Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
Abstracts, 3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p., 62 (Russian), 166 (English).


A STUDY OF THE PROXIMAL FACTORS AFFECTING NATAL DISPERSAL IN THE ALPINE MARMOT (MARMOTA MARMOTA)


S. Magnolon, D. Allainé, J. Coulon

Laboratoire de Biologie des Populations d'Altitude - CNRS UMR 5553, Villeurbanne Cédex, France


Four factors can be involved in the dispersal strategy of the Alpine marmot:
(1) Social behaviours : Social interactions between individuals belonging to the same familial group were recorded, in many groups, in order to assess potential differences among animals, according to their age, their sex, their social status or even their kinship. Since 1995, over 10000 interactions have been recorded. Could such differences explain the natal dispersal of some individuals?
(2) The weight growth during the active season: are future dispersers those who are the bigger at the end of the hibernation, or on the opposite, those who had the greatest loss of weight during the hibernation?
(3) The sex hormone levels, especially the testosterone levels : during the breeding season, blood samples were systematically taken on trapped animals of two or more years of age. About 75 samples were analysed. If the hormone levels were significantly different between dispersing and philopatric marmots, could this physiological parameter explain the dispersal strategy?
(4) The spatial distribution of marmots in their territory : through scans regularly performed on many individuals, we could check wether there is or not spatial isolation of the future dispersers.

Dispersion is a phenomenon known in a wide range of animal and vegetal species; this could be a key in the understanding of dynamics of the demographic and evolutionary aspects in populations, and could act as a link between ecology, genetics, ethology and evolution.

In the Alpine marmot, understanding the causes and impacts of dispersion should lead to a better management of such a wild species, in nature reserves as well as in reintroduction sites, or even in these places where it is considered as noxious.


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