Food wasting by house mice: variation among individuals, families, and genetic lines.

Under ad libitum conditions, laboratory house mice (Mus domesticus) fragment considerable amounts of pelleted food and leave it scattered in their cages. The proportion of food thus wasted (in relation to food eaten) varies remarkably among individuals, from 2% to 40%, but is highly consistent in consecutive trials, even when the mice were moved from 22 to -10 degrees C and food consumption doubled. Food wasting did not differ either between the sexes or between genetic lines that had been selected (10 generations) for high voluntary wheel-running behavior (n=4) and their unselected control lines (n=4). However, it varied significantly among replicate lines within the selection groups and among families within the lines (coefficient of intraclass correlation for full sibs, rhof=0.41 in room temperature trials and rhof=0.34 in cold trials). Moreover, the percent of food wasted was negatively correlated with food consumption in the cold trials (males: r=-.36, females: r=-.20) and with total litter mass at weaning (the litters into which they were born; r=-.24), two traits that may affect Darwinian fitness. We conclude that food wastage should not be ignored without justification in calculations of food consumption. In addition, "table manners" can convey reliable information about family origin of an individual and its quality, and therefore could potentially play a role in establishment of social status.