Native vegetation structure,landscape features and climate shape non-native plant richness and cover in New Zealand native shrublands

Aim

Studies investigating the determinants of plant invasions rarely examine multiple factors and often only focus on the role played by native plant species richness. By contrast, we explored how vegetation structure, landscape features and climate shape non-native plant invasions across New Zealand in mānuka and kānuka shrublands.

Location

New Zealand.

Method

We based our analysis on 247 permanent 20 × 20-m plots distributed across New Zealand surveyed between 2009 and 2014. We calculated native plant species richness and cumulative cover at ground, understorey and canopy tiers. We examined non-native species richness and mean species ground cover in relation to vegetation structure (native richness and cumulative cover), landscape features (proportion of adjacent anthropogenic land cover, distance to nearest road or river) and climate. We used generalized additive models (GAM) to assess which variables had greatest importance in determining non-native richness and mean ground cover and whether these variables had a similar effect on native species in the ground tier.

Results

A positive relationship between native and non-native plant species richness was not due to their similar responses to the variables examined in this study. Higher native canopy richness resulted in lower non-native richness and mean ground cover, whereas higher native ground richness was associated with higher native canopy richness. Non-native richness and mean ground cover increased with the proportion of adjacent anthropogenic land cover, whereas for native richness and mean ground cover, this relationship was negative. Non-native richness increased in drier areas, while native richness was more influenced by temperature.

Main Conclusions

Adjacent anthropogenic land cover seems to not only facilitate non-native species arrival by being a source of propagules but also aids their establishment as a result of fragmentation. Our results highlight the importance of examining both cover and richness in different vegetation tiers to better understand non-native plant invasions.     

Genetic variation in the Italian crested newt, Triturus carnifex, and the origin of a non-native population north of the Alps

Genetic variation over 40 protein loci and 46 populations representing three taxa of crested newts revealed moderate genetic distances between Triturus carnifex carnifex, T. c. macedonicus and T. cristatus. Two populations from the Geneva Basin (presumed to be introduced) were genetically similar to T. c. carnifex and dissimilar to T. c. macedonicus and T. cristatus, showing that they belong to T. c. carnifex and not to native T. cristatus. A significant pattern of spatial genetic variation was found within T. c. carnifex along a north to south axis, from Croatia to Calabria. The Genevan populations showed highest genetic similarity with T. carnifex from Tuscany, suggesting that the propagule originated from that area. Effects of a population genetic bottleneck associated with the introduction could not be documented. The observed high allelic variation in Genevan T. c. carnifex could not be directly explained by introgression from T. cristatus. Comparisons across the range, including zones of hybridization within the T. cristatus superspecies, indicated that some alleles typical for the Genevan population may represent the so-called `hybrizymes'.     

Wetland restoration in Central Europe: aims and methods

Abstract. Wetlands have always been of particular significance for mankind. While originally attractive as hunting grounds, they were later cultivated and modified from sinks into sources. Today, great efforts are being made to restore disturbed or destroyed wetland areas. Different models and goals for wetland restoration exist. From a global point of view, reduction of climatically relevant trace gas emissions is relevant, especially in the case of fens. Regionally and locally, the creation of retention basins for water and compounds or the establishment of characteristic fen species and communities may have high priority. In order to avoid goal conflicts, nature development plans are required which consider not just the wetland to be restored, but the entire catchment area. Such plans should include spatially and temporally differentiated recommendations for implementation of restoration measures and a proper land use system. When it comes to defining concrete aims, the participation of local people should be encouraged. Rewetting and oligotrophication are the most common approaches to boost biodiversity in fen ecosystems in Central and Western Europe. Rewetting includes both quantitative and qualitative aspects, requiring quantitative hydrological models and chemical analyses of the groundwater in the region. In addition, re-introduction of species is often necessary, at least in heavily fragmented cultural landscapes. Transfer of hay from donor areas to severely damaged, seed-depleted peatland to restore fen meadows, was successful. However, despite short-term successes, complete restoration of wetland areas requires a long period of time.     

