Polygene control and trait dominance in death-feigning syndrome in the red flour beetle Tribolium castaneum.

Death-feigning behavior is an anti-predatory technique used in several animal taxa and often correlates with inhibited movements (i.e., death-feigning syndrome). We performed a reciprocal crossing among strains exhibiting a genetically longer (L-strain) and shorter (S-strain) duration of death feigning. Then, we investigated related heritable factors in F1 and F2 populations. We also evaluated movement activities, which negatively responded to artificial selection for death feigning in T. castaneum. Our results indicated that death feigning occurred more frequently and for shorter periods in the F1 population. However, in the F2 population, death feigning and movement exhibited continuous segregation. Although the distribution of each trait value in the F2 generation differed from that of the parental generation, no individuals transgressing the distribution of trait values in the parental generation emerged from the F2 generation. Besides, chi-square analysis of the observed death feigning and movement of F1 and F2 progenies rejected the hypothesis of mono-major gene inheritance. These results suggested that the death-feigning syndrome was polygenically controlled, indicating the usefulness of reciprocal crossing experiments in assessing the quantitative inheritance of behavioral traits.