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  • Final Report Summary - PERSONALIHI (Species Personality - Do Consistent Behavioural Differences between Species and Individuals relate to their Life History? – A Comparative Approach in Shrews)

Final Report Summary - PERSONALIHI (Species Personality - Do Consistent Behavioural Differences between Species and Individuals relate to their Life History? – A Comparative Approach in Shrews)

Species Personality - Do Consistent Behavioural Differences between Species and Individuals relate to their Life History?

Just like humans, some animals are generally more bold or aggressive than others. Such consistent behavioural differences are called animal personality. There are different factors that are known or thought to influence the personality behaviour of a species, among them the life-history strategy of the species. Our main objective was, to understand a bit better the influence of life-history strategy and other ecological factors on personality differences between species. Shrews are small mammals that exist in a large number of different species that differ a lot in their their pace of life: the two large subfamilies of shrews, Soricinae and Crocidurinae, differ tremendously in life history and metabolic rate. We thus chose shrews as our model taxon, using several species from both subfamilies, that all occur in Europe. With our project, we aimed to answer several exciting questions: If there are species with lower and species with higher behavioural variance; how this variance is partitioned between inter- and intra-individual variance; and what ecological and evolutionary factors might form the basis for such differences, among them the diverse life-history strategies of different species.
Our project had four main objectives: We wanted to assess the amount of behavioural variation between the individuals of different species, and if this amount differs between the species (Individual Gradient). To understand, if species differences in amount of behavioural variation might be related to differences in life-history strategy (i.e. the pace of life of a species), we aimed at analysing a large range of different species (Taxonomic Gradient). Additionally, we wanted to find out, if there is an influence of geographic region or season on the personality variation in such species that occur in regions of Europe differing in climate (Geographic Gradient). Finally, we wanted to assess how the behavioural variation between the individuals of different species relates to their ability in a spatial learning task (Cognition).
During the course of this project, we conducted nine field trips in three different countries across Europe: four in Poland, three to Germany and two to Portugal. In those field trips, we were trapping and testing 157 individuals from five different species of shrews. With these individuals we conducted four different experiments – tests on boldness, aggression, exploration, and spatial learning – that yield the data to analyse for the four objectives of our project. To put the geographic differences of the assessed populations into a genetic frame-work, we are currently conducting a population genetic analysis. Our work in the lab includes also the molecular determination of the sex of our studied individuals of shrews, as for some species is it often impossible to determine sex just by visual examination.
Testing many individuals of different species across geographic regions and different seasons, we not only conducted the, to our knowledge, first personality tests on shrews, but also collected an unusually large data set of personality across species boundaries. We found significant correlations between the repeated trials of behavioural parameters for different species of shrews, resulting in a high repeatability that differs between species. Within these differences, species of the same genus behave more similar to each other in terms of personality types than between the genera. That seems to not only hold true for the qualitative differences, i.e. absolute differences between the taxa in terms of personality, but also quantitative differences: Different species indeed seem to differ in their degree of between-individual variance, thus in their personality structure. Although the final mixed model analysis is not finished, these results are exciting, as this was one of the key hypotheses of this project.
Our large data set also offers the opportunity to compare between populations of the same species across climatic regions and seasons. Our preliminary analysis proposes that the season has a larger effect on within-species differences than does the geographic region.
While we found a quite clear differentiation in personality structure between shrews of different taxa, the analysis of the cognition experiment did not yield such strong differences. Species of both subfamilies of shrews, Soricinae and Crocidurinae, were similarly successful in learning a simple spatial orientation task. However, the Soricinae species was slightly faster to learn and was using shorter paths than the Crocidurinae. This is an interesting and biologically coherent result, as it is of great importance for shrews of the high-metabolic Soricinae to save energy by e.g. choosing more efficient paths during foraging.
In an additional objective, which was developed during the course of this project, we re-analysed an existing data set on social behaviour in four species of Soricinae shrews. We aimed to test the social niche specialisation hypothesis, which predicts that species engaging in more social interactions can develop and maintain more different personalities. While three of the tested shrew species are strictly solitary, the fourth is much more sociable. This data set thus offered a perfect model two answer our question. Indeed, we found that the sociable species exhibited a much more diverse personality structure than the other three, supporting the social niche specialisation hypothesis.
Our laborious study, testing the behaviour of many individuals of several species of this sometimes hard-to-trap group of wild small mammals across different countries of Europe, provided us with a large data set that allows complex analysis. Even though our analysis is still ongoing, our first results are very promising. The publications that will be the final outcome of this project, will most likely have the ability to further our understanding of the importance of individual animal personalities on an across-species level.
On another perspective, our project strengthened the bonds between different working groups from Poland, Germany and Portugal. This collaboration did thus not only help to gather the current large data set, but it already lead to new ideas and concrete plans for future projects.

Dr. Sophie von Merten

Scientist in charge:
Prof. Leszek Rychlik

Department for Systematic Zoology
Adam Mickewicz University
ul. Umultowska 89
61-614 Poznan, Poland

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