Recent studies indicate that morphologically cryptic species may be ecologically more different than would be predicted from their morphological similarity and phylogenetic relatedness. However, in biodiversity research it often remains unclear whether cryptic species should be treated as ecologically equivalent, or whether detected differences have ecological significance. In this study, we assessed the ecological equivalence of four morphologically cryptic species of the amphipod genus Niphargus. All species live in a small, isolated area on the Istrian Peninsula in the NW Balkans. The distributional ranges of the species are partially overlapping and all species are living in springs. We reconstructed their ecological niches using morphological traits related to feeding, bioclimatic niche envelope and species’ preference for epi-hypogean habitats. The ecological meaning of differences in niches was evaluated using distributional data and co-occurrence frequencies. We show that the species comprise two pairs of sister species. All species differ from each other and the degree of differentiation is not related to phylogenetic relatedness. Moreover, low co-occurrence frequencies in sympatric zones imply present or past interspecific competition. This pattern suggests that species are not differentiated enough to reduce interspecific competition, nor ecologically equivalent to co-exist via neutral dynamics. We tentatively conclude that the question of ecological equivalence relates to the scale of the study: at a fine scale, species’ differences may influence dynamics in a local community, whereas at the regional level these species likely play roughly similar ecological roles.
COBISS.SI-ID: 3541071
The hindgut and foregut in crustaceans are lined by a cuticular matrix, secreted apically by epithelial cells. In this study the ultrastructure of hindgut apical matrices and cuticle in the selected embryonic and larval stages from the marsupium of the terrestrial isopod Porcellio scaber was described and compared to hindgut cuticle in adults to obtain data on the hindgut cuticular lining differentiation. Our results show that in late embryos of stages 16 and 18 the apical matrix in the hindgut ultrastructurally resembles the embryonic epidermal matrices described in several arthropods, suggesting a common principle in chitinous matrix differentiation. The hindgut matrix in the prehatching embryo of stage 19 shows characteristics of the hindgut cuticle, such as alignment to the apical epithelial surface and a prominent electron dense layer of epicuticle. In the preceding embryonic stage - stage 18 - an electron dense lamina, closely aposed to the apical cell membrane, is evident and is considered as the first epicuticle formation. In marsupial larvae mancae the advanced features of the hindgut cuticle and epithelium are evident: a more prominent epicuticular layer, formation of cuticular spines and an extensive apical labyrinth. In comparison to the hindgut cuticle of adults, the hindgut cuticle of marsupial manca is much thinner and the cuticle architecture in different anatomic regions of hindgut is not fully specified. These differences imply not fully developed structure and function of the hindgut cuticle in marsupial manca, possibly related also to different environments, as mancae develop in marsupial fluid.
COBISS.SI-ID: 3531855
The crucial question in the field of nanotoxicology is whether nanoparticles can induce a »particle-specific« induced effect on organisms that is distinct from those induced by metal ions. Current literature shows little evidence to confirm this hypothesis, but points out that the effects are governed by ions only. The main reason for this lies in the experimental approches used so far which mainly do not enable to detect the cellular changes at very low exposure doses. In the current work we have applied a Fourier-Transform InfraRed Microscopy (FTIRM) to perform a biomolecular profilling on the crustacean (Porcellio scaber) digestive glands exposed to ZnO NPs or ZnCl2. The activation of novel metabolic pathways, as evidenced by changed proteins’ structure, was found only in the case of ZnO NPs. This proves that Zn2+ are not the only inducers of the response to ZnO NPs. This study provides the evidence that ZnO NPs induce their own metabolic responses in the subtoxic range. The finding is important for the understanding of the nanomaterials' mechanisms of action on the organisms and to develop the basic concepts of nanosafety.
COBISS.SI-ID: 3553103
Carnolian honey bees, Apis mellifera carnica, are important pollinators, frequently exposed to pesticides. Many pesticides are applied together and there is the potential for heightened toxicity referred as synergism. In the present study the molecular immune response of honey bee workers at different developmental stages (prepupa, white-eyed pupa, adult) orally exposed to the acaricide coumaphos and the fungicide prochloraz individually and in combination were investigated. Expression of 17 immune-related genes was examined by quantitative RT-PCR. In treated prepupae downregulation of most immune-related genes was observed in all treatments, while in adults upregulation of most of the genes was recorded. The negative impacts of prochloraz and a combination of coumaphos and prochloraz on immune system differed among the different developmental stages of honey bees. This study shows for the first time synergistic effects of xenobiotics on the honeybee immune system and represents an important step towards understanding the mechanisms of their interactions.
COBISS.SI-ID: 3642248
Rhabdochlamydia porcellionis is a known intracellular pathogen in digestive glands of the terrestrial isopod crustacean Porcellio scaber. To describe the pathogenesis, tissue distribution and host response to R. porcellionis, we conducted microscopic observations and localization of infection in tissues by Fluorescent In Situ Hybridization (FISH). Digestive glands were confirmed as the primary site of infection. From there, R. porcellionis disseminates either through the apical membrane of infected cells into the lumen of digestive glands and further throughout the digestive tract or into the surrounding hemocoel by rupture of the basal membrane and lamina of infected digestive gland cells. Once in the hemocoel, R. porcellionis infects hindgut cells, hemocytes and hemopoetic tissues while the ventral nerve cord and gonads seem to be devoid of infection despite the presence of rhabdochlamydia on the surface of these organs. The host response to R. porcellionis includes aggregation of hemocytes around the infected cells and formation of multilayered melanized nodules exhibiting endogenous fluorescence. The structure of nodules is asymmetric when hemocytes are deposited on the basal side of infected gut and digestive glands cells, or symmetric, when nodules entrapping clusters of rhabdochlamydiae are deposited on other organs in the hemocoel. The study also revealed a high prevalence of infection in P. scaber populations (up to 27%) and confirmed its detrimental effect on the host. Although agility, behavior and molting cycle of infected animals appear unaffected, in the later stages R. porcellionis infection manifests as severe damage to the digestive system and decreased feeding, which eventually lead to the death of the host organism.
COBISS.SI-ID: 3293775