Trophic changes,without changes in the external nutrient loading

The impact of the fish population on trophic properties of lake water, was experimentally studied in an oligotrophic Swedish forest lake. Biotic changes following fish removal resulted in a development in oligotrophic direction as shown by the drop in limnetic primary production, pH, total phosphorus, total nitrogen and the increased transparency.     

EVOLUTION OF DIFFERENT GALL TYPES IN WILLOW-FEEDING SAWFLIES (HYMENOPTERA: TENTHREDINIDAE)

The sawflies that feed on the plant family Salicaceae can be divided into eight informal groups based on larval feeding habit or gall type: (1) species with free-living larvae; (2) leaf folders; (3) leaf blade gallers; (4) apical leaf gallers; (5) basal leaf gallers; (6) midrib and petiole gallers; (7) stem gallers; and (8) bud gallers. It has been proposed that the galling habit evolved from free-living larvae via leaf folders, and that the different gall types evolved gradually in the sequence mentioned above. Thus, the galling site would have “wandered” from the leaf margin toward the stem as a result of gradual changes in oviposition site preference. Allozyme data from eight informative loci were used to reconstruct the phylogeny of 18 representative sawfly species. The results suggest that indeed leaf folders seem to be a basal group; leaf blade gallers evolved independently of the other true gallers; apical and basal leaf gallers are not the ancestors of petiole and bud gallers, but they may share a common galling ancestor; bud gallers evolved from midrib/petiole gallers; and stem gallers are polyphyletic. The cause for the observed wandering of the galling site could be intraspecific competition due to a possible “nutrient shading effect” of galls situated closer to the host plant's main vascular system.     

Pollination mechanisms in sixCampanula species (Campanulaceae)

Pollination mechanisms within the genusCampanula were studied. Tests were undertaken to examine whether in vitro culture of pollen grains can serve as a useful tool for understanding the self- and cross-pollination mechanisms among species. Characteristics of pollen germination were interpreted in relation to mating system and floral biology. Four annual species (Campanula kremeri, C. dichotoma, C. afra, C. lusitanica), and two perennial species (C. rotundifolia andC. persicifolia) were investigated. In the annual species pollen germinability is controlled by (1) the age of pollen and/or (2) in what position pollen is deposited around the style. Correlations were found between pollen germinability and mating system in three of the four annual species. No correlations were found either between germinability and age of pollen or position on the style in the perennial species. Pollen germinability reached its maximum in the middle of the male phase in all species, except forC. dichotoma, which had a decreasing germinability throughout anthesis. The germinability was lowest at the time of stigma receptivity for all species except forC. persicifolia, where the stigma did not develop as long as pollen remained on the style. The pollen collecting hairs and pollen removal have been found to play an important role controlling the stigma development, thus affecting self-pollination. This was especially pronounced inC. persicifolia. Further studies will be undertaken to elucidate factors influencing pollination within the genusCampanula.     

Transient gene expression in strawberry (Fragaria x ananassa Duch.) protoplasts and the recovery of transgenic plants

Summary A transient ß-glucuronidase (GUS)-assay was performed to evaluate electroporation parameters and optimize DNA delivery conditions into strawberry protoplasts. Optimal GUS-activity was obtained when protoplasts were subjected to 400 V/cm for 20 ms. GUS-activity could be further increased by the addition of carrier DNA to the electroporation mixture. Callus selected on 10 g/ml hygromycin produced shoots which exhibited GUS-activity. The transformed nature of the shoots obtained after selection was confirmed by DNA-analysis.Abbreviations CaMV cauliflower mosaic virus - dCTP deoxycytidine-triphosphate - EtBr ethidium bromide - GUS ß-glucuronidase - MES 2(N-morpholino) -ethanesulfonic acid - X-gluc 5-bromo-4-chloro-3-indolyl glucuronide     

Photocatalytic Degradation of Bacteriophages Evidenced by Atomic Force Microscopy

Methods to supply fresh water are becoming increasingly critical as the world population continues to grow. Small-diameter hazardous microbes such as viruses (20–100 nm diameter) can be filtered by size exclusion, but in this approach the filters are fouled. Thus, in our research, we are investigating an approach in which filters will be reusable. When exposed to ultraviolet (UV) illumination, titanate materials photocatalytically evolve ^•OH and O2^•− radicals, which attack biological materials. In the proposed approach, titanate nanosheets are deposited on a substrate. Viruses adsorb on these nanosheets and degrade when exposed to UV light. Using atomic force microscopy (AFM), we image adsorbed viruses and demonstrate that they are removed by UV illumination in the presence of the nanosheets, but not in their absence.     

