The latitudinal diversity gradient predicts higher species richness at lower latitudes. Here, we utilize the data from a long-term monitoring with malaise traps to analyse if spider communities in Sweden are affected by geographic gradients and if these effects hold independent of forest type. The species richness and the effective number of species in spider communities were not significantly related to the latitudinal gradient. The effective number of species and the taxonomic distinctness of spider communities were related to longitude, with a higher number, but fewer related species in western parts of Sweden. The species and family composition were significantly related to latitude independent of forest type, with a dominance of Linyphiidae individuals and species in the north. Our study demonstrates the suitability of malaise trap sampling to contribute to a better understanding of local spider communities, as several rare and locally new species were recorded in this study.

Time allocation during breeding was studied in unmated male common frogs Rana temporaria Linnaeus in three populations along a gradient of altitude, climate and length of feeding season. The length of the breeding period decreased with increased altitude. All three populations had low activity levels (0-33% of the time during peak chorusing). Peak chorusing in the lowland population was due to more males participating in the chorus, and not to increased individual calling activity. An increase in mating effort at this time was nevertheless indicated by the males 'using more time for moving in the pond. At both montane localities, males called more sparsely, and not at all at night. During peak chorusing, calling and moving males became significantly rarer with increased altitude. Aggressive males were significantly rarer in the alpine population. Between-locality variation was evident in fat reserves after hibernation and during breeding; the relative fat body mass was significantly higher in lowland males than in mid-altitude and alpine males. We discuss male mating activity (here: calling, mate searching and aggression) in ultimate terms as a trade-off between mate acquisition and survival.

Teal (Anas crecca) broods were studied in 1988-2003 in a boreal watershed comprising 51 permanent wetlands. Brood size of near-fledged ducklings was negatively related to the hatching date, i.e. early pairs had higher reproductive success than late pairs. However, brood size of newly hatched ducklings was not related to the hatching date, implying that the advantage of early breeding is due to processes operating during the brood stage rather than during nesting. Half of the lakes never produced a brood, and among the 26 lakes that actually did, two `preferred' lakes generated 44% of the broods and 55% of the near-fledged ducklings. Early broods were over-represented on such `preferred' lakes, and late broods over-represented on `less preferred' lakes. Our study suggests that lake selection and early nesting may have important fitness consequences in teal.

We review the current and future threats to duck populations that breed, stage, moult and/or winter in the Nordic countries. Migratory duck species are sensitive indicators of their changing environment, and their societal value confirms the need to translate signals from changes in their distribution, status and abundance into a better understanding of changes occurring in their wetland environments. We used expert opinion to highlight 25 major areas of anthropogenic change (and touch briefly on potential mitigation measures through nature restoration and reserve management projects) that we consider key issues likely to influence Nordic duck populations now and in the near future to stimulate debate, discussion and further research. We believe such reviews are essential in contributing to development of successful management policy as well as stimulating specific research to support the maintenance of duck species in favourable future conservation status in the face of multiple population pressures and drivers.

Long-term mallard capture-recapture data from Sweden and Finland were analyzed to describe temporal mortality patterns and reasons. We used program MARK and Seber models to estimate annual survival (S) and recovery (r) rates. Survival rates were used in a Monte Carlo simulation to evaluate the correspondence between observed and predicted annual population sizes of a Finnish sub-population. About 90% of recovered birds died from hunting. Most recoveries were from the hunting season, and more males than females were shot. Predation was the most common cause of natural mortality. Finnish capture-recapture data fitted best the global model in which survival and recovery vary with age and sex. Annual survival and recovery rates for adult and juvenile males and females were overlapping, ranging from 0.46 to 0.90 (survival) and 0.07 to 0.17 (recovery), whereas pulli had lower survival rates (0.21-0.42). Pulli that were successfully sexed at the time of ringing had higher recovery rates (female pulli: 0.23; male pulli: 0.32) than juveniles and adults. Density-dependent fledgling production was detected in the Finnish sub-population and was accounted for in the Monte Carlo simulation, which estimated predicted breeding population size quite well, although one of the observed annual values (2003) fell outside the 95% confidence limits.

Cryptobiosis is an ametabolic state of life entered by some lower organisms (among metazoans mainly rotifers, tardigrades and nematodes) in response to adverse environmental conditions. Despite a long recognition of cryptobiotic organisms, the evolutionary origin and life history consequences of this biological phenomenon have remained unexplored. We present one of the first theoretical models on the evolution of cryptobiosis, using a hypothetical population of marine tardigrades that migrates between open sea and the tidal zone as the model framework. Our model analyses the conditions under which investments into anhydrobiotic (cryptobiosis induced by desiccation) functions will evolve, and which factors affect the optimal level Of Such investments. In particular, we evaluate how the probability of being exposed to adverse conditions (getting stranded) and the consequences for survival Of Such exposure (getting desiccated) affects the option for cryptobiosis to evolve. The optimal level of investment into anhydrobiotic traits increases with increasing probability of being stranded as well as with increasing negative survival effects of being stranded. However, our analysis shows that the effect on survival of being stranded is a more important parameter than the probability of stranding for the evolution of anhydrobiosis. The existing, although limited, evidence from empirical studies seems to support some of these predictions.

We studied patterns of prey size and abundance among 60 lakes that differed with respect to occupancy by mallards (Anas platyrhynchos) and teal (A. crecca crecca). Size distributions of prey in lakes with and without mallards did not differ in the way they deviated from the prey size distribution found in the average diet of the species; the same was true also for teal. However, in lakes with abundant food, average teal diet differed more from what was found in the environment than in lakes with less prey; in the mallard there were no differences in this respect. The densities of mallard and teal correlated positively rather than negatively with each other irrespective of food abundance, suggesting that interspecific competition, at least in ecological time, between the species may not be important in determing their abundance and distribution.

Using data from two independent field experiments, we address whether pair formation in introduced mallards Anas platyrhynchos is associated with habitat quality, specifically food limitation at the brood stage. Based on the concentration of total phosphorous in the water, the study lakes were divided into two groups, 'poor' and 'rich'. In one of the experiments we used mallard ducklings imprinted on humans to study mass change of ducklings in poor and rich lakes, respectively. It turned out that ducklings foraging on poor lakes gained less mass than ducklings foraging on rich lakes, the division of lakes thus reflecting habitat quality at the brood stage. Introduced mallards formed heterosexual pairs on lakes that were, in a relative sense, high-quality brood habitats, whereas they did not on lakes of low-quality brood habitat. Pair formation thus seemed to reflect the suitability of habitat for breeding.