Evolution of genetic variability in a population of the edible snail, Helix aspersa Müller, undergoing domestication and short-term selection.
The evolution of genetic variability is studied in six successive generations of a population originating from wild Helix aspersa. During the first three generations (G1 to G3), no artificial selection was applied. During the next three generations (G4 to G6), two lines were reared: a control line (C) and a line (S) selected for increased adult weight. Genetic variability is described by genealogical parameters (inbreeding, number of founders, effective number of founders and ancestors, effective number of remaining genomes) and by the additive genetic variance in adult weight. A large decrease in all parameters was observed between G1 and G2, suggesting strong natural selection: additive genetic variance in adult weight (transformed data) decreased from 0.0119 +/- 3.8 x 10(-3) to 0.0070 +/- 1.7 x 10(-3) (P < 0.05) and effective number of ancestors from 97.4 to 67.0. Selection also caused a large decrease during the first generation: additive genetic variance was 0.0079 +/- 2.1 x 10(-3) in G3 and 0.0040 +/- 1.1 x 10(-3) after the first selection cycle (P < 0.02). At the same time, the effective number of ancestors decreased from 59.2 to 29.5 and 24.2. This decrease is consistent with the theory of selection and the Bulmer effect.
Dupont-Nivet
M
M
Institut National de la Recherche Agronomique, Laboratoire de Génétique des Poissons, 78352 Jouy en Josas Cedex, France. dnivet@jouy.inra.fr
Mallard
J
J
Bonnet
J C
JC
Blanc
J M
JM
D000818:Animals; D000829:Animals, Domestic / Q000235:genetics; D001947:Breeding; D019020:Directed Molecular Evolution; D019143:Evolution, Molecular; D005260:Female; D014644:Genetic Variation; D006372:Helix, Snails / Q000235:genetics*; D008297:Male; D010375:Pedigree