The distribution and diversity of Chironomidae (Insecta: Diptera) in western Finnish Lapland, with special emphasis on shallow lakes

Aim Predictions of aquatic ecosystem change with global warming require basic data that accurately reflect the environmental conditions underlying species distributions. However, in remote arctic areas such baseline data are scarce. We assess the influence of environmental variables on chironomid distribution and taxon richness in shallow, isothermal lakes in a poorly studied arctic region. We pay particular attention to community variation along the treeline ecotonal zone where many environmental variables change abruptly in a relatively small area. Location Lake transect in Finnish Lapland spanning from boreal coniferous forest to arctic tundra. Methods Chironomid assemblages were determined from surface‐sediment samples of 50 shallow (< 10 m) natural lakes. Abundance and taxon richness data were related to 24 limnological variables using canonical ordination techniques (DCA, CCA, RDA). A Monte Carlo permutation procedure was used to assess the explanatory power of single variables. Between‐vegetation zone differences of richness were tested for statistical significance using one‐way anova . Results In total, 7771 chironomid head capsules were identified, consisting of 13 species, 10 species groups, four subgenera, 41 genera, four genus groups, five types and three with uncertain taxonomic affiliation. A hump‐shaped relationship between taxon richness and elevation was noted along the study transect with a peak in taxon richness occurring in mountain birch woodland lakes at middle elevations, decreasing then towards both warmer and colder ends of the elevation/temperature gradient. Of the individual parameters, sediment organic content, total organic carbon, pH, and lake‐specific air temperature accounted for the greatest amount of variation in the chironomid data. Main conclusions Maximum taxon richness occurred at mid‐elevations where aquatic algae also reached their maximum diversity. This area coincides with an ecotonal transitional zone, which seems more likely to account for the peak in species richness. Our study demonstrates that the factors most strongly affecting chironomids in Finnish Lapland (i.e. temperature, and ecosystem features) are those that with great probability will also change as a result of future climate change. This will likely have an effect on the distribution of chironomids in subarctic and arctic areas.     

Costly courtship or dishonest display? Intensely displaying sand goby males have lower lipid content

Intensely displaying sand goby Pomatoschistus minutus males had lower lipid content, indicating that signalling increased energy expenditure, or that low condition males increased their signalling effort. Display intensity correlated positively with nest‐defence and tended to correlate positively with filial cannibalism.     

Indirect effects of human-induced environmental change on offspring production mediated by behavioural responses

Human-induced rapid environmental changes often cause behavioural alterations in animals. The consequences that these alterations in turn have for the viability of populations are, however, poorly known. We used a population of threespine sticklebacks Gasterosteus aculeatus in the Baltic Sea to investigate the consequences of behavioural responses to human-induced eutrophication for offspring production. The investigated population has been growing during the last decades, and one cause could be increased offspring production. We combined field-based surveys with laboratory-based experiments, and found that an enhanced growth of macroalgae relaxed agonistic interactions among males. This allowed more males to nest, improved hatching success, and increased the number of reproductive cycles that males completed. Thus, the behavioural responses were adaptive at the individual level and increased offspring production. However, a larger proportion of small males of low competitive ability reproduced in dense vegetation. As male size and dominance are heritable, this could influence the genetic composition of the offspring. Together with a higher number of offspring produced, this could influence natural selection and the rate of adaptation to the changing environment. Thus, behavioural responses to a rapid human-induced environmental change can influence offspring production, with potential consequences for population dynamics and evolutionary processes.