Genetic evidence of human mediated,historical seed transfer from the Tyrolean Alps to the Romanian Carpathians in <Emphasis Type="Italic">Larix decidua</Emphasis> (Mill.) forests

Key message

Historic transfer of larch from Alpine sources to Southern and Eastern Carpathians has been verified by means of nuclear genetic markers. Tyrolean populations can be differentiated into a north-western and south-eastern group, while Romanian populations are separated according to the Southern and Eastern Carpathians. Low-level introgression from Alpine sources is found in autochthonous Carpathian populations.

Context

Large scale human mediated transfer of forest reproductive material may have strongly modified the gene pool of European forests. Particularly in European larch, large quantities of seeds from Central Europe were used for plantations in Southern and Eastern Europe starting in the mid nineteenth century.

Aims

Our main objective was to provide DNA marker based evidence for the anthropogenic transfer of Alpine larch reproductive material to native Carpathian populations.

Methods

We studied and compared 12 populations (N?=?771) of Larix decidua in the Alps (Austria, Italy) and in the Southern and Eastern Carpathians (Romania) using 13 microsatellites.

Results

High genetic diversity (H_e?=?0.752; R_S?=?9.4) and a moderate genetic differentiation (F_ST?=?0.13; G′_ST?=?0.28) among populations were found; Alpine and Carpathian populations were clearly separated by clustering methods. A Tyrolean origin of plant material was evident for one out of four adult Romanian populations. In the transferred population, a genetic influence from Carpathian sources was found neither in adults nor in juveniles, while the natural regeneration of two Romanian populations was genetically affected by Alpine sources to a minor degree (2.2 and 2.9% allochthonous individuals according to GeneClass and Structure, respectively).

Conclusion

Tracing back of plant transfer by means of genetic tools is straightforward, and we propose further studies to investigate gene flow between natural and transferred populations.

     

How representatively can we sample soil mineral nitrogen?

Spatial distribution of soil mineral‐N content (N_min) is a scale‐variant process. Precision farming assumes knowledge about the spatial distribution of N_min. Moreover, sampling in management zones is based on the assumption of spatial dependence between sampling points. In the present study, variability structure of N_min and the sources of variability were investigated. Within an agricultural landscape, N_min was investigated across a field in a nested design over four consecutive years. Temporally unstable structure of individual nests require a sampling with several nests in the field. In the investigated field, 35%–49% of the total variability derived from small‐scale variability observed at spatial distances of <5 m and from sampling and analytical errors. Differences between 10 and 26 kg N ha^–1 for the soil depth increment 0–60 cm can be expected. Uncertainty due to analytical errors were in the order of 5–10 kg N ha^–1 for a 0–60 cm layer.     

Solute transport in aggregated porous media: Comparing model independent and dependent parameter estimation

In many studies on solute transport soil column experiments arc used to obtain the transport characteristics for Convection-Dispersion-Models. Early breakthrough of the solute pulse has been attributed to a non-equilibrium in phase exchange. It is a standard procedure to determine several model parameter values from such breakthrough curves (BTC). This investigation is focused on the physical significance of simultaneously fitted parameter values used in the convection and diffusion-controlled mass transfer model (mobile — immobile phase concept). Saturated column experiments were conducted with solid phases consisting of porous and solid glass beads. One set of model parameter values was obtained from the breakthrough curves by simultaneous optimization and a second set was determined by independent measurements of individual parameter values. Both sets of parameter values described the BTCs equally well but deviated substantially from each other. These discrepancies were analysed in terms of local parameter sensitivities.     

III. Buchbesprechungen

Ohne Zusammenfassung     

Diatom derived polyunsaturated aldehydes do not structure the planktonic microbial community in a mesocosm study

Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.     

The role of sand lances (Ammodytes sp.) in the Northwest Atlantic Ecosystem: A synthesis of current knowledge with implications for conservation and management

The American sand lance (Ammodytes americanus, Ammodytidae) and the Northern sand lance (A. dubius, Ammodytidae) are small forage fishes that play an important functional role in the Northwest Atlantic Ocean (NWA). The NWA is a highly dynamic ecosystem currently facing increased risks from climate change, fishing and energy development. We need a better understanding of the biology, population dynamics and ecosystem role of Ammodytes to inform relevant management, climate adaptation and conservation efforts. To meet this need, we synthesized available data on the (a) life history, behaviour and distribution; (b) trophic ecology; (c) threats and vulnerabilities; and (d) ecosystem services role of Ammodytes in the NWA. Overall, 72 regional predators including 45 species of fishes, two squids, 16 seabirds and nine marine mammals were found to consume Ammodytes. Priority research needs identified during this effort include basic information on the patterns and drivers in abundance and distribution of Ammodytes, improved assessments of reproductive biology schedules and investigations of regional sensitivity and resilience to climate change, fishing and habitat disturbance. Food web studies are also needed to evaluate trophic linkages and to assess the consequences of inconsistent zooplankton prey and predator fields on energy flow within the NWA ecosystem. Synthesis results represent the first comprehensive assessment of Ammodytes in the NWA and are intended to inform new research and support regional ecosystem‐based management approaches.     

Local Labor Market Adjustment to Immigration: The Roles of Participation and the Short Run

ABSTRACT While previous research has generally found that immigration raises unemployment for natives, effects are often more muted than expected. Anticipated out‐migration responses have been similarly difficult to discern. However, these findings may be byproducts of the long‐run nature of most inquiries, which furthermore do not account for changes in natives’ labor force participation. In response, this study evaluates the impact of the arrival of low‐skilled immigrants on low‐skilled natives in urban areas over a five year period. Initial static results from the Census Basic Monthly Survey clearly indicate that immigrants have a significant negative impact on natives’ labor force participation. Building upon these static panel results, characteristics of immigrants’ destination choices are examined along with the ensuing adjustment process through dynamic analyses of local markets. Surges of immigrants significantly reduce the labor force participation of low‐skilled natives, emphasizing this often neglected channel for labor market adjustment. Previous work may thus understate the true impact of immigrants on local labor markets by focusing on the longer term and ignoring adjustments through participation.