placed in caves solely on the ground. Here we present an optimized technique of pitfall trapping to achieve a balance between sampling completeness and minimal disturbance of the fauna in the cave. Monthly we placed traps for two days in two parallel sets, a ground trap and an upper one−just below the ceiling−along the cave. In the upper set, about 10% additional species were recorded compared to the ground set. Greater species diversity in the cave was the consequence of both the increased sampling effort and the amplified heterogeneity of sampled microhabitats. In caves sampled by traditional pitfall trapping, overlooked species may be a consequence of methodological biases, leading to lower biodiversity estimates. In our research, incidence-based estimations mostly surpassed abundance-based ones and predicted 95% coverage of the species richness within about two years of sampling. The sampling used contributes at the same time to both the more effective and less invasive inventory of the subterranean fauna. Thus, it may serve as an optional sampling to achieve optimal balance between required data for biodiversity and ecological studies, and nature conservation goals.
Keywords: biodiversity estimators, microhabitats, sampling effort, sampling techniques, biological inventories
Published in DKUM: 30.10.2017; Views: 1201; Downloads: 384
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3.
Duality of terrestrial subterranean fauna
Tone Novak, Matjaž Perc, Saška Lipovšek Delakorda, Franc Janžekovič, 2012, original scientific article

Abstract: Terrestrial animals in subterranean habitats are often classified according to their degree of morphological or ecological specialization to the subterranean environment. The commonly held view is that, as distance into a cave increases, the frequency of morphologically specialized, i.e., troglomorphic, species or ecological specialization will increase. We tested this hypothesis for the fauna in 54 caves in Slovenia-the classical land for subterranean biology. We found that there exist two ecologically well separated terrestrial subsurface faunas: one shallow and one deep. 1) The shallow subterranean fauna, adapted to the terrestrial shallow subterranean habitats (SSHs) in the upper 10 m of subsurface strata, is most diverse. It consists of randomly distributed non-troglobionts and a major group of troglobionts adapted to the soil root zone. 2) The deep subterranean fauna is represented by a minor group of troglobionts, adapted to caves. Troglobionts are strictly divided between the two faunas. There is strong evidence that in karstic ecosystems with deep-rooted vegetation this might be a global pattern, or that in these locations only the shallow subterranean fauna exist.
Keywords: endemites, superficial subterranean habitats, trogloxenes, troglophiles, troglobionts
Published in DKUM: 04.08.2017; Views: 1266; Downloads: 454
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4.
Cold tolerance in terrestrial invertebrates inhabiting subterranean habitats
Tone Novak, Nina Šajna, Estera Antolinc, Saška Lipovšek Delakorda, Dušan Devetak, Franc Janžekovič, 2014, original scientific article

Abstract: Most organisms are able to survive shorter or longer exposure to sub-zero temperatures. Hypothetically, trogloxenes characterized as not adapted, and troglophiles as not completely adapted to thermally stable subterranean environment, have retained or partially retained their ability to withstand freezing, while most troglobionts have not. We tested this hypothesis experimentally on 37 species inhabiting caves in Slovenia, analyzing their lower lethal temperatures in summer and winter, or for one season, if the species was not present in caves during both seasons. Specimens were exposed for 12 hrs to 1°C-stepwise descending temperatures with 48 hr breaks. In general, the resistance to freezing was in agreement with the hypothesis, decreasing from trogloxenes over troglophiles to troglobionts. However, weak resistance was preserved in nearly all troglobionts, which responded in two ways. One group, withstanding freezing to a limited degree, and increasing freezing tolerance in winter, belong to the troglobionts inhabiting the superficial subterranean habitats. The other group, which equally withstand freezing in summer and winter, inhabit deep subterranean or other thermally buffered subterranean habitats. Data on cold resistance can thus serve as an efficient additional measure of adaptation to particular hypogean environments.
Keywords: endemites, superficial subterranean habitats, trogloxenes, troglophiles, troglobionts
Published in DKUM: 04.08.2017; Views: 1319; Downloads: 358
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5.
Malpighian tubule cells in overwintering cave crickets Troglophilus cavicola (Kollar, 1833) and T. neglectus Krauss, 1879 (Rhaphidophoridae, Ensifera)
Saška Lipovšek Delakorda, Tone Novak, Franc Janžekovič, Nina Weiland, Gerd Leitinger, 2016, original scientific article