The potato in Spain during the late 16th century

A study is presented of the Hospital de la Sangre account books in Seville at the Archivo Hispalense for the period 1546 to 1601, to verify purchases of potatoes (Solanum tuberosum) during that period. Potatoes were bought regularly in the Seville market from 1580 onwards, with the first record appearing in 1573 thus agreeing with Salaman’s conclusion that potatoes became established in Spain by about 1570. Purchases were confined almost entirely to December and January each year, lending weight to the hypothesis that these were short day adaptedS. tuberosum ssp.andigena, actually grown in Spain and forming tubers in the short days at the end of the year. If potatoes had been imported for direct consumption from South America shipping records indicate that they could have arrived in Seville at all times of the year. A listing of other fruits and vegetables bought in the Seville market shows a wide range of mostly mediterranean crops with some of Near Eastern origin and certain spices imported through Lisbon from the Ear East. Surprisingly, very few New World crops are mentioned.     

A preliminary phylogenetic analysis of ribbed-pine-borer (Rhagium inquisitor) based on mitochondrial COI sequences

The increased volume of intercontinental-trade had facilitated the distribution of species, including invaders. Wooden packaging materials, goods and timber are being transported via international ports in East of the Marmara Basin, where has vast forests. That forests provide an appropriate-mediator for the introduction and invasion of wood-boring insects, which are the most common group being transported between continents. One of them is Rhagium inquisitor, which has a pivotal role in wood decay, nevertheless, it is detrimental for industrial wood.We analyzed the 654 bp length of cytochrome c oxidase I (COI) gene, to determine native and introduced haplotypes of the ribbed-pine-borer, to investigate their phylogenetic relationships and possibly cryptic speciation of the morphospecies.It was found out that sixteen haplotypes were divided into five haplogroups. The groups were assembled on two main lineages: Eurasian and American. The genetic distance between the American (Groups 1–3), Asian (Group-4) and European (Group-5) clusters ranged from 3 to 10%; between haplotypes ranged from 0.2 to 10.9%. The distances between the specimens of the Marmara Basin (H9-12, Group-4) were lower compared to H16, which nested in Group-5. That haplotype was sampled on imported timber and was found out that it is shared between France, Germany, Italy, and Austria. Maximum Likelihood, Neighbor-Joining and Bayesian Inference trees showed the same topologies, and Median-Joining network also supported them.Contrary to the usual, our findings point out that some species might have been introduced from Europe to Asia. Furthermore, the high genetic diversity of the bark-runner between continents could be a sign of cryptic-allopatric speciation.     

Deduced RNA binding mechanism of ThiI based on structural and binding analyses of a minimal RNA ligand

ThiI catalyzes the thio-introduction reaction to tRNA, and a truncated tRNA consisting of 39 nucleotides, TPHE39A, is the minimal RNA substrate for modification by ThiI from Escherichia coli. To examine the molecular basis of the tRNA recognition by ThiI, we have solved the crystal structure of TPHE39A, which showed that base pairs in the T-stem were almost completely disrupted, although those in the acceptor-stem were preserved. Gel shift assays and isothermal titration calorimetry experiments showed that ThiI can efficiently bind with not only tRNA^Phe but also TPHE39A. Binding assays using truncated ThiI, i.e., N- and C-terminal domains of ThiI, showed that the N-domain can bind with both tRNA^Phe and TPHE39A, whereas the C-domain cannot. These results indicated that the N-domain of ThiI recognizes the acceptor-stem region. Thermodynamic analysis indicated that the C-domain also affects RNA binding by its enthalpically favorable, but entropically unfavorable, contribution. In addition, circular dichroism spectra showed that the C-domain induced a conformation change in tRNA^Phe. Based on these results, a possible RNA binding mechanism of ThiI in which the N-terminal domain recognizes the acceptor-stem region and the C-terminal region causes a conformational change of RNA is proposed.