Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: Gongolaria barbata (Sargassaceae, Fucales) is a widespread species for which several infraspecific taxa have been described, indicating its polymorphism. This study contributes to the understanding of the molecular, nomenclatural, morphological and ecological aspects of G. barbata in the Mediterranean and sheds light on the infraspecific diversity and its implications for the taxonomy of this species. Molecular analyses were performed using sequencing of the mitochondrial cox1 gene on both haptophytic and pleustophytic forms from different sites in the Adriatic and Tyrrhenian Seas. Vegetative and reproductive morphology was studied on thalli samples from the Adriatic. Our results showed that there are different morphotypes within G. barbata populations related to specific environmental conditions, suggesting infraspecific variation. In contrast, molecular analyses showed no differences between samples, regardless of whether individuals are growing “attached” to a substrate or “unattached”. We also discussed the taxonomic status and nomenclatural issues related to certain infraspecific taxa previously proposed for G. barbata. In particular, the confusion surrounding Cystoseira aurantia is clarified.
Ključne besede: ecotypes, taxonomy, Northern Adriatic, Cystoseira s.l.
Objavljeno v DiRROS: 16.05.2024; Ogledov: 18; Prenosov: 3
Datoteka (218,75 KB)

Povzetek: Vascular plant species (VP) and bryophytes (B) constitute a significant portion of forest biodiversity and respond to both management intensity and natural disturbances within forests. In this study, we investigated the cross-taxa congruence between understorey VP and B at both diversity and composition levels across a wide range of sustainably managed forests in Slovenia. The taxonomic and functional characteristics of the selected plant groups were studied, with a particular emphasis on ground-dwelling species. We employed a trait-based approach to examine the functional characteristics. On average, the species richness of B in sustainably managed temperate forests increased with the corresponding number of VP. Furthermore, a moderate positive correlation in species composition between the studied groups of ground-dwelling organisms was also observed. The ground-dwelling VP and B were congruent in terms of trait-based composition, which was influenced by soil reaction and nutrients and light availability, while trait-based diversity was only slightly similar in response to moisture. A negative correlation between the composition of stress-tolerant VP and B hemeroby was found, indicating forest environments with a low level of disturbance. This is likely due to the sustainable management of Slovenian forests, where climate change and natural disturbances have intensified in recent years. A cross-taxon comparison of the two groups at four different levels, namely taxonomic-based diversity and composition and trait-based diversity and composition, revealed varying degrees of congruence. It is therefore important to monitor the status and temporal trends of both groups from different aspects to draw reliable conclusions.
Ključne besede: understory, mosses, terricolous species, diversity, composition, taxonomy, life-history traits, environmental gradients, managed forest, ICP Forests program, Slovenia
Objavljeno v DiRROS: 10.10.2023; Ogledov: 508; Prenosov: 183
Celotno besedilo (2,04 MB)
Gradivo ima več datotek! Več...

Povzetek: Only very recently, has it been proposed that the hitherto existing Mycobacteriumkansasii subtypes (I–VI) should be elevated, each, to a species rank. Consequently, the former M. kansasii subtypes have been denominated as Mycobacterium kansasii (former type I), Mycobacterium persicum (II), Mycobacterium pseudokansasii (III), Mycobacterium innocens (V), and Mycobacterium attenuatum (VI). The present work extends the recently published findings by using a three-pronged computational strategy, based on the alignment fraction-average nucleotide identity, genome-to-genome distance, and core-genome phylogeny, yet essentially independent and much larger sample, and thus delivers a more refined and complete picture of the M. kansasii complex. Furthermore, five canonical taxonomic markers were used, i.e., 16S rRNA, hsp65, rpoB, and tuf genes, as well as the 16S-23S rRNA intergenic spacer region (ITS). The three major methods produced highly concordant results, corroborating the view that each M. kansasii subtype does represent a distinct species. This work not only consolidates the position of five of the currently erected species, but also provides a description of the sixth one, i.e., Mycobacterium ostraviense sp. nov. to replace the former subtype IV. By showing a close genetic relatedness, amonophyletic origin, and overlapping phenotypes, our findings support the recognition of the M. kansasii complex (MKC), accommodating all M. kansasii-derived species and Mycobacterium gastri. None of the most commonly used taxonomic markers was shown to accurately distinguish all the MKC species. Likewise, no species-specific phenotypic characteristics were found allowing for species differentiation within the complex, except the non-photochromogenicity of M. gastri. To distinguish, most reliably, between the MKC species, and between M. kansasii and M. persicum in particular, whole-genome-based approaches should be applied. In the absence of clear differences in the distribution of the virulence-associated region of difference 1 genes among the M. kansasii-derived species, the pathogenic potential of each of these species can only be speculatively assessed based on their prevalence among the clinically relevant population. Large-scale molecular epidemiological studies are needed to provide a better understanding of the clinical significance and pathobiology of the MKC species. The results of the in vitro drug susceptibility profiling emphasize the priority of rifampicin administration in the treatment of MKC-induced infections, while undermining the use of ethambutol, due to a high resistance to this drug.
Ključne besede: Mycobacteriumkansasii complex, Mycobacteriumostraviense sp. nov., non-tuberculous mycobacteria (NTM), whole genome sequencing, taxonomy
Objavljeno v DiRROS: 31.07.2020; Ogledov: 1930; Prenosov: 1359
Celotno besedilo (10,22 MB)
Gradivo ima več datotek! Več...