Abstract: During winter, cave cricket larvae undergo dormancy in subterranean habitats; this dormancy is termed diapause in second year Troglophilus cavicola larvae because they mature during this time, and termed quiescence in T. neglectus, because they mature after dormancy. Here we used electron microscopy to analyze ultrastructural changes in the epithelial cells in the Malpighian tubules (MTs) of T. cavicola during diapause, in order to compare them with previous findings on T. neglectus. Moreover, the autophagosomes were studied with immunofluorescence microscopy in both species. Although the basic ultrastructure of the cells was similar, specific differences appeared during overwintering. During this natural starvation period, the nucleus, rER, the Golgi apparatus and mitochondria did not show structural changes, and the spherites were exploited. The abundances of autophagic structures in both species increased during overwintering. At the beginning of overwintering, in both species and sexes, the rates of cells with autophagic structures (phagophores, autophagosomes, autolysosomes and residual bodies) were low, while their rates increased gradually towards the end of overwintering. Between sexes, in T. cavicola significant differences were found in the autophagosome abundances in the middle and at the end, and in T. neglectus at the end of overwintering. Females showed higher rates of autophagic cells than males, and these were more abundant in T. cavicola. Thus, autophagic processes in the MT epithelial cells induced by starvation are mostly parallel in diapausing T. cavicola and quiescent T. neglectus, but more intensive in diapausing females.
Keywords: cave cricket, overwintering, Troglophilus cavicola, Troglophilus neglectus
Published in DKUM: 19.06.2017; Views: 1138; Downloads: 366
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6.
Kratki priročnik uspešnega študija : napotki za načrtovanje in ocenjevanje uspešnosti lastnega študija
Tone Novak, Branka Čagran, 2009, other educational material

Abstract: Kratki priročnik uspešnega študija; napotki za načrtovanje in ocenjevanje uspešnosti lastnega študija
Keywords: visoko šolstvo, študij, priročniki
Published in DKUM: 30.12.2015; Views: 898; Downloads: 48
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7.
8.
Contribution of non-troglobiotic terrestrial invertebrates to carbon input in hypogean habitats
Tone Novak, Franc Janžekovič, Saška Lipovšek Delakorda, 2013, original scientific article

Abstract: Eleven of the most important terrestrial invertebrate species in Slovenian caves were analyzed for differences in their fresh and dry biomass, energy content and carbon bulk during winter. These data were combined with the species abundance in 54 caves and adits in order to estimate their organic carbon bulk and carbon input into these habitats. In Central European caves, Troglophilus cavicola, T. neglectus, Faustina illyrica, Amilenus aurantiacus and Scoliopteryx libatrix are the most important vectors of carbon between the epigean and hypogean habitats. In contrast to the general assumption, carbon total contribution to caves via dead bodies is only 0.15% of total migratory biomass, and it is not directly available to troglobionts because of infection with entomopathogenic fungi. In winter, together with predated migratory specimens, carbon input does not exceed 0.3% of the total migratory biomass. This situation should be carefully examined in every karstic region inhabited by distinctive fauna.
Keywords: biomass, carbon flux, caves, non-troglobiotic species, organic carbon, respiration
Published in DKUM: 21.12.2015; Views: 1510; Downloads: 85
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9.
10.
The harvestmen fauna (Arachnida: Opiliones) from the Sub Mediterranean region of Slovenia - II
Tone Novak, 2005, original scientific article

Abstract: In the present paper, further findings of harvestmen in the Sub Mediterranean region of Slovenia are presented, and comments on some actual problems with the species are added. With the exception of the possible discovery of a troglobitic species in the region, all species living there have presumptively been recorded. With the exclusion of Trogulus gr. nepaeformis and T. gr. tricarinatus, where more species are expected, 34 species and one subspecies have been found in the region. About 20 opilionid species are typical of the region; the others occur in the marginal habitats bordering other zoogeographical regions.
Keywords: zoologija, biogeografija, pajkovci, suhe južine, Opiliones, Arachnida, suhe južine, Slovenija, submediteran, zoology, biogeography, Opiliones, arachnids, harvestmen, Slovenia, Sub Mediterranean
Published in DKUM: 10.07.2015; Views: 2006; Downloads: 50
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