Microbial nitrogen and phosphorus co-limitation across permafrost region

The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long-term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large-scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co-limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming-induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.     

Ontogenetic change in effectiveness of chemical defence against different predators in Oxycarenus true bugs

Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators.     

Decomposing trends in bird populations: Climate,life histories and habitat affect different aspects of population change

Aim

Despite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.

Location

Czech Republic.

Methods

We used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.

Results

The first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump-shaped and U-shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump-shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.

Main Conclusion

Although habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non-trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.     

Incidence and genetic diversity of raspberry bushy dwarf virus (RBDV) in Rubus spp. in Turkey

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy.     

Annotated chromosome numbers of selected asiaticPotentilla species

Chromosome numbers are reported for 19 collections representing 16 AsiaticPotentilla taxa. The first chromosome records are reported forP. desertorum Bunge var.arnavatensis Wolf (2n=28),P. festiva Soják (2n=28),P. griffithii Hook f. subsp.beauvaisii (Cardot) Soják (2n=42),P. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják (2n=14),P. mollissima Lehm. (2n=28),P. moorcroftii Wall. exLehm. (2n=42),P. multicaulis Bunge (2n=14),P. [x]omissa Soják (2n=35, 56, 70) andP. stanjukoviczii Ovcz. exKoczk. (2n=14). Counts differing from those previously recorded are given forP. algida Soják (2n=56) andP. flagellaris Willd. exSchlecht. (2n=42). Chromosome numbers of the following species were confirmed:P. [x]agrimonioides Bieb. (2n=42),P. chinensis Ser. in DC. (2n=14),P. fragarioides L. (2n=14),P. lineata Trev. (2n=14) andP. sericea L. (2n=28). Taxonomy is briefly discussed. A new combinationP. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják stat. nov. is proposed.     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

Population genetic structure,parasite infection and somatic condition of pumpkinseed Lepomis gibbosus (Actinopterygii: Centrarchidae) in the Oder river basin

In Poland, distribution of non-native pumpkinseed Lepomis gibbosus (Centrarchidae) is strictly limited to the Oder river basin, where it was introduced in the early 20th century. Recently, several populations have been found in waterbodies adjacent to the Oder, particularly in its lower reaches. In this study, we compare the genetic relatedness of populations in the Oder basin with other European populations using nuclear (microsatellite) and mitochondrial (partial cytochrome c oxidase subunit I; cox1) markers. Microsatellite analysis indicated that four populations in the lower Oder form a separate cluster, while one in the middle Oder clustered with Danubian populations, from where probably having been introduced. Microsatellite data suggested that the lower Oder populations differ from other non-native European populations, making it impossible to estimate the source of introduction. Nevertheless, analysis of cox1 indicated that Oder pumpkinseeds belong to the same haplotype as the vast majority of European populations. Parasitological examination confirmed the presence of two North American species, the monogenean Onchocleidus dispar and trematode Posthodiplostomum centrarchi, in the lower Oder, both previously unknown in the region. Fifteen other parasite species were acquired, including glochidia of invasive Sinanodonta woodiana. In the middle Oder, parasite infection was more limited. Fish from the Gryfino Canal, considered one of the most invasive populations in Europe, showed the highest parasite abundance and diversity, and the highest somatic condition and growth rate due to warm water released from the Dolna Odra power plant. Our results highlight significant differences in somatic condition and parasite infection in long-established non-native pumpkinseed populations in the same river system, reflecting mainly environmental conditions.     

The effect of deoxycholate on yeast cell permeability

1. (1)
   Мембраны ненарушенных клеток дрожжей непроницаемы для солей янтарной кислоты и феррицианида, так что в их суспензии не наблюдается сукцинодегидрогеназы с феррикианидом как акцептором электронов.     

Effect of small doses of X-rays on formation of colour variants bySerratia marcescens

1. (1)
   Клетки Serratia marcescens, которые выжили после повторных облучений лучами Х, при новй однокртном облучении процент цветных мутантов. Процент мутаций возрастает в зависимости от дозы облучения ночти линейно.