In a questionnaire study we surveyed the owners of 113 companion dogs. Owners had to mark on a four-grade scale how long their dog remembered particular memory items (persons, other animals, events, objects). Additionally we collected descriptive data on the demographical characteristics of the dog and the keeping conditions. A principal component analysis on the memory items resulted in five components. From these, two were connected to people ('Family' and 'Intruders'), three other components contained individual items of memory of objects and events ('Going out' , Playing' and 'Doing something'). Analyses of variance revealed that the dog-owner relationship, the keeping conditions, age and breed of the dog affect the dogs' memory as described by the owner. The amount of time spent together or the education of the owner had no or minimal effect on these components. Our study showed that owners form stable opinions about their dogs' episodic memory capacity. Nevertheless, the results can be biased by such factors that affect either the owners' opinions about their dog-companions, or the dogs' access to particular stimuli, which can modify the formation of memory traces. In the future, these results can serve as a starting point for empirical testing of family dogs' memory.

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Clonal plants grow horizontally by producing multiple physiological individuals (ramets). We studied clonal growth in a homogeneous environment using a dynamic spatial model based on a stochastic cellular automaton. We investigated different growth forms from the aspect of ramet mortality. Non-steady-state and quasi-steady-state cases were defined, and we determined the number of steps suitable for making a reliable difference between these two types of cases. This given number of steps was used when testing for the proportion of quasi-steady-state cases in 1000 repetitions. We also tested the efficiency of occupation in these cases. Our expectation was that higher occupation would be associated with lower ramet mortality. The results only partially verified this hypothesis. Though with increasing ramet mortality, the average number of ramets tended to decrease, it was not the lowest ramet mortality that resulted in the highest occupation. Our results showed that very low ramet mortality was unfavourable for the plant, as the spreading front and the area behind this front were so packed that the plant was not able to return and recolonize the vacated sites in the central area. This resulted in a lower proportion of quasi-steady-state cases and lower occupation in these cases. Our results may contribute to a deeper understanding of clonal plant growth and its limiting factors.

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