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Investigating the endangered badger Meles meles population in Belarus we aimed to find out in accordance with which model, i.e. bottom-up or top-down, it is structured and functions. Two important factors (low earthworm biomass and high predation risk) were considered with a view to explaining the specificity in badger spatial structure and diet. The study was conducted in a semi-natural terrain in north-eastern Belarus. We analysed 1188 scats, radiotracked seven badgers and assessed variations in earthworm biomass. In the conditions of low biomass and uneven distribution of earthworms badgers were found to act as generalist predators tending to specialize on the more readily available foods during short seasonal periods. The earthworm portion in the species diet was relatively low and correlated with earthworm biomass and we did not find any evidence of badger feeding selectivity. Data on badger distribution and activity suggest that avoidance of high predation risk forces badgers towards the security of utilising primarily straight-line routes between setts. Such tactics limit availability of earthworms and other food resources and so determine low density in badgers.
Carnivore teeth, especially the carnassials, are subjects to selection in the presence of dietary competition. We compared several craniodental characters in the Finnish foxes before and after arrival of an invasive species, the raccoon dog. The female foxes displayed increased adaptation to carnivory, whereas we found no significant change in the male foxes after the arrival of the raccoon dog. We suggest that the presence of a new competitor may be driving the Finnish female foxes towards more carnivorous diet.
Warning signals of aposematic organisms often include patterns that contrast with background coloration, though controversy exists over their importance. Many dendrobatids have contrasting colors, but no work has established whether these are anti-predator components of the warning signal. We used 840 clay frog models to test whether a black spotted pattern on the red dorsum of the poison frog Oophaga pumilio (= Dendrobates pumilio) from Costa Rica enhances the aposematic signal. Model type, patterned or not patterned, did not predict predation. However, we did find evidence that background (i.e., contrast between an aposematic organism and its environment) influenced a predator's attack decision because models on white paper (higher contrast) were attacked significantly less than models on leaf litter (lower contrast). Our results indicate that the pattern of Costa Rican O. pumilio does not influence predation. Our results also support the hypothesis that novel backgrounds evoke a neophobic reaction and can affect predation rates.
A case of natural hybridization between pikeperch (Sander lucioperca) and perch (Perca fluviatilis) was confirmed based on the intermediate morphological, anatomical and genetic characteristics of the hybrid. Micro satellite analyses ruled out the possibility that the focal individual was of either pure species, and indicated it was a S. lucioperca backcross.
This study aims to investigate if patterns of immigration by voles into removal plots on the third day of trapping are evident in the grey-sided vole, and if altering the number of traps at each station will result in increased precision of the vole abundance estimate. Traps were placed using the small quadrat method, with one, three, or five traps placed at each corner. Traps were checked twice a day for five days. Mixed-effect models were used to investigate the relationship between the number of traps and the length of time the traps were out on the abundance index. There was no difference between having three or five traps. Having one trap resulted in an inflated estimate. Five traps had the highest number of successful trapping events, reducing the number of zeros in the data set and leaving fewer individuals unaccounted. There was a peak in catches on the third day, driven by younger individuals and by males. These are suspected immigrants that are exploiting the territories left by individuals trapped in the first two days, suggesting this is not a closed system.
Western Palearctic water frogs offer a unique possibility to study the genome dosage effect (GDE). There are two morphologically distinct species, Pelophylax ridibundus RR and Pelophylax lessonae LL, and their hybridogenetic hybrid Pelophylax esculentus (RL, LLR or RRL). It is supposed that RL have intermediate morphological features, LLR are more similar to P. lessonae, and RRL more similar to P. ridibundus. We tested if the morphology of the water frogs reflects the GDE, and whether it can be used in the field for determination of the genome composition. Mean values of the indices DP/CI, T/CI and F/T followed the order LL-LLR-RL-RRL-RR. After applying discriminant and canonical analyses 89% RR, 95% LL, 91% RL, 84% LLR and 52% RRL were correctly classified. Surprisingly, the L haplotype had bigger influence on morphology than the R haplotype — all hybrid genotypes were morphologically closer to P. lessonae than to P. ridibundus.