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MED-CORE Résumé de rapport

Project ID: ICA3-CT-2002-10003
Financé au titre de: FP5-INCO 2
Pays: Italy

Descriptors of behavioural variation affected by coastal state

Animal behavioural adaptations to environment are diversified according to variation in ecological features. We estimated behavioural adaptations in small, common animals (crustacean amphipods) living on beaches and at the edges of humid coastal environments (lagoons, river mouths, canals, entrance of a cave, etc.). We choose measurable descriptors, easy to record and to control, such as orientation on dry or wet substrates and activity rhythms under laboratory control conditions. Orientation would help the animals to rapidly find the optimal conditions when displaced, e.g. the shoreline when displaced on the dry upper beach.

As a result of circadian rhythmicity the animals are active at night avoiding harsh conditions of dryness and high temperatures. The rationale behind this study is that 1) each population is adapted to the environment where it lives; 2) behavioural adaptations are more precise in harsh habitats where they have a higher survival value than in habitats where animals can easily find what they need (e.g. a animals living on a beach are subject to higher selective pressure with respect to similar animals from a constantly humid zone), and 3) new colonising populations or populations living in rapidly changing environments would show less precise adaptations (behavioural flexibility) with respect to animals from more stable environments. To test these hypotheses we tested orientation and activity rhythms in different populations from different habitats at the study sites of the project.

Orientation and activity are measurable behaviours and the tests are easy to perform and replicate. Orientation is expressed as a direction (angle to the north or with respect to an expected direction, such as the direction of the sea on a beach). Distributions of angles can be analysed using the statistics of circular distributions. Current software packages of statistics do not contain the statistics of circular distributions, and we prepared ad hoc software running in S-Plus environment, available at request (result 38224). Time series of the locomotor activity permit to estimate the period (circadian, e.g. around 24 hours, or circatidal, around 12 hours), the signal to noise ratio and the phase. We used ad hoc software also in this case, prepared by D. Green, School of Bioscience, University of Birmingham. For each population we calculated mean values and the variation of the behaviour within the sample; we compared samples from different seasons, from different populations and different species.

We performed a regression analysis of orientation with the environmental and intrinsic (depending on the animals) conditions (see the result: 38224 for details). The background information for each study site gathered from other work packages helped the interpretation of the behavioural tests, and, conversely, we learned from the behavioural adaptations of the animals how suitable these sites were to them and estimated the impacts. In principle, the behaviour expressed by an animal integrates past experience on the environment where it lives, and an estimate of behaviour would be more informative than snapshots estimates of environmental variables. We used always the same techniques and protocols to build a data base, which would be useful for comparative studies of coastal areas in the Mediterranean coasts and the European Atlantic and Baltic ones, where the same species live. The survey has been extended to other related species south-American coasts, in Chile and Uruguay. This geographic extension will permit an evolutionary approach. Data bases of behavioural variation of beach arthropods are being prepared for wide dissemination in the web.

The dissemination of the results has been made in scientific conferences by the authors of the experiments, in scientific journals with impact factor, in university texts on ethology and in the web and . The potential use of this knowledge is in basic biological research with high euristic potential, as biodiversity is here analysed at different levels, individual, intra-population, inter-population, geographic).

Moreover the question of genetic versus environmental adaptation is still an open question in ethology and evolutionary science. Students of all ages (from elementary to adult education) are generally interested in behavioural studies, and this represents a very good example of connecting behaviour with the environment. From ethical point of view, such behavioural experiments do not disturb the small common animals observed. The attention of the students and public will be focused on the importance of the conservation of habitat diversity. Behavioural studies start from the point of view of the animals, integrated in their habitats.

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Reported by

Department of Evolutionary Biology - University of Florence
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