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Abstract: Historical biogeography is an integrative scientific field critical for testing evolutionary hypotheses pertinent to organismal distributions, but despite recent theoretical and analytical advances, biogeographic reconstructions continue to struggle with accuracy and rigor. Most modern studies include the three elements needed for historical biogeographic inference, namely a time-calibrated phylogeny, contemporary taxonomic distributions, and estimations of organismal dispersal probabilities. The latter, we argue, are particularly vague, and historical biogeography would greatly benefit from dispersal probability estimations that are better informed and biologically meaningful. To achieve that goal, next-generation biogeography should ideally consider: a) dispersal-related traits; b) ecology; c) geological histories; and d) geographical factors. We briefly recap the three case studies on spiders that have pioneered this approach. Due to their old age and mega-diversity—considering both phylogenetic and life style diversity—arachnids are an ideal animal lineage for modern biogeographic research. There is no reason, however, that the concept should not be applied to all life. Further modifications of the proposed concept and, particularly, methodological implementation are needed to render this biogeographic framework widely useful.
Keywords: next-generation biogeography, ancestral areas, dispersal biology, geological history, vicariance, extinction, arachnids
Published in DiRROS: 18.07.2024; Views: 345; Downloads: 161
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Abstract: The assemblages of marine benthic organisms and sediment characteristics were investigated in the coastal area between the Mario Zucchelli Antarctic Research Station and Adelie Cove in Terra Nova Bay (Ross Sea, Southern Ocean) during the 2015 summer season. Sediment samples were taken from 11 stations at depths between 25 and 140 m. The dominance of sand characterised sites, and the biochemical composition of the sedimentary organic matter resulted in very variable between the different sites. A total of 142 taxa were identified, with Annelida (68 taxa) and Arthropoda (35 taxa) constituting the main macrobenthic groups. The benthic community at deeper stations showed higher species richness and lower dominance compared to the shallower stations. For the first time in Antarctica, we also investigated the response of the AZTI’s Marine Biotic Index (AMBI) to the organic gradient. Of the 142 taxa found, 97 were not listed in the AMBI library, and we were able to assign as many as 88 taxa to an ecological group. All of these new species were added to the new AMBI species list. AMBI showed a good response to the organic gradient.
Keywords: antarctic benthos, ecological quality assessment, indexes, Ross Sea
Published in DiRROS: 18.07.2024; Views: 376; Downloads: 264
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Abstract: This perspective identifies the grand challenges in arachnid science: 1. Grasp the arachnid species diversity. There is a need to accelerate taxonomic research to obtain a sense of arachnid species diversity, however, at the same time, taxonomy needs to increase its quality, rigor, and repeatability. 2. Standardize arachnid systematics research. A solid phylogenetic definition and morphological diagnosis of Arachnida and its composing subgroups, usually treated at the rank of order, are needed. Studies should aim to stabilize and standardize phylogenetic efforts at all levels of hierarchy, and systematists should adopt criteria for higher level ranks in arachnid classification. 3. Interpret arachnid trait evolution through omics approaches. Among the field’s grand challenges is to define the genetic diversity encoding for the diverse arachnid traits, including developmental, morphological and ecological characteristics, biomaterials such as silks, venoms, digestive fluids, or allergens and bioproducts that cause diseases. Comparative genomics, transcriptomics, and proteomics will provide the empirical basis for biotechnology to modify arachnid genomes to fit numerous applications. 4. Facilitate biotechnological applications of arachnid molecules and biomaterials. Among the grand field challenges is to define potential applications of arachnid bioproducts from therapeutics to industry. New natural and biodegradable products, e.g. from spider silks, should ease our burden on ecosystems. 5. Utilize arachnids as models in ecological and biogeographic research. Biodiversity inventory sampling and analytical techniques should be extended from spiders to other arachnid groups. Spiders and their webs could be used as environmental DNA samplers, measuring or monitoring ecosystems’ overall biodiversity. Arachnids are excellent models to address biogeographical questions at the global to local scales. 6. Disentangle evolutionary drivers of arachnid diversity. Among the field grand challenges is a more precise evaluation to what extent the emergence of arachnid phenotypes is shaped by classical selection processes, and under what conditions, if any, sexual conflict needs to be invoked. 7. Define effective conservation measures for arachnids in the light of global changes. Effective conservation measures in arachnology should integrate the data from phylogenetic diversity, physiology, ecology, biogeography, and global change biology.
Keywords: diversity, systematics, arachnids, evolution, biomaterials
Published in DiRROS: 18.07.2024; Views: 343; Downloads: 162
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Abstract: In recent years, Lake Constance has experienced an invasion and domination of three-spined stickleback (Gasterosteus aculeatus) in the pelagic zone, which has coincided with a decline in the native whitefish (Coregonus wartmanni) population. Similar massive invasions of sticklebacks into pelagic zones have been recognized also in marine areas or small lakes worldwide. However, their diet overlaps with native species is rarely evaluated, especially in the winter season, which often presents a bottleneck for fish survival. In this study, we compared the diet of pelagic sticklebacks with the diet of the substantially larger native whitefish in different seasons, to evaluate the threat of the recent stickleback invasion on whitefish populations. By monthly sampling of zooplankton and both fish species diets, we could demonstrate that sticklebacks select similar prey throughout most of the year and consume more prey than whitefish during the winter. With relations between prey availability and prey selection, interspecific and intraspecific seasonal diet variability and indices like a prey-specific index of relative importance, we discuss the importance of zooplankton species traits and abundance for whitefish and stickleback predation. This study shows that sticklebacks, despite their small size, represent a serious potential diet competitor to native planktivorous fish. Sticklebacks quickly adapt to new environments, and thus we advocate precautions regarding their introduction into similar lakes as Lake Constance, as this could cause irreversible ecological changes.
Keywords: Bythotrephes longimanus, Lake Constance, overwintering strategy, pelagic whitefish diet, planktivory, predator size, seasonal prey selection, stickleback invasion
Published in DiRROS: 18.07.2024; Views: 438; Downloads: 252
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Abstract: Glioblastoma (GBM) is one of the most aggressive cancers, comprising 60–70% of all gliomas. The large G-protein-coupled receptor family includes cannabinoid receptors CB1, CB2, GPR55, and non-specific ion receptor protein transporters TRPs. First, we found up-regulated CNR1, GPR55, and TRPV1 expression in glioma patient-derived tissue samples and cell lines compared with non-malignant brain samples. CNR1 and GPR55 did not correlate with glioma grade, whereas TRPV1 negatively correlated with grade and positively correlated with longer overall survival. This suggests a tumour-suppressor role of TRPV1. With respect to markers of GBM stem cells, preferred targets of therapy, TRPV1 and GPR55, but not CNR1, strongly correlated with different sets of stemness gene markers: NOTCH, OLIG2, CD9, TRIM28, and TUFM and CD15, SOX2, OCT4, and ID1, respectively. This is in line with the higher expression of TRPV1 and GPR55 genes in GSCs compared with differentiated GBM cells. Second, in a panel of patient-derived GSCs, we found that CBG and CBD exhibited the highest cytotoxicity at a molar ratio of 3:1. We suggest that this mixture should be tested in experimental animals and clinical studies, in which currently used Δ9-tetrahydrocannabinol (THC) is replaced with efficient and non-psychoactive CBG in adjuvant standard-of-care therapy.
Keywords: glioblastoma, glioma, cannabigerol, cannabidiol, cannabinoid receptors, stem cells
Published in DiRROS: 18.07.2024; Views: 365; Downloads: 220
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