Genet. Sel. Evol. 35 (2003) 425-444
DOI: 10.1051/gse:2003032

Familial versus mass selection in small populations

Konstantinos Theodorou^{a, b} and Denis Couvet<sup>a

a</sup>  Muséum national d'histoire naturelle, Centre de recherches sur la biologie des populations d'oiseaux, 55 rue Buffon, 75005 Paris, France
^b  Current address: University of the Aegean, Department of Environmental Studies, University Hill, 81100 Mytilene, Greece

(Received 25 March 2002; accepted 18 December 2002)

Abstract
We used diffusion approximations and a Markov-chain approach to investigate the consequences of familial selection on the viability of small populations both in the short and in the long term. The outcome of familial selection was compared to the case of a random mating population under mass selection. In small populations, the higher effective size, associated with familial selection, resulted in higher fitness for slightly deleterious and/or highly recessive alleles. Conversely, because familial selection leads to a lower rate of directional selection, a lower fitness was observed for more detrimental genes that are not highly recessive, and with high population sizes. However, in the long term, genetic load was almost identical for both mass and familial selection for populations of up to 200 individuals. In terms of mean time to extinction, familial selection did not have any negative effect at least for small populations ( ). Overall, familial selection could be proposed for use in management programs of small populations since it increases genetic variability and short-term viability without impairing the overall persistence times.

Key words: familial selection / deleterious mutation / genetic load / extinction / genetic variation

Correspondence and reprints: D. Couvet
    e-mail: couvet@mnhn.fr

© INRA, EDP Sciences 2003