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In animals, as in humans, each individual has its own personality. The personality of small mammals – i.e. the boldness, curiosity and aggressiveness of an individual – influences all stages of seed dispersal. This has been shown by numerous studies conducted by Alessio Mortelliti, Associate Professor of Ecology at the Department of Life Sciences at the University of Trieste and former Associate Professor in Wildlife Habitat Conservation at the University of Maine.

The relationship between rodents and plants is ambivalent. In some circumstances mice are antagonistic as they prey on acorns, in other circumstances both mice and trees benefit and then the relationship is termed mutualistic. Past studies have shown that certain individuals, the more daring or curious ones, are more likely to disperse seeds, meaning that these individuals are particularly important for the functioning of an ecosystem. Understanding which characteristics are crucial to ecosystems and how to conserve them is of primary importance for the adaptation of species to global changes. 

The aim of the research project is to study this relationship between the individual personality of small mammals and seed dispersal. The project is entitled ‘Predicting the range-shifts of woody plant species by incorporating the critical role of small mammal scatter-hoarders’ and is financed by a PRIN (Research Projects of National Interest) – NRRP. Research is currently underway in the Alba Valley, but will be conducted for the first time in Europe by the research group from the University of Trieste, under the leadership of Professor Alessio Mortelliti and in collaboration with the Sapienza University of Rome and the Julian Pre-Alps Park.

The hypothesis is grounded on numerous studies that Professor Alessio Mortelliti's research group has conducted over the past decade in Maine (USA). In particular, the researchers have discovered that courageous individuals are those who travel greater distances with their seeds and hide them in optimal sites for germination. Within a species and an ecosystem, therefore, some individuals are particularly important for seed dispersal and, consequently, also for a plant's adaptation to climate change. It is these individuals, in fact, that will allow plants such as oaks and beeches to adapt to climate change by migrating in latitude and altitude.

The researchers will conduct two field experiments, also helped by scholars from the University of Maine, who are visiting Italy in early June. In the first phase they will measure the personality of rodents and expose them to new seeds. The chosen seeds belong to a woody species not yet present in the ecosystems under investigation, but which may arrive in the future precisely as a response to climate change. The hypothesis is that the boldest individuals will be the ones to interact the most with these new, unfamiliar seeds. By tracking the seeds with a fluorescent powder and measuring germination rates, the researchers will associate each individual rodent with the final arrival point of the seeds. In addition to assessing whether certain personality traits increase the likelihood of dispersal, the researchers will also identify seed traits (e.g. mass, shape) that increase the likelihood of seeds being preyed upon or dispersed. Finally, by conducting a series of simulations, they will evaluate the potential effects of personality on the composition of forest communities and the adaptability of species to global changes.

The project will also lead to the creation of a guide on how to exploit the role of rodents to improve assisted migration, (i.e. the human-assisted movement of plants to more climatically suitable habitats) and a checklist of traits and plant species with a high probability of successful expansion.

Alessio Mortelliti has cultivated 20 years' experience in studying the ecology and behaviour of mammals and how this knowledge can facilitate their conservation. In the past, he has carried out numerous field projects in Italy, Austria, the United States, Indonesia, Kenya, Tunisia and Mauritania.