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In all legal systems, possession and property are inextricably linked. Game theory captures this relationship in the Hawk-Dove game. When two contenders compete to appropriate an asset, one of the two most efficient outcomes is achieved when both play the bourgeois strategy: they coordinate in such a way that the incumbent possessor plays Hawk and the intruder plays Dove. In our Hawk-Dove experiment, we test the role of possession with respect to the emergence of such a bourgeois convention. Our treatment variation concerns the way the initial claim to the asset is established. We manipulate the type of information provided and the process of acquisition. We show that i) the highest level of bourgeois coordination emerges whenever the information is based on possession but also when the process is meritorious; ii) possession, both arbitrary and meritorious, induces only bourgeois coordination and never antibourgeois (this is the equally efficient opposite strategy of playing Hawk when the player is the intruder and playing Dove when he is the possessor); and iii) without merit or possession, coordination on a “bullying” equilibrium emerges, generating very inequitable outcomes. Possession thus triggers the establishment of property, and this prevents inequality from arising.

The river bullhead (Cottus gobio L.) is defined as a “Low Risk” species by the IUCN, but is very sensitive to changes and decreasing of environmental quality of living habitats, in particular due to riverbeds artificialisation. Moreover, the species is severely threatened by the predation on juveniles by trouts released into watercourses for fishing. The aim of this research is to analyse river bullhead populations describing their distributions and abundances and looking for biotic and abiotic factors that may influence them. The study area is extended along the eastern sector of the Emilia-Romagna region and includes from east to west the following river basins and sub-basins: Savio, Fiumi Uniti, Lamone, Reno, Panaro and Secchia. The research was carried out collecting fish fauna from 77 sampling sites of 27 different watercourses distribuited at more than 300 meters height above the sea level. The obtained results, compared and integrated with the use of Regional Italian Journal of Freshwater Ichthyology, 2014 vol. 1 Atti XIII Congresso Nazionale Associazione Italiana Ittiologi Acque Dolci – Sansepolcro (Ar) 312 Ichthyological Cards, provide a synthetic vision on the real distribution of river bullhead in the Adriatic sector of the eastern Tosco-Emiliano-Romagnolo Appennines and add information about their populations structure and abundance.

La biodiversità delle ittiocenosi d’acqua dolce dipende da una complessa interazione fra fattori ambientali, storici ed antropici. Una comunità ittica, infatti, a parità di condizioni zoogeografiche, deve la sua struttura principalmente all’effetto congiunto delle caratteristiche climatiche ed idrogeologiche del bacino di residenza con le particolari condizioni morfologiche locali. A queste si sommano il livello di antropizzazione del corso idrico, la tipologia e l’intensità delle attività umane nel bacino di impluvio sovrastante, le strategie di conservazione attuate dalle amministrazioni e l’impatto dell’attività alieutica. L’interazione fra questi fattori può dar luogo a risposte biologiche complesse difficilmente spiegabili da relazioni lineari. Alcuni fattori, inoltre, possono avere un effetto mediato da altre variabili ed essere pertanto ridondanti nello spiegare la diversità della fauna ittica. I dati provenienti da circa 500 rilevamenti della fauna ittica delle acque correnti delle province di Bologna, Ravenna e Forlì-Cesena sono stati pertanto associati alle caratteristiche geomorfologiche ed antropiche dei siti di campionamento allo scopo di individuare quali variabili abiotiche sono determinanti e sufficienti nello spiegare variazioni nei fattori biologici. Il risultato ottenuto è stato utilizzato per creare un modello a rete bayesiana diagnostico-predittivo della biodiversità ittica.

The following sections are included: INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

The following sections are included: INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES